Quantum Chemical Study Of Interaction Research Articles

Quantum Chemical Study of Interaction between Titanocene Dichloride Anticancer Drug and Al12N12 Nano-Cluster

In this study, we have investigated the interaction between Al12N12 nano-cluster and titanocene dichloride anticancer drug complex using B3P86 functional. Two interactions modes between Al12N12 nano-cluster and titanocene dichloride complex (TiCl2Cp2, Cp = η5-(C5H5)2) have been studied. The bonding interaction between the Al12N12 nano-cluster and anticancer drug has been examined through energy decomposition analysis (EDA). In addition, Shubin Liu’s energy decomposition analysis (EDA-SBL) has been used to study the source of energy different between various isomers of Al12N12···cp2TiCl2 complex. Charge transfer between fragments have been illustrated with electrophilicity-based charge transfer (ECT). The related molecular properties to the biological activity of these drug precursor molecules have been studied (octanol–water partition coefficient (log P), molecular volume (Vm)). The quantum theory of atoms in molecules (QTAIM) analysis has been applied to assess the Al–Cl bonds within the Al12N12···cp2TiCl2 complexes.

A quantum chemical study of interactions between AU3– anion and amino acids

Quantum chemical calculations are employed to examine the interactions of the Au3– cluster in its negatively charged states with several small amino acids. Thermodynamic parameters, electronic structures, bonding characteristics and spectroscopic properties of the resulting complexes are investigated in the framework of density functional theory (M06-2X functional) along with correlation consistent basis sets, namely aug-cc-pVTZ-PP for Au and aug-cc-pVTZ for nonmetals. Computed results show that these interactions are characterized by the nonconventional H-bonds N–H⋯Au and O–H⋯Au. In addition, the forming of the nonconventional H-bonds is likely to accompany with a charge transfer from Au3− to the bimolecular species.

Quantum chemical study of interactions of carbenes and their analogs of the EH2 and EHX types (E = Si, Ge, Sn; X = F, Cl, Br) with HX and H2, respectively: the insertion and substituent exchange reactions

Interactions of carbenes and carbene analogs EH2 and EHX with HX and H2 (E = C, Si, Ge, Sn; X = F, Cl, Br), respectively, were studied by quantum chemical methods. Theoretical analysis of the carbene and silylene systems was carried out at the G3 level of theory using the MP2(full)/6–31G(d) calculated geometries and vibrational frequencies. The stannylene systems were examined at the MP2 level using a modified LANL2DZ basis set for the Sn atoms and the 6–31+G(d,p) basis sets for other atoms. Transformations in the germylene systems were studied within the framework of both approaches, which gave similar results. This allowed one to compare the reaction pathways and their energy profiles for the whole series of systems. In addition to the insertions into the H-X and H-H bonds, the exchange reactions resulting in interconversions of EH2 and EHX can proceed in the systems under consideration. The effects of the nature of the E and X atoms on the reaction barriers and exothermicity of both the insertion and exchange reactions are analyzed. Possible role of radical processes in these systems is assessed.

Quantum-chemical study of interactions of trans-resveratrol with guanine-thymine dinucleotide and DNA-nucleobases

Trans-resveratrol, a natural phytoalexin present in red wine and grapes, has gained considerable attention because of its antiproliferative, chemopreventive and proapoptotic activity against human cancer cells. The accurate quantum-chemical computations based on the density functional theory (DFT) and ab initio second-order Møller-Plesset perturbation method (MP2) have been performed for the first time to study interactions of trans-resveratrol with guanine-thymine dinucleotide and DNA-derived nitrogenous bases: adenine, guanine, cytosine and thymine in vacuum and water medium. This compound is found to show high affinity to nitrogenous bases and guanine-thymine dinucleotide. The electrostatic interactions from intermolecular hydrogen bonding increase the stability of complexes studied. In particular, significantly strong hydrogen bonds between 4'-H atom of trans-resveratrol and imidazole nitrogen as well as carbonyl oxygen atoms of nucleobases studied stabilize these systems. The stabilization energies computed reveal that the negatively charged trans-resveratrol-dinucleotide complex is more energetically stable in water medium than in vacuum. MP2 method gives more reliable and significantly high values of stabilization energy of trans-resveratrol-dinucleotide, trans-resveratrol-guanine and trans-resveratrol-thymine complexes than B3LYP exchange-correlation functional because it takes into account London dispersion energy. According to the results, in the presence of trans-resveratrol the 3'-5' phosphodiester bond in dinucleotide can be cleaved and the proton from 4'-OH group of trans-resveratrol migrates to the 3'-O atom of dinucleotide. It is concluded that trans-resveratrol is able to break the DNA strand. Hence, the findings obtained help understand antiproliferative and anticancer properties of this polyphenol.

Quantum-chemical study of interaction between hydrogen sulfide and sulfides of iron, titanium, and tungsten

A quantum-chemical study of the interaction between hydrogen sulfide and the simplest MeS and MeS2 (Fe, Ti, W) sulfides was carried out. The correlations of catalytic activity in photodecomposition of hydrogen sulfide on Me/Al2O3 catalysts with the heat of formation of complexes MeS2 with hydrogen sulfide and changes in charge values of active metal upon complexation were found.

Quantum-chemical study of interaction of hydrogen atoms with graphene

The dependence of the binding energy and the activation energy of adsorption of hydrogen atoms on the number of previously adsorbed particles and their position—on one or both sides of a cluster, on nearest or distant neighbors (carbon atoms)—is investigated by quantum-chemical modeling. A hypothesis of the formation of adsorption sites (islands) on graphene at the initial stage of its saturation by hydrogen is discussed.

Quantum-Chemical Study of Interactions between the Hydroxonium Cation and the Monomethyl Mercury Cation in Aqueous Media

The potential surface of the reaction between the polyhydrated monomethyl mercury cation and the hydroxonium cation is considered. An \(S_{N^2 } \) type reaction, resulting in solvate-separated products (mercury dication and methane molecule), was found to be thermodynamically probable. The thermal balance of the reaction is 132.3 kJ/mole. The activation energy of the limiting stage of the process is 56.7 kJ/mole.

Quantum chemical study of interactions of ketones with zeolites

The CNDO/2 method is employed to study the interactions of acetone, methyl ethyl ketone and diethyl ketone with OH groups in zeolites modelled by the Si 3AlO 4(OH) 8 H clusters. It is demonstrated that this interaction, accompanied by the formation of the H-complexes of ketones, leads to the transfer of electron density from the ketone to the zeolite and polarization of the molecule. Both these effects then cause weakening of the CO, C-H and O-H bonds and strengthening of the C-C bonds. Similar perturbation of the acetone molecule is indicated by the results of model electrostatic calculations on the interactions of acetone with the Na cationic sites in zeolites. The calculated changes in the strengths of the individual bonds of the ketones interacting with the zeolite active sites correlate well with the shifts in the corresponding vibrational bands observed for ketones interacting with these centres.

Quantum-chemical study of interaction between a hydride ion and a water molecule

Results are presented from a quantum-chemical study of the interaction between a water molecule and the simple two-electron anion H . The calculations are performed in the Gaussian 4-31G** basis, which includes polarizing functions on the O and H atoms by means of the GAUSSIAN-76 program. Only planar structures are considered. Potential curves have been calculated for three directions of H attack on the H2O molecule: at a hydrogen atom along the O-H* bond line I, angle theta = 180, at the oxygen atom along the twofold axis of the H2O molecule II, and at the oxygen atom at 70 to that axis III. Further, structure I is used with the H ...H* distance optimized for theta = 180 (1.623 A) in varying the (H H*O) angle theta. In all calculations, the geometrical parameters of the water molecule were taken as unchanged (R(O-H) = 0.96 A, angle HOH* = 105). The energies of the H and H2O subsystems calculated in the same basis are -0.422442 and -75.951788 au correspondingly.

Quantum-chemical study of interaction of water with urea

1. Theab initio quantum-chemical method STO-3GF has been used to calculate the structure and heat of formation of urea complexes with water molecules. 2. The most stable urea-water complex is that with a structure in which the water molecule exists in a broad potential well, where it can almost freely move in space to distances up to 3 A. Therefore, the addition of urea increases the mobility of the molecules in liquid water and breaks down the water structure.