Bifunctional MOFs in Heterogeneous Catalysis

Abstract

The ever-increasing landscape of heterogeneous catalysis, pure and applied, utilizes many different catalysts. Academic insights along with many industrial adaptations paved the way for the growth. In designing a catalyst, it is desirable to have a priori knowledge of what structure needs to be targeted to help in achieving the goal. When focusing on catalysis, one needs to cope with a vast corpus of knowledge and information. The overwhelming desire to exploit catalysis toward commercial ends is irresistible. In today’s world, one of the requirements of developing a new catalyst is to address the environmental concerns. The well-established heterogeneous catalysts have microporous structures (<25 Å), which find use in many industrial processes. The metal–organic framework (MOF) compounds, being pursued vigorously during the last two decades, have similar microporosity with well-defined pores and channels. The MOFs possess large surface area and assemble to delicate structural and compositional variations either during the preparation or through postsynthetic modifications (PSMs). The MOFs, in fact, offer excellent scope as simple Lewis acidic, Brönsted acidic, Lewis basic, and more importantly bifunctional (acidic as well as basic) agents for carrying out catalysis. The many advances that happened over the years in biology helped in the design of many good biocatalysts. The tools and techniques (advanced preparative approaches coupled with computational insights), on the other hand, have helped in generating interesting and good inorganic catalysts. In this review, the recent advances in bifunctional catalysis employing MOFs are presented. In doing so, we have concentrated on the developments that happened during the past decade or so.

Two-Dimensional Cu(II)-MOF with Lewis Acid–Base Bifunctional Sites for Chemical Fixation of CO2 and Bioactive 1,4-DHP Synthesis via Hantzsch Condensation

“…The free pyrazine moiety of the linker is expected to stabilize incoming substrate molecules (such as CO 2 or carbonyl groups) via Lewis acid–base, electrostatic, and dispersion interactions inside the MOF, which can facilitate substrate binding and thus can promote the catalytic conversion . Thus, the concomitant presence of bifunctional Lewis acidic and Lewis basic sites inside the one-directional channel of the 2D-MOF structure can not only provide a synergistic platform to allow the easy diffusion of the substrate but also favor the close contact of substrate and catalyst, thus pave the path for efficient tandem catalytic conversion …”

High‐Entropy Lanthanide–Organic Framework as an Efficient Heterogeneous Catalyst for Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…Metal‐organic frameworks (MOFs), [18–20] also referred to as porous coordination polymers, are composed of metal ions/clusters and organic ligands [21] . The well‐defined structures, [22] high surface areas, [23,24] adjustable porous channels of MOFs make them widely used in purification, [25] energy conversion, [26,27] proton conduction, [28,29] gas storage, [30,31] sensing, [32] drug delivery, [33] and so on.…”

Exploring the Dual Realm of Solvent-Responsive Structural Transformations and Semiconducting Properties of Six 1D Coordination Polymers

“…CPs are typically created by coordinating metal ions or clusters with organic ligands. 14 They also find additional several applications in gas storage, 15 separation, 16 catalysis, 17 proton conduction, 18 sensing, 19 photoluminescence, 20 and solvent storage. 21 Out of these properties of CPs, the semiconducting properties have been the focus of modern research.…”