Rational synthesis, structural characterization and theoretical exploration on third-order nonlinear optical properties of isolated Agn (n=5, 8, 12) alkynyl clusters

Three silver(I) alkynyl compounds, [Ag-5(C (CBu)-Bu-t)(CF3COO)(7)(nBu(4)N)(3)center dot H2O] (1), [Ag-8(C (CBu)-Bu-t)(2)((CF3CBu)-Bu-t)(2)(CF3-COO)(10)(Et3N)(4)] (2), and [Ag-12(C (CBu)-Bu-t)(6)(CF3COO)(8)(nBu(4)N)(2)(Et3N)(2)(CF3COO)(2)] (3), have been obtained. Concomitantly, isolated [Ag-5(C (CBu)-Bu-t)(CF3COO)(7)](3-), [Ag-8(C (CBu)-Bu-t)(2)(CF3COO)(10)](4-) and [Ag-12(C (CBu)-Bu-t)(6)(CF3COO)(8)](2-) clusters (Ag-5, Ag-8 and Ag-12 for short) appear in 1-3, respectively. The synthesis of 1-3 demonstrates silver(I) alkynyls are better systems for the study of the template effect. ESI-MS analysis indicates compounds 1-3 can stably exist in methanol, and they have been proved to be potential wide gap semiconductor materials by the reflectance spectra. Notably, the second hyperpolarizabilities (gamma values) of Ag-5, Ag-8 and Ag-12 have been studied by using time-dependent density functional theory (TDDFT) calculations and the finite filed (FF) approach combining CAM-B3LYP. The calculated results show that they can be applied as potential third-order nonlinear optical (NLO) materials owing to their second hyperpolarizabilities rising from 39.1 x 10(-36), 60.3 x 10(-36) to 97.7 x 10(-36) esu with the growth of the number of Ag atoms and C C groups. (C) 2014 Elsevier Ltd. All rights reserved.