ALTERATION OF NONLINEAR REFRACTION BY MIXING CLUSTERS [WOS3CU3I(PY)(5)] AND [MOOS3CU3I(PY)(5)]

A new cluster compound [WOS3Cu3I(py)(5)] (I) was synthesized by substi tution reactions of (Et(4)N)(3)[WOS3Cu3I4] With pyridine and structura lly determined by X-ray diffraction. It crystallizes in monoclinic, sp ace group C2/c (No. 15), a = 24.341(1), b = 10.020(4), c = 26.64(1) An gstrom, V = 6424(3) Angstrom(3), and Z = 8. The cluster has a nest-sha ped skeleton. The nonlinear optical properties of both I and [MoOS3Cu3 I(py)(5)] (II) in acetonitrile solutions were measured using a Z-scan technique with 7-ns and 532-nm laser pulses. Compound I possesses a se lf-focusing property (n(2) = 1.6 x 10(-9) cm(2) W-1 M(-1)), while comp ound II exhibits a self-defocusing property (n(2) = -1.3 x 10(-10) cm( 2) W-1 M(-1)). Both compounds show reverse saturable absorption (alpha (2) = 1.5 x 10(-4) and 2.5 x 10(-5) cm W-1 M(-1) for compounds I and I I, respectively). We demonstrate that the nonlinear refraction of a mi xture containing the two compounds can be altered from self-focusing, through a state where self-lensing disappears, to self-defocusing by v arying the ratio of the two compounds.