MOFs@Top J：2023.3.19-2023.3.25

Recent progress in mixed rare earth metal-organic frameworks: From synthesis to application
Coordination Chemistry Reviews ， Pub Date : 2023-03-23 , DOI: 10.1016/j.ccr.2023.215121
Juan Chen, Hongyi Gao, Zhiping Tao, Linmeng Wang, Rushuo Li, Ge Wang

The synergistic effects of mixed-metal MOFs provide a promising platform to overcome the limitations of traditional monometallic MOFs and achieve superior performance, which are still in their infancy. Mixed-rare earth-based metal-organic frameworks (MRE MOFs) have emerged as a new class of mixed-metal MOFs and attracted significant attention due to the high and variable coordination numbers of rare-earth metal clusters, intriguing architectural structure, and distinguishing functional properties. Despite plenty of factors influencing the preparation of MRE MOFs, it is also a challenge to precisely characterize the states of mixed metals. Particularly, the MRE MOFs with multi-valent rare earth metal nodes are more sophisticated than mixed transition metal MOFs. Multi-scale computational calculation serves as a tool for in-depth interpretation and analysis of the MRE MOFs at the electronic level. In almost every case, several experimental techniques need to be wisely chosen to unambiguously characterize mixed-metal MOFs. In this review, we summarize the recent and important progress in the preparation method, characterization techniques of MRE MOFs prepared by mixing transition and rare-earth metals or mixing multi-rare-earth metals, and their applications in catalysis, adsorption decontamination and luminescence. Special emphasis is placed on the effects of different metals on their structure and properties. Finally, we also present a short conclusion and future research directions for MRE MOFs.

https://www.sciencedirect.com/science/article/abs/pii/S0010854523001108

Water-stable MOFs and hydrophobically encapsulated MOFs for CO2 capture from ambient air and wet flue gas
Materials Today， Pub Date : 2023-03-22 , 

DOI: 10.1016/j.mattod.2023.03.004
Xiaoyang Shi, Gahyun Annie Lee, Shuohan Liu, Dongjae Kim, Ammar Alahmed, Aqil Jamal, Lei Wang, Ah-Hyung Alissa Park

The extra CO2 that has already been released into the atmosphere has to be removed in order to create a carbon–neutral world. Technologies have been created to remove carbon dioxide from wet flue gas or even directly from ambient air; however, these technologies have not been widely deployed yet. New generations of CO2 sorbents have been produced as a consequence of recent improvements in material assembly and surface chemistry. We summarize recent progress on water-stable and encapsulated metal–organic frameworks (MOFs) for CO2 capture under a wide range of environmental and operating conditions. In particular, newly developed water-stable MOFs and hydrophobic coating technologies are discussed with insights into their materials discovery and the synergistic effects between different components of these hybrid sorbent systems. The future perspectives and directions of water-stable and encapsulated MOFs are also elucidated for Direct Air Capture of CO2 and CO2 capture from wet flue gas.

https://www.sciencedirect.com/science/article/abs/pii/S1369702123000664

Synthetic Access to a Framework-Stabilized and Fully Sulfided Analogue of an Anderson Polyoxometalate that is Catalytically Competent for Reduction Reactions
Journal of the American Chemical Society， Pub Date : 2023-03-22 ,

DOI: 10.1021/jacs.2c12992

Jiaxin Duan, Hafeera Shabbir, Zhihengyu Chen, Wentuan Bi, Qin Liu*, Jingyi Sui, Luka Đorđević, Samuel I. Stupp, Karena W. Chapman, Alex B. F. Martinson, Alice Li, Richard D. Schaller, Subhadip Goswami, Rachel B. Getman, and Joseph T. Hupp*

Polyoxometalates (POMs) featuring 7, 12, 18, or more redox-accessible transition metal ions are ubiquitous as selective catalysts, especially for oxidation reactions. The corresponding synthetic and catalytic chemistry of stable, discrete, capping-ligand-free polythiometalates (PTMs), which could be especially attractive for reduction reactions, is much less well developed. Among the challenges are the propensity of PTMs to agglomerate and the tendency for agglomeration to block reactant access of catalyst active sites. Nevertheless, the pervasive presence of transition metal sulfur clusters metalloenzymes or cofactors that catalyze reduction reactions and the justifiable proliferation of studies of two-dimensional (2D) metal-chalcogenides as reduction catalysts point to the promise of well-defined and controllable PTMs as reduction catalysts. Here, we report the fabrication of agglomeration-immune, reactant-accessible, capping-ligand-free CoIIMo6IVS24n– clusters as periodic arrays in a water-stable, hierarchically porous Zr-metal–organic framework (MOF; NU1K) by first installing a disk-like Anderson polyoxometalate, CoIIIMo6VIO24m–, in size-matched micropores where the siting is established via difference electron density (DED) X-ray diffraction (XRD) experiments. Flowing H2S, while heating, reduces molybdenum(VI) ions to Mo(IV) and quantitatively replaces oxygen anions with sulfur anions (S2–, HS–, S22–). DED maps show that MOF-templated POM-to-PTM conversion leaves clusters individually isolated in open-channel-connected micropores. The structure of the immobilized cluster as determined, in part, by X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analysis, and pair distribution function (PDF) analysis of total X-ray scattering agrees well with the theoretically simulated structure. PTM@MOF displays both electrocatalytic and photocatalytic competency for hydrogen evolution. Nevertheless, the initially installed PTM appears to be a precatalyst, gaining competency only after the loss of ∼3 to 6 sulfurs and exposure to hydride-forming metal ions.

https://pubs.acs.org/doi/abs/10.1021/jacs.2c12992

Recent advances in computational modeling of MOFs: From molecular simulations to machine learning
Coordination Chemistry Reviews ， Pub Date : 2023-03-21 ,

DOI: 10.1016/j.ccr.2023.215112
Hakan Demir, Hilal Daglar, Hasan Can Gulbalkan, Gokhan Onder Aksu, Seda Keskin

The reticular chemistry of metal–organic frameworks (MOFs) allows for the generation of an almost boundless number of materials some of which can be a substitute for the traditionally used porous materials in various fields including gas storage and separation, catalysis, drug storage and delivery. The number of MOFs and their potential applications are growing so quickly that, when novel MOFs are synthesized, testing them for all possible applications is not practical. High-throughput computational screening approaches based on molecular simulations of materials have been widely used to investigate MOFs and identify the optimal MOFs for a specific application. Despite the growing computational resources, given the enormous MOF material space, computational identification of promising MOFs requires more efficient approaches in terms of time and effort. Leveraging data-driven science techniques can offer key benefits such as accelerated MOF design and discovery pathways via the establishment of machine learning (ML) models and interpretation of complex structure-performance relationships that can reach beyond expert intuition. In this review, we present key scientific breakthroughs that propelled computational modeling of MOFs and discuss the state-of-the-art approaches extending from molecular simulations to ML algorithms. Finally, we provide our perspective on the potential opportunities and challenges for the future of big data-driven MOF design and discovery.

https://www.sciencedirect.com/science/article/pii/S0010854523001017

Covalent Organic Frameworks as Porous Pigments for Photocatalytic Metal-Free C–H Borylation
Journal of the American Chemical Society ， Pub Date : 2023-03-21 ,

DOI: 10.1021/jacs.3c00950
Ananda Basak, Suvendu Karak, Rahul Banerjee 

Covalent organic frameworks (COFs) are highly promising as heterogeneous photocatalysts due to their tunable structures and optoelectronic properties. Though COFs have been used as heterogeneous photocatalysts, they have mainly been employed in water splitting, carbon dioxide reduction, and hydrogen evolution reactions. A few examples in organic synthesis using metal-anchored COF photocatalysts were reported. Herein, we report highly stable β-keto-enamine-based COFs as photocatalysts for metal-free C–B bond formation reactions. Three different COFs have been availed for this purpose. Their photocatalysis performances have been monitored for 12 different substrates, like quinolines, pyridines, and pyrimidines. All the COFs showcase moderate-to-high yields (up to 96%) depending upon the substrate’s molecular functionality. High crystallinity, a large surface area, a low band gap, and a suitable band position result in the highest catalytic activity of TpAzo COF. The thorough mechanistic investigation further highlights the crucial role of light-harvesting capacity, charge separation efficiency, and current density during catalysis. The light absorbance capacity of the COF plays a critical role during catalysis as yields are maximized near the COF’s absorption maxima. The high photostability of the as-synthesized COFs offers their reusability for several (>5) catalytic cycles.

https://pubs.acs.org/doi/abs/10.1021/jacs.3c0095