Functional Porous Frameworks Research Articles

Adjacent Metal Atomic Pairs Within Atomically Dispersed Catalysts for Reaching a Synergistic Electrocatalytic CO2 Reduction: A Review

AbstractIn response to the global climate change and energy crisis, electrocatalytic CO2 reduction reaction (ECR) is regarded as one of the potential ways to simultaneously reach the CO2 conversion and obtain various value‐added products. Currently, several challenges remain for the in‐depth understanding of ECR from fundamentals, including ambiguous structure‐activity relationships, uncontrollable catalytic selectivity, and complex reaction mechanisms. Compared to traditional metal nanoparticle‐based materials, atomically dispersed catalysts (ADCs) have aroused significant interest owing to their maximal atomic utilization and simplified site configuration, offering a superior platform for discussing the structure‐activity relationships during ECR. Especially, adjacent metal atomic pairs (AAPs) within ADCs are gradually emphasized as a novel concept to follow various synergistic reaction mechanisms during ECR. Herein, for the first time a broad concept of AAPs and analyzed how AAPs within ADCs reached the synergistic effect during ECR is summarized. In view of the synergistic reaction mechanisms varying on different supports, three types of supports are illustrated (containing graphene model, functional porous frameworks, and metals and oxides), aiming to help scholars with more insights in broadening the feasible synergistic reaction mechanisms on AAPs within ADCs.

Post‐Assembly Modification of Homochiral Titanium–Organic Cages for Recognition and Separation of Molecular Isomers

AbstractA chiral metal–organic cage (MOC) was extended and fixed into a porous framework using a post‐assembly modification strategy, which made it easier to study the host–guest chemistry of the solid‐state MOC using a single‐crystal diffraction technique. Anionic Ti4L6 (L=embonate) cage can be used as a 4‐connecting crystal engineering tecton, and its optical resolution was achieved, thus homochiral ΔΔΔΔ‐ and ΛΛΛΛ‐[Ti4L6] cages were obtained. Accordingly, a pair of homochiral cage‐based microporous frameworks (PTC‐236(Δ) and PTC‐236(Λ)) were easily prepared by a post‐assembly reaction. PTC‐236 has rich recognition sites provided by the Ti4L6 moieties, chiral channels and high framework stability, affording a single‐crystal‐to‐single‐crystal transformation for guest structure analyses. Thus it was successfully utilized for the recognition and separation of isomeric molecules. This study provides a new approach for the orderly combination of well‐defined MOCs into functional porous frameworks.

Post-Assembly Modification of Homochiral Titanium-Organic Cages for Recognition and Separation of Molecular Isomers.

A chiral metal-organic cage (MOC) was extended and fixed into a porous framework using a post-assembly modification strategy, which made it easier to study the host-guest chemistry of the solid-state MOC using a single-crystal diffraction technique. Anionic Ti4 L6 (L=embonate) cage can be used as a 4-connecting crystal engineering tecton, and its optical resolution was achieved, thus homochiral ΔΔΔΔ- and ΛΛΛΛ-[Ti4 L6 ] cages were obtained. Accordingly, a pair of homochiral cage-based microporous frameworks (PTC-236(Δ) and PTC-236(Λ)) were easily prepared by a post-assembly reaction. PTC-236 has rich recognition sites provided by the Ti4 L6 moieties, chiral channels and high framework stability, affording a single-crystal-to-single-crystal transformation for guest structure analyses. Thus it was successfully utilized for the recognition and separation of isomeric molecules. This study provides a new approach for the orderly combination of well-defined MOCs into functional porous frameworks.