Facile Synthesis and Nonlinear Optical Properties of Push-Pull 5,15-Diphenylporphyrins.

A series of 5,15-diphenylporphyrinatonickel(II) derivatives containing electron-releasing (Me2NC6H4C⋮C−) and -withdrawing groups [−CHO, −CHC(CN)2, −CHC(CO2Et)2, −CHCHCHO] in opposite meso positions has been synthesized through the classical formylation, halogenation, Knoevenagel condensation, and palladium-catalyzed cross-coupling reaction of porphyrins. The molecular first hyperpolarizabilities (β) of two of these push−pull porphyrins, namely 5-(2‘,2‘-dicyanoethenyl)-15-[[4‘‘-(N,N-dimethylamino)phenyl]ethynyl]-10,20-diphenylporphyrinatonickel(II) (7) and 5-formyl-15-[[4‘-(N,N-dimethylamino)phenyl]ethynyl]-10,20-diphenylporphyrinatonickel(II) (8) have been determined experimentally by electric-field-induced second-harmonic generation (EFISH) at 1907 nm and computationally by semiempirical methods (ZINDO sum-over-states). The values of βμ (124 and 66 × 10-30 cm5 esu-1, for 7 and 8, respectively) are moderate because the acceptor group is significantly tilted with respect to the porphyrin core in these comp...