Computational Exploration of Xe Dimers Inside Fullerene Cages.

A systematic analysis for the determination of the optimum fullerene cage for encapsulation of xenon dimers was carried out using density functional theory and activation strain analysis. Our calculations indicate that tubular-like fullerenes are better candidates for the encapsulation of xenon atoms. However, the tubular-like structure should have at least a diameter that is proportional to the van der Waals radius of encapsulated atoms.

Electrostatic Fields Induce Accelerated Proton Coupled Electron Transfer Rates in Chlorophyll Model Compounds.

Chlorophyll-based pigments are crucial mediators of redox processes in photosynthesis, serving as the primary electron donors in photosystems I and II. Despite their structural similarities, these pigments exhibit a wide range of redox potentials (0.5-1.

Characterization of σ and π reaction channels in hydrogen atom transfer reactions.

C(sp)-H bond activation mechanisms typically involve σ- and π-channel pathways, as characterized by FeOH (or FeOC) angles of ca. 180° and 120°, respectively. It is well known that the preference for either the σ- or π-channel depends on the spin state, but doubts exist on what would be characteristic values for the FeOX (X = H or C) angles.

Characterization of Three Intermediates in an Unusual Copper-Dependent Enzyme.

Three intermediates in the formylglycine-generating enzyme are characterized at the molecular level.

Synthesis and Characterization of Copper Complexes Featuring a Redox-Active ONO Ligand in Three Molecular Oxidation States.

In this research article, we report the synthesis, characterization, and reactivity of a family of Cu complexes bearing a tridentate iminosemiquinone ligand and ancillary amine ligands ((ONO)Cu(L), : 1 or 2). The complexes were obtained following a one-pot synthetic protocol by mixing Cu, 3,5-di--butylcatechol, and aqueous ammonia in the presence of an amine base. The Cu complexes were structurally characterized by single-crystal X-ray diffraction analysis (SC-XRD).

A Transient, Highly Reactive Fe(IV)=O Species Revealed Through the Interference by O in the Activation of Organic Peracids by [(N4Py)Fe(II)].

Biomimetic models of high-valent species relevant to those formed by the activation of O by nonheme iron enzymes are essential for understanding reactivity. In synthetic complexes, oxidants such as peroxides and peroxyacids rather than O, are used to generate these species. However, although O is not the terminal oxidant in these models, its presence in reaction mixtures can negatively impact the outcome of catalytic reactions.

Generation of [(N4Py)Fe(IV)═O] through Heterolytic O-O Bond Cleavage in [(N4Py)Fe(II)(OOH)].

High-valent Fe(IV) oxido species are important intermediates in the catalyzed oxidation of organic compounds by nonheme iron enzymes. These species can be generated in biomimetic model complexes directly using oxygen atom transfer oxidants, e.g.

The Amsterdam Modeling Suite.

In this paper, we present the Amsterdam Modeling Suite (AMS), a comprehensive software platform designed to support advanced molecular and materials simulations across a wide range of chemical and physical systems. AMS integrates cutting-edge quantum chemical methods, including Density Functional Theory (DFT) and time-dependent DFT, with molecular mechanics, fluid thermodynamics, machine learning techniques, and more, to enable multi-scale modeling of complex chemical systems. Its design philosophy allows for seamless coupling between components, facilitating simulations that range from small molecules to complex biomolecular and solid-state systems, making it a versatile tool for tackling interdisciplinary challenges, both in industry and in academia.

A 5,000-fold increase in the HAT reactivity of a nonheme Fe=O complex simply by replacing two pyridines of the pentadentate N4Py ligand with pyrazoles.

A pentadentate [N5] ligand (N2Py2Pz) based on the classic N4Py (-bis(2-pyridylmethyl)--bis(2-pyridyl)methylamine) framework has been synthesized by replacing the two pyridylmethyl arms with corresponding (-methyl)pyrazolylmethyl units to form [bis(1-methyl-2-pyrazolyl)methyl--(-2-pyridylmethyl)amine] (L1). The oxidation of the iron(II) precursor (N2Py2Pz)Fe(OTf) () with (BuSO)CHIO at 298 K leads to the formation of the [Fe(O)(N2Py2Pz)] intermediate () with a near-IR band at 750 nm (ε = 250 Mcm) and a t ~ 2 min at 298 K. The introduction of the less basic pyrazolylmethyl ligands in place of two pyridylmethyl units generates Fe=O intermediate that exhibits a cyclohexane oxidation rate of 0.

Density Functional Theory Investigation of 2D Phase Separated Graphene/Hexagonal Boron Nitride Monolayers; Band Gap, Band Edge Positions, and Photo Activity.

Creating sustainable and stable semiconductors for energy conversion via catalysis, such as water splitting and carbon dioxide reduction, is a major challenge in modern materials chemistry, propelled by the limited and dwindling reserves of platinum group metals. Two-dimensional hexagonal borocarbonitride (h-BCN) is a metal-free alternative and ternary semiconductor, possessing tunable electronic properties between that of hexagonal boron nitride (h-BN) and graphene, and has attracted significant attention as a nonmetallic catalyst for a host of technologically relevant chemical reactions. Herein, we use density functional theory to investigate the stability and optoelectronic properties of phase-separated monolayer h-BCN structures, varying carbon concentration and domain size.

10-Fold Increase in Hydrogen Atom Transfer Reactivity for a Series of = 1 Fe═O Complexes Over the = 2 [(TQA)Fe═O] Complex via Entropic Lowering of Reaction Barriers by Secondary Sphere Cycloalkyl Substitution.

Nonheme iron enzymes utilize = 2 iron(IV)-oxo intermediates as oxidants in biological oxygenations. In contrast, corresponding synthetic nonheme Fe═O complexes characterized to date favor the = 1 ground state that generally shows much poorer oxidative reactivity than their = 2 counterparts. However, one intriguing exception found by Nam a decade ago is the = 1 [Fe(O)(MeNTB)] complex (MeNTB = [tris((-methyl-benzimidazol-2-yl)methyl)amine], ) with a hydrogen atom transfer (HAT) reactivity that is 70% that of the = 2 [Fe(O)(TQA)] complex (TQA = tris(2-quinolylmethyl)amine, ).

Enhanced Proton-Coupled Electron-Transfer Reactivity by a Mononuclear Nickel(II) Hydroxide Radical Complex.

The synthesis, characterization, and reactivity of a NiOH core bearing a tridentate redox-active ligand capable of reaching three molecular oxidation states is presented in this paper. The reduced complex [LNiOH] was characterized by single-crystal X-ray diffraction analysis, depicting a square-planar NiOH core stabilized by intramolecular H-bonding interactions. Cyclic voltammetry measurements indicated that [LNiOH] can be reversibly oxidized to [LNiOH] and [LNiOH] at very negative reduction potentials (-1.

Cu-Promoted -Hydroxylation of sp Bonds with Concomitant Aromatic 1,2-Rearrangement Involving a Cu-oxyl-hydroxo Species.

Herein, we report the first example of Cu-promoted β -hydroxylation of substituted benzophenones using a bidentate directing group (DG) and HO as an oxidant. In addition to the new C-O bond formed, the -oxidation induces a very unusual 1,2-rearrangement of the iminyl group to the vicinal γ position. This transformation is highly dependent on the substrate utilized (favored for 4-methoxy-substituted benzophenones) and on the DG used (2-picolylamine leads to selective γ-C-H functionalization, while β -oxidation requires 2-(2-aminoethyl)pyridine).

Copper-Catalysed Synthesis of (E)-Allylic Organophosphorus Derivatives: A Low Toxic, Mild, Economical, and Ligand-Free Method.

Organophosphorus compounds are fundamental for the chemical industry due to their broad applications across multiple sectors, including pharmaceuticals, agrochemicals, and materials science. Despite their high importance, the sustainable and cost-effective synthesis of organophoshoryl derivatives remains very challenging. Here, we report the first successful regio- and stereoselective hydrophosphorylation of terminal allenamides using an affordable copper catalyst system.

Role of non-redox innocent ligand units in the oxidation of alcohols with HO catalyzed by μ-oxido-diiron(III) bis-phenolato polypyridyl complexes.

Redox non-innocent ligands hold the potential to expand the redox chemistry and activity of transition metal catalysts. The impact of the additional redox chemistry of phenol ligands in oxidation catalysis is explored here in the complex μ-oxido-diiron(III) polypyridyl (1) [(L)Fe(III)(μ-O)Fe(III)(L)](ClO) (where HL is 2-(((di(pyridin-2-yl)methyl) (pyridin-2-ylmethyl) amino)methyl)phenol) and its tert-butyl substituted analog 2, in which each of the Fe(III) centers is coordinated to a phenolato moiety of the ligand. Complex 1 was shown earlier to catalyse the oxidation of benzyl alcohols to aldehydes with HO.

Exohedral Diels-Alder Reactivity of Endohedral Metallofullerene C.

Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage.

Investigating and Quantifying Molecular Complexity Using Assembly Theory and Spectroscopy.

Current approaches to evaluate molecular complexity use algorithmic complexity, rooted in computer science, and thus are not experimentally measurable. Directly evaluating molecular complexity could be used to study directed vs undirected processes in the creation of molecules, with potential applications in drug discovery, the origin of life, and artificial life. Assembly theory has been developed to quantify the complexity of a molecule by finding the shortest path to construct the molecule from building blocks, revealing its molecular assembly index (MA).

Tuning the Thermochemistry and Reactivity of a Series of Cu-Based 4H/4e Electron-Coupled-Proton Buffers.

Electron-coupled-proton buffers (ECPBs) store and deliver protons and electrons in a reversible fashion. We have recently reported an ECPB based on Cu and a redox-active ligand that promoted 4H/4e reversible transformations ( , 144, 16905). Herein, we report a series of Cu-based ECPBs in which the ability of these to accept and/or donate H equivalents can be tuned via ligand modification.

Torsion Effects Beyond the δ Bond and the Role of π Metal-Ligand Interactions.

Previous studies on bimetallic paddlewheel compounds have established a direct correlation between metal-metal distance and ligand torsion angles, leading to the rule that higher torsion results in longer metal-metal bond distances. Here, the new discovery based on diarylformamidinate Ru₂⁵⁺ paddlewheel compounds [RuCl(DArF)] that show an opposite behavior is reported: higher torsions lead to shorter metal-metal distances. This discovery challenges the assumption that internal rotation solely impacts the δ bond.

A tale of two topological isomers: Uptuning [Fe(O)(Mecyclam)] for olefin epoxidation.

TMC- and TMC- the two topological isomers of [Fe(O)(TMC)(CHCN)] (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, or Mecyclam), differ in the orientations of their Fe=O units relative to the four methyl groups of the TMC ligand framework. The Fe=O unit of TMC- points away from the four methyl groups, while that of TMC- is surrounded by the methyl groups, resulting in differences in their oxidative reactivities. TMC- reacts with HAT (hydrogen atom transfer) substrates at 1.

Generation of Ru(III)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme.

The reaction of [(Me/BnTPEN)Ru(NCCH)] (BnTPEN = -benzyl-,,-tris(pyridine-2-ylmethyl)ethane-1,2-diamine and MeTPEN = -methyl-,,-tris(pyridine-2-ylmethyl)ethane-1,2-diamine) with CPBA in the presence of chloride ions in CHCN : HO generated a novel (Me/BnTPEN)Ru-OCl species at room temperature. This hypochlorite adduct could also be obtained by the direct reaction of NaOCl and HClO with (L)Ru complexes. The current study mimics the synthesis of a metal hypochlorite adduct in a similar fashion as in the heme-dependent haloperoxidase enzyme.

The peptide bond rupture mechanism in the serine proteases: an study based on sequential scale models.

Given the importance of serine proteases for biochemical processes, we have studied the peptide bond rupture mechanism using three sequential scale models as representations of the KLK5 enzyme (a protein overexpressed in ovarian cancer). The first model contains the basic functional groups of the residues that conform to the catalytic triad present in serine proteases; the second model contains some additional residues and, finally, the last representation includes all atoms of the KLK5 protein together with 10.000 explicit water molecules.

Reductive Coupling of Nitric Oxide by Cu(I): Stepwise Formation of Mono- and Dinitrosyl Species to a Cupric Hyponitrite Intermediate.

Transition-metal-mediated reductive coupling of nitric oxide (NO) to nitrous oxide (NO) has significance across the fields of industrial chemistry, biochemistry, medicine, and environmental health. Herein, we elucidate a density functional theory (DFT)-supplemented mechanism of NO reductive coupling at a copper-ion center, [(tmpa)Cu(MeCN)] () {tmpa = tris(2-pyridylmethyl)amine}. At -110 °C in EtOH (<-90 °C in MeOH), exposing to NO leads to a new binuclear hyponitrite intermediate [{(tmpa)Cu}(μ-NO)] (), exhibiting temperature-dependent irreversible isomerization to the previously characterized κ-O,O'--[(tmpa)Cu(μ-NO)] () complex.

A 4H/4e Electron-Coupled-Proton Buffer Based on a Mononuclear Cu Complex.

In this research article, we describe a 4H/4e electron-coupled-proton buffer (ECPB) based on Cu and a redox-active ligand. The protonated/reduced ECPB (complex : ), consisting of Cu with 2 equiv of the ligand (LH: 1,1'-(4,5-dimethoxy-1,2-phenylene)bis(3-(-butyl)urea)), reacted with H/e acceptors such as O to generate the deprotonated/oxidized ECPB. The resulting compound, (complex : ), was characterized by X-ray diffraction analysis, nuclear magnetic resonance (H-NMR), and density functional theory, and it is electronically described as a cuprous bis(benzoquinonediimine) species.