Push-pull arylethynyl porphyrins: New chromophores that exhibit large molecular first-order hyperpolarizabilities

A new class of chromophores has been fabricated that features both electron-releasing and electron-withdrawing groups fused via an intervening ethynyl moiety to the carbon framework of a (porphinato)metal complex. These species possess large molecular first-order hyperpolarizabilities (beta). We report herein the synthesis, optical spectroscopy, and the hyper-Rayleigh scattering data used to determine the beta values of two archetypal members of this new class of exceptional nonlinear chromophores: [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4'-nitrophenyl)-ethynyl]-10,20-diphenylporphinato]copper and [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]- -10,20-diphenylporphinato]zinc(II). One of these compounds, [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), possesses beta values near 5000 x 10(-30) esu at incident irradiation wavelengths of both 830 and 1064 nm. These studies suggest that this chromophoric structural motif may find utility in the development of electrooptic devices as well as materials for efficient frequency doubling of incident irradiation (second harmonic generation).