Research On Synthesis And Properties Of Organic Photochromic Materials And Distyrylbenzene Fluorescent Materials

Optical functional organic materials with have been applied widely, andthe research on the synthesis, mechanism and fabrication of photo-functionalmaterials has just been growing up. In this dissertation, in order to solve theproblems of existing photochromic materials and fluorescent materials,several novel molecules have been synthesized, and their optical propertiesand applications have been studied.For photochrmic materials, the poor thermal stability as well as the weakfatigue resistance restricted them from broader utility， three kinds ofphotochromic molecules was designed: indolo[2,1-b][1,3]benzoxazinederivatives, photo-crosslinkable spiropyran derivatives, quinoline modifieddiarylethene derivatives. And the application of photochrmic materials inphoto-responsive surface wettability and fluorescence switch was studied. Asluminescent materials, the poor solubility and low luminous efficiency ofpoly(para-phenylene vinylene) restricts its practical application, the1,4-bis(2’-arylvinyl)benzene derivates was studied, their luminousperformance and energy level can be altered through the modification ofdifferent substituents.The detailed content is as follows:(1)2-nitro-5a,6,6-trimethyl-5a,6-dihydro-12H-indolo[2,1-b][1,3]benzo-xazines (BO) were synthesized as a novel photochromic compound. Thefast re-isomerization of the ring-opened species can be trapped by the addition of organic alkali. In protic solvents, the stabilizing effect of theorganic alkali disappeared. As the refractive index increased, the absorptionwavelengths of the stable colored species in aprotic solvents have red shift.The fast isomerization and excellent fatigue resistance of BO offer theopportunity to applied in optical switches, and molecular-scale logic circuits.(2) Bifunctional compounds with chalcone group and spiropyran groupwere synthesized, and used to prepare photosensitive films by spin-coating.Under the UV light irradiation, the photocrosslinking reaction betweenchalcone units, and photoinduced ring-opening reaction from spiropyran tomerocyanine proceeded coincidently. The stability of colored merocyanineform of spiropyran has been improved, due to the increasing of sterichindrances by photocycloaddition of chalcone moieties.(3) Two quinoline modified diarylethene derivatives were synthesized, theratio of the photoactive anti-parallel conformation was increased to67%duoto the quinoline group. The red shift of the absorption spectra showedquinoline group expanded the conjugated system. The time constant of thecyclization under UV irradiation is38.69s and41.63s, and the time constantof the reversion process under visible light irradiation is56.03s and59.51s,both of them belong to the first order reaction. And the recycling processshowed exellent fatigue resistence. Protonation by CF3COOH increased theratio of anti-parallel conformation.(4) Photo-responsive glass surfaces were obtained by modification ofsilane coupling agents and spiropyran derivates through N-alkylation orradical reaction. Spiropyran undergo a reversible transition from a closed, nonpolar form to a highly polar, open form when irradiated with UV light,yields the spiropyran coating surface more hydrophilic, contact angle changesfrom83o to76o. With the irradiation of visible light, glass surface convertedback to the relative hydrophobic status.(5) A new type of photochromic nanoparticles based on spiropyran wereprepared by means of a modified miniemulsion polymerization process. Theaverage particle size was less than65nm, PDI was less than0.15. Thethermal stability of the spiropyran colored form in the polymericnanoparticles was greatly increased, which could be attributed to that the freevolume of polymer was reduced by the cross-linking reaction inpolymerization process, and the protective microenvironment provided by thepolymeric matrix.(6) A novel type of fluorescent photoswitchable nanohybrid compositeswith average particle size less than50nm were obtained by means of thesame miniemulsion polymerization process. The nanohybrid compositesexhibited excellent fluorescent photoswitchable performance due to theefficient photo-induced intermolecular energy transfer between thefluorescent dyes and the open form of spiropyran. The nanohybridincorporated with highly hydrophobic, photostable perylene-based SG5showed the best fluorescence photoswitching performance(0.625/0.001).(7) A series of substituents modified1,4-bis(2’-arylvinyl)benzenederivates were synthesized, compared with non-substituent1,4-distyrylbenzen，their maxium absorption wavelength and fluorescenceemission wavelength are all red-shifted. Compounds with triphenyl amino or carbazole group have significantly red shifts, and high quantum yield(0.32,0.43) blue fluorescence, due to the extension of the conjugated system.Solvent effect on absorption and fluorescence spectra was investigated. Theenergy levels of the compouds were measured from the absorption spectraand cyclic voltammetry, the results showed that the compounds modifiedwith triphenyl amino and carbazole groups are potential hole transportingmaterials.This work provides the abundant experiment data which are significantfor the design, device fabrication and application of these photochromicmaterials and fluorescent materials.