Infinite metal-oxo metal-organic frameworks (MOFs) are recognized as promising platforms for developing all-round high-performance catalysts for both academic and industrial significance. Nevertheless, engineering infinite metal-oxo architectures typically requires harsh synthetic conditions, often yielding microcrystalline or even nanocrystalline products that hinder precise structure identifications. Herein, we propose a previously underestimated acetic acid-based solvothermal protocol for general engineering of 1D infinite metal-oxo (e.g. Zr, Hf, Ce) MOFs featuring large-size single crystals with well-identified crystallographic structures. As an example, the 1D Zr-BTB-derived catalyst exhibits a turnover frequency (TOF) of 1199.1 h-1, selectivity of 99.0% and long-term stability in the catalytic upgrading of natural feedstocks into high-value-added fuels. In comparison, the conventional Zr6O8 node-based counterpart only presents a TOF of 282.5 h-1, selectivity of 5.9% and poor recycling ability. This work opens the avenue to design industry-oriented performant heterogeneous catalysts for energy-critical transformations via rational engineering of versatile infinite metal-oxo units.

Selective separation of acetylene (C2H2) from carbon dioxide (CO2) and ethylene (C2H4) mixtures is critical in the petrochemical industry due to their similar size and physicochemical properties. Developing three-dimensional porous covalent organic frameworks (3D COFs) remains challenging in this context. In this work, a non-symmetrical 2-phenyl pyridine based three-dimensional covalent organic framework (COF-PPy) has been synthesized, which features a rare dia-C9 fold interpenetrated structure as suggested by computational simulations. COF-PPy exhibits high acetylene (C2H2) adsorption capacity (4.5 mmol g-1 at 298 K), as well as excellent separation and purification performance for C2H2/CO2 and C2H2/C2H4 mixtures. The in situ-FTIR studies suggest that the multi-point interactions between nitrogen centers of COF-PPy and H-C≡CH (COF-Pyridine-N···H-C≡C-H and COF-imine-N··H-C≡CH) account for the higher affinities for C2H2 over other gases. Furthermore, dynamic breakthrough studies reveal that COF-PPy can be employed as an effective adsorbent for the efficient separation of C2H2 from CO2 and C2H4. In addition, COF-PPy exhibits lower heat of adsorption (Qst) values with high adsorption capacity for C2H2 as compared to previously reported C2H2-selective adsorbents, indicating less regeneration energy. Our work therefore provides some new avenues for the design and construction of 3D COFs for efficient C2H2 capture and separation.

Light emission in the solid state is central for illumination, sensing, and imaging applications. Unlike luminescence in dilute solutions, where the excited states are unimolecular in nature, intermolecular interaction plays a significant role in the quantum yield of solid-state luminophores, manifested as competing aggregation-caused quenching (ACQ) and aggregation-induced enhancement (AIE). Both effects are extensively studied in various systems; however, it remains unclear how their competition depends on molecular conformation and intermolecular stacking. Here the direct observation of pressure-modulated AIE-ACQ competition in a crystalline hydrogen-bonded organic framework (HOF) is reported. Using in situ spectroscopies and computational modeling, the intramolecular vibration and intermolecular π-π stacking directly responsible for the non-radiative decay of the excited state are identified. The extent of these two contributions is modulated by hydrostatic pressure and guest molecules in the HOF pores. This work demonstrates a physically neat model system to understand and control solid-state luminescence, and a potential material platform for piezoluminescent sensing.

Converting CO2 to high-value fine chemicals represents one of the most promising approaches to combat global warming and subsequently achieve a sustainable carbon cycle. Herein, we contribute an organoboron functionalized ultra-thin metal-organic nanosheet (MON), termed TCPB-Zr-NS, featuring an abundance of exposed Lewis acidic B and formate sites, which can effectively promote CO2 conversion upon the addition of Lewis basic o-phenylenediamines. Compared with the prototypical 3D analogue TCPB-Zr-3D, the resultant TCPB-Zr-NS showcases dramatically improved catalytic activity for the cyclization of o-phenylenediamine as a result of the highly exposed active sites and efficient substrates/products diffusion. Strikingly, the incorporation of Lewis acidic B sites into ultra-thin Zr-based MON (Zr-MON) not only promotes the highly efficient CO2 conversion, but also enhances the recyclability/durability of catalysts. Additionally, the underlying catalytic mechanism has been well established by the comprehensive experiments and theoretical calculations, unveiling a formate-assisted frustrated Lewis pairs (FLP) mediated catalytic pathway. This work opens up a new avenue to heterogeneous FLP-based catalysts for small molecule activation and beyond.

The electrochemical oxygen evolution reaction (OER) is critically influenced by the rate-determining step (RDS) and intermediate binding at catalytic sites, yet achieving precise control over these factors to promote the OER remains challenging. Enzymatic systems exemplify how catalytic efficiency is dictated by not only active centers but also their surrounding microenvironments. Drawing inspiration from this paradigm, serrated stacking cobalt-corrole-based covalent organic frameworks (Co-CorCOFs) with well-defined active sites are developed as models for systematical investigation and manipulation of electrocatalytic behavior. It is shown that remote microenvironment tuning via oriented functionalization of COF linkages effectively alters the electronic structures of both the COF backbone and Co sites. This results in distinct reaction kinetics and electron transfer in covalently assembled composite Co-CorCOF/carbon nanotube (CNT) hybrids (Co-CorCOF@CNTs). Notably, introducing quinoline moieties into the linkages significantly boosts OER activity in Co-CorCOF-3@CNT versus an unmodified Co-CorCOF-2@CNT. Mechanistic studies reveal that microenvironment engineering fine-tunes the Co sites' d-band center, which facilitates oxygenated intermediate adsorption and shifts the RDS from *OH formation to *OH deprotonation with a substantial reduction in the energy barrier, thereby accelerating the reaction rate. This work offers a new avenue for the formulation of more efficient catalysts via a molecular-level microenvironment modulation strategy.

Nonsymmetrical oxygen-bridged binuclear copper centers have been proposed and modeled as intermediates and transition states in several C─H oxidation pathways, leading to the postulation that structural dissymmetry enhances the reactivity of the bridging oxygen. However, experimentally characterizing the structure and reactivity of these transient species is remarkably challenging. Here, we report the high-pressure synthesis of a metastable nonsymmetrical dicopper-μ-oxo compound with exceptional reactivity toward the mono-oxygenation of aliphatic C─H bonds. The nonequivalent coordination environment of copper stabilizes localized mixed valency and greatly enhances the hydrogen atom abstraction activity of the bridging oxygen, enabling room-temperature hydroxylation of methane under pressure. These findings highlight the role of dissymmetry in the reactivity of binuclear copper centers and demonstrate precise control of molecular structures by mechanical means.

Optimization of activity, selectivity, and stability of catalysts for practical application is a long -soughtafter goal. Recent progress in the advancement of rational catalyst design routinely takes queues from nature. Specifically, enzymes are renowned for their high efficiency and selectivity in diverse and significant reactions under mild conditions. Despite the well-known merits of enzymes, they often remain unsuitable for industrial catalysis due to issues, including limited environment (solvent/temperature/ pH) compatibility, considerable structural uncertainty, and highly specific reaction scopes. In the context of bioinspired catalysis design, the development of synthetic heterogeneous catalyst analogs, which may not only mimic enzymes to reproduce or even surpass their performance but also bypass their intrinsic limitations, is thus, desirable and has been extensively studied in the context of porous materials. The metal-organic framework (MOF) is a superior candidate for porous materials towards this goal, thanks to facile and modular preparation, explicit crystalline composition/structure, tunable pore size/environment, and excellent stability. The introduction of active molecular species such as bioactive molecules (e.g., proteins, enzymes, peptides, amino acids, porphyrins) and chemically active molecules (e.g., frustrated Lewis pairs) into metal-organic frameworks (MOFs) via pore encapsulation, chemical postmodification, or bottom -up construction has been shown to facilitate the cooperative enhancement of catalysis through the enforcement of proximity, enhancement of control/activity, and even inducement of unexpected selectivity. In this minireview, we sought to summarize the last 5 years of fruitful progress, exploiting MOFs housing active molecules for substantial catalysis applications, including asymmetric reactions, CO2 conversion (reduction, cycloaddition), biocatalytic H2O2/dye degradation, and so on, and discuss challenges and opportunities in the prospective exploration of these systems towards enzyme mimicry and new -to -nature catalysis.

The mitochondrial electron transport chain (ETC) of Plasmodium malaria parasites is a major antimalarial drug target, but critical cytochrome (cyt) functions remain unstudied and enigmatic. Parasites express two distinct cyt c homologs (c and c-2) with unusually sparse sequence identity and uncertain fitness contributions. P. falciparum cyt c-2 is the most divergent eukaryotic cyt c homolog currently known and has sequence features predicted to be incompatible with canonical ETC function. We tagged both cyt c homologs and the related cyt c1 for inducible knockdown. Translational repression of cyt c and cyt c1 was lethal to parasites, which died from ETC dysfunction and impaired ubiquinone recycling. In contrast, cyt c-2 knockdown or knockout had little impact on blood-stage growth, indicating that parasites rely fully on the more conserved cyt c for ETC function. Biochemical and structural studies revealed that both cyt c and c-2 are hemylated by holocytochrome c synthase, but UV-vis absorbance and EPR spectra strongly suggest that cyt c-2 has an unusually open active site in which heme is stably coordinated by only a single axial amino acid ligand and can bind exogenous small molecules. These studies provide a direct dissection of cytochrome functions in the ETC of malaria parasites and identify a highly divergent Plasmodium cytochrome c with molecular adaptations that defy a conserved role in eukaryotic evolution.

The development of metal-free and recyclable catalysts for significant yet challenging transformations of naturally abundant feedstocks has long been sought after. In this work, we contribute a general strategy of combining the rationally designed crystalline covalent organic framework (COF) with a newly developed chiral frustrated Lewis pair (CFLP) to afford chiral frustrated Lewis pair framework (CFLPF), which can efficiently promote the asymmetric olefin hydrogenation in a heterogeneous manner, outperforming the homogeneous CFLP counterpart. Notably, the metal-free CFLPF exhibits superior activity/enantioselectivity in addition to excellent stability/recyclability. A series of in situ spectroscopic studies, kinetic isotope effect measurements, and density-functional theory computational calculations were also performed to gain an insightful understanding of the superior asymmetric hydrogenation catalysis performances of CFLPF. Our work not only increases the versatility of catalysts for asymmetric catalysis but also broadens the reactivity of porous organic materials with the addition of frustrated Lewis pair (FLP) chemistry, thereby suggesting a new approach for practical and substantial transformations through the advancement of novel catalysts from both concept and design perspectives.

Incorporating radical ligands into metal complexes is one of the emerging trends in the design of single-molecule magnets (SMMs). While significant effort has been expended to generate multinuclear transition metal-based SMMs with bridging radical ligands, less attention has been paid to mononuclear transition metal-radical SMMs. Herein, we describe the first α-diiminato radical-containing mononuclear transition metal SMM, namely, [κ2-PhTttBu]Fe(AdNCHCHNAd) (1), and its analogue [κ2-PhTttBu]Fe(CyNCHCHNCy) (2) (PhTttBu = phenyltris(tert-butylthiomethyl)borate, Ad = adamantyl, and Cy = cyclohexyl). 1 and 2 feature nearly identical geometric and electronic structures, as shown by X-ray crystallography and electronic absorption spectroscopy. A more detailed description of the electronic structure of 1 was obtained through EPR and Mössbauer spectroscopies, SQUID magnetometry, and DFT, TD-DFT, and CAS calculations. 1 and 2 are best described as high-spin iron(II) complexes with antiferromagnetically coupled α-diiminato radical ligands. A strong magnetic exchange coupling between the iron(II) ion and the ligand radical was confirmed in 1, with an estimated coupling constant J < -250 cm-1 (J = -657 cm-1, DFT). Calibrated CAS calculations revealed that the ground-state Fe(II)-α-diiminato radical configuration has significant ionic contributions, which are weighted specifically toward the Fe(I)-neutral α-diimine species. Experimental data and theoretical calculations also suggest that 1 possesses an easy-axis anisotropy, with an axial zero-field splitting parameter D in the range from -4 to-1 cm-1. Finally, dynamic magnetic studies show that 1 exhibits slow magnetic relaxation behavior with an energy barrier close to the theoretical maximum, 2|D|. These results demonstrate that incorporating strongly coupled α-diiminato radicals into mononuclear transition metal complexes can be an effective strategy to prepare SMMs.

The strength of the relevant bonds in bond-making and bond-breaking processes can directly affect the overall efficiency of the process. Copper-oxygen sites are known to catalyze reactions with some of the most recalcitrant C-H bonds found in nature as quantified by bond dissociation free energy (BDFE), yet only a handful of copper-bound O-H bond strengths have been defined. Equally important in the design of synthetic catalysts is an understanding of the geometric and electronic structure origins of these thermodynamic parameters. In this report, the BDFE(OH) of two dicopper-hydroxo complexes, {[LCu]2-(µ-OH)}3+ and {[LCu]2-(µ-OH)}4+ (L = tris(2-pyridylmethyl)amine), were measured. Two key observations were made: i) the BDFE(OH) of these complexes were exceptionally high at 103.4 kcal/mol and 91.7 kcal/mol respectively, which are the highest condensed phase MO-H BDFE to date; and ii) that the higher oxidation state had a lower BDFE(OH), which is counter to expectations based on known mononuclear BDFE(OH) which increase with oxidation state. To understand the origin of these thermodynamic values, BDFE(OH) were measured and analyzed for the mononuclear complexes [LCu(OH2)]1+ and [LCu(OH2)]2+ in the same ligand environment. This treatment revealed "dinuclear effects" that include contributions from rehybridization of the oxygen, mixed-valency of the metals, magnetic exchange between the metals, and differences in solvation, and which are general with respect to [M]2-OH complexes to varying degrees. These analyses are important because they provide a starting point for rationally tuning the thermodynamics of catalytic intermediates broadly and for understanding how copper active-sites achieve activation of strong C-H bonds.

The reaction of Mn-II(O2CMe)(2) and NaCN or LiCN in water forms a light green insoluble material. Structural solution and Rietveld refinement of high-resolution synchrotron powder diffraction data for this unprecedented, complicated compound of previously unknown composition revealed a new alkali-free ordered structural motif with [Mn-4(II)((3)-OH)(4)](4+) cubes and octahedral [Mn-II(CN)(6)](4-) ions interconnected in 3D by Mn-II-NC-Mn-II linkages. The composition is {[Mn-II(OH2)(3)][Mn-II(OH2)](3)}((3)-OH)(4)][Mn-II(-CN)(2)(CN)(4)]H2O=[Mn-4(II)((3)-OH)(4)(OH2)(6)][Mn-II(-CN)(2)(CN)(4)]center dot H2O, which is further simplified to [Mn-4(OH)(4)][Mn(CN)(6)](OH2)(7) (1). 1 has four high-spin (S=5/2) Mn-II sites that are antiferromagnetically coupled within the cube and are antiferromagnetically coupled to six low-spin (S=1/2) octahedral [Mn-II(CN)(6)](4-) ions. Above 40K the magnetic susceptibility, chi(T), can be fitted to the Curie-Weiss expression, chi proportional to (T-theta)(-1), with theta = -13.4K, indicative of significant antiferromagnetic coupling and 1 orders as an antiferromagnet at T-c=7.8K.

The mono-μ-hydroxo complex {[Cu(tmpa)]2-(μ-OH)}3+ (1) can undergo reversible deprotonation at -30 °C to yield {[Cu(tmpa)]2-(μ-O)}2+ (2). This species is basic with a pKa of 24.3. 2 is competent for concerted proton-electron transfer from TEMPOH, but is an intrinsically poor hydrogen atom abstractor (BDFE(OH) of 77.2 kcal/mol) based on kinetic and thermodynamic analyses. Nonetheless, DFT calculations experimentally calibrated against 2 reveal that [Cu2O]2+ is likely thermodynamically viable in copper-dependent methane monoxygenase enzymes.