Assembly of three-dimensional networks based upon silver–ethynide complexes bearing pyridyl and carboxylate groups

Abstract

Two ligands with different geometries have been prepared to synthesize new silver–ethynide complexes bearing pyridyl and carboxylate groups. Reactions of 5-ethynylnicotinic acid (H₂22L1) and 5-ethynylpicolinic acid (H₂22L2) with silver nitrate afforded [Ag₂(L1)·AgNO₃]_n (1) and {[Ag₁₂(L2)₆·12AgNO₃]·5H₂O}_n (2), respectively. Crystallographic studies revealed that in 1, the L1 ligands connect linear silver chains to form a 2D layer through silver-ethynide interactions and Ag-carboxylate coordination bonds, and subsequently the layers are further linked through Ag–N(pyridyl) coordination bonds to generate a 3D network; however in 2, the L2 ligand interacts with Ag₈ units through Ag–N, Ag–O coordination bonds, silver–ethynide interactions and π–π stacking directly to assemble a 3D network. In the solid state, both complexes are luminescent at room temperature, assigned as the intraligand n–π* and π–π* transitions.