Mesoporous Ionically Tagged Cross-Linked Poly(vinyl imidazole)s as Novel and Reusable Catalysts for the Preparation of N-Heterocycle Spiropyrans

Abstract

Herein, two novel mesoporous cross-linked poly(vinyl imidazole)s with sulfonic acid tags, [PVI-SO₃H]Cl (<b>1</b>) and [PVI-SO₃H]FeCl₄ (<b>2</b>), were prepared and characterized by a variety of techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, elemental mapping, energy dispersive X-ray analysis, transmission electron microscopy, thermal gravimetry, derivative thermal gravimetry, and N₂ adsorption-desorption isotherms (Brunauer-Emmett-Teller). In addition, magnetic properties of poly(vinyl imidazole) sulfonic acid iron(IV) chloride [PVI-SO₃H]FeCl₄ (<b>2</b>) as an ionically tagged magnetic polymer were investigated using a vibrating sample magnetometer. The presented polymers, [PVI-SO₃H]Cl (<b>1</b>) and [PVI-SO₃H]FeCl₄ (<b>2</b>), were successfully applied as reusable and efficient catalysts for the preparation of N-heterocycle spiropyrans. The described catalysts were recycled and reused with a marginal decrease in their catalytic activities. The desired products were prepared under mild and green conditions. The structures of the obtained products were confirmed by various analysis techniques.