Synthesis, Electronic Characterisation and Significant Second‐Order Non‐Linear Optical Responses of meso ‐Tetraphenylporphyrins and Their Zn II Complexes Carrying a Push or Pull Group in the β Pyrrolic Position

This work describes the synthesis and characterisation by electronic absorption spectroscopy, cyclic voltammetry and by a solvatochromic investigation of meso ‐tetraphenylporphyrins and their Zn II complexes substituted at the β pyrrolic position by a pseudo‐linear, π‐delocalised organic linker carrying either an electron‐withdrawing (pull) or electron‐donating (push) group. The second‐order NLO response of these push‐pull porphyrinic chromophores has been investigated by the EFISH technique working with a non‐resonant incident wavelength of 1.907 µ;m. The porphyrin ring substituted at the β pyrrolic position by an electron‐acceptor π‐system behaves as a significant donor group, comparable to a ferrocenyl group or to a phthalocyanine. Unexpectedly, the porphyrin ring substituted at the β pyrrolic position with an electron‐donor π‐system shows a larger and significant second‐order NLO response. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)