Approaching the size limit of organometallic layers: synthesis and characterization of highly ordered silver–thiolate lamellae with ultra-short chain lengths

Abstract

Approaching the ultimate limits of material sizes provides a route for designing new functional materials with extraordinary properties. We report the first systematic synthesis and characterization study of a wide range of highly ordered silver alkanethiolate (AgSC_nH_2n+1 or AgSCn, n = 1–16) aliphatic lamellae. Single crystalline multilayer AgSCn are synthesized by a modified solution reaction method. Hot toluene recrystallization or Ostwald ripening enhances the structural ordering of the lamellar crystals. This work approaches the chain length limit of aliphatic lamellae by synthesizing highly ordered AgSCn (n = 1–3) with extremely short chains. All lamellae form single crystals with well-registered interlayer interfaces, similar to other alkyl-based lamellae but different from polyethylene lamellae. AgSC2 with a layer thickness of 1.08 nm is the thinnest organometallic layer ever reported. The composition, morphology, decomposition and structure of the lamellae are comprehensively studied. A new method quantifies the composition of the residual Ag and Ag₂S contents after the decomposition of the AgSCn: all of the Ag, none of the C and a fraction of the S remain in the residue. The structural orderings of the AgSCn crystals, which are probed by electron diffraction for the first time, are characterized in terms of chain conformation, interlayer lamellar ordering and intralayer lattice ordering. All AgSCn (n = 2–16) layers, except AgSC1, possess a common lattice packing and the same inorganic network structure.