Synthesis, crystal structure and large third-order nonlinear optical properties of two novel nest-shaped clusters [MOS3Cu3(SCN)(Py)5] (M=Mo, W)

Abstract

Two new candidates for nonlinear optical (NLO) materials, [MoOS₃Cu₃(SCN)(Py)₅] (1) and [WOS₃Cu₃(SCN)(Py)₅] (2), were synthesized. They show nest-shaped skeletal structure. The crystal structure of compound (1) was characterized by X-ray diffraction. The NLO properties of 1 and 2 were determined through the Z-scan technique. [MoOS₃Cu₃(SCN)(Py)₅] exhibits both very strong NLO absorption and a self-defocusing effect, α₂=4.8×10^-10 m W^-1 and n₂=-6.8×10^-17 W^-1 in a 2.0×10^-5 mol dm^-3 acetonitrile solution. NLO properties of compound [WOS₃Cu₃(SCN)(Py)₅] are similar to those of [MoOS₃Cu₃(SCN)(Py)₅], strong NLO absorption and self-defocusing effect, α₂=6×10^-11 m W^-1 and n₂=-1.2×10^-17 W^-1, when measured in a 1.9×10^-5 mol dm^-3 DMF solution. Their hyperpolarizability γ values were calculated to be 5.8×10^-27 esu for cluster 1 and 2.2×10^-27 esu for cluster 2, respectively. The large γ value should define clusters 1 and 2 as very promising candidates for NLO materials.