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1. Rapid design of top-performing metal-organic frameworks with qualitative representations of building blocks

   https://doi.org/10.1038/s41524-023-01125-1  

   Comlek, Yigitcan; Pham, Thang Duc; Snurr, Randall Q.; Chen, Wei (September 2023, npj Computational Materials)

   Abstract Data-driven materials design often encounters challenges where systems possess qualitative (categorical) information. Specifically, representing Metal-organic frameworks (MOFs) through different building blocks poses a challenge for designers to incorporate qualitative information into design optimization, and leads to a combinatorial challenge, with large number of MOFs that could be explored. In this work, we integrated Latent Variable Gaussian Process (LVGP) and Multi-Objective Batch-Bayesian Optimization (MOBBO) to identify top-performing MOFs adaptively, autonomously, and efficiently. We showcased that our method (i) requires no specific physical descriptors and only uses building blocks that construct the MOFs for global optimization through qualitative representations, (ii) is application and property independent, and (iii) provides an interpretable model of building blocks with physical justification. By searching only ~1% of the design space, LVGP-MOBBO identified all MOFs on the Pareto front and 97% of the 50 top-performing designs for the CO₂working capacity and CO₂/N₂selectivity properties. 

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2. Spectroscopic Evidence of Hyponitrite Radical Intermediate in NO Disproportionation at a MOF‐Supported Mononuclear Copper Site

   https://doi.org/10.1002/anie.202015359  

   Sun, Chenyue; Yang, Luming; Ortuño, Manuel A.; Wright, Ashley M.; Chen, Tianyang; Head, Ashley R.; López, Núria; Dincă, Mircea (March 2021, Angewandte Chemie International Edition)

   Abstract Dianionic hyponitrite (N₂O₂²⁻) is often proposed, based on model complexes, as the key intermediate in reductive coupling of nitric oxide to nitrous oxide at the bimetallic active sites of heme‐copper oxidases and nitric oxide reductases. In this work, we examine the gas‐solid reaction of nitric oxide with the metal–organic framework Cu^I‐ZrTpmC* with a suite of in situ spectroscopies and density functional theory simulations, and identify an unusual chelating N₂O₂^.−intermediate. These results highlight the advantage provided by site‐isolation in metal–organic frameworks (MOFs) for studying important reaction intermediates, and provide a mechanistic scenario compatible with the proposed one‐electron couple in these enzymes. 

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3. Elucidation of the role of metals in the adsorption and photodegradation of herbicides by metal-organic frameworks

   https://doi.org/10.1038/s41467-024-45546-y  

   Chiu, Nan Chieh; Lessard, Jacob M.; Musa, Emmanuel Nyela; Lancaster, Logan S.; Wheeler, Clara; Krueger, Taylor D.; Chen, Cheng; Gallagher, Trenton C.; Nord, Makenzie T.; Huang, Hongliang; et al (December 2024, Nature Communications)

   Abstract Here, four MOFs, namely Sc-TBAPy, Al-TBAPy, Y-TBAPy, and Fe-TBAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoic acid)pyrene), were characterized and evaluated for their ability to remediate glyphosate (GP) from water. Among these materials, Sc-TBAPy demonstrates superior performance in both the adsorption and degradation of GP. Upon light irradiation for 5 min, Sc-TBAPy completely degrades 100% of GP in a 1.5 mM aqueous solution. Femtosecond transient absorption spectroscopy reveals that Sc-TBAPy exhibits enhanced charge transfer character compared to the other MOFs, as well as suppressed formation of emissive excimers that could impede photocatalysis. This finding was further supported by hydrogen evolution half-reaction (HER) experiments, which demonstrated Sc-TBAPy’s superior catalytic activity for water splitting. In addition to its faster adsorption and more efficient photodegradation of GP, Sc-TBAPy also followed a selective pathway towards the oxidation of GP, avoiding the formation of toxic aminomethylphosphonic acid observed with the other M³⁺-TBAPy MOFs. To investigate the selectivity observed with Sc-TBAPy, electron spin resonance, depleted oxygen conditions, and solvent exchange with D₂O were employed to elucidate the role of different reactive oxygen species on GP photodegradation. The findings indicate that singlet oxygen (¹O₂) plays a critical role in the selective photodegradation pathway achieved by Sc-TBAPy. 

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4. Charge‐Separated and Lewis Paired Metal–Organic Framework for Anion Exchange and CO ₂ Chemical Fixation

   https://doi.org/10.1002/chem.202002823  

   Thapa, Sheela; Meng, Lingyao; Hettiarachchi, Eshani; Bader, Yousef_K; Dickie, Diane_A; Rubasinghege, Gayan; Ivanov, Sergei_A; Vreeland, Erika_C; Qin, Yang (October 2020, Chemistry – A European Journal)

   Abstract Charge‐separated metal–organic frameworks (MOFs) are a unique class of MOFs that can possess added properties originating from the exposed ionic species. A new charge‐separated MOF, namely, UNM‐6 synthesized from a tetrahedral borate ligand and Co²⁺cation is reported herein. UNM‐6 crystalizes into the highly symmetricP43nspace group with fourfold interpenetration, despite the stoichiometric imbalance between the B and Co atoms, which also leads to loosely bound NO₃⁻anions within the crystal structure. These NO₃⁻ions can be quantitatively exchanged with various other anions, leading to Lewis acid (Co²⁺) and Lewis base (anions) pairs within the pores and potentially cooperative catalytic activities. For example, UNM‐6‐Br, the MOF after anion exchange with Br⁻anions, displays high catalytic activity and stability in reactions of CO₂chemical fixation into cyclic carbonates. 

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5. A generative artificial intelligence framework based on a molecular diffusion model for the design of metal-organic frameworks for carbon capture

   https://doi.org/10.1038/s42004-023-01090-2  

   Park, Hyun; Yan, Xiaoli; Zhu, Ruijie; Huerta, Eliu_A; Chaudhuri, Santanu; Cooper, Donny; Foster, Ian; Tajkhorshid, Emad (February 2024, Communications Chemistry)

   Abstract Metal-organic frameworks (MOFs) exhibit great promise for CO₂capture. However, finding the best performing materials poses computational and experimental grand challenges in view of the vast chemical space of potential building blocks. Here, we introduce GHP-MOFassemble, a generative artificial intelligence (AI), high performance framework for the rational and accelerated design of MOFs with high CO₂adsorption capacity and synthesizable linkers. GHP-MOFassemble generates novel linkers, assembled with one of three pre-selected metal nodes (Cu paddlewheel, Zn paddlewheel, Zn tetramer) into MOFs in a primitive cubic topology. GHP-MOFassemble screens and validates AI-generated MOFs for uniqueness, synthesizability, structural validity, uses molecular dynamics simulations to study their stability and chemical consistency, and crystal graph neural networks and Grand Canonical Monte Carlo simulations to quantify their CO₂adsorption capacities. We present the top six AI-generated MOFs with CO₂capacities greater than 2m mol g⁻¹, i.e., higher than 96.9% of structures in the hypothetical MOF dataset. 

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