Accessing copper-tin-sulfide nanostructures from diorganotin(IV) and copper(I) 2-pyrazinyl thiolates

Abstract

Synthesis of air stable di-tert-butyltin(IV) and copper(I) complexes of 2-pyrazinyl thiolate (2-pyzSH), [tBu2Sn(Spyz)2] (1) and [Cu(Spyz)(PPh3)2] (2), as molecular precursors for metal sulfide nanomaterials is described. These complexes were isolated by the reactions of [tBu2SnCl2] and [CuCl(PPh3)3] with sodium 2-pyrazinyl thiolate at room temperature. The molecular structures of these complexes have been established by single crystal X-ray diffraction analyses and hetero nuclear NMR. The thermal analyses of 1 and 2 revealed closely related decomposition temperatures with the formation of the corresponding metal sulfide. Utility of these complexes as molecular precursors for the preparation of binary (SnS and Cu1.8S) and ternary Cu2SnS3 (CTS) metal sulfide nanostructures has been assessed. The phase purity, morphology and composition of nanostructures were investigated by PXRD, Raman, SEM, TEM and EDS analysis. The band gap of nanostructures as deduced from diffuse reflectance spectroscopy (DRS) are 1.4, 1.8 and 2.0 eV for CTS, SnS and Cu1.8S, respectively which are blue shifted relative to their respective bulk counterpart. It has been demonstrated that role of solvent is highly crucial for the phase purity of CTS nanostructures. The Photo-electrochemical studies revealed that CTS nanostructures pose as better photo responsive material as compared to Cu1.8S.