Design and synthesis, and experimental-computational analysis of an acetic acid-functionalized zinc tetrapyridinoporphyrazine catalyst for synthesizing acridine and quinoline derivatives

An acetic acid-functionalized zinc tetrapyridinoporphyrazine catalyst, [Zn(TPPACH₂CO₂H)]Cl, was synthesized and extensively characterized by UV-Vis, FT-IR, TGA, DTG, EDX, SEM, XRD, ICP, and CHN analyses. The introduction of carboxylic acid groups into the tetrapyridinoporphyrazine framework significantly enhanced the catalytic activity of the central zinc metal, as supported by density functional theory (DFT) calculations and natural bond orbital (NBO) analysis at the B3LYP/def2-TZVP level. The catalyst demonstrated excellent stability and recyclability with no detectable metal leaching during the solvent-free synthesis of 1,8-dioxodecahydroacridine and hexahydroquinoline derivatives. These findings highlight the crucial role of acid functionalization in improving the electronic environment and catalytic efficiency of the metal center, enabling the development of a robust and reusable heterogeneous catalyst.