Structural diversity of copper(<sc>i</sc>) alkynyl cluster-based coordination polymers utilizing bifunctional pyridine carboxylic acid ligands

The utilization of bifunctional ligands, specifically pyridine carboxylic acids, endowed with dual coordination sites, has been instrumental in the assembly of polymer materials. The ambidentate characteristics of these ligands play a crucial role in shaping the structure and framework of cluster-based polymers. In this study, we have synthesized a diverse array of multidimensional copper(i) alkynyl cluster-based polymers (CACPs) by employing four distinct pyridine carboxylic acids - namely, isonicotinic acid (INA), 6-isoquinolinecarboxylic acid (IQL), 4-pyridin-4-yl-benzoic acid (4-PyBA), and 3-pyridin-4-yl-benzoic acid (3-PyBA) - as linking ligands. These pyridine carboxylic acids not only serve as protective ligands but also act as pivotal linkers in constructing the cluster-based framework materials, exerting significant influence on the overall framework structures. Furthermore, the incorporation of auxiliary ligands has been shown to markedly impact the structural integrity and framework architecture of the CACPs. This study elucidates the indispensable role of pyridine carboxylic acids in the construction and stabilization of cluster-based framework materials, thereby advancing the frontier of research in metal cluster-based framework material synthesis.