London dispersion driven compaction of coordination cages in the gas-phase - a combined ion mobility and theoretical study.

Large self-assembled systems (such as metallosupramolecular rings and cages) can be difficult to structurally characterize, in particular when they show a highly dynamic behavior. In the gas-phase, Ion Mobility Spectrometry (IMS), in tandem with Electrospray Ionization Mass Spectrometry (ESI MS), can yield valuable insights into the size, shape and dynamics of such supramolecular assemblies. However, the detailed relationship between experimental IMS data and the actual gas-phase structure is still poorly understood for soft and flexible self-assemblies.

Flavin-Catalyzed, Photochemical Conversion of Dehydroalanine into 4,5-Dihydroxynorvaline.

The chemical synthesis of unnatural amino acids (UAA) is a key strategy for preparing designed peptides, including pharmaceutically active compounds. Alterations of existing amino acid residues such as dehydroalanine (Dha) are particularly important since selected positions can be addressed without the necessity of a complete de novo synthesis. The intriguing UAA 4,5-dihydroxynorvaline (Dnv) is found in a variety of naturally occurring peptides and biologically active compounds.

Spin parameter optimization for spin-polarized extended tight-binding methods.

We present an optimization strategy for atom-specific spin-polarization constants within the spin-polarized GFN2-xTB framework, aiming to enhance the accuracy of molecular simulations. We compare a sequential and global optimization of spin parameters for hydrogen, carbon, nitrogen, oxygen, and fluorine. Sensitivity analysis using Sobol indices guides the identification of the most influential parameters for a given reference dataset, allowing for a nuanced understanding of their impact on diverse molecular properties.

Zr-based metalloporphyrin MOF probe for electrochemical detection of parathion-methyl.

An electrochemical (EC) sensor based on metalloporphyrin metal-organic framework (MOF) for the detection of parathion-methyl (PM) has been developed. The prepared MOF-525(Fe) exhibits great signal enhancement toward the electrochemical detection of PM owing to its unique structural properties and electrochemical activities. Under optimal experimental conditions, the as-prepared MOF-525(Fe) based EC sensor exhibited excellent PM sensing performance with a wide linear detection range (0.

Enhancing Flavins Photochemical Activity in Hydrogen Atom Abstraction and Triplet Sensitization through Ring-Contraction.

The isoalloxazine heterocycle of flavin cofactors reacts with various nucleophiles to form covalent adducts with important functions in enzymes. Molecular flavin models allow for the characterization of such adducts and the study of their properties. A fascinating set of reactions occurs when flavins react with hydroxide base, which leads to imidazolonequinoxalines, ring-contracted flavins, with so far unexplored activity.

Benzene-1,4-Di(dithiocarboxylate) Linker-Based Coordination Polymers of Mn, Zn, and Mixed-Valence Fe.

Three new coordination polymers (CPs) constructed from the linker 1,4-di(dithiocarboxylate) (BDDTC)─the sulfur-analog of 1,4-benzenedicarboxylate (BDC)─together with Mn-, Zn-, and Fe-based inorganic SBUs are reported with description of their structural and electronic properties. Single-crystal X-ray diffraction revealed structural diversity ranging from one-dimensional chains in [Mn(BDDTC)(DMF)] () to two-dimensional (2D) honeycomb sheets observed for [Zn(BDDTC)][Zn(DMF)(HO)] (). Gas adsorption experiments confirmed a 3D porous structure for the mixed-valent material [Fe(BDDTC)(OH)] ().

Photochemical Desaturation and Epoxidation with Oxygen by Sequential Flavin Catalysis.

Catalytic desaturations are important strategies for the functionalization of organic molecules. In nature, flavoenzymes mediate the formation of α,β-unsaturated carbonyl compounds by concomitant cofactor reduction. Contrary to many laboratory methods for these reactions, such as the Saegusa-Ito oxidation, no transition metal reagents or catalysts are required.

Toward a Comprehensive Understanding of Photocatalysis: What Systematic Studies and Alcohol Surface Chemistry on TiO(110) Have to Offer for Future Developments.

Heterogeneous photocatalytic systems are usually described based on electrochemistry, which the vast majority of interpretations and strategies for optimizing photocatalysts rely on. Charge carrier dynamics are usually in the spotlight, whereas the surface chemistry of the photocatalyst is neglected. This is unjustified, because studies on alcohol photoreforming on metal-decorated rutile single crystals revealed that the electrochemical reaction model is not generally applicable.

A re-useable microreactor for dynamic and sensitive photocatalytic measurements: Exemplified by the photoconversion of ethanol on Pt-loaded titania P25.

Despite numerous advancements in synthesizing photoactive materials, the evaluation of their catalytic performance remains challenging since their fabrication often involves tedious strategies, yielding only low quantities in the μ-gram scale. In addition, these model catalysts exhibit different forms, such as powders or film(-like) structures grown on various supporting materials. Herein, we present a versatile gas phase μ-photoreactor, compatible with different catalyst morphologies, which is, in contrast to existing systems, re-openable and -useable, allowing not only post-characterization of the photocatalytic material but also enabling catalyst screening studies in short experimental time intervals.

Molecular flavin catalysts for C-H functionalisation and derivatisation of dehydroamino acids.

In nature, the isoalloxazine heterocycle of flavin cofactors undergoes reversible covalent bond formation with a variety of different reaction partners. These intermediates play a crucial role as the signalling states and in selective catalysis reactions. In the organic laboratory, covalent adducts with a new carbon-carbon bond have been observed with photochemically excited flavins but have, so far, only been regarded as dead-end side products.