Design of Bifunctional Zinc(II)–Organic Framework for Efficient Coupling of CO₂ with Terminal/Internal Epoxides under Mild Conditions

Abstract

The rational design of efficient catalytic materials for conversion of carbon dioxide (CO2), a greenhouse gas into valuable products has fascinated chemists ever since the advent of the area of green and sustainable catalysis. Herein, we report design of a bifunctional, 3D Zn-MOF, [Zn3(BINDI)(DATRZ)2(H2O)2]n by utilizing a Lewis acidic Zn(II) ion, long-chain, rigid aromatic tetracarboxylate ligand, N,N′-bis(5-isophthalic acid)naphthalenediimide (BINDIH4) and basic −NH2 rich 3,5-diamino-1,2,4-triazole (DATRZ) linker. The Zn-MOF possesses a BET surface area of 1085.8 m2/g and a high density of CO2-philic −NH2 groups lined in the 1D channels promoting selective and recyclable CO2 adsorption with a high heat of interaction energy of 44.3 kJ/mol. The high surface area combined with the presence of Lewis acidic (LA) and basic sites rendered Zn-MOF an ideal bifunctional heterogeneous catalyst for efficient coupling of CO2 with terminal/internal epoxides under eco-friendly, solvent-free, RT and atmospheric pressure (balloon) conditions. Interestingly, Zn-MOF showed excellent catalytic activity for fixation of CO2 even from simulated flue gas/dilute CO2 gas. Remarkably, Zn-MOF showed high recyclability for up to 10 cycles with retaining the framework stability and catalytic activity. Overall, this work demonstrates the rational integration of Lewis acidic and basic sites in a 3D framework for the efficient utilization of CO2 under environment-friendly conditions.

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