Theoretical investigation on degradation of CH[triple bond, length as m-dash]CCHOH by NO radicals in the atmosphere.

A detailed computational investigation is executed on the reaction between NO and CH[triple bond, length as m-dash]CCHOH at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) level. Addition/elimination and H-abstraction mechanisms are found for the NO + CH[triple bond, length as m-dash]CCHOH reaction, and they could compete with each other. The most feasible addition/elimination pathway through a series of central-C addition, 1,4-H migration to generate intermediates IM1 (CHCONOCHOH) and IM3 (CHCONOCHO), and then IM3 directly decompose into product P2 (CHCONOCHO + H).

An allosteric mechanism for potent inhibition of SARS-CoV-2 main proteinase.

The main proteinase (M) of SARS-CoV-2 plays a critical role in cleaving viral polyproteins into functional proteins required for viral replication and assembly, making it a prime drug target for COVID-19. It is well known that noncompetitive inhibition offers potential therapeutic options for treating COVID-19, which can effectively reduce the likelihood of cross-reactivity with other proteins and increase the selectivity of the drug. Therefore, the discovery of allosteric sites of M has both scientific and practical significance.

The influence of a single water molecule on the reaction of BrO + HO.

The influence of a single water molecule on the BrO + HO hydrogen extraction reaction has been explored by taking advantage of CCSD(T)/aug-cc-pVTZ//B3LYP/6-311 +  + G(d,p) method. The reaction in the absence of water have two distinct kinds of H-extraction channels to generate HOBr + O (Δ) and HBr + O, and the channel of generation of HOBr + O (Δ) dominated the BrO + HO reaction. The rate coefficient of the most feasible channel for the BrO + HO reaction in the absence of water is estimated to be 1.

A theoretical study of the gas-phase reactions of propadiene with NO: mechanism, kinetics and insights.

In this study, the conversion mechanisms and kinetics of propadiene (CH[double bond, length as m-dash]C[double bond, length as m-dash]CH) induced by NO were researched using density functional theory (DFT) and transition state theory (TST) measurements. The NO-addition pathways to generate IM1 (CHONOCCH) and IM2 (CHCONOCH) play a significant role. P3 (CHCONOCHO + H) was the dominant addition/elimination product.

Understanding the insight into the mechanisms and dynamics of the OH-initiated oxidation of CHFCFOCHF and the subsequent reactions in the presence of NO and O.

The mechanism and dynamics of CHFCFOCHF initiated by OH radical evaluated through the density functional theory and variflex code. The solvation pattern of PCM was utilized to analyze the influence of water on the CHFCFOCHF + OH reaction. The most feasible reaction channel is resulting in the product CFCFOCHF with HO by hydrogen abstraction.

Crystal Structure, Photophysical Study, Hirshfeld Surface Analysis, and Nonlinear Optical Properties of a New Hydroxyphenylamino Meldrum's Acid Derivative.

The structural, photophysical, and vibrational properties of a new hydroxyphenylamino Meldrum's acid derivative, 3-((2-hydroxyphenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione (HMD), were studied. The comparison of experimental and theoretical vibrational spectra can help understand basic vibration patterns and provides a better interpretation of IR spectra.

The influence of (HO) in the HOBr + HO gas-phase reaction.

The HOBr + HO reaction in the absence of water has three different channels for the abstraction of H to generate the corresponding products. The dominant channel is the generation of BrO + HO. The introduction of water molecules influences this dominant reaction the way the reactants interact with the water molecules.

Degradation of mevinphos and monocrotophos by OH radicals in the environment: A computational investigation on mechanism, kinetic, and ecotoxicity.

Known organophosphorus pesticides are used widely in agriculture to improve the production of crops. Based on the literature, the degradation of some organophosphorus pesticides was studied theoretically. However, the mechanisms and variation of toxicity during the degradation of mevinphos and monocrotophos are still unclear in the environment, especially in wastewater.

OH-initiated degradation of 1,2,3-trimethylbenzene in the atmosphere and wastewater: Mechanisms, kinetics, and ecotoxicity.

1,2,3-Trimethylbenzene (1,2,3-TMB) is an important volatile organic compound (VOC) present in petroleum wastewater and the atmosphere. This compound can be degraded by OH radicals via abstraction, addition and substitution mechanisms. Results show that the addition mechanism is dominant and H-abstraction is subdominant, while methyl abstraction and substitution mechanisms are negligible in the gas and aqueous phases.

Role of monomolecular water and bimolecular water in IO + CHO reaction.

A CCSD(T)//B3LYP method was employed to research the influence of monomolecular and bimolecular water molecules on the IO + CHO reaction. H-abstraction and addition/elimination mechanisms have been located, and the H-abstraction mechanism occupied the whole reaction without water. The introduction of water complicates the reaction, but the final product remains unchanged.

The influence of a single water molecule on the reaction of BrO + HONO.

Quantum chemical computations and transition state theory are employed to systematically research the influence of a single molecule water on the BrO + HONO reaction. Two distinct reactions, namely BrO + trans-HONO and BrO + cis-HONO are explored for the reaction in the absence of water, which is mainly decided by the configuration of HONO. With introduction a single water molecule to the reaction, the rate coefficient of the channel starting from BrO + cis-HONO and BrO + trans-HONO are 2.

Synthesis, Crystal Structures, and Density Functional Theory Studies of Two Salt Cocrystals Containing Meldrum's Acid Group.

Two salt cocrystals, CHNO () and CHNO (), were synthesized and their structures were determined by single-crystal X-ray diffraction. is made up of one (CHO) anion, one (CHN) cation, and one 5,6-dimethyl-1-benzo[]imidazole molecule. consists of one (CHN) cation and one (CHO) anion.

Structural and energetic features of the dimerization of the main proteinase of SARS-CoV-2 using molecular dynamic simulations.

The COVID-19 pandemic caused by SARS-CoV-2 has been declared a global health crisis. The development of anti-SARS-CoV-2 drugs heavily depends on the systematic study of the critical biological processes of key proteins of coronavirus among which the main proteinase (M) dimerization is a key step for virus maturation. Because inhibiting the M dimerization can efficiently suppress virus maturation, the key residues that mediate dimerization can be treated as targets of drug and antibody developments.

New theoretical investigation of mechanism, kinetics, and toxicity in the degradation of dimetridazole and ornidazole by hydroxyl radicals in aqueous phase.

Dimetridazole (DMZ) and ornidazole (ONZ) have been widely used to treat anaerobic and protozoal infections. The residues of DMZ/ONZ persist in the water environment. The mechanisms and kinetics of hydroxyl-initiated oxidation, the primary DMZ/ONZ degradation method, were evaluated by quantum chemical methods.

A theoretical investigation on the degradation reactions of CHCHCHNH and (CHCHCH)N radicals in the presence of NO, NO and O.

The degradation reactions of propylamino and dipropylamino radicals in the presence of NO, NO and O were investigated at the CCSD(T)/6-311++G (2d, 2p)//B3LYP/6-311++G (d,p) levels of theory. Result indicates that nitrosamines, nitramines, nitroso-oxy compounds and imines can be formed at atmosphere. Time dependent density functional theory (TDDFT) calculation shows that nitrosamines and nitroso-oxy compounds can photolyze under sunlight, while nitramines cannot undergo photolysis in the daytime.

Theoretical investigations on mechanisms and kinetics of methylketene with O(P) reaction in the atmosphere.

The O(P)-initiated conversion mechanism and dynamics of CHCHCO were researched in atmosphere by executing density functional theory (DFT) computations. Optimizations of all the species and single-point energy computations were implemented at the B3LYP/6-311++G(d,p) and CCSD(T)/cc-pVTZ level, respectively. The explicit oxidation mechanism was introduced and discussed.

Key residues of the receptor binding domain in the spike protein of SARS-CoV-2 mediating the interactions with ACE2: a molecular dynamics study.

The widespread coronavirus disease 2019 (COVID-19) has been declared a global health emergency. As one of the most important targets for antibody and drug developments, the Spike RBD-ACE2 interface has received extensive attention. Here, using molecular dynamics simulations, we explicitly analyzed the energetic features of the RBD-ACE2 complex of both SARS-CoV and SARS-CoV-2.

A novel label-free solid-state electrochemiluminescence sensor based on the resonance energy transfer from Ru(bpy) to GO for DNA hybridization detection.

Based on electrochemiluminescence resonance energy transfer (ERET) from Ru(bpy) to graphene oxide (GO), a novel label-free solid-state ECL sensor for sensitive detection of DNA was proposed. First, Ru(bpy)/AuNPs was successfully prepared by using a simple and green method and characterized by transmission electron microscopy (TEM), Energy Dispersive X-ray (EDX), and UV-vis spectroscopy. Then, the Ru(bpy)/AuNPs colloid was assembled on the gold electrode surface for solid-state ECL film which also later could be used to immobilize thiol-derivatized, single-stranded DNA (HS-ssDNA) via Au-S interactions.

Theoretical investigation of the reaction mechanisms and kinetics of CFClCHO and ClO in the atmosphere.

The reaction between CFClCHO radicals and ClO was studied using the B3LYP and CCSD(T) methods associated with the 6-311++G(d,p) and cc-pVTZ basis sets, and subsequently RRKM-TST theory was used to predict the thermal rate constants and product distributions. On the singlet PES, the dominant reaction is the addition of the ClO oxygen atom to the terminal-O of CFClCHO to generate adduct IM1 (CFClCHOOOCl), and then dissociation to final products P1 (CFClCHO + HO + Cl) occurs. RRKM theory is employed to calculate the overall and individual rate constants over a wide range of temperatures and pressures.

Theoretical investigations on mechanisms and kinetics of the CHCFClO· with ClO· reaction in the atmosphere.

The singlet and triplet potential energy surfaces of the ClO• radical reaction with the CHCFClO• radical have been investigated at the CCSD(T)/cc-pVTZ level based on the optimized geometries at the B3LYP/6-311++G(d,p) level. On the singlet potential energy surfaces (PES), the possible reaction involves association-dissociation, direct H-abstraction and Nucleophilic Substitution 2 (S2) mechanisms. On the triplet PES, S2 displacement and direct H-abstraction reaction pathways have been investigated, which are less competitive compared with the reaction pathways on the singlet PES.

Computational study on the mechanisms and kinetics of the CHBrO + ClO reaction in the atmosphere.

The singlet and triplet potential energy surfaces for the CHBrO + ClO reaction are studied at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) level. CHBrO is revealed to react with ClO through two kinds of mechanisms on the triplet potential energy surface (PES), namely, S2 displacement and H-abstraction, and the production of P3 (CHBrO + HOCl) H-abstraction is the dominant channel. Addition/elimination and S2 displacement mechanisms exist on the singlet PES and are more complicated.

Atmospheric chemistry of CFClO: a theoretical study on mechanisms and kinetics of the CFClO + HO reaction.

The singlet and triplet potential energy surfaces of the HO with CFClO reaction have been probed at the BMC-CCSD/cc-pVTZ level according to the B3LYP/6-311++G(d,p) level obtained geometrical structure. On the singlet PES, the association/dissociation, direct H- abstraction, and S2 displacement mechanisms have been taken into account. On the triplet PES, S2 displacement and indirect H- abstraction reaction mechanisms have been investigated and the H- abstraction channel makes more contribution to the CFClO with HO reaction.

Atmospheric chemistry of CFClO: a theoretical study on mechanisms and kinetics of the CFClO + ClO reaction.

The gas-phase reaction between CFClO and ClO was researched by means of quantum chemical methods. B3LYP method with the 6-311++G(d,p) basis set was used to obtain the geometric parameters of all stationary points including in the CFClO + ClO reaction. The singlet and triplet potential energy surfaces were characterized at the CCSD(T)/6-311++G(2d,2p)//B3LYP/6-311++G(d,p) level.

Theoretical investigations on mechanisms and kinetics of CHXO (X=F, Cl) with Cl reaction in the atmosphere.

The reactions of the CHXO (X=F, Cl) with chlorine radical have been firstly investigated utilizing the BMC-CCSD//B3LYP method. The comprehensive calculations indicate that the association-elimination and S2 displacement reaction mechanisms existed on the singlet potential energy surface (PES), and H-abstraction and S2 displacement reaction mechanism existed on the triplet PES for the CHXO (X=F, Cl) + Cl reactions. On the triplet PES, the dominant reactions are production of P3 (CHXO (X=F, Cl) + HCl) by direct H-abstraction.