Ebselen (1), the quintessential mimic of antioxidant selenoenzyme glutathione peroxidase (GPx), is a potential chemopreventative for various diseases associated with oxidative stress. Density-functional theory (DFT) and solvent-assisted proton exchange (SAPE) are used to model complex mechanism scavenging reactive oxygen species by 1. SAPE microsolvation method designed approximate role bulk solvent in chemical processes involving transfer. Consistent experimental studies, studies predict...

Understanding the explosive decomposition pathways of high-energy-density materials (HEDMs) is important for developing compounds with improved properties. Rapid reaction rates make detonation mechanisms HEDMs difficult to understand, so computational tools are used predict trigger bonds-weak bonds that break, leading detonation. Wiberg bond indices (WBIs) have been compare densities in reference molecules provide a relative scale strength activated most likely break an explosion. This...

Density functional theory studies of S···X and Se···X (X = Br, I) halogen-bonding interactions are used to interpret the selection selenium iodine for thyroid hormone signaling. A new mechanism dehalogenation in terms halogen bonding is proposed. The activation barriers deiodination an aromatic iodide by MeSeH MeSH (17.6 19.8 kcal/mol) consistent with relative rates iodothyronine deiodinase its cysteine mutant.

The synthesis, X-ray structures and photophysics of ten complexes CuX (X = I or Br) with bridging N-substituted N,N′-disubstituted piperazines (Pip) are presented. Depending on the steric demand Pip substituents, fall into four categories: (CuX)4(Pip)2, which networks linked Cu4X4 cubane units, (CuX)2(Pip), chains Cu2X2 rhombs, (CuX)2(Pip)2 (CuX)4(Pip)4, simple rhomboid dimers tetramers. A combination spectroscopic studies DFT calculations was used to investigate luminescence products....

Coordination of Cu(I) halides with N,N′-dimethylimidazole selone (dmise) and thione (dmit) ligands was examined by treating CuX (X = Cl, Br, I) one or two equivalents dmise dmit. The reaction CuI CuBr molar equivalent results in unusual selenium-bridged tetrameric Cu4(μ-dmise)4(μ-X)2X2copper complexes average Cu–Se bond lengths 2.42 Å a Cu2(μ-X)2 core I (1) Br (6)) that's rhomboidal structure. dmit trigonal planar different conformations the formula Cu(dmit)2X (3a, 3b, 4, 7) Cu(dmise)2X (2,...

Selenoproteins use the rare amino acid selenocysteine (Sec) to act as first line of defense against oxidants, which are linked aging, cancer, and neurodegenerative diseases. Many selenoproteins oxidoreductases in reactive Sec is connected a neighboring Cys able form ring. These Sec-containing redox motifs govern much reactivity selenoproteins. To study their fundamental properties, we have used (77)Se NMR spectroscopy concert with theoretical calculations determine conformational preferences...

π-Stacking interactions in derivatives of pentacene are explored from the perspective stack bond order to interpret conformational preferences these molecules important for organic electronics.

The ERα transcription factor that induces tumor growth is a potential target for breast cancer treatment. Each monomer of the DNA-binding domain (ERαDBD) homodimer has two conserved (Cys)4-type zinc fingers, ZF1 (N-terminal) and ZF2 (C-terminal). Electrophilic agents release Zn2+ by oxidizing coordinating Cys more labile to inhibit dimerization DNA binding. Microsecond-length molecular dynamics (MD) simulations show greater flexibility in ERαDBD leaves its solvent accessible less shielded...

Triscatecholate binding has been widely studied in the context of biological systems, supramolecular chemistry, and weak aggregate interactions. However, utilization triscatecholate motif for preparation metalloligands remains unexplored. Herein, we report synthesis, structural characterization, functional studies a ligand with an appended pyridyl residue as candidate such applications. Our findings reveal that selective formation cis‐triscatecholate‐based is influenced by electronic effects...

The identification of trigger bonds, bonds that break to initiate explosive decomposition, using computational methods could help direct the development novel, "green" and efficient high energy density materials (HEDMs). Comparing bond densities in energetic reference molecules Wiberg indices (WBIs) provides a relative scale for activation (%ΔWBIs) assign set 63 nitroaromatic conventional molecules. Intramolecular hydrogen bonding interactions enhance contributions resonance structures...

Characterization of Fe(<sc>ii</sc>)–thone and –selone complexes revealed that these ligands oxidize before Fe(<sc>ii</sc>), suggesting an iron-binding mechanism for similar antioxidants.

The principle of correspondence between the symmetry decompositions valence atomic orbitals (AOs) central metal and those hydride ligands is used to predict rationalize geometries simple transition polyhydride complexes. In this orbitally ranked analysis method (ORSAM) minimum energy structures have AOs whose irreducible representations match hydrides. agreement with previous work, hydrides prefer bond (n + 1)s nd orbitals, but ORSAM also includes 1)p in a natural way avoids having postulate...

Se···I Halogen bonding (XB) between triphenylphosphine selenide and organoiodides: 1,2-diiodotetrafluorobenzene (1,2-F4DIB), 1,4-diiodotetrafluorobenzene (1,4-F4DIB), tetraiodoethylene (TIE) has been used to assemble molecules into finite adducts, chains, two-dimensional layers. Phenyl embraces involving the groups extend these moieties additional dimensions, leading in two cases (1,4-F4DIB TIE) open structures, with filled or partially cavities. Comparison of structural parameters for 26...

Oxidation and disulfide coupling of cysteine, processes central to oxidative stress biochemical signaling, are modeled using DFT solvent-assisted proton exchange, a method microsolvation. Calculated barriers consistent with experimental kinetics observed product ratios suggest dependence on the polarity surrounding medium.

Co(<sc>i</sc>)<italic>versus</italic>Co(<sc>ii</sc>) in cobaloximes. The effect of a coordinated pyridine.

Theoretical 77Se chemical shifts of a series simple organoselenium compounds are compared to known NMR data for various derivatives selenoenzymes and selenoamino acids. Since the theoretical only differs from biochemical set by an overall approximately 15-30 ppm downfield shift, model studies suggested as additional tool interpretation selenoenzyme spectra. Further demonstrate that systems can be extended incorporate effects intramolecular interactions (such Se.N bonds).

Solid copper(I) cyanide occurs as extended one-dimensional chains with interesting photophysical properties. To explain the observed luminescence spectroscopy of CuCN, we report a series computational studies using short bare and potassium-capped [Cun(CN)n+1] − (n = 1, 2, 3, 4, 5, 7) CuCN models. On basis TD-DFT calculations these model chains, excitation transitions in UV spectrum are assigned Laporte-allowed π−π from MOs Cu 3dπ CN π character to empty 4p π* character. Transitions between...

Models of the tungstoenzyme acetylene hydratase (AH), which catalyzes addition water to through a nonredox process, are examined using density-functional theory (DFT). The relative energy adduct formation was calculated for several tungsten- and molydbenum-oxo dithiocarbamates (dtc) dithiolates (dtl). Stronger coordination tungsten dtc complexes is consistent with experimental Keq values attributed larger W 5d orbitals overall negative charge dithiolate complexes. recently solved AH X-ray...

Hydroxyl radical damage to DNA causes disease, and sulfur selenium antioxidant coordination hydroxyl-radical-generating Cu+ is one mechanism for their observed prevention. To determine how copper binding results in activity, biologically relevant selone thione ligands complexes of the formula [Tpm*Cu(L)]+ [Tpm* = tris(3,5-dimethylpyrazolyl)methane; L N,N′-dimethylimidazole or thione] were treated with H2O2 products analyzed by 1H, 13C{1H}, 77Se{1H} NMR spectroscopy, mass spectrometry, X-ray...

Bonding models of halogen bonding help understand how thyroid hormones and xenobiotic inhibitors affect activity through iodothyronine deiodinase.

Modeling of the glutathione peroxidase-like activity phenylselenol has been accomplished using density-functional theory and solvent-assisted proton exchange (SAPE). SAPE is a modeling technique intended to mimic solvent participation in transfer associated with chemical reaction. Within this method, explicit water molecules incorporated into gas-phase model allow relay through from site protonation reactant that product. The activation barriers obtained by for three steps GPx-like mechanism...