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 x 10-10 m W-1 and n2 = -6.8 x 10-17 m2 W-1 in a 2.0 x 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 x 10-11 m W- 1 and n2 = - 1.2 x 1017 m2 W-1, when measured in a 1.9 x 10-5 tool dm-3 DMF solution. Their hyperpolarizability γ values were calculated to be 5.8 x 10-27 esu for cluster 1 and 2.2 x 10-27 esu for cluster 2, respectively. The large γ value should define clusters 1 and 2 as very promising candidates for NLO materials.