Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO·...Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F. The geomet- ric structures and vibrational frequencies of these six complexes at the MP2/6-31+G(d,p), MP2/6-311++G(d,p), B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) levels are calculated by standard and counterpoise-corrected methods, respectively. The results indicate that in complexes HCHO···HNO and HCOOH···HNO the N—H bond is strongly contracted and N—H···O blue-shifted hydrogen bonds are observed. While in complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F, the N—H bond is elongated and N—H···O red-shifted hydrogen bonds are found. From the natural bond orbital analysis it can be seen that the X—H bond length in the X—H···Y hydrogen bond is controlled by a balance of four main factors in the opposite directions: hyperconjugation, electron density redistribu- tion, rehybridization and structural reorganization. Among them hyperconjugation has the effect of elongating the X—H bond, and the other three factors belong to the bond shortening effects. In complexes HCHO···HNO and HCOOH···HNO, the shortening effects dominate which lead to the blue shift of the N—H stretching frequencies. In complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F where elongating effects are dominant, the N—H···O hydrogen bonds are red-shifted.展开更多
Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transitio...Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-to-metal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intraligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes.展开更多
Ab initio molecular orbital calculations have been used to investigate the thermal decomposition kinetics of 2-chloroethylethyldichlorosilane at the B3LYP/6-311+G^**,B3PW91/6-311+G^**,and MPW1PW91/6-311+G^** ...Ab initio molecular orbital calculations have been used to investigate the thermal decomposition kinetics of 2-chloroethylethyldichlorosilane at the B3LYP/6-311+G^**,B3PW91/6-311+G^**,and MPW1PW91/6-311+G^** levels of theory.Among these methods,the results(activation parameters) obtained using the B3LYP/6-311+G** level are in good agreement with the available experimental data.The calculated data imply that in the unimolecular β-elimination reactions of the studied compound in the gas phase,the polarization of C(1)-Cl(3) and C(1)-H(4) bonds in the sense of C(1)^δ+-Cl(3)^δ-and C(1)^δ+-H(4)^δ-,respectively,is a determining factor in the gas phase elimination reactions 1,2 and 3.Analysis of bond order,natural bond orbital charges,bond indexes,synchro-nicity parameters,and IRC calculations suggest the elimination of 2-chloroethylethyldichlorosilane via reactions 1~3 can be described as concerted and slightly asynchronous.The transition state structures of these reactions are a four-membered cyclic structure.展开更多
In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to...In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to SC state occurs in presence of different dopants. Recently in the Fe-based materials at high pressures, the SC was obtained at room critical temperature. In this paper, we present the results of calculations of the isolated cluster representing infinitum crystal with Rh and Pd as dopants. All calculations are performed with the suite of programs Gaussian 16. The obtained results are compared with our previous results obtained for embedded cluster using Gaussian 09. In the case of embedded cluster our methodology of the Embedded Cluster Method at the MP2 electron correlation level was applied. In the NBO population analysis two main features are revealed: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. This is similar to the Anderson’s spinless holon and confirms our conclusions in previous publications that the possible mechanism for superconductivity can be the RVB mechanism proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.展开更多
N-benzyl-1-(5-(3-chlorophenyl)-1,3,4-oxadiazol-2-yl)cyclopentanamine was synthesized via one-pot reaction of appropriate benzylamine, cyclopentanone,(N-isocyanimino)triphenylphosphorane and m-chlorobenzoic acid....N-benzyl-1-(5-(3-chlorophenyl)-1,3,4-oxadiazol-2-yl)cyclopentanamine was synthesized via one-pot reaction of appropriate benzylamine, cyclopentanone,(N-isocyanimino)triphenylphosphorane and m-chlorobenzoic acid. The quantum theoretical calculations for crystal structure were performed by density functional theory(DFT/B3LYP/6-311+G*). From the optimized structure, geometric parameters were obtained and experimental measurements were compared with the calculated data. Frontier molecular orbitals(FMOs), total density of states(DOS), molecular electrostatic potential(MEP), molecular properties, natural charges, NMR parameters and NBO analysis for the product were investigated by theoretical calculations.展开更多
The compound(4-chlorophenyl)-N-(4-methylphenyl)nitrone(4CPNMPN)has been selected as one of the new nitrone derivative for our study.The molecular structure of the compound was investigated based on frontier orbital an...The compound(4-chlorophenyl)-N-(4-methylphenyl)nitrone(4CPNMPN)has been selected as one of the new nitrone derivative for our study.The molecular structure of the compound was investigated based on frontier orbital analysis and natural bond orbital(NBO)theory.The present work also focuses on the inhibition efficiency of the compound.It is an attempt to find the correlation between the molecular structure of the compound and possible behaviour like corrosion inhibitors.The NBO analysis and the values of electric dipole moment(μ)of the investigated molecule were computed using DFT calculations.The molecule orbital contributions were studied by using the total(TDOS)density of states.The strong evidences that the compound can be used as an efficient nonlinear optical(NLO)of 4CPNMPN were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.展开更多
The photoluminescence of four polyoxoniobates [Nb6O19]8-, [Nb10O28]6-, [Ti2Nb8O28]8- and [H2Si4Nb16O56]14- was observed, and its origin was revealed in the view of molecular orbital by means of the computational metho...The photoluminescence of four polyoxoniobates [Nb6O19]8-, [Nb10O28]6-, [Ti2Nb8O28]8- and [H2Si4Nb16O56]14- was observed, and its origin was revealed in the view of molecular orbital by means of the computational method. The photoluminescence is originated from singlet transitions, and the calculated values agree well with the experimental data. The results indicate that the size of clusters and the foreigner atoms can affect the fluorescent properties of PONbs. The absorption and emission of these PONbs are originated molecular orbitals contributed mainly by μ2-O and Nb atoms according to NBO analysis. These PONbs were also found as electrochemical catalysts with high performance for water oxidation, which can effectively split water into oxygen under basic condition with a high catalytic current, and pH values have remarkable influence on the electrocatalytic activities of these PONbs for water oxidation.展开更多
The equilibrium geometries and electronic properties of AunAl, up to n=13, have been systematically investigated using the density functional theory. The results show that, for the AunAl clusters, two patterns are ide...The equilibrium geometries and electronic properties of AunAl, up to n=13, have been systematically investigated using the density functional theory. The results show that, for the AunAl clusters, two patterns are identified. Pattern one (n=2, 3, 8), the lowest-energy geometries prefer two-dimensional structures. Pattern two (n=4-7, 9-13), the lowest-energy geometries prefer three-dimensional structures. According to the analysis of the binding energy and the fragmentation energy, AunAl clusters with odd n are found to be more stable than those with even n. The same trend of alternation can be illuminated according to the computational results in the HOMO-LUMO gap, the ionization potential, and the electron affinities. The Al atom not only changes the structures of pure gold clusters, but also enhances their stabilities. NBO analysis indicates 6s orbital of Au atom hybridizes with 3p orbital of Al atom.展开更多
基金the National Natural Science Foundation of China(Grant No.20477043)Knowledge Innovation Program by Chinese Academy of Sciences(KJCX2-SW-H08)
文摘Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F. The geomet- ric structures and vibrational frequencies of these six complexes at the MP2/6-31+G(d,p), MP2/6-311++G(d,p), B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) levels are calculated by standard and counterpoise-corrected methods, respectively. The results indicate that in complexes HCHO···HNO and HCOOH···HNO the N—H bond is strongly contracted and N—H···O blue-shifted hydrogen bonds are observed. While in complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F, the N—H bond is elongated and N—H···O red-shifted hydrogen bonds are found. From the natural bond orbital analysis it can be seen that the X—H bond length in the X—H···Y hydrogen bond is controlled by a balance of four main factors in the opposite directions: hyperconjugation, electron density redistribu- tion, rehybridization and structural reorganization. Among them hyperconjugation has the effect of elongating the X—H bond, and the other three factors belong to the bond shortening effects. In complexes HCHO···HNO and HCOOH···HNO, the shortening effects dominate which lead to the blue shift of the N—H stretching frequencies. In complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F where elongating effects are dominant, the N—H···O hydrogen bonds are red-shifted.
文摘Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-to-metal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intraligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes.
文摘Ab initio molecular orbital calculations have been used to investigate the thermal decomposition kinetics of 2-chloroethylethyldichlorosilane at the B3LYP/6-311+G^**,B3PW91/6-311+G^**,and MPW1PW91/6-311+G^** levels of theory.Among these methods,the results(activation parameters) obtained using the B3LYP/6-311+G** level are in good agreement with the available experimental data.The calculated data imply that in the unimolecular β-elimination reactions of the studied compound in the gas phase,the polarization of C(1)-Cl(3) and C(1)-H(4) bonds in the sense of C(1)^δ+-Cl(3)^δ-and C(1)^δ+-H(4)^δ-,respectively,is a determining factor in the gas phase elimination reactions 1,2 and 3.Analysis of bond order,natural bond orbital charges,bond indexes,synchro-nicity parameters,and IRC calculations suggest the elimination of 2-chloroethylethyldichlorosilane via reactions 1~3 can be described as concerted and slightly asynchronous.The transition state structures of these reactions are a four-membered cyclic structure.
文摘In introduction we presented a short historical survey of the discovery of superconductivity (SC) up to the Fe-based materials that are not superconducting in a pure state. For this type of material, the transition to SC state occurs in presence of different dopants. Recently in the Fe-based materials at high pressures, the SC was obtained at room critical temperature. In this paper, we present the results of calculations of the isolated cluster representing infinitum crystal with Rh and Pd as dopants. All calculations are performed with the suite of programs Gaussian 16. The obtained results are compared with our previous results obtained for embedded cluster using Gaussian 09. In the case of embedded cluster our methodology of the Embedded Cluster Method at the MP2 electron correlation level was applied. In the NBO population analysis two main features are revealed: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. This is similar to the Anderson’s spinless holon and confirms our conclusions in previous publications that the possible mechanism for superconductivity can be the RVB mechanism proposed by Anderson for high T<sub>c</sub> superconductivity in cuprates.
基金supported by the University of Zanjanthe grant NRF-2015-002423 of the National Research Foundation of Korea
文摘N-benzyl-1-(5-(3-chlorophenyl)-1,3,4-oxadiazol-2-yl)cyclopentanamine was synthesized via one-pot reaction of appropriate benzylamine, cyclopentanone,(N-isocyanimino)triphenylphosphorane and m-chlorobenzoic acid. The quantum theoretical calculations for crystal structure were performed by density functional theory(DFT/B3LYP/6-311+G*). From the optimized structure, geometric parameters were obtained and experimental measurements were compared with the calculated data. Frontier molecular orbitals(FMOs), total density of states(DOS), molecular electrostatic potential(MEP), molecular properties, natural charges, NMR parameters and NBO analysis for the product were investigated by theoretical calculations.
文摘The compound(4-chlorophenyl)-N-(4-methylphenyl)nitrone(4CPNMPN)has been selected as one of the new nitrone derivative for our study.The molecular structure of the compound was investigated based on frontier orbital analysis and natural bond orbital(NBO)theory.The present work also focuses on the inhibition efficiency of the compound.It is an attempt to find the correlation between the molecular structure of the compound and possible behaviour like corrosion inhibitors.The NBO analysis and the values of electric dipole moment(μ)of the investigated molecule were computed using DFT calculations.The molecule orbital contributions were studied by using the total(TDOS)density of states.The strong evidences that the compound can be used as an efficient nonlinear optical(NLO)of 4CPNMPN were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.
文摘The photoluminescence of four polyoxoniobates [Nb6O19]8-, [Nb10O28]6-, [Ti2Nb8O28]8- and [H2Si4Nb16O56]14- was observed, and its origin was revealed in the view of molecular orbital by means of the computational method. The photoluminescence is originated from singlet transitions, and the calculated values agree well with the experimental data. The results indicate that the size of clusters and the foreigner atoms can affect the fluorescent properties of PONbs. The absorption and emission of these PONbs are originated molecular orbitals contributed mainly by μ2-O and Nb atoms according to NBO analysis. These PONbs were also found as electrochemical catalysts with high performance for water oxidation, which can effectively split water into oxygen under basic condition with a high catalytic current, and pH values have remarkable influence on the electrocatalytic activities of these PONbs for water oxidation.
基金Project supported in part by the National Natural Science Foundation of China (Grant No 10174086)the Foundation for the research starting of East China University of Science and Technology (Grant No YK0142109)
文摘The equilibrium geometries and electronic properties of AunAl, up to n=13, have been systematically investigated using the density functional theory. The results show that, for the AunAl clusters, two patterns are identified. Pattern one (n=2, 3, 8), the lowest-energy geometries prefer two-dimensional structures. Pattern two (n=4-7, 9-13), the lowest-energy geometries prefer three-dimensional structures. According to the analysis of the binding energy and the fragmentation energy, AunAl clusters with odd n are found to be more stable than those with even n. The same trend of alternation can be illuminated according to the computational results in the HOMO-LUMO gap, the ionization potential, and the electron affinities. The Al atom not only changes the structures of pure gold clusters, but also enhances their stabilities. NBO analysis indicates 6s orbital of Au atom hybridizes with 3p orbital of Al atom.