The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinitie...The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.展开更多
The oxygenation constants and thermodynamic parameter (△H°, △S°) of a series of novel Co (Ⅱ) complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performan...The oxygenation constants and thermodynamic parameter (△H°, △S°) of a series of novel Co (Ⅱ) complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X (X = Cl, OCH3) and Y (Y = H, CH3, Cl) groups bonded to the aromatic rings of the Co (Ⅱ) complexes were investigated.展开更多
Sulfide minerals are found in porous media in both aerobic and anaerobic environments, they should have a high affinities for certain metals. The relative binding affinities and reaction processes for 10 metal/metallo...Sulfide minerals are found in porous media in both aerobic and anaerobic environments, they should have a high affinities for certain metals. The relative binding affinities and reaction processes for 10 metal/metalloid ions reacting with four sulfide mineral surfaces has been defined.The order of reactivity is chalcocite > pyrite > galena >> sphalerite. For any particular metal and mineral, the greater reactivity occurs in the single-ion metal system except Ag(I) on pyrite and Cu(II) on galena.Both precipitation and adsorption reaction can decrease metal ion mobility on porous media, the order of metal mobility in the presence of the four sulfide minerals is predicted to be: Zn(II), Cd(II) and Ni(II) - mobile; Cu(II), Pb(II), Fe(III), As(III) and Cr(III) - variable mobility and Ag(I) - immobile.MINTEQA1 predictions on metal phase distribution / partitioning compared quite well with those observed experimentally. Solubility product considerations, intrinsic acidity constant of the mineral, EH, pH and the carbonate equilibrium are major factors controlling the phase distribution of metals reacting singularly or in combination with sulfide mineral surfaces.展开更多
Tetracycline analogs were designed and synthesized and their bone affinities were tested on hydroxyapatite. The results showed that the carbonyl-amide-enol structure in A ring and phenol-ketone structure in BCD ring m...Tetracycline analogs were designed and synthesized and their bone affinities were tested on hydroxyapatite. The results showed that the carbonyl-amide-enol structure in A ring and phenol-ketone structure in BCD ring may be responsible for tetracycline's high bone affinity and either A ring or BCD ring has a planar conformation is essential. 2007 Ling Ling Weng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed...The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.展开更多
There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011).'Supra-S...There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011).'Supra-Subduction zone'(SSZ)ophiolites such as the well-studied Tethyan ophiolites,generally display a characteristic sequential evolution from mid-oceanic ridge basalts(MORBs)to island arc tholeiities(IATs)or bonites(BONs)(Pearce,2003;Dilek and Furnes,2009,2011),which were generated in sequence from the decompression melting of asthenospheric mantle and partial melting of subduction-metasomatized depleted mantle(Stern and Bloomer,1992;Dilek and Furnes,2009;Whattam and Stern,2011).However,ophiolites with MORB and/or oceanic-island basalt(OIB)affinities are rare,and their origin and tectonic nature are poorly understood(Boedo et al.,2013;Saccani et al.,2013).It is interesting that the composition of these ophiolites from the central Tibetan Plateau(CTP)is dominated by MORBs and minor OIBs and a distinct lack of IATs and BONs,which is inconsistent with most ophiolites worldwide(Robinson and Zhou,2008;Zhang et al.,2008).But the generation and tectonic nature of these ophiolites are still controversial.*In this study,we present new geochronological,mineralogical and Sr-Nd isotopic data for the Chayong and Xiewu mafic complexes in the western Garzê-Litang suture zone(GLS),a typical Paleo-Tethyan suture crossing the CTP(Fig.1).The Triassic ophiolite in the western GLS has been described by Li et al.(2009),who foundthat it mainly consists of gabbros,diabases,pillow basalts and a few metamorphic peridotites.The ophiolite has been tectonically dismembered and crops out in Triassic clastic rocks and limestones as tectonic blocks.The Chayong and Xiewu mafic complexes are generally regarded as important fragments of the Triassic ophiolites(e.g.,Jin,2006;Li et al.,2009).Zircon LA-ICP-MS U-Pb ages of234±3 Ma and 236±2 Ma can be interpreted as formation times of the Chayong and Xiewu mafic complexes,respectively.The basalts and gabbros of the Chayong complexexhibitenrichedMORB(E-MORB)compositional affinities except for a weak depletion of Nb,Ta and Ti relative to the primitive mantle,whereas the basalts and gabbros of the Xiewu complex display distinct E-MORB and OIB affinities.The geochemical features suggest a probable fractionation of olivine±clinopyroxene±plagioclase as well as insignificant crustal contamination.The geochemical and Sr-Nd isotopic data reveal that the Chayong mafic rocks may have been derived from depleted MORB-type mantle metasomatized by crustal components and Xiewu mafic rocks from enriched lithosphericmantlemetasomatizedbyOIB-like components.The ratios of Zn/Fet,La/Yb and Sm/Yb indicate that these mafic melts were produced by the partial melting of garnet+minor spinel-bearing peridotite or spinel±minor garnet-bearing peridotite.We propose thatback-arcbasinspreadingassociated with OIB/seamount recycling had occurred in the western GLS at least since the Middle Triassic times,and the decompression melting of the depleted MORB-type asthenospheremantleandpartialmeltingof sub-continental lithosphere were metasomatized by plume-related melts,such as OIBs,which led to the generation of the Chayong and Xiewu mafic melts.展开更多
Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calc...Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calcuIations show that the ionization potentiaIs and electron affinities of Cu. (n = 2-7) atom ic clusters have a sharp even / odd alternation with increasing their sizes, which are related to the electronic structure of Cun atomic clusters. The theoretical results are consistent with the related ex perimental ones.展开更多
The electron affinities of the isomer XC6H4CH2/ XC6H4CH2- (X=F, Cl, Br) species have been determined using seven density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarizati...The electron affinities of the isomer XC6H4CH2/ XC6H4CH2- (X=F, Cl, Br) species have been determined using seven density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities are obtained at the DZP++ BPW91, BP86, and B3LYP level of theory. The BPW91 methods are the closest to the experiment values; The BHLYP method predicts the smallest EAad and B3P86 method predicts the largest EAad, which are the worst reliable methods. In addition, for a given halogen substituent, the meta isomer has the largest electron affinity and the para isomer has the smallest.展开更多
The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99(1) eV for LaO, 1.00(1) eV for CeO, 1...The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99(1) eV for LaO, 1.00(1) eV for CeO, 1.00(1) eV for PrO, and 1.01(1) eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.展开更多
Wavelet Neural Network (WNN) was employed in a rapid calculation of the atomic electron affinities, with atomic ionization potentials and atomic electron configurations chosen as input parameters. Many unmeasured valu...Wavelet Neural Network (WNN) was employed in a rapid calculation of the atomic electron affinities, with atomic ionization potentials and atomic electron configurations chosen as input parameters. Many unmeasured values were obtained, and the estimates appeared to be sufficiently accurate for potential applications.展开更多
The flora of the eastern China is the main part of Sino-Japaners floristic region. It shows from the analysis and comparison that the floristic relation of East China with Japan is closer than that with northeast Chin...The flora of the eastern China is the main part of Sino-Japaners floristic region. It shows from the analysis and comparison that the floristic relation of East China with Japan is closer than that with northeast China and Korea. The similarity indices of genera and species of seed plants in the two regions are very high, being 72.6% and 43.3% respectively. The structure and species composition of broad-leaval evergreen forests in the two regions are also similar, and there exist many corresponding communities, such as the forests of Castanopsis carlesii and C. sieboldii. Many plants in East China are conspecific with there in Japan, such as Cercidiphyllum japonicum, Magnolia sieboldii, Nandina domestica etc. Though the genera of Ginkgo, Liriodendron, Sassafras etc. existing now in China are extinct from Japan, their fossils have been discovered from the Tertiary strata in Japan. It seems to indicate that the phytogeographical affinities between East China and Japan are closer in ancient the than it is now, and both of the forest floras originated from the same flora. The flora in Japan did not evolve independently until it separated from Chinese continent and drifted northeastwards in the late period of the Tertiary.展开更多
The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The hi...The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.展开更多
The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with c...The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.展开更多
The oxygenation constants (Ko2) of cobalt(Ⅱ) hydroxamates (CoL^1 2-CoL^3 2) with benzo-15-crown-5 (B15C5) pendants were measured over the range of -5 to +20 ℃, and the values of thermodynamic parameters (...The oxygenation constants (Ko2) of cobalt(Ⅱ) hydroxamates (CoL^1 2-CoL^3 2) with benzo-15-crown-5 (B15C5) pendants were measured over the range of -5 to +20 ℃, and the values of thermodynamic parameters (ΔH^0 and ΔS^0) were calculated based on these (Ko2) values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.展开更多
The molecular structures and electron affinities of 5- and 6-halouracils(XU, X=F, Cl, Br) were determined by means of five different density functional methods. The basis set used in this work is of double-(plus po...The molecular structures and electron affinities of 5- and 6-halouracils(XU, X=F, Cl, Br) were determined by means of five different density functional methods. The basis set used in this work is of double-(plus polariza- tion(DZP) quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries were fully optimized with each density functional theory(DFT) method, and discussed. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity(AEA), the vertical electron affinity(VEA), and the vertical detachment energy(VDE). An excellent agreement between our B3LYP results and those obtained by other calculations regarding the structural modifications and electron affinities of neutral and anion 5XU was found. The differences in charge distribution between uracil and halogenated uracils were indicated, thus the ability to form the hydrogen bonds of halogenated uracils was discussed. It shows the applicability of the DFT/DZP++ method to predict the similar molecular models at a highly economical computational cost.展开更多
B3LYP/6-31+g (d, p) method was used to calculate the lithium and sodium affinities of n-alkyl fluoride. These affinities were found to obey the Holmes relationship, i.e. they correlate linearly with the quotient n/(n...B3LYP/6-31+g (d, p) method was used to calculate the lithium and sodium affinities of n-alkyl fluoride. These affinities were found to obey the Holmes relationship, i.e. they correlate linearly with the quotient n/(n+1), where n is the number of carbon atoms in the alkyl chain. From the correlation the limiting values of lithium and sodium affinities for very long alkyl chain were predicted to be 153.3 kJ/mol and 108.4 kJ/mol, respectively.展开更多
The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-pha...The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.展开更多
The flora of eastem China is the main part of Sino-Japanese floristic region. It shows by the analysis and com-parison that the floristic relations of Eastem China with Japan are closer than that ofnortheast China wit...The flora of eastem China is the main part of Sino-Japanese floristic region. It shows by the analysis and com-parison that the floristic relations of Eastem China with Japan are closer than that ofnortheast China with Korea. The simi-larity indices of genera and species of seed plants in the two regions are very high, being 72.6% and 43.3% respectively.The strure and species compositi6n of broad-leaved evergreen forests in the two regions are also similar, in which there'exist the corresponding communities, such as the forests of Castanopsis carlesii,C.Sieboldii.. Many plants in Easter Chinaare nonspecilic with those in Japan, e. g, Cercidiphyllum japonicum, Magolia sieboldii, Nandina domestica etc.. Though thegnera Ginkgo, Liriodendron, Sassafixis etc. existing now in China are extinct from Japan, their fossils have been discov-ered from the Tertiary Strata in Japan. It seems to indicate that the Phytogeographical affinities between Japan and E. Chinawas closer in ancient time than it is now; and both of the forest floras originated from one same flora. The flora in Japan did not evolve indepently until it separated from Chinese continent and drifted to northeast in the late period of the Tertiary.展开更多
文摘The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
基金This work is supported by the National Natural Science Foundation of China(Grant No.2007205).
文摘The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.
基金supported by the National Natural Science Foundation of China(No.2007205).
文摘The oxygenation constants and thermodynamic parameter (△H°, △S°) of a series of novel Co (Ⅱ) complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X (X = Cl, OCH3) and Y (Y = H, CH3, Cl) groups bonded to the aromatic rings of the Co (Ⅱ) complexes were investigated.
文摘Sulfide minerals are found in porous media in both aerobic and anaerobic environments, they should have a high affinities for certain metals. The relative binding affinities and reaction processes for 10 metal/metalloid ions reacting with four sulfide mineral surfaces has been defined.The order of reactivity is chalcocite > pyrite > galena >> sphalerite. For any particular metal and mineral, the greater reactivity occurs in the single-ion metal system except Ag(I) on pyrite and Cu(II) on galena.Both precipitation and adsorption reaction can decrease metal ion mobility on porous media, the order of metal mobility in the presence of the four sulfide minerals is predicted to be: Zn(II), Cd(II) and Ni(II) - mobile; Cu(II), Pb(II), Fe(III), As(III) and Cr(III) - variable mobility and Ag(I) - immobile.MINTEQA1 predictions on metal phase distribution / partitioning compared quite well with those observed experimentally. Solubility product considerations, intrinsic acidity constant of the mineral, EH, pH and the carbonate equilibrium are major factors controlling the phase distribution of metals reacting singularly or in combination with sulfide mineral surfaces.
基金This work was supported by the National Natural Science Foundation of China (No. 30070883).
文摘Tetracycline analogs were designed and synthesized and their bone affinities were tested on hydroxyapatite. The results showed that the carbonyl-amide-enol structure in A ring and phenol-ketone structure in BCD ring may be responsible for tetracycline's high bone affinity and either A ring or BCD ring has a planar conformation is essential. 2007 Ling Ling Weng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.
基金financially supported by the National Nature Science Foundation of China (Grant 41272079)
文摘There is a general consensus that most ophiolites formed above subduction zones(Pearce,2003),particularly during forearc extension at subduction initiation(Shervais,2001;Stern,2004;Whattam and Stern,2011).'Supra-Subduction zone'(SSZ)ophiolites such as the well-studied Tethyan ophiolites,generally display a characteristic sequential evolution from mid-oceanic ridge basalts(MORBs)to island arc tholeiities(IATs)or bonites(BONs)(Pearce,2003;Dilek and Furnes,2009,2011),which were generated in sequence from the decompression melting of asthenospheric mantle and partial melting of subduction-metasomatized depleted mantle(Stern and Bloomer,1992;Dilek and Furnes,2009;Whattam and Stern,2011).However,ophiolites with MORB and/or oceanic-island basalt(OIB)affinities are rare,and their origin and tectonic nature are poorly understood(Boedo et al.,2013;Saccani et al.,2013).It is interesting that the composition of these ophiolites from the central Tibetan Plateau(CTP)is dominated by MORBs and minor OIBs and a distinct lack of IATs and BONs,which is inconsistent with most ophiolites worldwide(Robinson and Zhou,2008;Zhang et al.,2008).But the generation and tectonic nature of these ophiolites are still controversial.*In this study,we present new geochronological,mineralogical and Sr-Nd isotopic data for the Chayong and Xiewu mafic complexes in the western Garzê-Litang suture zone(GLS),a typical Paleo-Tethyan suture crossing the CTP(Fig.1).The Triassic ophiolite in the western GLS has been described by Li et al.(2009),who foundthat it mainly consists of gabbros,diabases,pillow basalts and a few metamorphic peridotites.The ophiolite has been tectonically dismembered and crops out in Triassic clastic rocks and limestones as tectonic blocks.The Chayong and Xiewu mafic complexes are generally regarded as important fragments of the Triassic ophiolites(e.g.,Jin,2006;Li et al.,2009).Zircon LA-ICP-MS U-Pb ages of234±3 Ma and 236±2 Ma can be interpreted as formation times of the Chayong and Xiewu mafic complexes,respectively.The basalts and gabbros of the Chayong complexexhibitenrichedMORB(E-MORB)compositional affinities except for a weak depletion of Nb,Ta and Ti relative to the primitive mantle,whereas the basalts and gabbros of the Xiewu complex display distinct E-MORB and OIB affinities.The geochemical features suggest a probable fractionation of olivine±clinopyroxene±plagioclase as well as insignificant crustal contamination.The geochemical and Sr-Nd isotopic data reveal that the Chayong mafic rocks may have been derived from depleted MORB-type mantle metasomatized by crustal components and Xiewu mafic rocks from enriched lithosphericmantlemetasomatizedbyOIB-like components.The ratios of Zn/Fet,La/Yb and Sm/Yb indicate that these mafic melts were produced by the partial melting of garnet+minor spinel-bearing peridotite or spinel±minor garnet-bearing peridotite.We propose thatback-arcbasinspreadingassociated with OIB/seamount recycling had occurred in the western GLS at least since the Middle Triassic times,and the decompression melting of the depleted MORB-type asthenospheremantleandpartialmeltingof sub-continental lithosphere were metasomatized by plume-related melts,such as OIBs,which led to the generation of the Chayong and Xiewu mafic melts.
文摘Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calcuIations show that the ionization potentiaIs and electron affinities of Cu. (n = 2-7) atom ic clusters have a sharp even / odd alternation with increasing their sizes, which are related to the electronic structure of Cun atomic clusters. The theoretical results are consistent with the related ex perimental ones.
文摘The electron affinities of the isomer XC6H4CH2/ XC6H4CH2- (X=F, Cl, Br) species have been determined using seven density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities are obtained at the DZP++ BPW91, BP86, and B3LYP level of theory. The BPW91 methods are the closest to the experiment values; The BHLYP method predicts the smallest EAad and B3P86 method predicts the largest EAad, which are the worst reliable methods. In addition, for a given halogen substituent, the meta isomer has the largest electron affinity and the para isomer has the smallest.
基金This work was supported by the National Natural Science Foundation of China (No.20933003) and the National Basic Research Program of China (No.2010CB732306).
文摘The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99(1) eV for LaO, 1.00(1) eV for CeO, 1.00(1) eV for PrO, and 1.01(1) eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.
文摘Wavelet Neural Network (WNN) was employed in a rapid calculation of the atomic electron affinities, with atomic ionization potentials and atomic electron configurations chosen as input parameters. Many unmeasured values were obtained, and the estimates appeared to be sufficiently accurate for potential applications.
文摘The flora of the eastern China is the main part of Sino-Japaners floristic region. It shows from the analysis and comparison that the floristic relation of East China with Japan is closer than that with northeast China and Korea. The similarity indices of genera and species of seed plants in the two regions are very high, being 72.6% and 43.3% respectively. The structure and species composition of broad-leaval evergreen forests in the two regions are also similar, and there exist many corresponding communities, such as the forests of Castanopsis carlesii and C. sieboldii. Many plants in East China are conspecific with there in Japan, such as Cercidiphyllum japonicum, Magnolia sieboldii, Nandina domestica etc. Though the genera of Ginkgo, Liriodendron, Sassafras etc. existing now in China are extinct from Japan, their fossils have been discovered from the Tertiary strata in Japan. It seems to indicate that the phytogeographical affinities between East China and Japan are closer in ancient the than it is now, and both of the forest floras originated from the same flora. The flora in Japan did not evolve independently until it separated from Chinese continent and drifted northeastwards in the late period of the Tertiary.
文摘The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.
基金the National Natural Science Foundation of China.
文摘The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.
基金The authors gratefully acknowledge the grants from the National Natural Science Foundation of China(No.20072025)Education 0ffice Foundation of Sichuan Province(No.2005C012)Sichuan Provincial Department of Science&Technology(No.2006J13-143)in support of this work.
文摘The oxygenation constants (Ko2) of cobalt(Ⅱ) hydroxamates (CoL^1 2-CoL^3 2) with benzo-15-crown-5 (B15C5) pendants were measured over the range of -5 to +20 ℃, and the values of thermodynamic parameters (ΔH^0 and ΔS^0) were calculated based on these (Ko2) values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.
基金Supported by the National Natural Science Foundation of China(No.20573042)
文摘The molecular structures and electron affinities of 5- and 6-halouracils(XU, X=F, Cl, Br) were determined by means of five different density functional methods. The basis set used in this work is of double-(plus polariza- tion(DZP) quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries were fully optimized with each density functional theory(DFT) method, and discussed. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity(AEA), the vertical electron affinity(VEA), and the vertical detachment energy(VDE). An excellent agreement between our B3LYP results and those obtained by other calculations regarding the structural modifications and electron affinities of neutral and anion 5XU was found. The differences in charge distribution between uracil and halogenated uracils were indicated, thus the ability to form the hydrogen bonds of halogenated uracils was discussed. It shows the applicability of the DFT/DZP++ method to predict the similar molecular models at a highly economical computational cost.
文摘B3LYP/6-31+g (d, p) method was used to calculate the lithium and sodium affinities of n-alkyl fluoride. These affinities were found to obey the Holmes relationship, i.e. they correlate linearly with the quotient n/(n+1), where n is the number of carbon atoms in the alkyl chain. From the correlation the limiting values of lithium and sodium affinities for very long alkyl chain were predicted to be 153.3 kJ/mol and 108.4 kJ/mol, respectively.
文摘The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.
文摘The flora of eastem China is the main part of Sino-Japanese floristic region. It shows by the analysis and com-parison that the floristic relations of Eastem China with Japan are closer than that ofnortheast China with Korea. The simi-larity indices of genera and species of seed plants in the two regions are very high, being 72.6% and 43.3% respectively.The strure and species compositi6n of broad-leaved evergreen forests in the two regions are also similar, in which there'exist the corresponding communities, such as the forests of Castanopsis carlesii,C.Sieboldii.. Many plants in Easter Chinaare nonspecilic with those in Japan, e. g, Cercidiphyllum japonicum, Magolia sieboldii, Nandina domestica etc.. Though thegnera Ginkgo, Liriodendron, Sassafixis etc. existing now in China are extinct from Japan, their fossils have been discov-ered from the Tertiary Strata in Japan. It seems to indicate that the Phytogeographical affinities between Japan and E. Chinawas closer in ancient time than it is now; and both of the forest floras originated from one same flora. The flora in Japan did not evolve indepently until it separated from Chinese continent and drifted to northeast in the late period of the Tertiary.