Photorefractive hyper-structured molecular glasses constructed by calix[4]resorcinarene core and carbazole-based methine nonlinear optical chromophore.

Seven C- methylcalix[4]resorcinarene (CRA)-based photorefractive (PR) hyper-structured molecular glasses (HSMGs) containing carbazole-based methine nonlinear optical (NLO) chromophores were designed and synthesized via esterification between carboxyl-containing asymmetric CRA core molecule and hydroxyl-containing functional compounds. When the feed ratio of hydroxyl-containing NLO functional compounds to carboxyl groups of CRA-COOH was kept at 1.5/1 by mole, the degree of introduction of NLO chromophore to the CRA core was above 70%. All the HSMGs show low glass transition temperatures ( T g ), and good solubility in common low boiling point solvents such as THF, CHCl 3 , etc . Powder XRD and UV–vis absorption in films of HSMGs indicate that the aggregation, packing and crystallization of the NLO chromophores in these HSMGs had been effectively reduced. Doping with N -ethyl-carbazole (ECz) as a plasticizer and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) as a photosensitizer, all the HSMGs composites showed good PR effects. All the coupling gain coefficients ( Γ ) of HSMGs-based composites are about twice to the corresponding small molecular NLO chromophores-based composites, thanks to the decreased NLO chromophores antiparallel packing caused by the asymmetric CRA core. Among them, CRA-CSN/ECz/PCBM (69:30:1, wt%) composite exhibited the best performance with the Γ value of 78.2 cm −1 at the external electric field of 12.5 V μm −1 , which is one of the best performance in molecular glasses under the same test conditions. Coupled with their convenient synthesis, this work will provide a new simple design strategy for organic PR materials. [ABSTRACT FROM AUTHOR]