Post‐synthetic modification of IR-MOF‐3 as acidic-basic heterogeneous catalyst for one-pot synthesis of pyrimido[4,5-b]quinolones

In this study, a modified IR-MOF-3 via a multi-step post-synthesis modification, namely IR-MOF-3-ILOAc-Fe(acac)3, was prepared as an ion-pair heterogeneous catalyst for synthesis of pyrimido[4,5-b]quinoline derivatives in the absence of any co-catalyst. Firstly, modified MOF with 4-pyridinecarboxaldehyde (4-PC), followed by 2-chloroethylamine for formation of ionic liquid on the surface (as basic agent) with anion exchange of Cl− to OAc− was prepared. Finally, it was modified with iron(III) acetylacetonate to generate Lewis acid site. The catalyst was characterized by PXRD, FT-IR, FESEM-EDS, TGA and BET techniques. The catalyst has excellent reusability while maintaining continuous activity. A little amount of leaching from the reused catalyst was observed that could be attributed to the loss of the catalyst after each washing process. Kinetic and isotherm of the reaction were also studied.Graphical abstractIn this study, a modified IR-MOF-3 via a multi-step post-synthesis modification, namely IR-MOF-3-ILOAc-Fe(acac)3, was prepared as ion-pair heterogeneous catalysis for synthesis of pyrimido[4,5-b]quinoline derivatives in the absence of any co-catalyst. Firstly, modified MOF with 4-pyridinecarboxaldehyde (4-PC), followed by 2-chloroethylamine for formation of ionic liquid on the surface (as basic agent) with anion exchange of Cl− to OAc− was prepared. Finally, it was modified with iron(III) acetylacetonate to generate Lewis acid site. The catalyst was characterized by PXRD, FT-IR, FESEM-EDS, TGA and BET techniques. The catalyst has excellent reusability while maintaining continuous activity. A little amount of leaching from the reused catalyst was observed.