Stoichiometry-Regulated Synthesis of Three Adenine-Based\nCoordination Polymers for Catalytic Excellence through the Synergistic\nAmalgamation of Coordinative Unsaturation and Lewis Basic Sites

Nucleobase\nadenine is a promising candidate for synthesizing fascinating\ncoordination polymers (CPs) due to the presence of five potential\nmetal-ion binding centers. In recent years, CPs have emerged as promising\nLewis acid–base centers containing heterogeneous catalysts\nfor a wide range of organic transformations. However, the crucial\nrole of stoichiometric regulations of the starting materials and their\nconsequential impact on catalytic performance are rarely studied.\nHerein, we have synthesized three adenine (Ad)-based cadmium CPs with\n5-nitro isophthalic acid (H<sub>2</sub>NIPA) by a mixed linker approach\nby tuning the substrate’s stoichiometric proportion. The single-crystal\nX-ray diffraction analysis of the synthesized CPs, SSICG-11, [Cd(Ad)(NIPA)(H<sub>2</sub>O)]·H<sub>2</sub>O; SSICG-12, [Cd(Ad)<sub>2</sub>(NIPA)(H<sub>2</sub>O)]; and SSICG-13, [Cd<sub>4</sub>(Ad)(NIPA)<sub>3</sub>]·H<sub>2</sub>O·DMF, reveals that these three compounds exhibit distinct\nasymmetric units, each reflecting varying precursor proportions. Due\nto their high chemical stability and the presence of both Lewis acidic–basic\nsites, SSICG-11–13 were employed as heterogeneous catalysts\nfor Hantzsch and Strecker reactions. However, SSICG-12 is more efficient\ndue to its capacity to form an open metal sites (OMSs) and the presence\nof a higher number of adenine moieties. Overall, this study demonstrated\nthe stoichiometrically controlled synthesis of adenine-based CPs and\ndissected their efficiency as a heterogeneous catalyst by correlating\ntheir structures and compositions.