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 (2) and trinuclear grid-like heterobimetallic Ag(I)-Au(I)-NHC cluster (3) starting from 3-picolyl-functionalized multitopic NHC ligand 1-methyl-3-(pyridylmethyl)imidazo[1,5-a]pyridin-4-ylium hexafluorophosphate (1·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, 2, to a well-defined trinuclear Ag(I)-Au(I) mixed metal cluster, 3. Complex 3 leads to a two-dimensional polymer through Au(I)-Au(I) interactions. On the basis of silver and gold chemistry, the optoelectronic properties of 2 and 3 are studied. Current-voltage (I-V) measurements of complexes 2 and 3 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 2 exhibits higher electrical conductivity compared to that of heterobimetallic Ag(I)-Au(I) complex 3. Our results can be used as a model to understand the optoelectronic properties of other Ag(I) and Au(I) polymeric complexes.