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

Abstract

Three silver(Ι) alkynyl compounds, [Ag5(CCtBu)(CF3COO)7(nBu4N)3·H2O] (1), [Ag8(CCtBu)2(CF3COO)10(Et3N)4] (2), and [Ag12(CCtBu)6(CF3COO)8(nBu4N)2(Et3N)2(CF3COO)2] (3), have been obtained. Concomitantly, isolated [Ag5(CCtBu)(CF3COO)7]3–, [Ag8(CCtBu)2(CF3COO)10]4– and [Ag12(CCtBu)6(CF3COO)8]2– clusters (Ag5, Ag8 and Ag12 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 (γ values) of Ag5, Ag8 and Ag12 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 × 10−36, 60.3 × 10−36 to 97.7 × 10−36 esu with the growth of the number of Ag atoms and CC groups.