Self-assembly patterns of non-metalloid silver thiolates: structural, HR-ESI-MS and stability studies

Abstract

Screening of AgNO₃/AgS^<i>t</i>Bu solutions in DMF, DMSO and NMP resulted in the isolation of three novel nanosized silver/thiolate complexes with a torus-like {Ag₂₀(S^<i>t</i>Bu)₁₀} core. The structures of [NO₃@Ag₂₀(S^<i>t</i>Bu)₁₀(NO₃)₉(DMF)₆] (1) and [NO₃@Ag₂₀(^<i>t</i>BuS)₁₀(NO₃)₈(NMP)₈][NO₃@Ag₁₉(^<i>t</i>BuS)₁₀(NO₃)₈(NMP)₆]₂(NO₃) (2) were studied by single crystal X-ray diffraction (SCXRD). The self-assembly process leading to 1 can be switched to a different outcome using Br^-, resulting in [Br@Ag₁₆(S^<i>t</i>Bu)₈(NO₃)₅(DMF)₃](NO₃)₂ (3), which is the one of the few genuine host-guest complexes in the silver/thiolate systems. Solutions of the individual complexes in CH₃CN were studied by HR-ESI-MS techniques, which revealed a dynamic behavior for each complex, driven by a redistribution of the {AgNO₃} units. This dynamics results in the appearance of both cationic and anionic species, based on unchanged silver-thiolate cores. Daylight causes degradation of 3 with the formation of a composite material based on defective orthorhombic Ag₂S with a porous morphology, as observed using the SEM technique. The electrocatalytic HER activity of such a material was studied.