Effects of metal substitution on third-order optical non-linearity of porphyrin macrocycle

The effects of axial ligands in Sn(IV)-substituted 5,10,15,20-tetrakis [4-(carboethoxymethyleneoxy)phenyl]porphyrin and divalent transition metal substitution in 5,10,15,20-tetraphenylporphyrin on the second molecular hyperpolarizability (gamma) at 802 nm were studied using the Z-scan technique. A significant increase in gamma for divalent metal ions is observed with decreasing d-shell occupancy. In the case of the tetravalent metal-substituted porphyrin a dramatic enhancement of gamma is seen when a strongly electronegative axial ligand such as I-2 is attached to the metal ion. A plausible explanation for the observed trend of gamma has been sought in terms of metal-ligand interaction. Copyright (C) 1999 , Ltd