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The catalytic activity of multifunctional, microporous materials is directly linked to the spatial arrangement of their structural building blocks. Despite great achievements in the design and incorporation of isolated catalytically active metal complexes within such materials, a detailed understanding of their atomic-level structure and the local environment of the active species remains a fundamental challenge, especially when these latter are hosted in non-crystalline organic polymers. Here, we show that by combining computational chemistry with pair distribution function analysis, 129 Xe NMR, and Dynamic Nuclear Polarization enhanced NMR spectroscopy, a very accurate description of the molecular structure and confining surroundings of a catalytically active Rh-based organometallic complex incorporated inside the cavity of amorphous bipyridine-based porous polymers is obtained. Small, but significant, differences in the structural properties of the polymers are highlighted depending on their backbone motifs., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

An earth-abundant nickel(II) bipyridine catalyst, combined with lithium hexamethyldisilazide as base, demonstrates its wide applicability in the direct arylation polymerization of di- and tri-thiophene heteroaryls with poly(hetero)aryl halides. With a nickel catalyst loading of 2.5 mol%, a series of twenty highly cross-linked organic polymers is obtained in 34 to 99 % yields. Using mixed polytopic coupling partners allows obtaining alternating and optically active thiophene-based solids with intrinsic porosity., (© 2022 Wiley-VCH GmbH.)

The molecular-level structuration of two full photosystems into conjugated porous organic polymers is reported. The strategy of heterogenization gives rise to photosystems which are still fully active after 4 days of continuous illumination. Those materials catalyze the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a single framework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long-term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenced by in situ ultrafast time-resolved spectroscopy., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A molecular catalyst [Cp*Rh(4,4'-bpydc)] 2+ and a molecular photosensitizer [Ru(bpy) 2 (4,4'-bpydc)] 2+ (bpydc=bipyridinedicarboxylic acid) were co-immobilized into the highly porous metal-organic framework MIL-101-NH 2 (Al) upon easy postsynthetic impregnation. The Rh-Ru@MIL-101-NH 2 composite allows the reduction of CO 2 under visible light, while exhibiting remarkable selectivity with the exclusive production of formate. This Rh-Ru@MIL-101-NH 2 solid represents the first example of MOFs functionalized with both a catalyst and a photosensitizer in a noncovalent fashion. Thanks to the coconfinement of the catalyst and photosensitizer into the cavity's nanospace, the MOF pores are used as nanoreactors and enable molecular catalysis in a heterogeneous manner., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The addition of a CO 2 -adsorption component (substituted imidazolate-based SIM-1 crystals) to a gas-diffusion layer-type catalytic electrode enhances the activity and especially the selectivity towards >C1 carbon chain products (ethanol, acetone, and isopropanol) of a Pt-based electrocatalyst that is not able to form products of CO 2 reduction involving C-C bond formation under conventional (liquid-phase) conditions. This indicates that the increase of the effective CO 2 concentration at the electrode active surface is the factor controlling the formation of >C1 products rather than only the intrinsic properties of the electrocatalyst., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We use density functional theory, newly parameterized molecular dynamics simulations, and last generation 15 N dynamic nuclear polarization surface enhanced solid-state NMR spectroscopy (DNP SENS) to understand graft-host interactions and effects imposed by the metal-organic framework (MOF) host on peptide conformations in a peptide-functionalized MOF. Focusing on two grafts typified by MIL-68-proline (-Pro) and MIL-68-glycine-proline (-Gly-Pro), we identified the most likely peptide conformations adopted in the functionalized hybrid frameworks. We found that hydrogen bond interactions between the graft and the surface hydroxyl groups of the MOF are essential in determining the peptides conformation(s). DNP SENS methodology shows unprecedented signal enhancements when applied to these peptide-functionalized MOFs. The calculated chemical shifts of selected MIL-68-NH-Pro and MIL-68-NH-Gly-Pro conformations are in a good agreement with the experimentally obtained 15 N NMR signals. The study shows that the conformations of peptides when grafted in a MOF host are unlikely to be freely distributed, and conformational selection is directed by strong host-guest interactions., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first photosensitization of a rhodium-based catalytic system for CO2 reduction is reported, with formate as the sole carbon-containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H2 -storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post-synthetic linker exchange, and characterization of a new metal-organic framework (MOF) Cp*Rh@UiO-67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF-based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of ∼10 % molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H2 . There is no precedent for a MOF catalyzing the latter reaction so far., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Novel nickel-based catalytic systems for the C-H arylation of azoles with haloarenes and aryl triflates have been developed. We have established that Ni(OAc)(2)/bipy/LiOtBu serves as a general catalytic system for the coupling with aryl bromides and iodides as aryl electrophiles. For couplings with more challenging electrophiles, such as aryl chlorides and triflates, the Ni(OAc)(2)/dppf (dppf = 1,1'-bis(diphenylphosphino)ferrocene) system was found to be effective. Thiazoles, benzothiazoles, oxazoles, benzoxazoles, and benzimidazoles can be used as the heteroarene coupling partner. Upon further investigation, we discovered a new protocol for the present coupling using Mg(OtBu)(2) as a milder and less expensive alternative to LiOtBu. Attempts to reveal the mechanism of this nickel-catalyzed heterobiaryl coupling are also described. This newly developed methodology has been successfully applied to the syntheses of febuxostat (a xanthine oxidase inhibitor that is effective for the treatment of gout and hyperuricemia), tafamidis (effective for the treatment of TTR amyloid polyneuropathy), and texaline (a natural product having antitubercular activity)., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)