Large nonlinear optical absorption and self-defocusing effects of cluster [MoS4Cu4I2(py)(6)]

Pentanuclear 'open' structure cluster compound [MoS4Cu4I2(py)(6)] has been prepared by the reaction of (NH4)(2)MoS4, CuI and 2,2'-bpy with py. Its non linear optical (NLO) properties have been determined though Z-scan techniqu e. The normalized transmittance of [MoS4Cu4I2(py)(6)] from NLO absorptive d ata drops to about 40% at the focus; it shows that the cluster has very str ong NLO absorption. Its alpha (2) value was calculated to be 1.2x10(-9) m W -1 in a 5.0x10(-5) mol dm(-3) DMSO solution. The value is the biggest for M o-S clusters. The title compound has also strong self-defocusing behaviour. Its third-order NLO refractive index n(2) is -7.5x10(-17) m(2) W-1. The da ta are superior to those of many Mo-S clusters.