Study On Stimulus Response Property And Application Of Cyanostilbene Derivatives

Organic fluorescent materials are widely used in optoelectronic materials,information storage,chemical sensing,biological imaging etc,due to their advantages of easy modification and design.Organic fluorescent materials produce fluorescence changes under external stimulation,which is called stimulus-responsive fluorescent materials.Since most of the fluorophores in the aggregate state will produce aggregation-caused quenching(ACQ),the fluorescence in solid state is very weak and difficult to observe,which will reduce the stimulus response ability.Therefore,using simple strategies to design and synthesize solid-state luminescent materials and to explore the relationship between structure and stimulus responsiveness is a hot topic of current research.It is very important to construct stimulus-responsive fluorescent materials,select appropriate fluorophore and design the environment in which the molecule is located.First,the fluorophore should have the characteristics of high fluorescence quantum yield and easy modification in solid state.Secondly,the energy exchange between the fluorescence molecule and the environment may make the fluorescence of the fluorophore increase or decrease or the emission location move.Therefore,it is necessary to build a suitable environment for the fluorophore to enhance its luminescent properties.In this paper,based on cyanostilbene,we firstly introduced appropriate responsive groups and rigid molecular environment to obtain turn-on solid fluorescent materials that can respond to acid and base.Secondly,it was used as ligand to synthesize metal-organic frame material,and the effect of solvent on the fluorescence of the frame material was studied.The details are as follows:System 1:A molecule ACN-1 with acid-base double stimulation fluorescence response was synthesized by replacing cyano-stilbene benzene ring with pyridine group and phenol group.Based on the EI-Sayed rule,the two groups simultaneously provide the lone pair electron,which promotes the intermolecular cross-transfer,resulting in the non-fluorescence of molecular ACN-1.After acid stimulation,it showed yellow fluorescence.After alkali stimulation,it showed green fluorescence.Realize high contrast fluorescence"turn-on",two different color fluorescence change.Further loading the molecules onto the cellulose filter paper can still achieve the same fluorescence response behavior,and the fluorescence intensity is greatly improved,to achieve the amplification of response effect.The material has great applications in the fields of anti-counterfeiting ink,information storage and so on.System 2:By modifying formic acid groups on both sides of cyanostilbene,the molecular CNS-2COOH with coordination function was formed,which was assembled with Zn and Zr metals respectively to form a metal-organic framework CNS-Zn/Zr-MOF.Among them,Zn-MOF,stimulated by different organic solvents,can realize the color change from blue fluorescence to green fluorescence and cross color gamut.However,the fluorescence intensity of ZrMOF was significantly increased after acid stimulation,showing a fluorescent"turn-on" behavior.The underlying mechanism is that the solvent affects the conformation and stacking of the molecule in MOF.CNS-Zn-MOF and CNSZr-MOF have expanded the stimulus response fluorescent material library.