Just published in Angewandte! Methyl Substitution Destabilizes Alkyl Radicals

We have quantum chemically investigated how methyl substituents affect the stability of alkyl radicals MemH3−mC⋅ and the corresponding MemH3−mC−X bonds (X = H, CH3, OH; m = 0 – 3) using density functional theory at M06-2X/TZ2P. The state-of-the-art in physical organic chemistry is that alkyl radicals are stabilized upon an increase in their degree of substitution from methyl<primary<secondary<tertiary, and that this…

New in CEJ! Unravelling Enzymatic Features in a Supramolecular Iridium Catalyst by Computational Calculations

Non-biological catalysts following the governing principles of enzymes are attractive systems to disclose unprecedented reactivities. Most of those existing catalysts feature an adaptable molecular recognition site for substrate binding that are prone to undergo conformational selection pathways. Herein, we present a non-biological catalyst that is able to bind substrates via the induced fit model according…

New in Dalton Transactions! Ni(i)-TPA stabilization by hydrogen bond formation on the second coordination sphere: a DFT characterizationNew in Dalton Transactions!

Ni(I) compounds are less common than those of either Ni(0) or Ni(II). Recently, a series of Ni(I) tris(2-pyridylmethyl)amine (TPA) complexes were synthetized through the reduction of Ni(II)–TPA complexes and their stabilization was attributed to the formation of H-bonds (Chem. Commun., 2021, 57, 753–756). Because of the growing relevance of Ni(I) complexes in the field of catalysis,…

New in Nature Communications! 3D and 2D aromatic units behave like oil and water in the case of benzocarborane derivativesNew in Nature Communications!

A large number of 2D/2D and 3D/3D aromatic fusions that keep their aromaticity in the fused compounds have been synthesized. In addition, we have previously proven the electronic relationship between the 3D aromaticity of boron hydrides and the 2D aromaticity of PAHs. Here we report the possible existence of 3D/2D aromatic fusions that retain the…

New in JOC! Through-Space Stabilization of an Imidazolium Cation by Aromatic RingsNew in JOC!

Imidazole-based compounds are widely found in natural products, synthetic molecules, and biomolecules. Noncovalent interactions between the imidazole ring and other functional groups play an important role in determining the function of diverse molecules. However, there is a limited understanding of the underlying noncovalent interactions between imidazoles and aromatic systems. In this work, we report physical-organic…

New in CEJ! C-X Bond Activation by Palladium: Steric Shielding versus Steric AttractionNew in CEJ!

The C−X bond activation (X = H, C) of a series of substituted C(n°)−H and C(n°)−C(m°) bonds with C(n°) and C(m°) = H3C− (methyl, 0°), CH3H2C− (primary, 1°), (CH3)2HC− (secondary, 2°), (CH3)3C− (tertiary, 3°) by palladium were investigated using relativistic dispersion-corrected density functional theory at ZORA-BLYP-D3(BJ)/TZ2P. The effect of the stepwise introduction of substituents was…

Published in JOC! Probing Noncovalent Interactions in [3,3]MetaparacyclophanePublished in JOC!

Arene–arene interactions are fundamentally important in molecular recognition. To precisely probe arene–arene interactions in cyclophanes, we designed and synthesized (2,6-phenol)paracyclophanes and (2,6-aniline)paracyclophanes that possess two aromatic rings in close proximity. Fine-tuning the aromatic character of one aromatic ring by fluorine substituents enables investigations on the intramolecular interactions between the electron-rich phenol and aniline with tetra-H-…

Published in Communications Chemistry! Reading and erasing of the phosphonium analogue of trimethyllysine by epigenetic proteinsPublished in Communications Chemistry!

Nε-Methylation of lysine residues in histones plays an essential role in the regulation of eukaryotic transcription. The ‘highest’ methylation mark, Nε-trimethyllysine, is specifically recognised by Nε-trimethyllysine binding ‘reader’ domains, and undergoes demethylation, as catalysed by 2-oxoglutarate dependent JmjC oxygenases. We report studies on the recognition of the closest positively charged Nε-trimethyllysine analogue, i.e. its trimethylphosphonium derivative (KPme3), by Nε-trimethyllysine…

Published in Angewandte! Aromaticity and Extrusion of Benzenoids Linked to [o-COSAN]-. Clar has the AnswerNew in Angewandte!

Benzene and pyrene can be synthetically linked to [o-COSAN]− keeping their aromaticity. In contrast, naphthalene and anthracene are extruded in the same reaction. We have proven that extrusion is only favorable if the number of Clar’s π-sextets remains constant. Thus, Clar has the answer to whether an attached polycyclic aromatic hydrocarbon to [o-COSAN]− is extruded or not….

Published in JCC! Rational design of iron catalysts for C-X bond activation

We have quantum chemically studied the iron-mediated CX bond activation (X = H, Cl, CH3) by d8-FeL4 complexes using relativistic density functional theory at ZORA-OPBE/TZ2P. We find that by either modulating the electronic effects of a generic iron-catalyst by a set of ligands, that is, CO, BF, PH3, BN(CH3)2, or by manipulating structural effects through the introduction of…

Published in CEJ! C(spn)−X (n=1–3) Bond Activation by Palladium

We have studied the palladium-mediated activation of C(spn)−X bonds (n = 1–3 and X = H, CH3, Cl) in archetypal model substrates H3C−CH2−X, H2C=CH−X and HC≡C−X by catalysts PdLn with Ln = no ligand, Cl−, and (PH3)2, using relativistic density functional theory at ZORA-BLYP/TZ2P. The oxidative addition barrier decreases along this series, even though the strength of…

Published in CEJ! Probing the Lewis Acidity of Boronic Acids through Interactions with Arene Substituents

Boronic acids. Hammett analysis of 2,6-diarylphenylboronic acids reveals that their Lewis acidity remains unchanged upon the introduction of EWG/EDG at the distant para position of the flanking aromatic rings. Structural and computational studies demonstrate that polar-π interactions and solvation effects contribute to the stabilization of boronic acids and boronate forms by aromatic rings, providing a valuable molecular…