Study On Design,Synthesis And Property Of Novel Photofunctional Molecules

Organoluminescent molecules are the research focus in the field of optical functional materials.Among them,organic solid-state light-emitting materials are an important part of photoelectric devices,and have widely been used in organic light-emitting diodes,organic solid-state fluorescence sensors,organic solid-state lasers and other fields.When the optical functional materials are stimulated by the surrounding environment,their fluorescence emission will change,so that people can learn about the characteristics of the surrounding environment or some specific information in the environment.In this paper,the structure design and properties of novel organic conjugated molecules with optical functions are studied,and the specific work includes:the synthesis and photophysical properties of novel indolium derivatives;the synthesis and photophysical properties of new class fluorescent probe molecules based on naphthalimide-aniline derivative;the synthesis and properties of novel indolium spiropyrans photochromic compounds.The following innovative research results have been obtained:1.Four new fluorescent molecules,5-(4-ethoxyphenyl)-2,3,3-trimethyl-3H-indole(PI),N,N-dimethyl-4-(2,3,3-trimethyl-3H-indol-5-yl)aniline(NI),N,N-diphenyl-4(2,3,3-trimethyl-3H-indol-5-yl)aniline(TI)and 2,3,3-trimethyl-5-(4-(trifluoromethyl)phenyl)-3H-indole(FI),were synthesized by attaching phenyl-based derivatives to the indolium moiety.As D-?-A compounds,the solutions of PI,NI,TI and FI show a variable red-shifted emission owing to the different push-pull electronic effects of substituents.The solutions of PI,NI,TI and FI all have sensitive and specific responses to protons.With the change of environmental pH,their luminescence properties have specific changes,which can be well applied in the field of proton sensors.PI solution has a triple response to proton concentration,showing its potential in the field of logic gates.For the four new fluorescent molecules,their crystallization and precipitation samples show multiple chromism effects and varied fluorescence.In this work,the principle of the change of luminescence properties was also discussed,providing a design idea for the study of multi-functional fluorescent probes.2.Four new schiff bases chromophores NP-N1,NP-N2,NP-EN1 and NP-EN2 were designed and synthesized.The results show that the four molecules have excellent thermal properties and very small energy gaps.Thanks to their twisted structures,the four chromophores experienced little ?-? stacking interaction in their condensed phase and therefore exhibited obvious fluorescence emission in the solid state.In addition,they underwent dramatic fluorescence change upon addition of acid as a result of the protonation of the nitrogen atoms in solution or in a solid state.The difference of functional groups can change the protonation site,which results in the change of the display law of fluorescence signal.The four new schiff bases chromophores showed high selectivity and sensitivity for metal ions and H+in DMF solution due to the electrostatic interaction and complexation mechanisms which influence C=N isomerization.The long chain-N-CH2-CH2-N=C-bonded in the molecule makes it easier for the molecule to interact with metal ions.Such novel chromophores with AIE property and sensitive response to H+and ions may hold great potential for applications in biological testing and material science.3.Based on the previous work of the research group about novel indolium spiropyran derivative(BI-NO2),another three derivative(BI-F,BI-H and BI-CH3)were synthesized.The effect of the push-pull electron capacity of the substituents on the discoloration of spiropyran was investigated,which can provide effective reference value for the subsequent molecular design and property regulation of photochromic spiropyran.It is found that the different substituents on benzopyranes have a great influence on the stability of the colored body,and only when the electronegativity of the substituents is strong enough can the molecular exhibit excellent photochromic properties.In addition,the series of molecules designed in this work introduced bromine atoms into the indolium ring making the molecules more easily to be modified,thus further expanding the functions of the molecules.