The unexpected similar second-order NLO response for nearly planar and largely twisted push-pull stilbazole chromophores: EFISH and theoretical TD-DFT evidence.

The molecular second-order nonlinear optical properties of planar (E)-4-[2-(4-(N-methyl-N-hexadecylaminophenyl)ethenyl]pyridine (L1) and [cis-Ir(CO)2ClL1] and of the significantly twisted new chromophores (E)-4-[(5,6,7,8-tetrahydro-5-isoquinolylidene)methyl]-N-methyl-N-hexadecylaniline (L2) and [cis-Ir(CO)2ClL2] are reported, evidencing for the first time that planarity of a conventional (donor)(pi-bridge)(acceptor) structure is not compulsory to reach a large NLO response.