Search

Formamides are important feedstocks for the manufacture of many fine chemicals. State-of-the-art synthesis of formamides relies on the use of an excess amount of reagents, giving copious waste and thus poor atom-economy. Here, we report the first example of direct synthesis of N-formamides by coupling two challenging reactions, namely reductive amination of carbonyl compounds, particularly biomass-derived aldehydes and ketones, and fixation of CO 2 in the presence of H 2 over a metal-organic framework supported ruthenium catalyst, Ru/MFM-300(Cr). Highly selective production of N-formamides has been observed for a wide range of carbonyl compounds. Synchrotron X-ray powder diffraction reveals the presence of strong host-guest binding interactions via hydrogen bonding and parallel-displaced π⋅⋅⋅π interactions between the catalyst and adsorbed substrates facilitating the activation of substrates and promoting selectivity to formamides. The use of multifunctional porous catalysts to integrate CO 2 utilisation in the synthesis of formamide products will have a significant impact in the sustainable synthesis of feedstock chemicals., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Deuterium labelling of organic compounds is an important process in chemistry. We report the first example of photocatalytic dehalogenative deuteration of both arylhalides and alkylhalides (40 substrates) over a metal-organic framework, MFM-300(Cr), using CD 3 CN as the deuterium source at room temperature. MFM-300(Cr) catalyses high deuterium incorporation and shows excellent tolerance to various functional groups. Synchrotron X-ray powder diffraction reveals the activation of halogenated substrates via confined binding within MFM-300(Cr). In situ electron paramagnetic resonance spectroscopy confirms the formation of carbon-based radicals as intermediates and reveals the reaction pathway. This protocol removes the use of precious-metal catalysts from state-of-the-art processes based upon direct hydrogen isotope exchange and shows high photocatalytic stability, thus enabling multiple catalytic cycles., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The structure and vibrational spectroscopy of centrohexaindane, 1, was investigated. This unusual molecule has a quaternary carbon atom that is coordinated to four further such quaternary carbon atoms as its core, each pair of which is bonded to an ortho-phenylene unit. Previous NMR studies have shown that the molecule has tetrahedral (T d ) symmetry in solution. The infrared and Raman spectra of chloroform and deuterochloroform solutions of 1 are completely in agreement with this conclusion, as the only modes that are visible are those allowed for T d symmetry. This is not the case in the solid state: X-ray powder diffraction indicates that the unit cell is triclinic or monoclinic with a volume in excess of 4000 Å 3 . The vibrational spectroscopy is consistent with C 1 site symmetry and the presence of at least two molecules in the primitive cell. It is likely that the space group is centrosymmetric., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The development of cost-effective sorbents for direct capture of trace CO 2 (<1 %) from the atmosphere is an important and challenging task. Natural or commercial zeolites are promising sorbents, but their performance in adsorption of trace CO 2 has been poorly explored to date. A systematic study on capture of trace CO 2 by commercial faujasite zeolites reveals that the extra-framework cations play a key role on their performance. Under dry conditions, Ba-X displays high dynamic uptake of 1.79 and 0.69 mmol g -1 at CO 2 concentrations of 10000 and 1000 ppm, respectively, and shows excellent recyclability in the temperature-swing adsorption processes. K-X exhibits perfect moisture resistance, and >95 % dry CO 2 uptake can be preserved under relative humidity of 74 %. In situ solid-state NMR spectroscopy, synchrotron X-ray diffraction and neutron diffraction reveal two binding sites for CO 2 in these zeolites, namely the basic framework oxygen atoms and the divalent alkaline earth metal ions. This study unlocks the potential of low-cost natural zeolites for applications in direct air capture., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

We report reversible high capacity adsorption of SO 2 in robust Zr-based metal-organic framework (MOF) materials. Zr-bptc (H 4 bptc=biphenyl-3,3',5,5'-tetracarboxylic acid) shows a high SO 2 uptake of 6.2 mmol g -1 at 0.1 bar and 298 K, reflecting excellent capture capability and removal of SO 2 at low concentration (2500 ppm). Dynamic breakthrough experiments confirm that the introduction of amine, atomically-dispersed Cu II or heteroatomic sulphur sites into the pores enhance the capture of SO 2 at low concentrations. The captured SO 2 can be converted quantitatively to a pharmaceutical intermediate, aryl N-aminosulfonamide, thus converting waste to chemical values. In situ X-ray diffraction, infrared micro-spectroscopy and inelastic neutron scattering enable the visualisation of the binding domains of adsorbed SO 2 molecules and host-guest binding dynamics in these materials at the atomic level. Refinement of the pore environment plays a critical role in designing efficient sorbent materials., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Selective oxidation of benzylic C-H compounds to ketones is important for the production of a wide range of fine chemicals, and is often achieved using toxic or precious metal catalysts. Herein, we report the efficient oxidation of benzylic C-H groups in a broad range of substrates under mild conditions over a robust metal-organic framework material, MFM-170, incorporating redox-active [Cu 2 II (O 2 CR) 4 ] paddlewheel nodes. A comprehensive investigation employing electron paramagnetic resonance (EPR) spectroscopy and synchrotron X-ray diffraction has identified the critical role of the paddlewheel moiety in activating the oxidant t BuOOH (tert-butyl hydroperoxide) via partial reduction to [Cu II Cu I (O 2 CR) 4 ] species., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

We report the precise postsynthetic control of the composition of β-Fe 1+x Se by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X-ray diffraction. We access the full phase width of 0.011+x Se forms a new phase in the presence of oxygen above a 100 °C which has the same anti-PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)