Spectroscopic Performance Of Spiropyran In Different Media And The Applications In Environmental Detection

The spectroscopic performance of the optical functional spiropyran is profoundlyinfluenced by different circumstance factors. In this thesis, the thermodynamic andkinetic behaviors of the photochromism of spiropyran in different solvents, and therelationships between the different intermolecular interactions and thesolvatochromism of spiropyran and the impact of different media on the fluorescenceof spiropyran as well are investigated in details. Per the conclusions obtained, thesynthesized fluorescent spiropyran cellulose material was successfully exploited for thedetection of aniline in environment.The spiropyran molecules containing alkyl or carboxyl moiety were synthesizedaccording to the general routine and the chemical structures of the objective compoundswere characterized by FTIR and1HNMR.The investigation into the thermodynamic and kinetic behaviors of thephotochromism of spiropyran in different solvents with a scale of polarity fromethylene glycol to petroleum ether was conducted by UV-Vis. The results indicate thatthe change of polarity of solvents can reverse the negative or positive photochromicprocess of spiropyran. Therefore, the definitions of negative/positive chromism wereproperly modified from a thermodynamic perspective. In solvents of moderate polarity,the spiropyran behaves the first order kinetics, however, it is completely different at theboth ends of the polarity scale. In extremely nonpolar solvents, it exhibits the stepwisefirst-order kinetics, while in the highly polar solvents, the fractional order kinetics.The discrete behavior of alcohols in the plots between the solatochromic propertiesof spiropyran with respect to the polarity of solvents was observed. Hansen solubilityparameter is originally employed to analyze the effects of different intermolecularinteraction on the solvatochromism of spiropyran. The consistency of the theoreticaldeduction and the experimental results proves that λmaxshift is dominated only by the polarity and hydrogen bonding, but for the absorbance at λmax, the dispersion forcecannot be overlooked.When the spiropyran that scarcely exhibit fluorescence in solution was appendedon to cellulose matrix, the synergy of the high polar interior environment, theconformational constraint in cellulose cavities and and the elimination of the solventinfluence enhances the ratio of merocyanine and its quantum yield, and thensubstantially improves the fluorescence of spiropyran.The UV-Vis spectra of spiropyran shows a selective absorption in aniline solutionand the existing of aniline also can quench the fluorescence of the spiropyran cellulosepaper. Herein，the experiments attempted to detect the spilled aniline in environmentbased on UV-Vis spectra of spiropyran and the fluorescent response of spiropyrancellulose paper were conducted. Finally, a comprehensive method for colormetric andfluorometric detections of aniline in environment is proposed and it works well.