Covalently grafted MOP-on-MOF hybrid ionic-porous composite for efficient adsorption and catalysis

Abstract

Development of multifunctional hybrid porous composite materials with significantly enhanced properties is highly desirable; however, it remains challenging due to the lack of proper synthetic strategies. Here, we present a facile design principle to construct multifunctional hybrid ionic porous composite materials through covalent linking of amino pendant nanosized cationic metal–organic polyhedra (MOPs) with an amino-functionalized anionic metal–organic framework (MOF) using dynamic covalent chemistry of strong secondary amide bonds. The optimized MOP-on-MOF hybrid nanocomposite was synthesized via covalent grafting, followed by electrostatic-driven assembly of Zr-MOP-NH₂ on the surface of Ti-MIL-125-NH₂ using a series of organic linkers. The developed nanocomposites revealed tunable enhanced physicochemical properties with intact crystal structure, morphology, porosity, and stability of the parent MOF, while effectively preventing the aggregation and leaching of MOPs. Importantly, the hybrid nanocomposite demonstrated significantly improved selective adsorption properties toward polyiodide species in water, which is important from the point of view of radioiodine sequestration from water, and served as a potential platform for efficient heterogeneous catalysis toward Lewis acid-mediated phosphate-ester hydrolysis of toxic nerve agents with high product selectivity and good recyclability. This unique covalently grafted MOP-on-MOF strategy offers a promising means of introducing novel multifunctional robust porous composite materials for various potential applications.