Padgettthomasen7551

Unraveling the formation mechanism of hydroxyl radicals (OH˙) is one of the outstanding issues in photocatalytic reactions, where 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is widely utilized as a trapping agent to detect OH˙ radicals in experiments. In this study, we carry out density functional theory calculations to reveal the origin and formation process of OH˙ radicals by investigating the interaction of water with DMPO on a rutile TiO2(110) surface. Our results clearly show that the OH˙ radicals trapped by DMPO stem from water upon illumination. The charge compensation mechanism dominates the formation of DMPO-OH from the reaction between DMPO and water on the rutile TiO2(110) surface. These findings provide new insights into the photocatalytic mechanism and may achieve new frontiers in photocatalytic research.Covalent organic frameworks (COFs) are constructed from the precise integration of small organic blocks into an extended, porous framework via covalent linkages. COFs can also be viewed as an organic solid consisting of a periodic array of one dimensional (1-D) channels. SKI II clinical trial Although a wide range of applications have been envisioned for COFs, understanding the structure-property correlation at the level of chemical linkages, topology, pore size and functionality is needed to unlock the potential of these materials. Herein, we review some emerging applications of two-dimensional (2D) COFs in solid-state photoluminescence, stimuli-responsive COFs, gas storage, ion conduction and energy storage, and discuss the intricate design principles that enable these COFs to perform better than their building blocks or polymeric counterparts. Going beyond bulk 2D-COFs, molecular thin organic layers called COFene can be derived from the exfoliation of 2D COFs, generating new properties for applications in optoelectronic devices, catalysis and separation.We report herein the first detailed study of the mechanism of redox reactions occurring during the gas-phase dissociative electron transfer of prototypical ternary [CuII(dien)M]˙2+ complexes (M, peptide). The two final products are (i) the oxidized non-zwitterionic π-centered [M]˙+ species with both the charge and spin densities delocalized over the indole ring of the tryptophan residue and with a C-terminal COOH group intact, and (ii) the complementary ion [CuI(dien)]+. Infrared multiple photon dissociation (IRMPD) action spectroscopy and low-energy collision-induced dissociation (CID) experiments, in conjunction with density functional theory (DFT) calculations, revealed the structural details of the mass-isolated precursor and product cations. Our experimental and theoretical results indicate that the doubly positively charged precursor [CuII(dien)M]˙2+ features electrostatic coordination through the anionic carboxylate end of the zwitterionic M moiety. An additional interaction exists between the indole ring of the tryptophan residue and one of the primary amino groups of the dien ligand; the DFT calculations provided the structures of the precursor ion, intermediates, and products, and enabled us to keep track of the locations of the charge and unpaired electron. The dissociative one-electron transfer reaction is initiated by a gradual transition of the M tripeptide from the zwitterionic form in [CuII(dien)M]˙2+ to the non-zwitterionic M intermediate, through a cascade of conformational changes and proton transfers. In the next step, the highest energy intermediate is formed; here, the copper center is 5-coordinate with coordination from both the carboxylic acid group and the indole ring. A subsequent switch back to 4-coordination to an intermediate IM1, where attachment to GGW occurs through the indole ring only, creates the structure that ultimately undergoes dissociation.A synthetic method was developed to enable the microwave-assisted solid-state preparation of double molybdate and double tungstate scheelite-type phosphors of formula NaRE(MO4)2 (RE = La, Pr, Eu, Dy; M = Mo, W). Starting from subgram-scale stoichiometric mixtures of metal carbonates and oxides and with the aid of granular activated charcoal as a microwave susceptor, ternary (NaEu(MO4)2), quaternary (NaLa0.95Eu0.05(MO4)2), and quinary phosphors (NaLa0.95Pr0.025Dy0.025(MO4)2) were obtained upon heating in a countertop microwave oven. The synthesis of crystalline and phase-pure materials required heating times ranging from 18 to 27 min, significantly shorter than those typically encountered in solid-state reactions assisted by conventional heating. Depending on chemical composition, the speed-up factor ranged from 30 to 40. More importantly, photoluminescence studies performed on the compositionally complex quinary molybdate NaLa0.95Pr0.025Dy0.025(MoO4)2 showed that phosphors synthesized using microwave and conventional heating have nearly identical luminescence responses. The synthetic method described in this contribution is robust, fast, simple, and ideally suited for exploratory synthesis and rapid screening of group VI metalate phosphors, as well as for the preparation of binary precursors to these materials (e.g., Na2MoO4 and Na2WO4).Protonation and hydration of biomolecules govern their structure, conformation, and function. Herein, we explore the microhydration structure in mass-selected protonated pyrimidine-water clusters (H+Pym-Wn, n = 1-4) by a combination of infrared photodissociation spectroscopy (IRPD) between 2450 and 3900 cm-1 and density functional theory (DFT) calculations at the dispersion-corrected B3LYP-D3/aug-cc-pVTZ level. We further present the IR spectrum of H+Pym-N2 to evaluate the effect of solvent polarity on the intrinsic molecular parameters of H+Pym. Our combined spectroscopic and computational approach unequivocally shows that protonation of Pym occurs at one of the two equivalent basic ring N atoms and that the ligands in H+Pym-L (L = N2 or W) preferentially form linear H-bonds to the resulting acidic NH group. Successive addition of water ligands results in the formation of a H-bonded solvent network which increasingly weakens the NH group. Despite substantial activation of the N-H bond upon microhydration, no intracluster proton transfer occurs up to n = 4 because of the balance of relative proton affinities of Pym and Wn and the involved solvation energies.