Syntheses,crystal structures,and quantum chemistry calculation of two Ni(Ⅱ)coordination polymers

Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmethyl)butane(bib)by a hydrothermal method,respectively.X⁃ray crystallography reveals a 2D network constructed by six⁃coordinated Ni(Ⅱ)centers,bib,and Hpdc2-ligands in complex 1,while a 2D network is built by Ni(Ⅱ)and bib ligands in 2.Furthermore,the quantum⁃chemical calculations have been performed on‘molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method in Gaussian 16 and the VASP program.CCDC:2343794,1;2343798,2.

Quantum Chemistry Calculations on the Interaction Between Kaolinite and Gold

The density,function and discrete variation method (DFT - DVM) is used to study the interaction between kaolinite and gold. The correlation among the structure, chemical bond and stability is discussed. Several models are selected without gold and with gold in different directions and sites. The results show that the models with gold on the edge of kaolinite basal layer are more stable than those with gold above or under the layer, the models with gold near to [AlO2 (OH)(4)] octahedra are more stable than those with gold near to the vacancy without aluminium. The interaction between gold and the surface ions of kaolinite is strong enough to form the surface complexes.

STURCTURAL CHARACTERISTICS AND QUANTUM CHEMISTRY CALCULATION OF AI-DOPED BORON CARBIDES

Structural characteristics, chemical bonds and thermoelectric properties of Al-doped boron carbides are studied through calculations of various structural unit models by using a self-consistent-field discrete variation X. method. The calculations show that Al atom doped in boron carbide is in preference to substituting B or C atoms on the end of boron carbide chain, and then may occupy interstitial sites, but it is difficult for Al to substitute B or C atom in the centers of the chain or in the icosahedra. A representative structural unit containing an Al atom is [C - B -Al]-[B11C]-,while the structural unit without Al is [C-B-B(C)]- - [B11C]C+, and the coexistence of these two different structural units makes the electrical conductivity increased. As the covalent bond of Al-B or Al-C is weaker than that of B-B or B-C, the thermal conductivity decreases when Al is added into boron carbides. With the electrical conductivity increasing and the thermal conductivity decreases, Al doping has significant effect on thermoelectric properties of baron carbides.

Quantum Chemistry Calculation of Quercetin-silver Complex

Three possible molecular structures of quercetin-silver complexes obtained from the reaction of quercetin and Ag^＋ in equivalent molar ratio were designed and optimized by using Gaussian 98 program at the B3LYP/LanL2DZ basis set. Through theoretical analysis, one of the three designed structures is discovered to have the most stable coordination position. Then its geometry structure, natural bond orbital analyses, vibrational frequency and biological activity were performed. The results show that it has good stability and relatively stronger antioxidative activity because it is favorably attacked by O2^-. Therefore theoretical foundation is provided for the development of new quercetin metal complexes with higher activity antioxidants.

Synthesis，Characterization，Crystal Structure and Quantum Chemistry Calculation of the Mixed Ligand Complexes ［Ln（CF_3COO）_3·（Phen）_2·（H_2O）_2］·CH_3COCH_3·H_2O

The complexes of rare earth trifluoroacetate with two 1, 10-phenanthroline Ln (CF_3COO)_3 ·(Phen )_2· CH_3COCH_3·3H_2O (Ln=La, Pr, Nd, Sm, Eu) have prepared in the mixed slovents of H_2O and CH_3COCH_3, and the single crystal Nd (CF_3COO)_3· (Phen )_2· CH_3COCH_3· 3H_2O was determined by four-circle X-ray diffractometer. The crystal is a monoclinic system with space group P2_1/n(14# ), a=0. 9253 ( 1 )nm , b=2. 1500 ( 2 ) nm , c=1.8981 ( 4 ) nm, β= 95. 28( 1 )°, V=3.760(8) nm￣3 , Z=4 , R=0. 035. The coordination number of Nd is 9 , and the coordination polyhedron of Nd atom is distorted tricapped triagonal prism. The electronic structures and chemical bonds of the complex Nd (CF_3COO)_3· (Phen )_2· CH_3COCH_3·3H_2O is studied by the spin unrestricted INDO method.

The Quantum Chemistry Calculation and Thermoelectricsof Bi-Sb-Te Series

The density junction theory and discrete variation method ( DFT - DVM) was used to study correlation between composition, structure, chemical bond, and property of thermoelectrics of Bi-Sb-Te series. 8 models of Bi20-xSbxTe32(x = 0,2,6,8,12,14,18 and 20) were calculated. The results show that there is less difference in the ionic bonds between Te( I)-Bi(Sb) and Te(Ⅱ)-Bi(Sb) , but the covalent bond of Te(Ⅰ)-Bi( Sb ) is stronger than that of Te(Ⅱ)-Bi( Sb ) . The interaction between Te(Ⅰ) and Te(Ⅰ) in different layers is the weakest and the interaction should be Van Der Wools power. The charge of Sb is lower than that of Bi, and the ionic bond of Te-Sb is weaker than that of Te-Bi. The covalent bond of Te-Sb is also weaker than that of Te-Bi. Therefore, the thermoelectric property may be imfiroved by adjusting the electrical conductivity and thermal conductivity through changing the composition in the compounds of Bi-Sb-Te. The calculated results are consistent with the experiments.

Quantum Chemistry Calculation on Oxygen and Nitrogen Adsorption in Carbon Nanotude

Oxygen and nitrogen adsorption in single walled carbon nanotube (SWCNT) is studied by density function and discrete variational (DFT-DVM) method.The models of O 2 and N 2 adsorption in the SWCNT are optimized based on the energy minimization.The calculated results of density of state,populations and energy gaps of the molecular orbitals show that oxygen adsorption in SWCNT increases the carbon nanotube`s electrical conductivity more notably than nitrogen adsorption,which is consistent with the experiment.

STUDIES OF QUANTUM CHEMISTRY CALCULATION ON VALENCE-BOND STRUCTURE AND HYDRATION ACTIVTY OF C_(12)A_7

The structure, chemical bonds and hydra-tion activity of C12A were studied by SCC-DV-Xa method of computational quantum chemistry. The calculated results show that Ca-O bond will be first broken off when C12A hydrates, the reactivity of Al(2)O4 tetrahedron is superior to that of Al(1)O4 tet, thedron and the rupture of the Al-O-Al chain composed of two types of AlO4 tetrahedra under the action of water lies in the very weak Al(2)-O(2) bonds. the Al-O bond strength of C12A7 is between C3A and C11A7·CaF2.

Investigation of the Short-Time Photodissociation Dynamics of Furfural in S2 State by Resonance Raman and Quantum Chemistry Calculations

Raman(resonance Raman,FT-Raman),IR and UV-visible spectroscopy and quantum chemistry calculations were used to investigate the photodissociation dynamics of furfural in S2 state.The resonance Raman(RR)spectra indicate that the photorelaxation dynamics for the S0→S2 excited state is predominantly along nine motions:C=O stretchν5(1667 cm-1),ring C=C antisymmetric stretchν6(1570 cm-1),ring C=C symmetric stretchν7(1472 cm-1),C2-O6-C5 symmetric stretch/C1-H8 rock in planeν8(1389 cm-1),C3-C4 stretch/C1-H8 rock in planeν9(1370 cm-1),C5-O6 stretch in planeν12(1154 cm-1),ring breathν13(1077 cm-1),C3-C4 stretchν14(1020 cm-1),C3-C2-O6 symmetric stretchν16(928 cm-1).Stable structures of S0,S1,S2,T1 and T2 states with Cs point group were optimized at CASSCF method in Franck-Condon region there are S2/S1 conical intersection was found by state average method and RR spectra.

Reaction Activity of Kao linite Surfaces:Quantum Chemistry Calculations

The anion kaolinite surface interactions and AuS - adsorption onto the surfaces of kaolinite were studied using the self consistent field discrete variation (SCF-X α-DV) method.Electronic structure and energies of the system of anion AuS - adsorbed on an atomic cluster of kaolinite were calculated.The results show that the systems with lower total energy are those AuS - adsorbed on the edge surfaces,which indicates that the systems of adsorption of AuS - on the edges are more stable relative to those adsorbed on the basal plane.On the other hand,bond order data suggest that significant shifting of atomic charge and the overlapping of electronic cloud between Au (Ⅰ) of the AuS - and the surface ions of kaolinite would take place in the systems with AuS - being adsorbed on the edges,especially at the site near Al octahedra.Therefore,it can be concluded that edge sites will dominate the complexation reactions of the surfaces of kaolinite,with negligible contributions from other functional groups on the basal plane,which are dominated by either siloxane sites in silica layers or aluminol sites in gibbsite layers.

Synthesis, Crystal Structure and Quantum Chemistry Calculation of a Bis(dafone) Di(dmf) Copper(Ⅱ) Complex

The title compound [Cu(dafone)2(DMF)2]?2ClO4 1 (dafone = 4,5-diazafluoren- 9-one, dmf = N,N?-dimethyl formamide) was synthesized by the reaction of Cu(ClO4 )2 and dafone in DMF solution at room temperature with pH = 3.0. The single-crystal X-ray analysis has revealed that 1 crystallizes in monoclinic, space group P21/n with a = 8.4853(8), b = 13.1520 (14), c = 14.3866(12) ?, β = 102.629(3)o, V = 1566.7(3) ?3, C28H26Cl2CuN6O12, Mr = 773.00, Z = 2, Dc = 1.639 g/cm3 , F(000) = 790, μ = 0.942 mm-1, the final R = 0.0438 and wR = 0.1214 for 3165 obser- ved reflections with I > 2σ(I). X-ray analysis shows that compound 1 has unsymmetric chelation of dafone with one Cu–N bond being much longer than the other. Coordination geometry of Cu is a highly distorted octahedron and the whole structure is stabilized by π-π stacking and static attractive forces from [ClO4]- anions. Based on the crystal data, quantum chemistry calculation at the DFT/ B3LPY level was used to reveal the electronic structure of 1.

GRADIENT VARIATION OF COMPOSITION AND QUANTUM CHEMISTRY CALCULATION OF(Ti-Nb)C-Ni COMPOSITE

(Ti, Nb)C-Ni composite is prepared. The analyses of SEM, EPMA and TEM/EDAX show that (Ti, Nb)C-Ni consists of three phases,which are called interior, transitional and Ni phases respectively. Several models are calculated by self-consistent-field variational X alpha(SCF-DV-X alpha) method, one of the quantum chemistry calculating methods. The calculated results show that when Ni element increases, the bond orders (measures of strength of covalent bonding) of Ti-C and Ni-C in the models decrease correspondingly, which is to say that there is a gradient variation of the covalent bond in the transitional phase which is compatible with both the interior and Ni phases. It is beneficial for improving the mechanical properties of the materials.

A review on nitrogen transformation and conversion during coal pyrolysis and combustion based on quantum chemical calculation and experimental study

The emission of NOx during coal combustion contributes to the formation of acid rain and photochemical smog,which would seriously affect the quality of atmospheric environment.Therefore,the decrease of NOx is of great importance for improving the efficient utilization of coal.The present review comprehensively summarized the influence factors and mechanisms of migration and transformation of nitrogen during the coal pyrolysis and combustion based on experimental study and quantum chemical calculation.Firstly,in the process of pyrolysis:the occurrence state and transformation of nitrogen were concluded.The influence of temperature,atmosphere,heating rate and catalyst on formation of NOx precursor and nitrogen migration path at the molecular level were summarized;Secondly,during the process of combustion:the influence of temperature,ambient oxygen concentration,physical structure of coal char,catalyst on heterogeneous oxidation of char(N)were summarized;The effects of char surface properties,catalyst and ambient atmosphere on heterogeneous reduction of NOx were also concluded.Based on the quantum chemical calculation,the reaction path of heterogeneous oxidation of char-N and heterogeneous reduction of NOx were described in detail.Current studies focus more on the generation of HCN and NH3,but in order to reduce the pollution of NOx from the source,it is necessary to further improve the process conditions and the optimal formula of producing more N2 during pyrolysis,as well as clarify the path of the generation of N2.Experiments study and quantum chemistry calculation should be combined to complete the research of directional nitrogen reduction during pyrolysis and denitration during combustion.

The Thermal Decomposition Mechanism and the Quantum Chemical Calculation of[Mg（H2O）6]（NTO）2·2H2O

[Mg(H2O)6](NTO)2·2H2O Was prepared by adding magnesium carbonate hydroxide to the aqueous solution of 3-nitro-1，2，4-triazol-5-one(NTO)．Its thermal decomposition mechanism was studied by DSC，TG／DTGand IR．The quantum chemical calculation on the title complex as a structure unit with the experimental geometry as atartmg values was carried out at B3LYP level with 6-31G basis set．The results show that the bonds between the coordinate waters and the Mgatom have certain extent covalent character．The net charges on nitrogen atoms of the NTO ring appear to be negative while the nitrogen atom on the nitro group(—NO2)appears to be positive which indicates—NO2 will lost first when the complex is heated to some uniform temperature and this result is in agreement with that of the thermal decomposition experiment．

Hydrothermal Synthesis,Crystal Structure,Spectrum Properties and Quantum Chemical Calculation of a Trinuclear Copper(Ⅱ) Complex with 3-(Pyridin-2-yl)-1,2,4-triazole

A three-dimensional framework copper（Ⅱ） coordination polymer with copper carbonate basic and 3-（pyridin-2-yl）-1,2,4-triazole （Hpt） has been hydrothemally synthesized.The complex （2,C14 H10 CuN8 ·3H2 O） crystallizes in tetragonal,space group P4 2 /n,a=2.08581（12）,b=2.08581（12）,c=0.72331（4） nm,M r=761.73,V=3.1468（3） nm 3,Dc=1.608 g/cm 3,Z=4,F（000）=1552,GOOF=1.07,R=0.0515 and wR=0.1689.Every asymmetric unit molecular structure of the complex is composed with one copper ion,one and half water molecules and two Hpt molecules.Each copper ion is coordinated with five nitrogen atoms from four Hpt molecules,forming a distorted square pyramidal geometry.The fluorescence spectrum analysis shows that the title complex at room temperature exhibits intense photoluminescence with maximum emission at 450 nm.The quantum chemistry calculation study on the complex has been performed.The stability,some frontier molecular orbital energies and composition characteristics of some frontier molecular orbitals of the complex have been investigated.

Vibrational Spectra and Quantum Calculations of Ethylbenzene

Normal vibrations of ethylbenzene in the first excited state have been studied using resonant two-photon ionization spectroscopy. The band origin of ethylbenzene of S1-S0 transition appeared at 37586 cm-1. A vibrational spectrum of 2000 cm-1 above the band origin in the first excited state has been obtained. Several chain torsions and normal vibrations are obtained in the spectrum. The energies of the first excited state are calculated by the time- dependent density function theory and configuration interaction singles （CIS） methods with various basis sets. The optimized structures and vibrational frequencies of the So and S1 states are calculated using Hartree-Fock and CIS methods with 6-311＋＋G（2d,2p） basis set. The calculated geometric structures in the So and $1 states are gauche conformations that the symmetric plane of ethyl group is perpendicular to the ring plane. All the observed spectral bands have been successfully assigned with the help of our calculations.

Modeling Metal Binding Sites in Proteins by Quantum Chemical Calculations

Modeling Metal Binding Sites in Proteins by Quantum Chemical

Quantum chemical calculations on structure of Mo_(8)O_(26)^(4-)

Two possible structures of Mo 8O 4- 26 were optimized using the Polak-Ribiere method of Molecular Mechanics Optimization and the termination condition is RMS (Root-mean-square) gradient of 0.42 kJ/mol. Based on the calculations of the molecular dynamics, Lengevin dynamics and Monte Carlo dynamics simulation, the structure models of Mo 8O 4- 26 with the lowest energy were acquired respectively according to the energy of the systems calculated using the ZIDO/1 and PM3 methods. The total energy, energies of some frontier molecular orbitals and atomic charges of Mo 8O 4- 26 were computed at the HF/3-21G and HF/STO-3G levels. The calculation results show that the contortion of the structure with eight MoO 6 is smaller than that of the structure with six MoO 6 and two MoO 4. The total energies of the two structures are nearly equal because the contortion of the structure with six MoO 6 and two MoO 4 would make the exclusion force decreased.

Spin direction dependent quantum anomalous Hall effect in two-dimensional ferromagnetic materials

We propose a scheme for realizing the spin direction-dependent quantum anomalous Hall effect(QAHE)driven by spin-orbit couplings(SOC)in two-dimensional(2D)materials.Based on the sp^(3)tight-binding(TB)model,we find that these systems can exhibit a QAHE with out-of-plane and in-plane magnetization for the weak and strong SOC,respectively,in which the mechanism of quantum transition is mainly driven by the band inversion of p_(x,y)/p_(z)orbitals.As a concrete example,based on first-principles calculations,we realize a real material of monolayer 1T-SnN_(2)/PbN_(2)exhibiting the QAHE with in-plane/out-of-plane magnetization characterized by the nonzero Chern number C and topological edge states.These findings provide useful guidance for the pursuit of a spin direction-dependent QAHE and hence stimulate immediate experimental interest.

Reactivity of Tourmaline by Quantum Chemical Calculations

ZnAb initio calculations on reactivity of tourmaline were performed using both Gaussian and density function theory discrete variation method （DFT-DVM）. The HF, B3LYP methods and basis sets STO-3G（3d,3p）,6-31G（3d,3p） and 6-311＋＋G（3df,3pd） were used in the calculations. The experimental results show energy value obtained from B3LYP and 6-31＋＋1G（3df,3pd） basis sets is more accurate than those from other methods. The highest occupied molecular orbital （HOMO） of the tourmaline cluster mainly consists of O atom of hydroxyl group with relative higher energy level, suggesting that chemical bond between those of electron acceptor and this site may readily form, indicating the higher reactivity of hydroxyl group. The lowest unoccupied molecular orbital （LUMO） of the tourmaline cluster are dominantly composed of Si, O of tetrahedron and Na with relative lower energy level, suggesting that these atoms may tend to form chemical bond with those of electron donor. The results also prove that the O atoms of the tourmaline cluster have stronger reactivity than other atoms.