The influence on properties with different conjugated direction of phenoxazine and phenothiazine-based chromophores for organic nonlinear optical materials

A serial of phenoxazine and phenothiazine based organic chromophores were synthesized with facile routes. Then these chromophores were applied in organic nonlinear optical materials to study the effect of different conjugated direction, extra phenyl ring and alkyl chain on the decomposition temperature, energy level, photophysical properties through Uv–vis spectral, density functional theory calculations. The electro-optic coefficient of poled films containing these chromophores doped in amorphous polycarbonate afforded the largest values of 19 pm/V, 49 pm/V and 23 pm/V at 1310 nm for chromophores B, L1 and L2 respectively. To our regret, chromophore A is not stable enough for test. The geometries of the chromophores were optimized to gain insight into the molecular structure and electron distribution. These results showed that when the phenyl ring was added in chromophore A, B, nearly 90°of the dihedral angle between PTZ and phenyl ring unit leads to the intramolecular charge transfer transition (HOMO-LUMO) being prohibited and showed a smaller hyperpolarizability (β) value.