The accuracy of judgments of learning (JOLs) is vital for efficient self-regulated learning. We examined a situation in which participants overutilize their prior knowledge of a topic (“domain familiarity”) as a basis for JOLs, resulting in substantial overconfidence in topics they know the most about. College students rank ordered their knowledge across ten different domains and studied, judged, and then completed a test on facts from those domains. Recall and JOLs were linearly related to self-rated knowledge, as was overconfidence: participants were most overconfident for topics they knew more about, indicating the overutilization of domain familiarity as a cue for JOLs. We examined aspects of the task that might contribute to this pattern, including the order of the task phases and whether participants studied the facts blocked by topic. Although participants used domain familiarity as a cue for JOLs regardless of task design, we found that studying facts from multiple topics blocked by topic led them to overutilize this cue. In contrast, whether participants completed the rank ordering before studying the facts or received a warning about this tendency did not alter the pattern. The relative accuracy of participants’ JOLs, however, was not related to domain familiarity under any conditions. Learners are not blank slates, and they are not all equally able to learn new content cf. . One facAs The term metacognition refers to people’s knowledge, monitoring, and control of other mental states or cognitive processes cf. . For exaPeople make metacognitive judgments inferentially, using “cues” about the cognitive process under consideration to make their judgments cf. . To the In the present studies, we examined an error in a particular type of metacognitive judgment: judgments of learning (JOLs). These are prospective judgments about memory or learning that a person makes in between the encoding and testing of target information . For exaTwo common measures of JOL accuracy cf.  are direThe second, relative accuracy, refers to participants’ ability to discriminate learned from unlearned items with their JOLs. A common way to assess relative accuracy involves calculating a gamma correlation across items between a participants’ JOLs and recall outcomes . The valGiven that people’s learning of new information across domains is often positively related to how much information they already know from those domains, it makes sense for them to use domain knowledge as a cue for JOLs. People often—appropriately—give higher JOLs to new information they are learning from topics they know more about than topics they know less about cf. . Often, In contrast, As noted earlier, participants make JOLs inferentially, but we do not know exactly how they utilize their domain familiarity as a cue for these judgments. For example, both In contrast, the analytic processing theory proposed by Given the assumptions of analytic processing theory, in the present studies we sought to identify factors that might lead people to exhibit the overutilization pattern when studying facts across multiple topics. We hypothesized that some conditions of the task—such as whether participants studied facts blocked by topic or not—might make them more or less likely to demonstrate this pattern.Participants’ learning and JOLs are often positively related to their domain familiarity. Therefore, using domain familiarity as a cue for JOLs should be a useful and predictive cue for learners to consider when making JOLs across topics. That said, some researchers have also been interested in whether greater domain knowledge allows learners to demonstrate greater relative accuracy within topics e.g., . One majF = 0.917, MSE = 0.233, p = .515, pη2 = .092. Concordantly, there was no linear relationship between relative accuracy and domain familiarity .As we noted above, calculating a gamma correlation across items between a participants’ JOLs and recall outcomes is a common way to assess relative accuracy. Gamma, however, is sometimes incalculable if either measure shows low variance. Importantly, consider a situation like The main reason that a gamma correlation might not be calculable is that one (or both) of the variables being correlated show little or no variance. As an example, consider participants who correctly recall all items; even if their JOLs are quite varied, there is no variance for the recall measure, so a gamma correlation cannot be calculated. The participants could not have assigned higher JOLs to recalled items and lower JOLs to nonrecalled items, because they recalled all the items. In ps < .001), indicating that participants’ relative accuracy within topics was better than chance after adding in the missing values and that inputting values of zero did not artificially deflate these scores beyond consideration  = 1.014, MSE = 0.226, p = .428, pη2 = .020, the linear relationship was significant, , with relative accuracy higher for better-known topics than for lesser-known topics. As inputting 0 s for missing values allowed us to consider relative accuracy more fully under the current paradigm, we also used this strategy in the subsequent studies.To examine the relationship between relative accuracy and domain familiarity further, we input values of zero for any gamma correlation that could not be calculated. All means were still significantly greater than zero  on 7 February 2010. We have uploaded the materials and data for the present studies to Specifically, we examined the relationship between participants’ domain familiarity, their learning of facts from 10 different domains, and the accuracy of their JOLs for those facts. We based the basic paradigm on As we reviewed above, participants often factor their beliefs about cognition—correctly or not—into their JOLs . In the Before we could examine the (presumably nonconscious) effects of task experience on the overutilization pattern, we first wanted to consider if the pattern reflected participants’ application of beliefs about domain familiarity to their JOLs. To do so, in Study 1 we explained the overutilization pattern to half the participants and warned them not to utilize domain familiarity as a basis for their JOLs cf. . If partpη2 = .017.The participants were 100 undergraduate students from Texas Tech University. They participated online for course credit. When we conducted the present studies, we based our sample sizes on those of The materials were the same 100 facts and 100 test questions from Study 1 used a 2 (warning vs. no warning) × 10 (topic ranking: 1 (most known) to 10 (least known)) mixed design, with warning as a between-participants independent variable and topic ranking as a within-participants quasi-independent variable. The dependent variables were recall performance (percent correct), JOL magnitude, absolute accuracy , and relative accuracy .The procedure for the No-Warning Group was the same as the procedure for Experiment 1 in The procedure for the Warning Group was identical to the procedure for the No-Warning Group except that, just before these participants began the study and JOL phase of the task, they read the following warning: “Participants often make their judgments for each item based on their familiarity with the topic area that the fact comes from. Put differently, they tend to make their judgments for each specific piece of information based on how much they already know about the topic area in general rather than how well they have learned that specific piece of information. Try not to do this when you make your judgments for each item! Instead, for each piece of information, try to focus on how well you know that single piece of information regardless of what topic it is a part of. Try not to let your judgments be biased by your existing knowledge of that topic in general.”Note that for all analyses in all the studies, we used each participants’ rank ordering of the 10 topics from their personally best-known topic (1) to least-known topic (10) as a quasi-independent variable. We did not have any hypotheses about the specific topics, so we did not analyze any dependent variable based on the specific topics. Therefore, the same topic  could have been the best-known topic for one participant and the least-known topic for another participant.Most correct answers involved either a single word or a short phrase, so there was not much variance in the responses provided by participants. In this and all other studies, we therefore scored answers as correct or incorrect; we did not award any partial credit.F = 0.140, MSE = 2750.669, p = .709, pη2 = .001. Recall differed by topic ranking, F = 12.419, MSE = 260.697, p < .001, pη2 = .112, with a polynomial contrast indicating that recall performance was linearly related to topic ranking (p < .001). Warning and ranking did not interact, F = 1.180, MSE = 260.697, p = .305, pη2 = .012.For each participant, we calculated the percentage of questions they answered correctly for each topic ranking a. We anaF = 0.945, MSE = 2944.033, p = .333, pη2 = .010. JOLs differed by topic ranking, F = 33.049, MSE = 249.128, p < .001, pη2 = .252, with a polynomial contrast indicating that JOLs were linearly related to topic ranking (p < .001). Warning and ranking did not interact, F = 1.512, MSE = 249.128, p = .139, pη2 = .015.For each participant, we calculated the mean JOL for each topic ranking a. We anaF = 1.442, MSE = 3630.634, p = .233, pη2 = .015. Absolute accuracy differed by topic ranking, F = 4.680, MSE = 299.651, p < .001, pη2 = .046, with a polynomial contrast indicating that absolute accuracy was linearly related to topic ranking (p < .001). Warning and ranking did not interact, F = 0.920, MSE = 299.651, p = .507, pη2 = .009. That said, to provide analyses in line with those of Studies 2 and 3, we also examined the relationship between absolute accuracy and topic ranking within each group. In line with the omnibus analysis, absolute accuracy was linearly related to topic ranking for both the No-Warning Group  and the Warning Group .For each participant, we calculated the absolute accuracy  for each topic ranking b. We anaps < .001), indicating that participants’ relative accuracy within topics was better than chance, and that inputting values of zero did not artificially deflate these scores beyond consideration. We then analyzed relative accuracy using a 2 (warning vs. no warning) × 10 (topic ranking: 1 (most known) to 10 (least known)) mixed ANOVA. Relative accuracy did not differ by warning, F = 0.532, MSE = 0.634, p = .467, pη2 = .005, or by topic ranking, F = 0.906, MSE = 0.225, p = .519, pη2 = .009. Warning and ranking did not interact, F = 0.287, MSE = 0.225, p = .978, pη2 = .003.For each participant, we calculated the relative accuracy  for each topic ranking c. Gamma The basic results of Study 1 replicated those of The warning to avoid overutilizing domain familiarity as a cue for JOLs cf.  did not In Study 1 and in both of pη2 = .017.The participants were 100 undergraduate students from Texas Tech University. They participated online for course credit. None had participated in Study 1. As detecting a potential interaction for our absolute accuracy measure was of primary interest, power analysis in G*Power  indicateThe materials and procedure for the Ranking-First Group in Study 2 were the same as for the No-Warning Group in Study 1. For the Ranking-Last Group, the procedure was the same as for the Ranking-First Group, except that the participants completed rank ordering after studying, making JOLs, and testing of the facts.F = 0.035, MSE = 2551.188, p = .851, pη2 < .001. Recall differed by topic ranking, F = 17.264, MSE = 272.009, p < .001, pη2 = .150, with a polynomial contrast indicating that recall performance was linearly related to topic ranking (p < .001). Order and ranking did not interact, F = 1.653, MSE = 272.009, p = .096, pη2 = .017.We analyzed recall performance a using aF = 1.293, MSE = 3617.258, p = .258, pη2 = .013. JOLs differed by topic ranking, F = 38.121, MSE = 237.537, p < .001, pη2 = .280, with a polynomial contrast indicating that JOLs were linearly related to topic ranking (p < .001). Order and ranking did not interact, F = 1.578, MSE = 237.537, p = .117, pη2 = .016.We analyzed JOLs a using aF = 1.542, MSE = 3932.156, p = .217, pη2 = .015. Absolute accuracy differed by topic ranking, F = 2.485, MSE = 336.739, p = .008, pη2 = .025, with a polynomial contrast indicating that absolute accuracy was linearly related to topic ranking (p < .001). Order and ranking did not interact, F = 1.393, MSE = 336.739, p = .187, pη2 = .014.We analyzed absolute accuracy b using apη2 = .014 was just shy of our calculated effect size for a significant interaction of pη2 = .017. Additionally, p = .040). Indeed, absolute accuracy was linearly related to topic ranking for the Ranking-First Group , but not for the Ranking-Last Group . We have provided these analyses for completeness, but we will interpret this interaction as being “not significant” in the remainder of the paper per the standards of null-hypothesis significance testing (NHST).Although the interaction was not significant in the omnibus ANOVA, the obtained effect size of ps < .001), indicating that participants’ relative accuracy within topics was better than chance, and that inputting values of zero did not artificially deflate these scores beyond consideration. We then analyzed relative accuracy  = 1.198, MSE = 0.525, p = .276, pη2 = .012, or by topic ranking, F = 1.175, MSE = 0.224, p = .308, pη2 = .012. Order and ranking did not interact, F = 0.963, MSE = 0.224, p = .470, pη2 = .010.We input values of zero for any gamma correlation that could not be calculated due to low variance. All means were significantly greater than zero , participants studied the facts blocked by topic. Having participants study facts blocked by topic could have inflated the relationship between rankings and JOLs, leading to the overutilization pattern. To examine this possibility, in Study 3, we varied whether participants studied and judged the facts blocked by topic or in a completely random order with no blocking. If blocking produces the overutilization pattern, then this pattern should be reduced (or even eliminated) for participants who study the facts without blocking by topic.pη2 = .017.The participants were 100 undergraduate students from Texas Tech University. They participated online for course credit. None had participated in Studies 1 or 2. As detecting a potential interaction for our absolute accuracy measure was of primary interest, power analysis in G*Power  indicateThe materials and procedure for the Blocking Group in Study 3 were the same as for the No-Warning Group in Study 1 and the Ratings-First Group in Study 2. For the No-Blocking Group, the procedure was the same as for the Blocking Group except that the participants studied and judged the 100 facts in a random order with no blocking by topic and later tested over the 100 facts in a random order with no blocking by topic.F = 1.351, MSE = 2425.406, p = .248, pη2 = .014. Recall differed by topic ranking, F = 12.840, MSE = 282.572, p < .001, pη2 = .116, with a polynomial contrast indicating that recall performance was linearly related to topic ranking (p < .001). Blocking and ranking did not interact, F = 0.530, MSE = 282.572, p = .853, pη2 = .005.We analyzed recall performance a using aF = 0.019, MSE = 4158.770, p = .889, pη2 < .001. JOLs differed by topic ranking, F = 40.650, MSE = 187.063, p < .001, pη2 = .293, with a polynomial contrast indicating that JOLs were linearly related to topic ranking (p < .001). Blocking and ranking interacted significantly, F = 4.378, MSE = 187.063, p < .001, pη2 = .043. Additionally, the linear relationship between JOLs and topic ranking varied by group (p < .001). Specifically, JOLs were linearly related to topic ranking in both groups, but the effect size was slightly larger for the Blocking Group  than for the No-Blocking Group .We analyzed JOLs a using aF = 0.479, MSE = 4863.133, p = .491, pη2 = .005. Absolute accuracy differed by topic ranking, F = 3.236, MSE = 279.248, p < .001, pη2 = .032, with a polynomial contrast indicating that absolute accuracy was linearly related to topic ranking (p < .001). Blocking and ranking interacted significantly, F = 3.007, MSE = 279.248, p = .002, pη2 = .030. Additionally, the linear relationship between absolute accuracy and topic ranking also varied by group (p < .001). Specifically, absolute accuracy was linearly related to topic ranking for the Blocking Group , but not for the No-Blocking Group .We analyzed absolute accuracy b using aps < .001), indicating that participants’ relative accuracy within topics was better than chance, and that inputting values of zero did not artificially deflate these scores beyond consideration. We then analyzed relative accuracy  = 0.391, MSE = 0.571, p = .533, pη2 = .004, or by topic ranking, F = 0.468, MSE = 0.214, p = .896, pη2 = .005. Blocking and ranking did not interact, F = 0.691, MSE = 0.214, p = .717, pη2 = .007.We input values of zero for any gamma correlation that could not be calculated due to low variance. All means were significantly greater than zero . If studying facts blocked by topic is a major contributor to the overutilization pattern, then only studying facts from one topic should reduce or eliminate it as happened in Study 3 when participants studied all the facts intermixed.Study 4 also allowed for a better test of the relationship between relative accuracy and domain familiarity, as participants only studied facts from one topic, and they studied 20 facts instead of 10 as in the other studies. These conditions should increase the chance that a linear relationship between domain familiarity and relative accuracy could occur.pη2 = .010.The participants were 160 undergraduate students from Texas Tech University. They participated online for course credit. None had participated in Studies 1, 2, or 3. As detecting a potential interaction for our absolute accuracy measure was of primary interest, power analysis in G*Power  indicateStudy 4 was very similar to the prior studies, but also involved significant changes. We created another 100 facts (10 per topic), so each topic had 20 facts. As in the prior studies, participants first rank ordered the 10 topics from their best-known topic to their least-known topic. The survey software then randomly assigned each participant to study 20 facts from only one topic: either the topic they rated as their first best-known topic, fourth best-known topic, seventh best-known topic, or tenth best-known topic . They studied and made JOLs for those 20 facts in a random order, then tested on just those 20 facts in a new random order.F = 8.271, MSE = 506.707, p < .001, pη2 = .137, with a polynomial contrast indicating that recall was linearly related to topic ranking (p < .001).We analyzed recall performance a using aF = 10.993, MSE = 493.461, p < .001, pη2 = .175, with a polynomial contrast indicating that JOLs were linearly related to topic ranking (p < .001).We analyzed JOLs a using aF = 0.198, MSE = 572.690, p = .897, pη2 = .004.We analyzed absolute accuracy b using aps < .001), indicating that participants’ relative accuracy within topics was better than chance, and that inputting values of zero did not artificially deflate these scores beyond consideration. We then analyzed relative accuracy  = 0.365, MSE = 0.168, p = .779, pη2 = .007.We input values of zero for any gamma correlation that could not be calculated due to low variance. All means were significantly greater than zero  might have been the most likely to allow this relationship to be found (across groups).In the present studies, we further explored the relationship between domain familiarity and the accuracy of JOLs. We examined whether factors such as participants’ metacognitive beliefs (Study 1), performing the rank-order phase before the study and judgment phase (Study 2), and studying facts blocked by topic (Studies 3 and 4) contribute to the occurrence of the “overutilization of domain familiarity as a cue for JOLs” pattern. We also examined whether a linear relationship between participants’ domain familiarity and the relative accuracy of their JOLs would occur consistently .Our primary research question involved examining factor(s) that might contribute to the occurrence of the overutilization pattern. The results of the present studies closely replicated the findings from In Study 1, we instructed one group of participants—the Warning Group—to avoid overutilizing domain familiarity as a cue for their JOLs. Nevertheless, they showed the same patterns as the No Warning Group, including a linear relationship between their domain familiarity and absolute accuracy, which suggests that they overutilized this cue for JOLs despite the instructions to avoid doing so. This finding sheds some doubt on the possibility that participants directly apply explicit metacognitive beliefs about the relationship between domain familiarity and learning to make JOLs, although certainly this possibility could be explored using other methods to assess metacognitive beliefs.The negative result in Study 1 led us to focus on aspects of the procedure that might make the overutilization pattern more or less likely to occur. In Study 2, we varied whether participants rank ordered the topics to indicate their domain familiarity before study and judgment (Ranking-First Group) or after the test (Ranking-Last Group), but the occurrence of the overutilization pattern did not differ. In Study 3, we varied whether participants studied the facts organized into blocks by topic (Blocking Group) or in a random order (No-Blocking Group); the No-Blocking Group did not demonstrate the overutilization pattern. In Study 4, we only had participants study facts from one topic after they indicated their domain familiarity . Across the four groups, JOLs did not demonstrate the overutilization pattern.Together, the present results suggest that studying the facts blocked by topic contributes to the occurrence of the overutilization pattern. Of course, there might also be other factors that contribute to the occurrence of the pattern , but identifying those other factors and how they all work together to produce this pattern will require additional research. Future research could examine how blocking by topics leads to the overutilization pattern. One possibility is that studying the facts blocked by topic produces greater fluency than does studying the facts in a random order cf. , and thiAnother possibility, which we did not examine in the present studies, is that studying facts blocked by topic changes how participants convert their confidence in their learning to their JOL values cf. . For exaAdmittedly, the overutilization pattern might be a very rare occurrence, only occurring when participants are studying information across multiple domains and blocked by topic. But the findings above are still useful for understanding how domain familiarity relates to metacognitive monitoring in general. Based on the present results, aspects of the study design likely alter the experience that learners have while studying, leading them to make JOLs differently and producing the overutilization pattern (or not). The results are compatible with aspects of both analytic processing theory  and isomOur secondary research question involved considering whether a linear relationship between domain familiarity and relative accuracy would occur consistently using the present paradigm. Findings have been inconsistent as to whether having greater domain familiarity leads to better relative accuracy for learning within that domain e.g., . Whereasor negative. Study 4 might have been the fairest test of whether domain familiarity relates to relative accuracy, as participants only studied and judged facts from one topic and they had 20 facts to judge rather than 10 (per topic), which should have allowed for greater variance of relative-accuracy scores. Even in this case, however, the relationship did not occur.Participants’ overutilization of domain familiarity as a cue for JOLs might have curbed differences in relative accuracy across topics. In Studies 3 and 4, however, changes to the procedure eliminated the overutilization pattern  but did not lead to linear relationships between relative accuracy and domain familiarity—positive It is possible that domain familiarity relates to the relative accuracy of people’s metacognitive judgments as originally suggested by Our results suggest that the experience of studying facts blocked by topic contributes to the occurrence of the overutilization pattern in the present paradigm. That said, there are other potential explanations for the pattern that we should address.Dunning–Kruger Effect . In the present situation, however, such accounts struggle to explain why participants are often the most overconfident for the topic they know best; both regression to the mean and the hard–easy effect would predict a pattern in which participants are overconfident for the topics they know the least about and underconfident for the topics they know the most about. Critics might note that performance in our present studies was fairly low, with recall averaging around 25% across topic rankings and across studies, but with JOLs averaging around 50%. Such accounts could help to explain the persistent overconfidence , but they cannot explain why the greatest overconfidence occurs for the best-known topics; these accounts would predict less overconfidence for better-known topics (higher performance) and more overconfidence for lesser-known topics (lower performance). Furthermore, such accounts cannot explain why the manipulation in Study 3 eliminated the overutilization pattern without affecting the overall magnitude of participants’ recall or JOLs (versus the comparison group). If the overutilization pattern occurs because JOLs are spuriously “too high” or recall is spuriously “too low”, then reducing or eliminating the occurrence of the pattern should have required lowering JOLs or increasing recall cf. , neitherBy definition, and much like the Dunning–Kruger Effect, the overutilization of domain familiarity pattern is one of imperfect correlation cf. ; but whyThe present studies suggest that people might overutilize domain familiarity as a cue for JOLs when studying facts from multiple topics blocked by topic. The results help to explain this effect, but they are also informative for understanding how people make metacognitive judgments in general and what factors can augment or moderate the accuracy of those judgments. The results highlight an important aspect of metacognition that is best described by analytic processing theory : people The original research question  stemmed


Chirality is a fundamental property which plays a major role in chemistry, physics, biological systems and materials science. Chiroptical artificial molecular motors (AMMs) are a class of molecules which can convert light energy input into mechanical work, and they hold great potential in the transformation from simple molecules to dynamic systems and responsive materials. Taking distinct advantages of the intrinsic chirality in these structures and the unique opportunity to modulate the chirality on demand, chiral AMMs have been designed for the development of light-responsive dynamic processes including switchable asymmetric catalysis, chiral self-assembly, stereoselective recognition, transmission of chirality, control of spin selectivity and biosystems as well as integration of unidirectional motion with specific mechanical functions. This review focuses on the recently developed strategies for chirality-led applications by the class of intrinsically chiral AMMs. Finally, some limitations in current design and challenges associated with recent systems are discussed and perspectives towards promising candidates for responsive and smart molecular systems and future applications are presented. Chirality is a fundamental property which plays a major role in chemistry, physics, biological systems and materials science. The importance of dynamic chirality in designing smart materials and molecular systems.2. The design principles of chiral AMMs for targeting applications.3. Recent advances using chiral AMMs as multistate chiroptical photoswitches.4. Representative examples utilizing unidirectional rotary motion of chiral AMMs for various applications.5. Challenges and prospects for the future of chiral AMMs.1.1–7 Apart from the intrinsically chiral small molecules and chiral macromolecular architectures like DNA and proteins, chiral recognition and dynamic transfer of chirality across different length scales in living systems is vital for biological functions,6–9 ranging from enzyme catalysis to the helical tendril coiling behavior of cucumbers10 and the sensing of dynamic polarization vision by mantis shrimps.11 Intrigued by the beauty and prominent role of chirality, chemists have made tremendous efforts in searching for the origin of homochirality in life1 – in the context of biogenesis and to elucidate Nature's organizational and molecular recognition principles. In addition, the development of biomedical active compounds based on chiral molecules is of prime importance in pharmaceutical industry and essential in modern society to help to cure patients.12,13 Furthermore, the field of asymmetric catalysis, based on metal-chiral ligands14 or chiral organo-catalysts15–19 and enzyme catalysis20,21 is crucial in controlling chirality in synthetic systems ranging from drugs and fragrances to liquid crystal materials.Chirality is a ubiquitous and essential feature in the evolution of Nature, from small chiral molecules to macroscopic objects. In living creatures, molecular asymmetry is commonly regarded as a bio-signature for its central role in biological structures and processes.4 This is not surprising, since the chirality of molecules in many applications might have been considered less essential, while synthetic difficulties and challenging chiral separations also likely limited the full exploitation of these molecules in materials science. In recent years the picture has completely changed and novel approaches to control chirality along length scales from molecules and supramolecular assemblies to macromolecular systems enabled unprecedented control over structure and function. In particular as part of the current transition from molecules to dynamic molecular systems, mimicking life-like functions, dynamic control of chirality emerges as a key factor.Despite the major role of small chiral molecules in catalysis and medicinal chemistry, many opportunities offered by the introduction of chirality in materials and molecular systems remained unexplored in the past decades.22 especially light-driven artificial molecular motors23,24 (AMMs) are appealing due to the intrinsic and dynamic chirality in their structures allowing for the control of chiral functions, as well as driving systems out-of-equilibrium by chirality-controlled unidirectional rotary motion. Due to the non-invasive nature of light used as the stimulus that triggers the rotation of AMMs, these systems are waste-free and allow high spatiotemporal precision; properties that are highly valuable for many applications. Taking these distinct advantages, AMMs have been designed for the development of various light-responsive systems and functions in recent years,25–29 including self-assembly,30–32 surface modification,33,34 liquid crystal (networks),35 porous materials,36–38 responsive polymers,39–41 artificial muscles42,43 and autonomous translational motion44  and bottom (stator) halves  steps  to revert to the stable isomer, making it a new class of P-type chiroptical photoswitch  .23,47 Th) halves .48 In thI) steps . Subsequtoswitch .5152,53 or through asymmetric synthesis for specific AMM structures.54–58 Information regarding the synthesis and purification of chiral molecular motors has been clearly summarized in another recent review, to which we direct the interested reader.59 Here, we will display representative examples, focusing on the specific design principles that are required for chirality-led applications. We expand further on some of the areas for which it is evident that chiral AMMs have made an impact in nanotechnology and are promising in the control of various functions.Generally, chiral AMMs can be obtained by chiral separation, either by chiral HPLC or SFC techniques,3.60,61 is a rapidly emerging field that shows great potential for non-invasive dynamic control of catalysts, with a switchable feature both towards activity and selectivity. Particularly, the integration of asymmetric catalysis with light-controlled enantioselectivity into one single design is a highly challenging goal. Due to their intrinsic chirality and invertible helical chirality, AMMs and related chiroptical switches22,62,63 are of great value as scaffolds in controlling asymmetric catalysis operating as bi- or multi-functional catalysts or ligands.Photoswitchable catalysis3.1.64 This concept was realized by installing 4-dimethylaminopyridine (DMAP) and thiourea substituents to the motor core as a chiral organocatalyst --trans isomer could be isomerized by 312 nm light irradiation to the metastable --cis isomer, activating the asymmetric catalysis ability of the motor. Subsequent heating led to the THI step, generating the stable --cis isomer, reversing the chirality of the product. Regeneration of the stable --trans isomer could be realized by repeating the irradiation/THI steps. Using this light/heat modulation of the motor-based chiral catalyst, the racemic or each enantiomer of the reaction product could be obtained at will. Subsequent studies further proved the elegance of this strategy by dual stereocontrol over the Henry reaction.65Our group developed the first example in which a chiral molecular motor was applied as a catalyst in an asymmetric transformation . It coulcatalyst . These t66 All three motor isomers show 1 : 1 stoichiometric binding affinity with chloride anions in this design, while different isomers show distinct configurations upon anion binding in the formation of supramolecular helical structures. The --trans isomer was first investigated as a catalyst in this asymmetric anion binding controlled reaction, with a 1-chloroisochroman derivative as the substrate. The absence of cooperativity between the two oligotriazole branches only gave racemic 1-methoxyisochroman as the product. On the contrary, both cis isomers of the catalyst gave the enantiomeric product with different enantiomeric ratio e.r. values. The --cis isomer gave lower (e.r.) than --cis isomer, possibly due to a less optimal geometry for chloride binding. The Δe.e. value of the products was found to be up to 142%.Another example showed successful stereodivergent anion binding catalysis with high enantiomeric excess (e.e.) by molecular motors with two oligotriazole anion receptors attached to a first generation motor core .66 All t3.2.i.e. the asymmetric allylic cyclization of a symmetric bis-carbamate substrate --trans state gave a racemic product, while the enantioselectivity can be boosted to 93/7 e.r. for --cis-state and 6/94 e.r. for the enantiomer product using the --cis-state of the catalyst, which is comparable with conventional chiral bis-phosphorous ligands.Apart from photoswitchable organocatalysts, photoswitchable bidentate phosphorus ligands based on molecular motor cores also proved to be practical in promoting palladium-catalyzed desymmetrization reactions, ubstrate .70 The -catalyzed conjugate addition of diethylzinc to 2-cyclohexen-1-one to afford an enantiodivergent product controlled by light.68Phosphoramidite ligands are known as powerful chiral ligands in asymmetric catalysis since being introduced by our group in 1994.structed . Taking iii)-salen catalyst -salen catalyst, which was known to catalyze the epoxidation reaction of alkenes,72,73 the helically chiral photoswitchable ligand can be bound in a supramolecular complex to the achiral manganese(iii)-salen catalyst, inducing chirality in the catalyst. The crystal structures of the metal complex M6 in the stable and metastable states showed the successful chirality transfer from the switch ligand to manganese(iii)-salen catalyst. Studies of the switchable catalytic asymmetric epoxidation showed that the Δe.e. values obtained by this catalyst were up to 118%.In 2022, the groups of Nolte, Elemans and Feringa developed an elegant photoswitchable chiral anionic ligand, which can axially coordinate and transfer its chirality to an achiral manganese-cis-M8, a helical structure of the supramolecular polymer is formed. Micelles are formed in the -trans-M8 state by 312 nm light irradiation of -cis-M8 with a subsequent THI step. Irradiation of -trans-M8 sample at 312 nm, -cis-M8 and -trans-M8 at photostationary state (PSS) in a ratio of 32 : 68 exhibited worm-like fibers. The subsequent THI step did not regenerate the initial morphology, possibly due to the low ratio of -cis-M8 in the mixture. Hence, a H2O/THF (7/3) solvent mixture was applied to increase the PSS to 70 : 30, which allowed the THI step to recover the initial morphology.Recently, a multi-state photo-responsive supramolecular polymer based on a homochiral first generation molecular motor was developed, that could transfer chirality from molecular level to various supramolecular architectures through self-assembly in water.achieved . C6 alky75 In this study, the l stable isomer self-assembles into well-defined nanofiber-based clusters in methylcyclohexane, due to the strong π–π stacking interactions of PBI units  shows a right-handed CPL signal (R-CPL) with a glum of 5.4 × 10-3 in solution (glum = 0), possibly due to destruction of the co-facial π–π stacking interactions. This example further confirmed the ability of chiral AMMs to transfer their chirality along different length-scales using a dynamic self-assembly strategy.In another application from Qu and co-workers it was shown that a chiral overcrowded alkene unit bearing two PBI units could self-assemble in a chiral manner in its stable state, and exhibits circularly polarized luminescence (CPL).BI units . This chsolution . Under 35.Controlling molecular recognition is an important and central goal of the field of supramolecular chemistry. In particular, chiral recognition, such as enantioselective discrimination, is extremely appealing due to its significance in manufacturing drugs and controlling biological processes. Applying external stimuli, especially the use of light-triggered switches, capable of dynamic control over binding properties of artificial receptors in a harmless manner has proven to be a highly promising strategy towards achieving this goal. In particular, intrinsically chiral AMMs are privileged candidates among most of the other switches designed for manipulation molecular chiral recognition.78 Both -cis-M10 and -cis-M10 fit the 1 : 1 binding model towards a chiral phosphate. -cis-M10 preferentially binds to (R)-phosphate with a KR/KS = 4.2 ratio. On the contrary, -cis-M10 shows an opposite bias as a KS/KR = 3.2 ratio was obtained. This pioneering result shows that an artificial functionalized motor, here a chiral AMM, could serve as a receptor capable of enantiomer recognition in a dynamic fashion.Enantiopure first generation motors functionalized with two urea moieties can serve as chiral receptors to enantioselectively bind to a chiral Binol phosphate anion guest .78 Both 79 By tuning the length of oligo-ethylene glycol chains attached to the first generation motor core, unidirectional rotation of the motor host was accomplished. Subsequently, enantiomerically pure motorized macrocycle M11 with a crown ether functionality was separated by chiral HPLC, and was subsequently used to establish dynamic control over binding affinity of a chiral dialkylammonium guest in a 1 : 1 binding model. Preferential binding was found in this host–guest system, e.g., -cis-M11 exhibited selectivity for binding of the (S)-enantiomer of the ammonium salt (KS/KR = 1.7). By contrast, -trans-M11 shows a poor binding affinity to the guest as the crown ether moiety is less accessible. Subsequent photoisomerization of motorized macrocycle to a -trans and -cis mixture led to the reversed binding bias, i.e., the (R)-enantiomer of the ammonium salt binds stronger with a ratio of binding constant KR/KS = 2.5.Another stereoselective guest recognition motor was based on a motorized macrocycle host–guest system .79 By tu6.26,28,80,81 Enantiomerically pure AMMs compounds are prerequisite in order to dynamically deliver and amplify chirality from molecular to macromolecular or supramolecular level.The transmission of chirality through space and across length scales by AMMs can enable dynamic control of function for diverse applications in various areas in chemistry, biology and materials science.6.1.39 Polyisocyanate is a special dynamic polymer that can fold its chain into helices in response to chiral information.82 Thus, the use of a chiral molecular motor in its different isomeric states could control the helicity of the resultant isocyanate polymers. In the stable-trans state the obtained polymer is racemic. Subsequent irradiation of racemic motorized polymer, leads to the exclusive formation of the M-helical polymer as a result of chirality transfer. After thermal helix inversion, the stable-cis motorized polymer exhibits P-helicity, reversing the helicity as a result of the chirality transfer process from molecular motor to dynamic isocyanate polymer.Our group employed an optically pure molecular motor as the initiator for the polymerization of isocyanates .39 Polyivia non-covalent ionic interactions , which represents an efficient transfer of chirality from the dopant to the polymer. Photoisomerization of motor-doped polymer in this case was achieved by first disassociation, then re-association with the polymer after isomerization of the motor to induce the opposite chirality. This in situ light irradiation inverts the chirality of motor, which then in turn is transferred to dynamic helical polymers, establishing control of the polymer helicity.Another example pertains to the chirality transfer from a molecular motor to a dynamic helical polymer, the so-called Yashima polymer, ractions .40 The Y6.2.83 Molecular motors show change in helicity upon irradiation accompanied by large changes in helical twisting power (HTP), leading to applications in motor-doped systems such as rotating objects on a surface,35 supramolecular vortices,84 swimming85 and reconfigurable chiral droplets,86 as well as adaptive optical materials.87,88 A recent review by Yang and co-workers discusses the relationship between AMMs and liquid crystals in detail.89 Therefore, here, we select a few representative examples to show the interaction between optically pure AMMs as multi-state photoswitches and liquid crystal phases (LC network).Liquid crystals (LCs) with long-range organization and fluidity show great potential for chiral transmission and amplification, and high responsiveness to small chirality changes at the nanoscale.P,P)-trans-M15, into nematic LC (E7) with a weight ratio of 6.6% enables a violet colored reflection band to be observed.90 Irradiation with UV light led to the isomerization of -trans-M15 -trans-M15 thermally by THI, thus recovering the initial reflection band. In this case, the reflection wavelength can be tuned readily throughout the entire visible spectrum simply by changing the irradiation time.Doping optically pure first generation molecular motor -trans isomer is quickly converted to -trans isomer. On the contrary, the -cis isomer exhibits a longer half-life, up to 25 d. The -cis isomer can be either converted to -cis isomer by a THI step or -trans isomer by irradiation at 365 nm, thus enables a three-state manipulation of this system. By modifying molecular motor structures . The key to the helical motion of the LC droplet is the Marangoni effect.92 That is, the presence of surfactants in water can form a micellar morphology, which solubilizes small amounts of the LCs, creating inhomogeneities in surface tension that are compensated by a flow that drives the droplets forward. Doping a chiral second generation molecular motor (M19 or M20) into this system transfers its chirality to modulate the helicity of LC (ca. 1 s for complete inversion of helicity) of the molecular motor, which thus reorients the direction of the moving droplet.Katsonis and co-workers developed a motile LC droplet system that shows light-responsive behavior.ty of LC . Subsequglum) in a dynamic and reversible way via external stimuli is important and appealing for its application in optoelectronic devices, including externally addressable materials for displays. Recently, an example shows that doped chiral molecular motors and achiral dyes in LC phase can achieve dynamic control of CPL by chirality transfer from molecular motors to achiral BODIPY dyes  and glum (up to 0.45) showed the powerful interplay in this design, together with the reversibility and non-invasiveness of this system. By doping different molecular motor cores (M17 and M21 to M23) and dyes , the emission color (from blue to red) can be programmed with different states of chiral molecular motors.Programming CPL with a high degree of circular polarization -M24 and right-handed helical motion for (S)-M24  holds promise to not only maintain functions as dopants in LCs, but also results in more complex functions which could be utilized in applications such as soft robotics. To control sophisticated motion by molecular motors, our group successfully copolymerized a second generation molecular motor functionalized with diacrylate into a LCN by a polymerization process. (S)-M24 . In a su7.96,97 To control dynamic control of spin-selectivity enabled by chiral switchable AMMs, in 2019, the first example was reported by sandwiching a thin layer of second-generation AMM core M25 between Al2O3 (3 nm)/Ni (50 nm) and a gold (20 nm) electrode -trans-M26, the averaged current magnitude measured with the magnetic field pointing up (Hup) is higher than for magnetic field pointing down (Hdown) for all non-zero voltages -cis-M26 isomer -cis-M26. Starting from -cis-M26 in an identical study gave consistent results though formation of -trans-M26, -trans-M26. Interestingly, the motor rotation is uncompromised on the gold surface, but the barriers of the THI steps are quite different compared to those in solution. A drop-casted sample on the surface showed similar thermal half-lives of the thermal helix inversion steps of both metastable cis-M26 and metastable trans-M26 isomers (ca. t1/2 ≈1 h). In THF, the half-lives were determined to be t1/2 =21 h and t1/2 =10 s, for metastable cis-M26 to stable cis-M26 and metastable trans-M26 to stable trans-M26, respectively.To achieve multi-state spin selectivity control, a first generation molecular motor M26  based syvoltages . UV ligh6 isomer . Thermalans-M26, , followe8.R or S) at the allylic position of the overcrowded alkene (resulting in clockwise and anti-clockwise rotation). Thus, targeting applications where uniform directionality is paramount, the molecular motors integrated into the system must be completely homochiral in order to amplify the unidirectional motion, instead of cancelling it out – which would occur in the case of a racemate. Here we describe a few examples that exploit enantiomerically pure molecular motors to amplify molecular motion across length scales.In the previous sections, we have described multiple cases in which the chirality of the different isomers of light-driven molecular motors are used for their applications. Additionally, AMMs are also unique for their unidirectional rotational motion controlled by the chirality of the substituent at the stereogenic centre  surface by the cooperative rotation of the AMM units upon sequential electronic and vibrational excitation. By tuning the chirality of the individual motor units, the molecule can be adapted to different trajectories on surface. Interestingly, when the meso- isomer is adsorbed onto the surface in the proper orientation  isomer cannot move because of the combined “cancelling out” effects of the motor units, thus impeding translational movement of the molecule  and  isomers rotate in a disrotatory fashion, resulting in random movements or ideally spinning motion  as a key step, they constructed a polymer hydrogel with motor M28 units reticulated in the network  maturation and force-dependent T-cell activation.In another design, Campo and co-workers intercalated polymer chain-linked chiral motor M29 between a membrane receptor and engineered biointerface in order to apply forces by light-triggered contraction of a motorized polymer at cell-matrix and cell–cell junctions .106 When8.5.107 The motor core, M30, is based on a Feringa-type second-generation molecular motor and was synthesized in an enantiomerically pure form to ensure unidirectionality of the system , the authors found that the reversible untwisting can be converted to its initial state in the dark at 45 °C for 9 d. This finding indicates that in this highly strained system, the inversion of the motor rotation occurred to release the strain in the macrocycle by crossing both thermal helix inversion and E/Z isomerization barriers at the ground state.Giuseppone and co-workers reported an independent system that small chiral AMM can act as a light-driven molecular whirligig .108 In t8.6.109 They demonstrated that out-of-equilibrium actuation dynamics of fast rotary motion leads to the increase of the fractional ion transport activity. The AMM attached with two 18-crown-6 ethers as the macrocyclic units M32 was designed --cis state  control over molecular motion with high precision of these AMMs make them undoubtedly unique and highly promising in the field of smart materials. Through the elegant examples, we could draw a picture in the design principle for the choice of AMMs in different applications. Generally, for the multistate-related applications, for instance asymmetric catalysis, the long existence of metastable isomers is crucial for the sufficient chirality transmission, at least being stable during the catalytic process. Under this prerequisite, first generation motors which usually have several hours to days half-life time in , covalent organic frameworks (COFs) and porous organic polymers (POPs). UV light can cause harm to sensitive chemical biology systems, and has to be replaced by alternatives such as visible light and near infrared (NIR) light. In addition, AMMs may be susceptible to photo-degradation under UV light irradiation. Therefore, new structures of AMMs with intrinsically red-shifted absorption wavelengths must be developed, or known AMMs must be modified towards operation with visible light or NIR light for instance using sensitizers, 2-photon excitation or upconversion methods.111The operation wavelength of light used in most cases still lies in the UV regime, which limits the applications as well as practical operation of the motors. For instance, highly energetic UV light suffers from limited penetration depth, which will be inefficient when applied into bulk matter, 2.i.e. the quantum yield of key photoisomerization step) of light-driven AMMs constitutes an ongoing fundamental challenge. Since the development of AMMs in 1999, decades of efforts from our group and many others have led to improve the quantum efficiency of light-driven AMMs. However, this property is more complicated to modify or improve compared to the ground state rotary-speed tuning. There are a few methods that may improve the quantum yields of AMMs, but the functionalization that boost the photo-efficiency may also impede their applicability. Therefore, AMMs with orthogonal accessibility for molecular functioning and high photo-efficiency are highly warranted in the future. Related is the quest for tuning the excited state energy landscape allowing the control over dual functional motors like rotary motion and fluorescence without compromising each function.112,113The photoefficiency (3.vide infra) shows a chiral helical structure of the supramolecular polymer in stable-cis state, while showing worm-like fibers in stable-trans/metastable-cis mixture (32/68) at PSD states.31 It is very difficult to distinguish whether the mixture of stable-trans/metastable-cis mixture or solely the metastable-cis isomer itself formed this morphology. Thus, a high PSD in photochemical steps of AMMs is crucial not only to obtain highly enantiopure products based on multistate chiral catalysts, but also to achieve better control in dynamic systems such as chiral supramolecular assemblies.High photostationary distributions (PSDs) of AMMs are necessary for specific applications. Considering the control of functions using AMMs as multi-state photoswitches, the high PSD is very important to control dynamic states with high selectivity. In particular, as a switchable asymmetric catalysts or ligands, high PSDs are one of the prerequisites needed to obtain products with high Δe.e. or Δd.r. values. In addition, to precisely control the self-assembly morphology, the high PSD will be useful to understand the self-assembly process in each state (excluding co-assembly of isomers in the PSD). For instance, motor amphiphile M8 114 Recently, using photoswitchable catalysts to control polymerization has shown some inspiring advances but remains challenging.115 By rational design of chiral motor-based catalysts, there are possibilities to synthesize polymers, which encode chiral information that could be toggled by light.Switchable catalysis to manipulate the microstructures of polymeric materials in a controllable way is appealing and important since the minor changes in tacticity, head-to-tail structure, sequence, and/or chain topology will induce significant effects on the macroscopic properties of a synthetic polymer.(b)36 or modulate porosity of the framework materials.38 Ideally, by incorporation of enantiopure motor monomers into a solid material framework we could encode chiral information in porous solids, which could be further applied to heterogeneous asymmetric catalysis or switchable enantiomer separation.Nowadays emerging porous materials show great advantages in gas and/or guest storage and separation. Incorporation of overcrowded alkene-based molecular motors into porous materials can deliver unidirectional motion(c)116 the design of photo-regulated supramolecular helical systems remains challenging.117 Therefore, taking advantage of the intrinsically dynamic and reconfigurable chirality of AMMs, there is ample room for the development of reversible supramolecular helical systems based on chiral AMMs.Though supramolecular assembly induced asymmetry transfer and amplification across different length scales is intriguing,(d)94,95 and supramolecular muscles42,43 opens avenues for designing light-responsive artificial soft robotics by programmable construction of AMMs in actuating materials.The bending and helical motion controlled by the chirality of molecular motors in LC networks(e)To achieve sophisticated functions in responsive systems, it is necessary to use orthogonal-/multi-stimuli to trigger complex tasks in a “smart” way. Such stimuli can control the transmission of chirality in a logic gate system or in a sequential manner, showing high spatiotemporal precision.(f)33 in particular the synchronous rotation toward one direction by chiral molecular motors will enable such surfaces to act as mechanical devices or responsive interfaces for specific applications.Incorporation of molecular motors on surfaces renders them able to induce dynamic functions triggered by light. Inspired by the unidirectional molecular motors on surfaces,(g)104 as well as being applied to control ion transport and the fate of stem cells.109,110 While it is still largely unexplored, this field holds bountiful potential for chiral AMMs to achieve chiral recognition in biological systems, such as on–off recognition in distinct chiral states by light-manipulation and control transport and cellular function. Particular appealing are also biohybrid systems, like channel proteins,118–120 with artificial motors incorporated at precisely defined positions in there structure to allow non-invasive control.Molecular motors have been used to open cell membranes by drilling through cellular bilayers,Light-driven molecular motors with intrinsic chirality embedded in their core open many new avenues for designing responsive and mechanical smart materials and molecular systems with exquisite control over motion at distinct length scales as illustrated in the recent examples discussed here. With the rapid expansion of the AMM family and ongoing interdisciplinary efforts within this field, it is evident that the prospects of light-driven chiral AMMs are bright, lighting up the future of the nanoworld in motion.J. S. wrote the initial version of the manuscript and carried out the bibliographic research. D. R. S. P. helped to edit and revise the manuscript. B. L. F. revised and finalized the manuscript and secured funding.There are no conflicts to declare.


Molecularly imprinted polymers (MIPs) are synthetic receptors that mimic the specificity of biological antibody–antigen interactions. By using a “lock and key” process, MIPs selectively bind to target molecules that were used as templates during polymerization. While MIPs are typically prepared using conventional monomers, such as methacrylic acid and acrylamide, contemporary advancements have pivoted towards the functional potential of dopamine as a novel monomer. The overreaching goal of the proposed review is to fully unlock the potential of molecularly imprinted polydopamine (MIPda) within the realm of cutting-edge sensing applications. This review embarks by shedding light on the intricate tapestry of materials harnessed in the meticulous crafting of MIPda, endowing them with tailored properties. Moreover, we will cover the diverse sensing applications of MIPda, including its use in the detection of ions, small molecules, epitopes, proteins, viruses, and bacteria. In addition, the main synthesis methods of MIPda, including self-polymerization and electropolymerization, will be thoroughly examined. Finally, we will examine the challenges and drawbacks associated with this research field, as well as the prospects for future developments. In its entirety, this review stands as a resolute guiding compass, illuminating the path for researchers and connoisseurs alike. It is widely acknowledged that, while every individual possesses their own distinct set of fingerprints, each finger exhibits its unique pattern as well. This analogy drawn from the realm of fingerprints finds relevance in the context of chemical species, where each molecule bears its distinctive imprint characterized by specific size, functional group, and shape attributes. To generate such molecular imprints, a polymerization process is employed, wherein the target molecule is incorporated within the polymer structure. The subsequent elimination of the target molecule yields a polymer endowed with specific imprints tailored for the desired analyte. This resulting polymer is referred to as a Molecularly Imprinted Polymer (MIP) ,2.MIPs are synthetic receptors that emulate the affinity seen in biological antibody–antigen interactions. These polymers function through a “lock and key” mechanism, selectively capturing the molecules they were templated with during the polymerization process . When coAlthough the polymerization method is a critical phase, the selection of monomers is a crucial aspect in designing MIPs with desired recognition properties. The most used functional monomers are methacrylic acid , acrylamDopamine, a small molecule, exhibits susceptibility to undergo polymerization under mildly alkaline conditions through oxidation mechanisms. This polymerization process gives rise to a cohesive and adherent material known as polydopamine (PDA), which draws inspiration from the adhesive properties observed in mussel adhesive proteins ,21,22. DGiven the current surge in research activities focusing on MIPs based on PDA , we recoDifferent core/substrate materials are listed, which have been modified with MIPda for specific templates . These m2 . M. M34]. M2 , fibrous2 [2 , and pol2 [2 . The preications . The SiO2 shells . The mod polymer .Metal/metal oxide substrates contribute to the development of MIPda-based materials with enhanced photoelectrochemical properties, allowing for efficient energy conversion and sensing applications . MoreoveThe synthesis methods involve self-polymerization or electropolymerization in the presence of the respective templates. The resulting MIPda materials exhibit diverse morphologies such as spherical particles, smooth surfaces, compact layers, or rougher surfaces, depending on the specific configuration and core/support material used. Overall, Dopamine was applied for various templates such as ions, small molecules, epitopes, proteins, and viruses. Dopamine has gained significant attention as a monomer in the synthesis of ion-imprinted polydopamine (IIPda) due to its unique chemical properties and biological relevance. IIPda is a versatile material that can selectively bind specific ions, making it useful for various applications. For example, IIPda was developed for the electrochemical detection of Nickel ions .The use of dopamine as a monomer in IIPda offers several advantages. Firstly, dopamine possesses both catechol and amine functional groups, which can form strong coordination bonds with metal ions through complexation reactions. This allows for the incorporation of metal ions into the polymer matrix during the synthesis process. Additionally, dopamine is known for its self-polymerization ability, which simplifies the preparation of IIPda without the need for complex synthetic procedures.The resulting IIPda materials exhibit remarkable properties. The polymer matrix provides structural stability and mechanical robustness, while the imprinted metal ions confer specific recognition sites within the material. This molecular imprinting process leads to the creation of binding cavities that are complementary, in shape, size, and chemical functionality, to the target ions.However, while the advantages of using dopamine as a monomer in IIPda are evident, it is crucial to acknowledge the broader context. One notable challenge emerges from the relative scarcity of works focusing on IIPs, which may indicate certain complexities in the synthesis process. For instance, the removal of ions from polydopamine matrices often requires an acid medium, which, while effective for ion removal, can also impact the structure of polydopamine. This indicates the need for the further exploration and optimization of synthesis conditions to mitigate potential drawbacks.Dopamine has been explored for the creation of MIPda. Dopamine possesses functional groups such as catechol and amine, which can form various types of interactions, including hydrogen bonding, electrostatic interactions, and π-π stacking, with the target molecule during the polymerization process. This allows for the creation of specific binding sites that are complementary to the shape, size, and chemical functionality of the target molecule.Dopamine has been exploited to prepare MIP for a large variety of small molecules such as sulfamethoxazole , diethylMIPda was employed to discern the chirality of molecules. In this regard, Arabi et al. proposed a recognition mechanism known as the “inspector” recognition mechanism (IRM) . This meUtilizing virtual template molecules that share a similar chemical structure to the target molecules can prevent the issues arising from template molecule leakage. Miao et al. demonstrated the usefulness of bisphenol-A as a dummy template for Dichlorodiphenyltrichloroethane .PDA coatings have been utilized as versatile platforms for the immobilization of proteins, offering robust and adhesive surfaces that facilitate the stable attachment and biofunctionalization of various biomolecules . This fePDA exhibits numerous advantageous characteristics that make it an exceptional polymer system for protein imprinting. Its structure encompasses a wide array of functional groups, including amino groups, hydroxyl groups, and π–π bonds. These functional groups can be effectively utilized for protein recognition in MIPs. One of the key benefits of PDA is its high hydrophilicity, enabling its synthesis in an aqueous environment that is compatible with the protein templates. This aqueous synthesis provides a favorable setting for incorporating proteins into the polymer matrix, ensuring their proper imprinting and retention of their structural features. Dopamine has been employed to prepare MIPs for a large variety of proteins such as Pepsin , carcinoIn the process of polymerization, dopamine monomers tend to gather around protein templates through interactions involving functional groups, such as hydrogen bonds and π–π interactions. This leads to the incorporation of protein templates within the resulting PDA film. MIPda offers amino groups that adsorb, selectively and non-selectively, protein templates, leading to non-specific adsorption. Han et al. introduced a straightforward approach to mitigate nonspecific adsorption by enveloping the imprinted PDA coatings with mildly crosslinked nonlinear poly(ethylene glycol) (PEG) layers through aqueous precipitation polymerization prior to removing the template .2@PDA [3O4@PDA [The bio-inspired PDA chains displayed non-covalent functionalities, including amine, hydroxyl groups, and π–π bonds, which played a role in selectively binding with the amino acids of proteins on the virus surface. Dopamine possesses redox-active functional groups, such as phenolic hydroxyl and catechol moieties. These groups can facilitate the incorporation of target virus-related molecules during the imprinting process. Moreover, PDA has been extensively studied for its biocompatibility and low cytotoxicity, making it suitable when designing virus-imprinted materials intended for diagnostic or therapeutic purposes. In the self-polymerization under mild conditions of dopamine, forming PDA films or nanoparticles is convenient for imprinting viruses. For instance, the whole hepatitis A virus was imprinted on SiO2@PDA  and Fe3O[3O4@PDA  while, i[3O4@PDA . The MIPThe self-polymerization of dopamine is the most used technique for the synthesis of MIPda with a percentage of 65%. Dopamine, a small molecule, can undergo oxidative polymerization in the presence of a basic medium and room oxygen. The use of an oxygen-saturated solution  and purgThe self-polymerization method can be conducted in batches or by dipping solid support in a solution containing dopamine monomer . TraditiThe self-polymerization of dopamine into PDA occurs using various solvents, such as sodium hydroxide, sodium bicarbonate, PBS, and Tris, resulting in PDA with distinct morphological and physicochemical characteristics associated with each solvent, as demonstrated by Patel et al. when they investigated their effects under similar pH = 8.5 . NeverthOver the years, the use of the self-polymerization technique to prepare MIP was not applied only with dopamine monomer but also with other catecholamines such as norepinephrine ,77. In aThe electrochemical synthesis of MIPda is a technique that utilizes an electrochemical process to fabricate MIPs. The process involves the electrooxidation of dopamine monomers on an electrode surface to initiate the polymerization and imprinting of target molecules. Typically, a conductive substrate, such as a glassy carbon electrode, is used as the working electrode. Dopamine monomers are dissolved in a suitable electrolyte solution, and the electrode is immersed in this solution. When an electrical potential is applied to the electrode, dopamine undergoes electrooxidation, leading to the formation of a PDA film on the electrode surface. During this electrochemical polymerization, template molecules are introduced into the system. The dopamine monomers polymerize around the template molecules, resulting in the formation of imprinted sites that possess a specific affinity for the target molecule .The electrochemical synthesis of MIPda offers advantages such as precise control over the film thickness, improved accessibility of the imprinted sites, and the ability to integrate the MIPDA films onto various electrode surfaces for sensor and sensing applications.Before the synthesis of MIPda, the immobilization of IgG on the electrode surface takes place. Subsequent entries highlight diverse approaches, including the use of sulfamethoxazole , an aminThe number of electropolymerization cycles has a significant effect on the imprinting process. The development and sensing efficacy of the imprinted polymeric membrane hinged on the number of scan cycles . A low cOn the other hand, the pH of the electropolymerization solution plays an important role in MIPda-based electrochemical sensors. The pH of the MIP solution has a significant impact on the electrode sensing performance. At high pH levels, the phenolic group in PDA becomes deprotonated while, at low pH levels, the amino group becomes protonated. This property can influence PDA synthesis, necessitating pH optimization of the MIP solution. The findings revealed that the highest current values were observed at pH 7.5 and 8.0. While Yang et al. achieved the thickest PDA growth at pH 8.5, the resulting MIP PDA lacked satisfactory sensitivity . Recent 2 to remove oxygen from the electropolymerization solutions [Self-polymerization may interfere with electropolymerization, particularly when electropolymerization is conducted in the basic medium at a low rate. However, the researchers avoid this interference by bubbling Nolutions ,54.As shown in The structure of PDA remains highly intricate and, as of yet, a definitive and comprehensive understanding of its formation and complete structure has not been conclusively established. Despite numerous proposed structures and mechanistic pathways, as presented in the literature , a clear2 NPs [2 exhibited a higher Rq value, suggesting a rougher surface compared to the NIP-QCM crystal and NIP-SiO2. Moreover, the surface of MIPda-SiO2 and NIP-SiO2 are rougher than the SiO2 surface, confirming the well decoration of PDA on the SiO2 [Surface roughness plays a critical role in characterizing the properties of MIPda. To investigate surface morphologies, atomic force microscopy (AFM) was utilized to analyze MIPda-coated and NIP-coated quartz crystal microbalance (QCM) crystals  and SiO22 NPs . The roothe SiO2 . These fthe SiO2 , film  [2 nanosheets, and MoS2 nanoflowers to achieve high sensitivity and specificity. The sensors can detect CEA concentrations in a linear range of 0.01 ng/mL to 10 μg/mL, with a remarkably low LOD of 3.5 pg/mL. This work holds promise for improving the early detection of CEA-associated cancers.Lu et al. developed a unique approach using MIPda in a sandwich structure, combined with dual signal amplification using MnOen (CEA) . The senAnother interesting approach was introduced by Wang et al. for the detection of antibiotics using an optical sensor based on SPR . This stMIPda is emerging as a promising functional material for designing highly selective electrochemical sensors ,59,90,91Another interesting application of MIPda in electrochemical sensing has been introduced by Yin et al. for sunset yellow sensing . They utRecently, the detection of nitro-explosives has been explored using the MIPda-based electrochemical sensor. In this context, Leibl et al. developed a sensitive electrochemical sensor to detect nitro-explosives in water using thin MIPda films . The MIP3Fe(CN)6 and KCl electrolyte to detect OVA. The sensor demonstrated remarkable sensitivity with a detection limit of 10.76 nM, a linear range from 23.25 to 232.50 nM, and strong selectivity against other proteins. Successful detection in wine samples showed potential for broader use in identifying allergenic proteins in the food chain  analysis, the magnetic imprinted polymers were effectively employed for SPE and the detection of HSA in urine samples, yielding successful recoveries ranging from 91.95% to 97.8%.Another interesting application of MIPda in SPE, as reported by Yin et al., is for protein capture . Indeed,3O4@PDA@MIP) through an environmentally friendly process (3O4@PDA@MIP exhibited a strong imprinting factor (3.0 ± 0.05), showcasing remarkable selectivity against interfering substances such as patent blue and other food matrix components. The MDSPE approach was paired with a smartphone-based colorimetric detection method, yielding performance akin to UV–visible spectroscopy detection. The achieved reliable ERT-B quantification within the range of 0.5–10 mg/L, with a detection limit of 0.04 mg/L. The developed method was successfully applied to determine ERT-B content in various food samples, including juice, candy, and candied cherries, yielding satisfactory recovery values (82–97%).Recently, Elfadil et al. have introduced a study for extracting and quantifying erythrosine B (ERT-B) in food samples . The aut process . This coFirstly, in the case of general MIPs, the template molecule typically undergoes a self-assembly process where hydrogen bonds form between the specific functional groups of the monomer and the template. However, dopamine oxidizes and rearranges before polymerization, disrupting the interactions between the monomer and the template. This oxidative process hinders the formation of the desired imprinted cavities. Secondly, dopamine exhibits high reactivity, leading to covalent reactions with certain templates during its polymerization under low-alkaline conditions. As a result, the extraction of the template becomes challenging. The strong covalent bonds formed between dopamine and the template impede the efficient removal of the template molecule .Furthermore, while MIPda has demonstrated robustness, biocompatibility, and ease of synthesis, it is essential to recognize that these materials may encounter challenges related to long-term stability. Indeed, PDA is composed of oligomeric species that typically reach only up to the tetramer level . This coWhile dopamine’s unique chemical properties facilitate its self-polymerization, it is important to acknowledge that this may not inherently lead to the same degree of three-dimensionality as observed with conventional cross-linker-mediated imprinting. As such, the resulting molecular cavities in MIPda may exhibit distinct characteristics due to the polymerization mechanism and thin-layer nature of PDA. This aspect underscores the need for a thorough investigation into the dimensionality and stability of the imprinted cavities, which we recognize as an important consideration in the overall framework of our study.Non-specific binding is a common challenge of MIPs including MIPda. The particular challenge with MIPda is that PDA has important functional groups that can bind several compounds in the matrix rather than the target analyte. PDA can undergo degradation over time, especially under harsh environmental conditions. This can affect the long-term stability and performance of MIPda-based materials in some applications.While dopamine-based polymers have been successfully employed in various applications, their use may be limited to specific target molecules or classes of compounds. This lack of versatility can restrict the broader applicability of MIPda in diverse fields. In general, the electropolymerization method, including the electropolymerization of dopamine, encounters a challenge when applied to electroactive templates with oxidation potentials falling within the electropolymerization range. This difficulty arises due to the possible oxidation of templates during the electropolymerization process. Furthermore, the self-polymerization of dopamine in the basic medium in the presence of some classes of molecules, particularly phenols, leads to the oxidation of the template molecules.Lastly, the washing step required to remove the template molecule often involves harsh conditions, including the use of acidic mediums. However, unlike other polymers, PDA is not stable under these acidic conditions . ConsequTo overcome these limitations, ongoing extensive research is exploring alternative monomers and optimization strategies to improve the creation and stability of imprinted cavities using dopamine as a functional monomer.Despite the challenges and limitations associated with the use of dopamine as a functional monomer in MIPda, there are several perspectives worth considering for future research and development. Enhancing the stability of MIPda materials is important for long-term performance and practical applications. Researchers can explore strategies, such as cross-linking agents or surface modifications, to improve the stability of MIPda and mitigate the issues related to degradation and detachment. Understanding the specific interactions between dopamine-based polymers and different templates is crucial for achieving high selectivity and avoiding non-specific binding. Further investigations can focus on identifying templates that are compatible with dopamine and on designing tailored monomers to enhance the molecular recognition properties of MIPda. Developing efficient and gentle extraction methods for removing templates from MIPda is essential. Exploring alternative approaches to template removal, such as environmentally friendly solvents or non-destructive techniques, can help preserve the integrity of the imprinted cavities and improve the overall performance of MIPda. Expanding the versatility of dopamine-based polymers and MIPda is another perspective to consider. By exploring different target molecules or classes of compounds and optimizing the synthesis parameters, it may be possible to broaden the scope of applications for MIPda beyond specific targets. This would increase the potential impact of MIPda in various research fields.In conclusion, despite the challenges and limitations associated with dopamine as a monomer in MIPda, there are promising perspectives for future research. By focusing on monomer optimization, template compatibility, stability enhancement, broadening applicability, and extraction methods, researchers can overcome these limitations and unlock the full potential of MIPda for molecular recognition and other applications.


Among factors determining the pathway and the outcome of a chemical reaction, only some depend on the structural and electronic features of the molecules of reactants, which are now considered to be well understood. This is not the case for the “environmental variables”  many of For these reasons, understanding chemical reactivity in solutions requires much more than knowledge of molecular structures of reactants; moreover, we must go far beyond the present knowledge of specific solvent and solvation effects related to starting compounds, intermediates and transition states that emerge along the reaction pathway. The real reacting species in solutions seem to be not just individual molecules but more complex supramolecular entities that, generally, comprise both solute and solvent molecules. It appears that only detailed knowledge of the structure of reaction solution at the nano- and mesoscale level could reveal novel effective means for modulation of chemical reactions and processes. We believe that further progress in understanding chemical reactivity could be only achieved if we enlarge and deepen our knowledge of the structure of reaction solutions.This Research Topic is a first attempt to gather a series of important works by the leading experts on the subject and to provide a balanced Research Topic of theoretical and experimental studies of structure of solutions and chemical reactivity.The Research Topic includes one mini review article, and three original research articles, which come from Japan, Mexico, Germany, and Russia.Ishiwata et al. covers recent advances in the development of 1,2-cis selective glycosylations, including glycosyl donor modification, choice of reaction conditions, and activation methods for inter- and intra-molecular glycosylation. Of special importance for the current Research Topic is the use of inter-molecular interactions, such as hydrogen bonding, between the molecules of reactants to achieve the desired stereochemistry. A well-known but little understood influence of concentration of reactants on stereochemical outcome of glycosylation is also covered.The mini review by The importance of concentration for performing chemical reactions is already realized, and for this reason, it is not unsurprising that two articles are devoted to studies of the structure of solutions of various concentrations with special emphasis on ultra-dilute solutions.Ryzhkina et al. self-organization in solutions of doxorubicin (Dox), a highly effective cytostatic antibiotic, and impact of Dox diluted aqueous solutions  on hydrobionts are studied by a variety of physicochemical methods. It is established that aqueous solutions of Dox are dispersed systems which rearrange their dispersed phase measuring hundreds of nm in size (nanoassociates) upon dilution, followed by concerted changes in nanoassociates’ parameters  and properties of systems, as well as their bioassay results. Electron microscopy results confirm and complement the light scattering data indicating the existence of nanoassociates in dilute Dox solutions.In the article by Woods using a combination of THz spectroscopy measurements with molecular dynamics simulations, which successfully reproduce the observed signatures from experimental measurements. The author has uncovered that the reorganization of the sample surface residue dynamics at the solvent-protein interface leads to both structural and kinetic heterogeneous dynamics that ultimately create interactions that enhance the binding probability of the antigen binding site. The results obtained indicate that the modified interfacial dynamics of antibodies to interferon gamma and to the interferon gamma receptor 1 are directly associated with alterations in the complementarity regions of the distinct antibodies that designate both antigen-antibody affinity and recognition.Unusual properties of ultra-dilute protein (antibodies) solutions, which demonstrate an altered antigen-antibody specificity, are studied in the article by Hernández-Lima et al. suggest their answer to this fundamental question in the implementation of explicit solvation. The authors performed NMR experiments which allowed them to determine the number of solvent molecules around the solute molecule which belong to the first coordination sphere. DFT and QTAIM calculations revealed interaction between the solute molecule and the solvent molecules from this solvent sphere. It was possible to determine how the first solvent sphere around a solute molecule modulates the solute conformation and selectivity of a chemical reaction involving the solute.Computer modeling of solvation is a widely used approach to explain and predict chemical reactivity in solutions. When the energies of solute-solvent and solvent-solvent interactions are close in magnitude, invoking explicit solvation model is required. However, it is not obvious where the explicit solvent molecules should be located. In their paper, Summarizing, this Research Topic is a small but essential step towards a more comprehensive understanding structure of solutions and chemical reactivity. We hope that it will stimulate other researchers to get involved in this exciting area of scientific research.We cannot not finish this short preface without acknowledging all the authors and reviewers who have contributed to this Research Topic. We also want to thank all the editorial assistants. There would not be such a nice Research Topic without your kind cooperation and great efforts.