Synthesis And Characterization Of Calix[4]resorcinarene-based Star-shaped Hyper-structure Molecules

Photorefractive materials are materials that combine photoconductivity andnonlinear optical (NLO) response to modulate the refractive index of the medium.Photorefractive hyper-structured molecules (HSM) combine the necessary factorssuch as NLO chromophore, hole-transporting group, into a complex moleculethrough covalent bonds. Compared with small organic glass, HSM have betterfilm-forming ability, higher mechanical strength and lower crystallizability, whichresult from its much higher molecular weight and three-dimensional (3-D) structure.Furthermore,3-D structure of HSM could provide necessary free volume forchromophore reorientation, which is consistent with the expectation for PR materials.Resorcinarenes (CRA) can be easily synthesized and their derivatives have goodsolubility in some common solvents. Using the derivative of CRA as a core, carbazoleas hole-transporting group and nitro azobenzene as NLO chromotography, severalHSMs were synthesized. Their chemical stuctures, polydispersity index, opticalproperties and thermal properties were characterized through NMR, Ft-IR, EA, GPC,UV-vis, TG, etc.Firstly, in order to investigate the complex HSM based on CRA, two simplemodel compounds R-Cz and R-Cz-Azo were synthesized. R-OH with two hydroxylgroups linking to benzene ring via ethylene was synthesized from resorcinol. ThenR-Cz and R-Cz-Azo were prepared by esterification reaction of R-OH with Cz3containing functional carbazole groups and Cz4with containing nitro azobenzene,respectively. R-Cz shows absorption in the range of300~350nm, which ischaracteristic absorption peaks of carbazole group. R-Cz-Azo shows the absorption inthe range of430~500nm, which can ascribe to the absorption of azobenzene group.And in the Ft-IR spectrum of R-Cz-Azo, the peak at1519cm-1is the asymmetricstretching vibration of right position on azobenzene NO2.Secondly, Four CRA-H-Cz-xAzo HSMs based on CRA were synthesized andcharacterized, where x represent the theoretical number of feed NLO chromophoreamong total monomer. CRA-OH with eight hydroxyl groups linking to CRA backbone via ethylene was synthesized from CRA through two steps. Thecorresponding star-shaped hyper-structure molecules CRA-H-Cz, CRA-H-Cz-8Azo,CRA-H-Cz-2Azo and CRA-H-Cz-4Azo were prepared by the esterification reactionof CRA-OH with Cz3and Cz4, respectively. Their chemical structures were verifiedby NMR, Ft-IR, UV-vis and EA. The target products have good solubility, and highthermal decomposition temperature (Td). The Tdof CRA-H-Cz, CRA-H-Cz-8Azo,CRA-H-Cz-2Azo and CRA-H-Cz-4Azo is268℃,242℃,238℃and245℃,respectively, which can meet the operating temperature range of photorefractivematerial. Moreover, the Tgof CRA-H-Cz and CRA-H-Cz-8Azo is30℃and35℃,respectively, closely to room temperature. It is very beneficial to the use ofphotorefractive materials.