Chain to Grid Supramolecular Assembly: Organometallic Ag(I) and Ag(I)–Au(I)–NHC Supramolecules with Tunable Optoelectronic Properties

The multidentate hybrid C, N donor N-heterocyclic carbene ligand is used to synthesize an unprecedented Ag(I)-NHC complex and afford controllable assembly of an organometallic Ag(I)-Au(I)-NHC complex. Both experimental and theoretical studies were performed to characterize the organometallic linear chain Ag(I)-NHC polymer (<b>2</b>) and trinuclear grid-like heterobimetallic Ag(I)-Au(I)-NHC cluster (<b>3</b>) starting from 3-picolyl-functionalized multitopic NHC ligand 1-methyl-3-(pyridylmethyl)imidazo[1,5-<i>a</i>]pyridin-4-ylium hexafluorophosphate (<b>1</b>·HPF₆). After several spectroscopic studies, including IR, UV-vis, NMR, mass, etc., the final structural characterizations were fully achieved by single-crystal X-ray diffraction, confirming their molecular geometry and coordination environment. Importantly, replacing Ag(I) with sister coinage metal Au(I) led to a distinct transformation from a polymeric linear chain Ag(I) complex, <b>2</b>, to a well-defined trinuclear Ag(I)-Au(I) mixed metal cluster, <b>3</b>. Complex <b>3</b> leads to a two-dimensional polymer through Au(I)-Au(I) interactions. On the basis of silver and gold chemistry, the optoelectronic properties of <b>2</b> and <b>3</b> are studied. Current-voltage (<i>I-V</i>) measurements of complexes <b>2</b> and <b>3</b> reveal Schottky barrier diode (SBD) behavior. Key parameters, including the ideality factor, barrier height, and series resistance, were extracted using thermionic emission (TE) theory. Additionally, space-charge-limited current (SCLC) analysis was employed to determine the charge transport properties, such as the effective carrier mobility and transit time. Notably, Ag(I) complex <b>2</b> exhibits higher electrical conductivity compared to that of heterobimetallic Ag(I)-Au(I) complex <b>3</b>. Our results can be used as a model to understand the optoelectronic properties of other Ag(I) and Au(I) polymeric complexes.