Quantum-Chemical Interpretation of the Spectroscopy of Highly Luminescent 1,3,5-Triazapentadiene Complexes of Platinum（Ⅱ）

The quantum-chemical calculations were performed to determine the nature of the equilibrium geometry of the ground and excited states of the 1,3,5-triazapentadiene complexes of platinum（Ⅱ） and theirs nature and structure of molecular orbitals.

A quantum-chemical model of the inhibition mechanismof viral DNA HIV-1 replication by Iodine complexcompounds

The interaction of molecular iodine with virus DNA nucleotide is studied by ab initio RHF/3-21G** method. Formation of the nucleoprotein complex of the HIV DNA, molecular iodine and the HIV-1 integrase co-factor is considered to cause the inhibition action of the integrase enzyme. Experimental data on the anti-HIV effect of the molecular iodine complex compounds and the results of calculations suggest that molecular iodine contained in iodine polymer complexes may be considered as a compound inhibiting the catalytic center of the integrase enzyme. Unlike the known integrase inhibitors, molecular iodine also changes the virus DNA structure and produces the N-I bond in the purine bases of adenosine and guanosine nucleotides.

Interaction of Molecules of Phosphorus-Containing Inorganic Additives with Iron Surface: Quantum-Chemical Analysis and Tribotechnical Testing

Сondensed phosphates of metaphosphatic structure with the equal relation of metal oxide and phosphorus pentoxide are promising inorganic oleophilic antifrictional, antiwear and anti-seize, heat-resistant and eco-friendly additives to greases. We study in detail one group of these compounds, phosphorowolframates of alkaline metals MIPWO6 (MI = Li, Na, K, Rb, Cs), by using the ADF software package based on the DFT approach. Three stages of interaction of molecules of these substances with an iron surface are investigated: change of the shape of molecules near a surface, formation of the adsorptive complex and its disintegration. It is shown that a strong covalent binding between molecules of phosphorowolframates and a surface appears in the course of adsorption. High strength of this binding and also low inner strength of the chain and its flexibility provide effective protection of iron surface against wear. It is also found that at adsorption of phosphorowolframates on an iron surface, there is a change of local structure of the surface.

SYNTHESIS,STRUCTURE,PROPERTIES AND QUANTUM-CHEMICAL STUDIES OF CUBANE-LIKE CLUSTER COMPOUND WITH ALL-CHELATING LIGANDS [(C_2H_5)_4N]_2{Fe_4S_4[S_2CN(C_2H_5)_2]_4}

Under anaerobic and water-free condition and pure dinitrogen atmosphere, the title com-pound has been synthesized from FeCl_2, (NH_4)_2WS_4, NaS_2CN(C_2H_5)_2 and (C_2H_5)_4NBr. Thecompound crystallizes in the monoclinic space group Cc with cell constants a = 22. 125(6)A,b = 11.313(3) A, c = 25.053(8) A, β= 118.05(2)°, V = 5534.2A^3, Z = 4. It contains cubane-like Fe_4S_4 core. Each Fe atom in the compound is coordinated by a disulfide-chelate ligand.The determination results of the Mossbauer spectrum arid XPS, and quantum-chemical cal-culation all show that the compound contains two kinds of Fe in different valence states butin an equal amount. The scheme of the formation reaction for the compound is given. Thespectra of IR and UV-vis, and redox properties for the compound are reported.

A Quantum-Chemical Insight into the Role of Charge-Transfer States in Organic Emitters for Electroluminescence

The rapid progress of the design and development of efficient organic electroluminescent emitters without heavy transition metals has been achieved in recent experimental investigations.In this minireview,based on his recent theoretical works on purely organic emitters,the author provides a quantum-chemical insight into the role of charge-transfer(CT)electronic states in electroluminescence exploiting organic thermally activated delayed fluorescence(TADF)and radical emitters.

Quantitative prediction of substituted products based on quantum-chemical parameters and neural network method

The criterion of orientating group of electrophilic aromatic nitration was discussed by means of pattern recognition method with quantum-chemical parameters as features, and the product ratios of the reactions were quantitatively calculated using artificial neural network (ANN) method with the same parameters as inputs, based on the ab initio calculation of quantum chemistry, The quantum-chemical parameters involved orbital energy, orbital electron population, atomic total electron density and atomic net charge. The predicted values are in agreement with experimental results and the predicted error of the ANN with quantum-chemical parameters for the reaction is the smallest among the all methods.

Quantum-chemical investigation on hydrogen bonding interaction of hydrogen fluoride dimer at various mutual orientations

Hydrogen bonding interaction in hydrogen fluoride dimer has been investigated by quan- tum-chemical calculation with 6-311G^(**) basis set at various mutual orientations.Atomic charges and charge transfer have been calculated by means of potential-derived method,and decomposition of hydro- gen bonding interaction has been executed.The calculation results show that there is a variation range for the energy-stable orientations,the charge transfer in the range presents maximum value,and the charge transfer interaction plays a decisive role in the hydrogen bonding.

A quantum-chemical study on the Mannich reaction with polynitromethanes

According to the results of SCF-CNDO/2 computation, we propose employing the'ladder weighting summation' to define a G_e index which is used to measure the relative magnitudeof the nucleophilicity of the relevant amine and pseudo acid components in a Mannich reaction. Wealso put forward an A_e index to measure the relative magnitude of the electrophilicity of methylene-amine cationic species in the same reaction. A combined use of both G_e and A_e indices is suggestedto evaluate the feasibility of a Mannich reaction for the polynitromethanes and the stability of theproducts. These results are consistent with those conclusions drawn from 'soft-hard acid-basetheory'.

Mechanism of the Initial Stage of Thermal Decomposition of Nitroguanidine

A theoretical and experimental study of the thermal decomposition of nitroguanidine(NQ) has been carried out. Various thermolysis channels were studied by quantum chemistry methods at the CCSD(or DLPNO-CCSD) level using the aug-cc-pVDZ basis set. It is shown that the lowest activation enthalpies(170-180kJ/mol) are characteristic of the reactions of NO2abstraction from the initial NQ and the reaction channel with the transfer of oxygen from the nitro group to carbon in the limiting stage. Additionally, the thermolysis of NQ was studied experimentally in a nonisothermal mode with heating rates from 1 to 10K/min. In these experiments, the weight loss of the sample, thermal effects, and mass spectra of the products were recorded. An analysis of the experimental data confirmed the results of a theoretical study of the mechanism of thermal decomposition of NQ. The main thermolysis products are N2O, HNCO, NH3, and NO2, which fully corresponds to quantum chemical calculations.

Pyrrole and Pyrimidine Derivatives as Possible Electron Donors for Colored Charge-Transfer Complexes with a Weakly Electrophilic Energetic Material,FOX-7:A Theoretical Study

A number of electron-rich heterocycles are studied as potential reagents for visual colorimetric detection of FOX-7 due to colored charge-transfer complexes formation.The obtained results suggest that pyrrole and pyrimidine derivatives can form such complexes playing the role of electron donors despite a low electrophilicity of FOX-7.Density functional theory calculations,as well as quantum theory of atoms in molecules analysis,suggest stacking binding mode as the most preferable one with the binding energy of about 21-36 kJ/mol.All the complexes demonstrate a clear single charge-transfer absorption band in the visible region and the expected colors of the complexes are varying from violet and blue to red and orange.The calculations of the crystalline state of the studied complexes indicate high lattice energies,which are higher than that of pure FOX-7 and are close to the recently reported hydrogen-bonded complex of FOX-7 with 1,10-phenanthroline.Additional analysis of the studied charge-transfer complexes using properties based on density difference grids clearly suggests the acceptor role of FOX-7 in the complexes.This analysis can be effectively applied to identify the nature of other possible complexes of FOX-7,in which its role is unclear because of the specific reactivity,namely,both weak electrophilic and nucleophilic properties at the same time.

Controlled release and enhanced antibacterial activity of salicylic acid by hydrogen bonding with chitosan

Microcapsules of salicylic acid （SA） with chitosan were prepared by spray drying method. Various analytical methods were used to characterize the nature of microcapsules. Fourier-transform infrared spectroscopy （FTIR） confirmed the presence of intermolecular interactions between chitosan and SA. Particle size analysis showed that the average size ofmicrocapsules ranged from 2 to 20 pro, Scanning electron microscopy （SEM） studies indicated that the microspheres were spherical and had a relatively smooth surface. Microbiological assay of antibacterial activity for SA and its microcapsules was measured using different bacterial strains. It was found that the antibacterial activity of SA was improved after the formation of microcapsules. The in vitro release profile showed that the microcapsules could control SA release from I h to 4 h. Kinetic studies revealed that the release pattern follows Korsmeyer-Peppas mechanism. Enhanced antibacterial activity of the SA micro- capsules was attributed to the synergistic effects of intermolecular hydrogen-bonding interactions N-H...O and O-H...O=C between SA and chitosan. It was also confirmed by quantum chemical calculation.

Theoretical and Experimental Study of Reaction of Transesterification of Vegetable Oils in an Alcohol Environment in the SbCF and SCF Conditions with the Ultrasonic Emulsification of Reaction Mixture and the Use of Heterogeneous Catalysts

A quantum-chemical study of the mechanism of transesterification reaction carried out in the traditional and supercritical fluid (SCF) conditions has been performed. Samples of biodiesel fuel have been derived from rapeseed oil in the environment of supercritical ethanol using a flow type unit, both in the absence and in the presence of heterogeneous catalysts-metal oxides. Experimental studies of kinematic viscosity of a large array of samples of derived biodiesel have been performed. The viscous correlation allowing determining the content of the desired product-fatty acid ethyl esters (FAEE)-in biodiesel samples, has been made based on the obtained experimental data on the kinematic viscosity of biodiesel samples. The influence of change of the dielectric permittivity of working environments on the rate of reaction of transesterification in the supercritical fluid conditions has been revealed.

Reactivity of N-Methylidenemalonates of 3-Arylaminoindoles and p-Dimethylamino-N-Phenylaniline in the Course of Their Analysis by Electrospray Ionization Mass Spectrometry

The behavior of N-methylidenemalonates of 3-arylaminoindoles and p-dimetylamino-N-phenylanyline (M = ANa) was studied during their analysis with ESI mass spectrometer operated in negative (NI) and positive (PI) ion modes. Anions [A] and both [M + H]+ and [M + Na]+ were recorded under conditions of the NI-ESI and PI-ESI, respectively. The fragmentation processes of [A] and [M + H]+ were found that probably occurred as “insource collusion induced dissociation”. The main paths for [A] proved to be elimination of CO2 and breakage of the N-methylidenemalonate bond. A route [A]- - CO2 - ROH (R = Me or Et) was less expressed and occurred for the indolyl-containing compounds with the NH bond only. Experiments employing heavy water demonstrated the isotope exchange to occur involving the hydrogen atom of this bond. This and other facts evidenced that the last fragmentation included abstraction of just this atom. Quantum-chemical calculations allowed picking out a structure for the product ion from the possible ones. The calculations also indicated that the protonation of M occurred at the anionic oxygen atom of the malonate moiety. The fragmentation of [M + H]+ ions included elimination of two water molecules that was supported by their MS2 spectra. A common feature of the NI- and PI-ESI mass spectra was the presence of oligomeric ions, up to tetramers and trimers for the NI- and PI-ESI ones, respectively. The oligomers were formed by interaction of the corresponding ions with neutral molecules. When ions contained extra hydrogen atoms, they were introduced by hydrolysis.

Theoretical and Experimental Study of the Mechanism of Reaction Formation of Cyanine Dyes

To study the theoretical bases of the mechanism of reaction formation of cyanine dyes, special importance is gained by methods of quantum chemistry. The use of these methods is provided with the known molecular and dynamic HyperChem program. The purpose of studying was quantum and chemical studying of features of a geometrical and electronic structure of model molecules of penicillin acid, of derivative of glutaconic dialdehyde (DGD), and the cyanine dyes, and also an assessment of power of process of their formation. For studying was carried out the experimental mark of chemism of course of reaction with theoretical justification of the mechanism of reaction formation of cyanine dyes. The results show that all studied model molecules are thermodynamic steady systems to what values of enthalpies of their formation, rather high on an absolute value, testify negative on a sign. Reaction goes by the mechanism of nucleophilic addition.

Isolation of Nanocellulose from Cotton Cellulose and Computer Modeling of Its Structure

Nanocellulose is a new class of derivatives of cellulose, which is characterized by high crystallinity, surface area, degree of dispersion, ability to decomposition by microorganisms and etc. There is high attention solving problems of obtaining nanocellulose and its application as high quality filler for polymers, biodegradable materials, additives for papers, clotting dispersion and etc. Obtaining of particles of nanosized nanostructure on the base cellulose, studying of processes of their formation, properties and creation nanotechnology on this basis give the chance to obtain materials with unique properties. In this work nanocellulose was obtained from cotton cellulose by hydrolysis with sulfuric acid, ultrasonic dispersion and microwave irradiation. The properties and structure of nanocellulose are investigated by AFM, IR-spectroscopic, X-ray methods. Nanocellulose has rod-like shape with sizes 50 - 300 nm in length and 10 - 40 nm in diameters and spherical shape with sizes 50 - 300 nm depending on the synthesis conditions of obtaining. Quantum-chemical methods have been used to calculate the electronic characteristics of nanocellulose;the change in the energy difference between HOMO and LUMO is shown, showing the change in reactivity and the manifestation of specific properties.

[Azo-Hyd] Tautomerism and Structure of Selected Metal Complex Dyes AM1 and ZINDO/1 Methods

Quantum-chemical calculation methods have been used to examine an influence of tautomeric equilibrium [Azo Hydrazo] on a structure of 1:2 chromium metal complex dyes called Gryfalan Navy Blue RL (CI 15 707, Acid Blue 193) and Gryfalan Black RL (Acid Black 194). Chromatographic analysis indicates that synthesis yields a mixture of several dyes with different shades. Studies conducted to date have suggested that such dye complexes can constitute Drew-Pfitzner or Pfeiffer-Schetty structural isomers [1]. It is a know fact, that o-hydroxy-azo dyes exist in equilibrium of tautomeric azo and hydrazone forms. We decided to examine, whether color properties of examined metal-complex dyes can be influenced also by an azo-hydrazone equilibrium and what kind of influence on it has sulphonic groups present in molecules. Calculation and optimization of the geometrical structure were performed using the AM1 methods for monoazoo-hydroxy-azo dyesand ZINDO/1 for 1:2 chromium metal complex dyes. It was stated that monoazo dyes can create complexes in both forms: azo and hydrazone, because energy differences between each form of the metal complex dye are so small, that the monoazo dye can, in practice, create complexes in both the azo and the hydrazone form, with energy differences not exceeding about 4 - 11 kcal/mol. It is calculated that spatial structure changes with an angle of about 90° between two molecules of the dye, and angles of 10° - 20° between the naphthalene moieties. Similar electron density on the hydroxyl and ketone groups suggests that the mixture contains a dominant share of the azo form. The presence of an ionised sulphonic group was also found to affect on the tautomer equilibrium.

A New Pyridine-3,4-dicarboxylic Acid Bridged Zinc(Ⅱ) Coordination Complex: Crystal Structure,Quantum Chemistry and Luminescence Property

A new 2D metal coordination polymer,[Zn(pydc)(L)(H_(2)O)]n·5nH_(2)O(1,H2pydc=pyridine-3,4-dicarboxylic acid,L=3-(2-pyridyl)pyrazole),was synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction,powder XRD,FT-IR,thermogravimetric,fluorescence spectrum and elemental analysis techniques.Complex 1 belongs to the monoclinic system,P21/c space group,with a=10.707(5),b=14.221(5),c=13.278(5)A,β=102.071(5)°,V=1977.1(14)A^(3) and Z=2.It features a 2D network constructed by pydc2-and L ligand.In addition,the quantum-chemical calculations were accomplished on‘molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method built in Gaussian 16 Program.The calculation values denoted the distinct covalent interaction between the coordinated atoms and Zn(Ⅱ)ion.

Synthesis,Crystal Structure and Quantum Chemistry of a Pb(Ⅱ)Coordination Polymer Based on Adipic Acid and Phenanthroline Derivatives

A new Pb(Ⅱ)coordination polymer,[Pb(adip)(L)_(2)]_(n)(1,H_(2)adip=adipic acid,L=2-(4-N,N’-dimethylphenyl)-1-H-imidazo[4,5-f][1,10]phenanthroline),was synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction,powder XRD,FT-IR,thermogravimetric,fluorescence spectrum and elemental analysis techniques.Complex 1 crystallizes in triclinic system,space group P1 with a=11.406(3),b=12.036(4),c=17.520(5)Å,V=2228.3(11)Å^(3),M_(r)=1028.09,D_(c)=1.532 g·cm^(-3),F(000)=1024,μ(Mo Kα)=3.842,R_(int)=0.0274 and Z=2.The final R=0.1055 and w R=0.3277 for 6954 observed reflections with I>2σ(I).It features a one-dimensional chain linked by adip^(2-) ligand.Moreover,complex 1 exhibits strong green luminescence with emission peak of 514 nm.In addition,the quantum-chemical calculations were accomplished on’molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method built in Gaussian 16Program.The calculation values denoted the distinct covalent interaction between the coordinated atoms and Pb(Ⅱ)ion.

Electronic Structure of the Charge Transfer Complex (PH_3)_2Pt·C_(60)

C60 is the third form of elementary C, which was discovered in recent years.In C60, each C atom links with three adjacent C atoms in terms of sp2-like hybridorbitals, in which there are two long bonds and one short bond. At present, sincemacro-quantity of C60 is able to be produced with simple method, interest instudy on C60 shifts to its chemical properties from the structure. （P（C6H5）3）2Ptand C60 themselves are stable valence-saturated molecules, however, they can form sta-ble complexes through the charge transfer, in which （P（C6H5）3）2 Pt is complexed