A hierarchical ab initio benchmark up to CCSDT(Q)/CBS in combination with a DFT performance study reveals meta-hybrid M06-2X functional as the best performing for accurately describing pericyclic reactions.

The catalytic effect of various weakly interacting Lewis acids (LAs) across the periodic table, based on hydrogen (Group 1), pnictogen 15), chalcogen 16), and halogen 17) bonds, Diels-Alder cycloaddition reaction between 1,3-butadiene methyl acrylate was studied quantum chemically by using relativistic density functional theory. Weakly LAs accelerate lowering barrier up to 3 kcal mol

A series of macrocyclic ligands were considered for the chelation Pb2+: 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO3S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-10-acetamido-1,4,7,10-tetraazacyclododecane (DO3SAm), 1,7-bis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane-4,10-diacetic acid (DO2A2S), 1,5,9-tris[2-(methylsulfanyl)ethyl]-1,5,9-triazacyclododecane (TACD3S),...

The Cu2+ complexes formed by a series of cyclen derivatives bearing sulfur pendant arms, 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO3S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-10-acetamido-1,4,7,10-tetraazacyclododecane (DO3SAm), and 1,7-bis[2-(methylsulfanyl)ethyl]-4,10-diacetic acid-1,4,7,10-tetraazacyclododecane (DO2A2S), were studied in aqueous solution at 25 °C from thermodynamic...

Organodiselenides are an important class of compounds characterized by the presence two adjacent covalently bonded selenium nuclei. Among them, diaryldiselenides and their parent compound diphenyl diselenide attract continuing interest in chemistry as well close disciplines like medicinal chemistry, pharmacology biochemistry. A search SCOPUS database has revealed that last three years 105 papers have been published on archetypal its use organic catalysis drug tests. The reactivity Se-Se bond...

The reactivity of differently substituted diselenides and ditellurides toward H₂O₂, an ancient but still currently debated issue, was investigated<italic>in silico</italic>to assess the role chalcogen groups directly bound to it have on reaction energetics.

Major depressive disorder is a psychiatric disease having approximately 20% lifetime prevalence in adults the United States (U.S.), as reported by Hasin et al. JAMA Psichiatry 2018 75, 336–346. Symptoms include low mood, anhedonia, decreased energy, alteration appetite and weight, irritability, sleep disturbances, cognitive deficits. Comorbidity frequent, patients show social functioning high mortality rate. Environmental genetic factors favor development of depression, but mechanisms which...

The (seleno)cysteine residues in some protein families react with hydroperoxides rate constants far beyond those of fully dissociated low molecular weight thiol or selenol compounds. In case the glutathione peroxidases, we could demonstrate that high are achieved by a proton transfer from chalcogenol to residue active site [Orian et al. Free Radic. Biol. Med. 87 (2015)]. We extended this study three more (OxyR, GAPDH and Prx). According DFT calculations, within is prerequisite for both,...

With a half-life of 7.45 days, silver-111 (βmax 1.04 MeV, Eγ 245.4 keV [Iγ 1.24%], 342.1 6.7%]) is promising candidate for targeted cancer therapy with β– emitters as well associated SPECT imaging. For its clinical use, the development suitable ligands that form sufficiently stable Ag+-complexes in vivo required. In this work, following sulfur-containing derivatives tetraazacyclododecane (cyclen) have been considered potential chelators silver-111:...

Zolpidem (N,N-Dimethyl-2-[6-methyl-2-(4-methylphenyl)imidazo[1,2-a]pyridin-3-yl]acetamide) is a well-known drug for the treatment of sleeping disorders. Recent literature reports on positive effects zolpidem therapy improving renal damage after cisplatin and reducing akinesia without sleep induction. This has been ascribed to antioxidant neuroprotective capacity this molecule, tentatively explained according generic structural similarity between melatonin. In work, we investigate in silico...

The C-X bond activation (X = H, C) of a series substituted C(n°)-H and C(n°)-C(m°) bonds with C(n°) C(m°) H

Abstract Methylmercury is a highly toxic compound and human exposure mainly related to consumption of polluted fish seafood. The inactivation thiol‐based enzymes, promoted by the strong affinity binding electrophilic mercuric ions thiol selenol groups proteins, likely an important factor explaining its toxicity. A key role played chemistry reactivity mercury–chalcogens bond, particularly HgS HgSe, which focus this computational work (level theory: (COSMO)‐ZORA‐BLYP‐D3(BJ)/TZ2P). We analyze...

The so-called peroxidatic cysteines and selenocysteines in proteins reduce hydroperoxides through a dual attack to the peroxide bond two-step mechanism. First, proton dislocation from thiol/selenol close residue of enzymatic pocket occurs. Then, nucleophilic anionic cysteine/selenocysteine one O atom takes place, while is shuttled back second atom, promoting formation water molecule. In this computational study, we use molecular model GPx demonstrate that environment significantly lowers...

The interest in diphenyl ditelluride (Ph2Te2) is related to its strict analogy diselenide (Ph2Se2), whose capacity reduce organic peroxides largely exploited catalysis and green chemistry. Since the latter also a promising candidate as an antioxidant drug mimic of ubiquitous enzyme glutathione peroxidase (GPx), use organotellurides medicinal chemistry gaining importance, despite fact that tellurium has no recognized biological role toxicity must be cautiously pondered. Both Ph2Se2 Ph2Te2...

New sulphur derivatives of cyclen, with potential complementary properties respect to known compounds, have been synthesized and studied.

Abstract We have quantum chemically studied the palladium‐mediated activation of C( sp n )−X bonds (n=1–3; X=F, Cl, Br, I) in archetypal model substrates H 3 C−CH 2 −X, C=CH−X, and HC≡C−X by a bare palladium catalyst, using relativistic density functional theory at ZORA‐BLYP/TZ2P. The bond reaction barrier decreases, for all ‐hybridized carbon centers, when substituent X substrate is changed from X=F to I. Activation strain energy decomposition analyses reveal that enhanced reactivity along...

The intramolecular oxidative coupling converting a bis-acetylene complex of formula CpM (C2 H2 )2 (Cp=C5 H5- ; M=Co, Rh, Ir) into 16-electron metallacycle is studied in silico. This reaction paradigmatic acetylene [2+2+2] cycloaddition to benzene catalyzed by fragments, being the step with highest activation energy, and thus affecting whole catalysis. Our strain quantitative molecular orbital (MO) analyses elucidate mechanistic details reveal why cobalt performs better than rhodium iridium...

The reactivity of phenothiazine (PS), phenoselenazine (PSE), and phenotellurazine (PTE) with different reactive oxygen species (ROS) has been studied using density functional theory (DFT) in combination the QM-ORSA (Quantum Mechanics-based Test for Overall Free Radical Scavenging Activity) protocol an accurate kinetic rate calculation. Four radical scavenging mechanisms have screened, namely hydrogen atom transfer (HAT), adduct formation (RAF), single electron (SET), direct oxidation...

Silver-111 is an attractive unconventional candidate for targeted cancer therapy as well single photon emission computed tomography and can be complemented by silver-103 positron noninvasive diagnostic procedures. However, the shortage of chelating agents capable forming stable complexes tethered to tumor-seeking vectors has hindered their in vivo application so far. In this study, a comparative investigation series sulfur-containing structural homologues, namely,...

Abstract Half‐sandwich Rh I compounds display good catalytic activity toward alkyne [2+2+2] cycloadditions. A peculiar structural feature of these catalysts is the coordination metal to an aromatic moiety, typically a cyclopentadienyl anion, and, in particular, possibility change bonding mode easily by slipping over this moiety. Upon modifying ancillary ligands, or proceeding along cycle, hapticity changes can be observed; it varies from η 5 , if five metal–carbon distances are identical,...

We have studied the palladium-mediated activation of C(sp

Metal-catalyzed alkyne [2+2+2] cycloadditions provide a variety of substantial aromatic compounds interest in the chemical and pharmaceutical industries. Herein, mechanistic aspects acetylene cycloaddition mediated by bimetallic half-sandwich catalysts [Cr(CO)3IndRh] (Ind = (C9H7)−, indenyl anion) are investigated. A detailed exploration potential energy surfaces (PESs) was carried out to identify intermediates transition states, using relativistic density functional theory (DFT) approach....

We set up an in silico experiment and designed a chimeric compound integrating molecular features from different efficient ROS (Reactive Oxygen Species) scavengers, with the purpose of investigating potential relationships between structure antioxidant activity. Furthermore, selenium centre was inserted due to its known capacity reduce hydroperoxides, acting as mimic glutathione peroxidase; finally, since this organoselenide is precursor N-heterocyclic carbene ligand, Au(I) complex examined....