Third-order susceptibilities of asymmetric pentaazadentate porphyrin-like metal complexes

The third-order nonlinear optical properties of a series of asymmetric pent aazadentate porphyrin-like metal complexes ([(R-APPC)M]Cl-n) with different conjugated R groups and metal centers have been investigated by degenerate four wave mixing experiments using 40 ps laser pulses at 532 nm. The molec ular second-order hyperpolarizabilities (gamma) for these complexes range f rom 1.1X10(-31) to 1.2X10(-30) esu and depend strongly on both the nature o f the metal and the R group. The gamma values of the [(R-APPC)Cd]Cl complex es are 2-7 times larger than those of PbPc(CP)(4) and SiNc, two of the most promising nonlinear optical materials for optical limiting applications. M easurements of the individual components of the chi((3)) tensor indicate th at the nonlinearity is predominantly electronic in origin when 40 ps laser pulses are used. (C) 1999 American Institute of Physics. [S0003-6951(99)020 22-7].