Molecular Nonlinear Optical Properties of Acceptors Substituted 2,2′-Bipyridine and 1,10-Phenathroline Complexes of Nickel Dithiolate

Abstract

Linear and nonlinear optical properties of two new nickel(diimine)(dithiolate) complexes, nickel(4,4′-dinitro2,2′-bipyridyl)(tfd), Ni(NO2bipy)(tfd), (tfd = 1,2-trifluoromethylethene-1,2-dithiolate) and nickel(4,7-diphenyl-1,10-phenathroline)(tfd), Ni(dpphen)(tfd) are reported. Ni(NO2bipy)(tfd) has a potent electronic acceptor substituted on the diimine ligand and exhibits an enhanced molecular first hyperpolarizability (β0 = −31 × 10−30 esu), which is more than three times greater than that (β0 = −10 × 10−30 esu) of Ni(dpphen)(tfd). Ni(NO2bipy)(tfd) also possesses the longest absorption wavelength, the largest solvatochromic shift, and one of the largest dipole moment changes (-16 debye from ground to excited state) among nickel(diimine)(dithiolate) complexes. Crystal X-ray structure of Ni(NO2bipy)(tfd) is used to compared the π-bonding structure of central (N=C-C=N)Ni(S-C=C-S) unit with that of previously known nickel(4,4′-bis(butyloxycarbonyl)-2,2′-bipyridyl)(tfd), Ni(CO2Bubipy)(tfd).