A novel flexible egtazic acid/cerium-based metal organic framework as a potent catalyst for the synthesis of benzochromenoquinolinones and triazolopyrimidines

Abstract

The sponge-like structures of metal–organic frameworks (MOFs) are ideal platforms for various applications due to their structural diversity and adjustability, which allow for targeted design and synthesis. In recent years, substantial advances in the field of MOFs have been achieved, especially those containing aromatic ligands. Although there are several publications related to aliphatic ligands, the aliphatic MOFs developed are rather limited. Herein, a novel cerium-based flexible MOF (Ce-MOF-EGTA) constructed from an aliphatic tetratopic EGTA linker is reported. The framework exhibits high crystallinity, permanent porosity, and thermal stability up to 360 °C, as confirmed by FT-IR, EDX, elemental mapping, FESEM, XRD, TGA/DTA, and BET/BJH analyses. The presented flexible MOF is highly crystalline in nature and is stable up to 360 °C. Owing to the combination of intrinsic framework flexibility and accessible Ce Lewis acid sites, Ce-MOF-EGTA functions as an efficient heterogeneous catalyst for the synthesis of 6H-chromeno [4,3-b]quinolin-6-ones and 1,2,4-triazolo[4,3-a]pyrimidines, providing high yields under mild conditions with short reaction times. The catalyst demonstrates excellent stability and reusability over five consecutive cycles, with negligible cerium leaching and preservation of the original framework structure.