Hydroxide Ligands Cooperate with Catalytic Centers in Metal–Organic Frameworks for Efficient Photocatalytic CO2 Reduction

Integrating the g-C3N4 Nanosheet with B-H Bonding Decorated Metal-Organic Framework for CO2 Activation and Photoreduction

BIF-20, a zeolite-like porous boron imidazolate framework with high density of exposed B-H bonding, is combined with graphitic carbon nitride (g-C₃N₄) nanosheets via a facile electrostatic self-assembly approach under room temperature, forming an elegant composite BIF-20@g-C₃N₄ nanosheet. The as-constructed composite preferably captures CO₂ and further photoreduces CO₂ in high efficiency. The photogenerated excitations from the carbon nitride nanosheet can directionally migrate to B-H bonding, which effectively suppresses electron-hole pair recombination and thus greatly improves the photocatalytic ability. Compared to the g-C₃N₄ nanosheet, the BIF-20@g-C₃N₄ nanosheet composite displayed a much-enhanced photocatalytic CO₂ reduction activity, which is equal to 9.7-fold enhancements in the CH₄ evolution rate (15.524 μmol g^-1 h^-1) and 9.85-fold improvements in CO generation rate (53.869 μmol g^-1 h^-1). Density functional theory simulations further prove that the presence of B-H bonding in the composite is favorable for CO₂ adhesion and activation in the reaction process. Thus, we believe that the implantation of functional active sites into the porous matrix provides important insights for preparation of a highly efficient photocatalyst.

Site-Selective Catalysis of a Multifunctional Linear Molecule: The Steric Hindrance of Metal-Organic Framework Channels

The site-selective reaction of a multifunctional linear molecule requires a suitable catalyst possessing both uniform narrow channel to limit the molecule rotation and a designed active site in the channel. Recently, nanoparticles (NPs) were incorporated in metal-organic frameworks (MOFs) with the tailorable porosity and ordered nanochannel, which makes these materials (NPs/MOFs) highly promising candidates as catalytic nanoreactors in the field of heterogeneous catalysis. Inspired by a "Gondola" sailing in narrow "Venetian Canal" without sufficient space for a U-turn, a simple heterogeneous catalyst based on NPs/MOFs is developed that exhibits site-selectivity for the oxidation of diols by restricting the random rotation of the molecule (the "Gondola") in the limited space of the MOF channel (the narrow "Venetian Canal"), thereby protecting the middle functional group via steric hindrance. This strategy is not limited to the oxidation of diols, but can be extended to the site-selective reaction of many similar multifunctional linear molecules, such as the reduction of alkadienes.

A multifunctional MOF as a recyclable catalyst for the fixation of CO2 with aziridines or epoxides and as a luminescent probe of Cr(vi)

A multifunctional metal-organic framework (1) can serve as an efficient and recyclable catalysts for the conversion of CO₂ with aziridines or epoxides. Furthermore, the material can also act as a recyclable luminescent probe for Cr(vi) species among twenty anions.

Copper-catalyzed one-pot domino reactions via C–H bond activation: synthesis of 3-aroylquinolines from 2-aminobenzylalcohols and propiophenones under metal–organic framework catalysis

A Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones. This Cu-MOF was considerably more active towards the one-pot domino reaction than a series of transition metal salts, as well as nano oxide and MOF-based catalysts. The MOF-based catalyst was reusable without a significant decline in catalytic efficiency. To the best of our knowledge, the transformation of 2-aminobenzylalcohols to 3-aroylquinolines was not previously reported in the literature, and this protocol would be complementary to previous strategies for the synthesis of these valuable heterocycles.

Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones.