A calix[4]resorcinarene-based hyper-structured molecule bearing disperse red 1 as the chromophore with enhanced photorefractive performance under non-electric field

A hyper-structured molecule (HSM) CRA-DR1 and a model molecule Ph-DR1 for photorefractive (PR) application under non-electric field were designed and synthesized via highly reactive "click" reaction between alkynyl derivatives of calix [4]resorcinarene (CRA) or resorcinol and an azide derivative of disperse red 1 (DR1) in satisfactory yields. XRD pattern and UV-Vis absorption spectra indicated that the CRA-DR1 with three-dimensional (3D) CRA core could effectively decrease the aggregation, packing and crystallization of the nonlinear optical (NLO) chromophores. AFM images showed a smooth and pinhole-free morphology of the CRA-DR1 film. Two-beam coupling (TBC) experiment was used to test the photorefractive performance in optically transparent films of Ph-DR1 and CRA-DR1 doped with [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) as a photo-sensitizer and N-ethyl-carbazole (ECz) as a plasticizer. Without poling and without external electric filed, the coupling gain coefficient obtained in the CRA-DR1-based composite is 147.4 cm(-1), which is higher than that of Ph-DR1-based composite (132.6 cm(-1)) owing to its asymmetrical 3D CRA core. Coupled with its convenient synthesis and commercial DR1, CRA-DR1 could serve as a good candidate for PR application.