Study On Molecule Probes With Aggregation-Induced Emission Characteristics And A Photo-Controllable Third-Order Nonlinear Optical Switch Metal Complex

Optical functional materials have constantly attracted considerable attention because their potential applications in optical information storage,sensor,optical communications,optical data processing,anti-counterfeiting technology and laser protection.In this dissertation,a series of fluorescent probes with aggregation-induced emission characteristics and a photo-controllable third-order nonlinear optical switch metal complex based on salicylaldehyde derivatives have been designed and synthesized.Firstly,three kinds of 4-N,N-dimethylaminoaniline salicylaldehyde Schiff-base derivatives substituted with different electron-donor/acceptor groups were designed and facilely prepared.They exhibit typical AIE properties with various fluorescence emissions from green to red and high fluorescence quantum yield in aggregated state.These compounds exhibit unique p H-dependent optical properties.Different compound shows different titration jump p H,which indicated their potential application prospects in p H sensing.Compared with the carbon-nitrogen double-bond in general Schiff-base compounds,the three compounds exhibited higher activities:the electron donor group of N,N-dimethylamino in the three compounds increases the electron density of carbon-nitrogen double-bond,which could be broken easily by proton electrophilic substitution.The three compounds can be hydrolyzed in acid conditions with different p H,resulting in nonluminous mixture of4-N,N-dimethylaminoaniline and corresponding salicylaldehyde derivatives.Secondly,a benzothiazole-based aggregation-induced emission luminogen of2-(5-(4-carboxyphenyl)-2-hydroxyphenyl)benzothiazole was designed and synthesized,which exhibited multi-fluorescence emissions in different dispersed or aggregated state.The compound was successfully used as a ratiometric fluorescent chemosensor for the detection of p H,which exhibited reversible acid/base-switched yellow/cyan emission transition.More importantly,the p H jump of the compound was very precipitous from 7.0 to 8.0 with a midpoint of 7.5,which was well matched with the physiological p H.This feature makes the compound very suitable for the highly sensitive detection of p H fluctuation in biosamples and neutral water samples.The compound was also successfully used as a ratiometric fluorescence chemosensor for the detection of acidic and basic organic vapors in test papers.Thirdly,furan-2-carbohydrazide-5-(2-thienyl)-salicylaldehyde Schiff base was designed and synthesized for the detection of Zn(II)in aqueous solution at neutral p H.The compound exhibited aggregation-induced emission characteristic with a fluorescence emission at 567 nm,after binding to Zn(II)with a molar ratio of 1:1,the compound showed a new fluorescence emission peak at 493 nm and exhibited a70-fold fluorescence enhancement.Meanwhile,a significant emission color change from orange-red to yellow was observed,enabling detecting Zn(II)by naked eye under illumination with a UV lamp.In addition,the chemosensor could distinguish Zn(II)from most of the common metal ions effectively.A linear range of 0.10-10.00μmol/L and a detection limit of 77 nmol/L Zn(II)were achieved.Finally,a novel photo-controllable third-order nonlinear optical(NLO)switch based on rhodamine B salicylaldehyde hydrazone metal complex was developed.The complex was found to undergo reversible intramolecular spirolactam ring-open reaction upon UV irradiation,which led to distinct third-order NLO properties change.Before light irradiation,the complex in its spirolactam ring-close form exhibited no NLO property.After light irradiation,the complex turned to its spirolactam ring-open form and exhibited strong NLO properties of self-focusing refraction and saturable absorption.The third-order NLO responses of the complex were investigated systematically by top-hat Z-scan and time-resolved pump-probe with phase object(PO-pump-probe)techniques.These results showed that the π-conjugation of rhodamine xanthen part is indispensable for third-order NLO properties.More importantly,the first excited singlet state lifetime of the complex is remarkably shorter than that of corresponding rhodamine B dye,which suggests that the complex not only could be used as photo-controlled switch with excellent reversibility and fatigue resistance,but also could be used as third-order NLO switch with fast recovery rate.