Redox-Switchable Chromophores Based on Metal (Ni, Pd, Pt) Mixed-Ligand Dithiolene Complexes Showing Molecular Second-Order Nonlinear-Optical Activity

Abstract

The synthesis and full characterization of the redox-active nickel triad mixed-ligand dithiolene complexes based on Bz(2)pipdt = 1,4-dibenzylpiperazine-3,2-dithione and dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate ligands are reported. These complexes show a reversibly bleacheable solvatochromic peak and a remarkably high negative molecular first hyperpolarizability, whose values depend on the metal being highest for the platinum(II) compound.

High Second-Order NLO Response Exhibited by the First Example of Polymeric Film Incorporating a Diimine–Dithiolate Square-Planar Complex: The [Ni(o-phen)(bdt)]

“…In 1 the solvatochromic effect is remarkably smaller (26 nm) than those found for other diimine− dithiolate 30,31,69 and dithione−dithiolate 20,21 complexes (80− 140 nm). Furthermore, the energies of the maxima of the solvatochromic bands present a linear behavior vs solvent polarity parameters (r 2 > 0.939) as proposed by Eisenberg for several Pt-diimine−dithiolate compounds 69 ( Figure S6a); as expected, the solvatochromic shift, obtained from the plot's slope, is smaller (0.074) than those reported in ref 69 and for other push−pull compounds 20,21,30,31 in agreement with the smaller solvatochromic effect exhibited by 1. A similar trend (r 2 > 0.938) is also observed when Reichardt's solvent polarity parameters are used ( Figure S6b).…”

Expanding the Scope of Ligand Substitution from [M(S2C2Ph2] (M = Ni2+, Pd2+, Pt2+) To Afford New Heteroleptic Dithiolene Complexes

“…Compounds of this type, so called "pushpull" complexes, have elicited interest for possible applications arising from their nonlinear optical properties. Previously reported examples of this compound type have the S=CS2C2S2 2-(dimercaptoisotrithione ligand(2-), dmit) and have made by an alternate, less direct route involving the transfer of dmit(2-) from [ n Bu4N]2[M(dmit)2] to [M(R2pipdt)Cl2] and displacementof Clupon mixing solution samples [34][35][36]. Ligands that do not displace dithiolene from [M(S2C2Ph2)2] include [C≡N] 1-, which instead reduces the compound by one electron (Scheme 2), presumably forming cyanogen as byproduct.The [Ni(S2C2Ph2)2] 1anion was identified structurally as its Et4N + salt 37.…”

Synthesis, structure and solid-state electrical conductivity of bis(1,2-diphenylethylene-1,2-dithiolate)nickel(II)

“…[1][2][3] Later on, these were found to have its application in biology 4,5 and more importantly in material science. [6][7][8][9][10] In the latter area dithiolene complexes were found to be conducting, 6,7 catalytic, 8 non-linear optical, 9 near IR absorbing, 10 etc. The high electrical conductivity by pure metals is due to its enough overlap of atomic orbitals to produce the conduction path.…”