Host-guest assembly of ligand systems for metal ion complexation. Synergistic solvent extraction of copper(II) and silver(I) by 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclodecane in combination with carboxylic acids.
Host-guest formation between 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclodecane (1) and lipophilic organic carboxylic acids in chloroform has been investigated and the effect of such ligand assembly on the solvent extraction of copper(II) and silver(I) has been probed. NMR titration experiments in the absence of a metal ion confirm the formation of weak 1:1 and 1:2 (macrocycle:carboxylic acid) assemblies in CDCl(3) between 1 and palmitic (hexadecanoic) acid or 4-tert-butylbenzoic acid while difunctional salicylic acid showed a 1 [ratio] 2 interaction that is somewhat stronger. The interaction between the former two acids and the tetra-N-benzylated macrocycle is significantly less than that reported previously for its non-substituted parent, cyclam; a result that likely reflects the presence of the less-basic, more sterically hindered tertiary nitrogens in 1 relative to the secondary nitrogens present in cyclam. Carboxylic acid-containing assemblies of this type have been used as extractants in a series of solvent extraction (water/chloroform) experiments. From both previous observations as well as from entropy considerations, it was anticipated that the use of a host-guest assembly of the above type for metal-ion complexation might contribute to enhanced metal ion binding (and concomitant enhanced metal ion extraction). Such behaviour is postulated to arise from the components of the coordination sphere being, at least in part, assembled for complex formation. In accord with this, the use of the ligand assembly involving palmitic acid/macrocycle 1 was found to lead to enhanced (synergistic) extraction of copper(II) at a metal ion concentration of 10(-3) mol dm(-3) while, for silver(I), synergism was somewhat marginal at this concentration but was clearly apparent under related conditions when the silver concentration was reduced to 10(-4) mol dm(-3). Similar behaviour towards silver was also observed when 4-tert-butylbenzoic acid was substituted for palmitic acid, while the use of salicylic acid resulted in enhanced (synergistic) extraction at both metal ion concentrations.
Metals, macrocycles and molecular assemblies - macrocyclic complexes in metallo-supramolecular chemistry.
In this tutorial review the use of macrocyclic complexes as building blocks in a selection of supramolecular systems is discussed with emphasis on the properties, such as enhanced stabilities, that cyclic ligands and their complexes may impart on the resulting assemblies. An aim of the review is to exemplify the versatility of macrocyclic ligand complexes for use as components in a range of both discrete and polymeric systems. The use of macrocyclic systems for controlling CuI aggregation, as scaffolds for metal-cluster formation, as the cyclic components in interlocked catenane and rotaxane structures, for constructing assemblies based on macrocycle exo-coordination, for forming columnar stacks, as well as their roles as both structural and redox centres in a range of coordination polymer types are all presented.
Medieval Modal Theories and Modal Logic Handbook of the History of Logic. Volume 2: Mediaeval and Renaissance Logic
1The translation of the Categories is edited by L. Minio-Paluello in Aristoteles Latinus 1.1-5 (Bruges-Paris: Descl~e de Brouwer, 1961) and the translation of the De interpretatione by L. Minio-Paluello in Aristoteles Latinus II.1-2 (Bruges-Paris: Descl~e de Brouwer, 1965). The translation of Porphyry's Isagoge is edited by L. Minio-Paluello and B.G. Dod in Aristoteles Latinus 1.6-7 (Bruges-Paris: Descl~e de Brouwer, 1966). Boethius's commentary on Aristotle's Categories is found in Patrologia Latina (ed. J.-P. Migne), 64, 159-294, De syllogismis categoricis in Patrologia Latina 64, 793-832, In Ciceronis Topica in Patrologia Latina 64, 1039-1169; an English translation with notes and an introduction by E. Stump, and De differentiis topicis in Patrologia Latina 64, 1174-1216; an English translation with notes and essays by E. Stump, Boethius's De topicis differentiis (Ithaca and London: Cornell University Press, 1978), Boethius's In Ciceronis Topica (Ithaca and London: Cornell University Press, 1988). Boethius's two commentaries on De interpretatione are edited by C. Meiser (Leipzig: Teubner, 1877-1880), his two commentaries on Porphyry's Isagoge by S. Brandt, Corpus Scriptorum Ecclesiasticorum Latinorum 48 (Leipzig: G. Freytag, Vienna: F.Tempsky, 1906), De hypotheticis syllogismis by L. Obertello (Brescia: Paideia, 1969) and De divisione by J. Magee, with a translation and commentary (Leiden: Brill, 1998). Some other ancient works were also used, such as Apuleius's Peri hermeneias (ed. C. Moreschini in Opera III (Stuttgart: Teubner, 1991), Augustine's Dialectica, trans, with notes by B.D. Jackson from the text edited by J. Pinborg, Synthese Historical Library 16 (Dordrecht: Reidel, 1975), and pseudo-Augustinean De decern categoriis, ed. L. Minio-Paluello, in Aristoteles Latinus 1.1-5, 133-75. For the sources of eleventh and twelfth century logic, see J. Marenbon, 'Medieval Latin Commentaries and Glosses on Aristotelian Logical Texts, Before c. 1150 AD' in Ch. Burnett (ed.), Glosses and Commentaries on Aristotelian Logical Tezts (Warburg Institute Surveys and Texts 23), (London: Warburg Institute, 1993), 77-127, republished and revised in J. Marenbon, Aristotelian Logic, Platonism, and the Contezt of Early Medieval Philosophy in the West, Variorum Collected Studies Series (Aldershot: Ashgate, 2000). 2Analytica priora, ed. L. Minio-Paluello, Aristoteles Latinus III.l-4 (Bruges-Paris: Descl~e de Brouwer, 1962), Analytica posteriora, ed. L. Minio-Paluello and B.G. Dod, Aristoteles Latinns IV.l-4 (Bruges-Paris: Descl~e de Brouwer, 1968), Topica, ed. L. Minio-Paluello and B.G.