Second-order non-linear optical response of metallo-organic compounds: towards switchable materials

A series of coordination compounds, [M(PM-L)(2)(NCS)(2)], with large aromat ic ligands (PM-L) and a divalent metal ion (M-II = Mn, Fe, Co, Ni and Zn) h ave been synthesized. The magnetic data are consistent with divalent metal ions in an octahedral ligand field environment. Hyper-Rayleigh scattering m easurements show an enhancement of the molecular hyperpolarizabilities (bet a) from Ni compounds (with two unpaired electrons) to Mn compounds (five un paired electrons). In the case of the Fe(LI) metal ion, the influence of th e ligand on the beta values is reported. This work provides attractive info rmation for the design of switchable materials based on the spin-crossover phenomenon. (C) 2000 Elsevier Science B.V. All rights reserved.