Switching properties of fluorescent photochromic poly(methyl methacrylate) with spironaphthoxazine and D-π-A type pyran-based fluorescent dye.
Fluorescent photochromic poly(methyl methacrylate) (PMMA) with spironaphthoxazine (SPO) and D-π-A type pyran-base fluorescent dye as a fluorophore was synthesized by typical free radical copolymerization. The poly(MMA-co-SPO-co-fluorophore) in both solution and solid film exhibited excellent photoregulated fluorescence switching behavior and reversible modulation of fluorescence intensity using alternating irradiation with UV and visible light. The poly(MMA-co-SPO-co-fluorophore) also showed viscosity and conductivity switching behaviors along with photoresponse.
Synthesis and properties of photochromic spirooxazine with aggregation-induced emission fluorophores polymeric nanoparticles
Abstract We designed and synthesized photochromic fluorescent poly (MMA-co-SPO-co-TPE) nanoparticles with pendant spirooxazine (SPO) dye and tetraphenylethylene (TPE) fuorophores attached to poly (methyl methacrylate) (MMA) backbone by semi-continuous polymerization. The polymerization reactions were accomplished in water with randomly methylated-β-cyclodextrin (β-CD) at 80 °C in the presence of potassium peroxodisulfate which can be used as free radical initiator. This new synthetic method leads to uniform and smooth nanoparticles with a narrow particle size distribution. In addition, the poly (MMA-co-SPO-co-TPE) nanoparticles exhibit aggregation induced emission (AIE) properties and excellent photochemical properties because of spirooxazine dyes convert reversibly to merocyanine form upon ultraviolet (UV) irradiation, which active the intramolecular energy transfer pathway and quench the fluorescence of TPE in polymers. Consequently, the fluorescence of the poly (MMA-co-SPO-co-TPE) nanoparticles can be reversibly switched “on” and “off” upon UV and visible light, which maybe have potential application in biological fluorescent labeling as well as in optical fields like individually light–addressable nanoscale devices.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
An ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl-rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires-Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires-Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires-Nafion modified electrode.