Polyethylene glycol (PEG) supported (diacetoxy)iodobenzene as soluble polymer reagent can smoothly oxidize acid hydrazides into corresponding dimmers in good yields under very mild conditions.
The double bonds in the vegetable oils can be conjungated and Diels-Alder react when they are heated in the existence of the catalyst. The percent of the double bond will decrease and the oxidative stability of the ve...The double bonds in the vegetable oils can be conjungated and Diels-Alder react when they are heated in the existence of the catalyst. The percent of the double bond will decrease and the oxidative stability of the vegetable oils can be ameliorated. Dimmer acid can react with different carbon chain length of alcohols to form dimmer acid esters. A series of dimmer acid esters were synthesized and their rheological characteristics （viscosity, viscosity index, pour point） and tribological characteristics （the coefficient of friction at different load, the characteristic of extreine pressure （ PB ）, the wear scare diameter （ D30min^196N ） were evaluated and analyzed. The results showed that the characteristics of Di-iso-octanol dimmer acid ester were the best among the synthesized dimmer esters. It＇ s a lubricant with good properties（the viscosity is 94.5 mm^2/s, the viscosity index is high up to 141 and the pour point is - 49℃ ）. It is a kind of newly interesthing ester type lubricant. Its rheological and tribological characteristics are even better than those of the slap-up synthesized lubricant--pentaerythritol esters （C7-9 acidate）. The FT-IR spectrophotometer was used to analyze the structure of the synthetic esters. Their IR spectra are the same as the typical IR spectrum of ester. The test indicated that Di-iso-octanol dimmer acid ester could be used as a kind of base lubricant with excellent quantity.展开更多
The title complex [Ni(TSSB)(phen)H2O]?C2H5OH?0.5H2O (C23H26N3NiO6.5S, TSSB = taurine salicylaldehyde Schiff base, phen = 1,10-phenanthroline) has been synthesized by the reaction of taurine salicylaldehyde Schiff base...The title complex [Ni(TSSB)(phen)H2O]?C2H5OH?0.5H2O (C23H26N3NiO6.5S, TSSB = taurine salicylaldehyde Schiff base, phen = 1,10-phenanthroline) has been synthesized by the reaction of taurine salicylaldehyde Schiff base (TSSB), 1,10-phenanthroline and nickel acetate in water-ethanol. Its single-crystal structure was determined by X-ray diffraction method. The crystal belongs to triclinic, space group P1 with a = 1.0562(2), b = 1.1604(2), c = 2.1170(3) nm, α = 103.257(3), β = 96.958(4), γ = 105.179(3)°, Mr = 539.24, V = 2.3917(6) nm3, Z = 4, Dc = 1.498 g/cm3, μ = 0.945 mm-1 and F(000) = 1124. The compound is a one-dimensional network, infinitely extending with hydrogen bonds. The Ni(Ⅱ) is 6-coordinated by one nitrogen and two oxygen atoms from taurine salicylaldehyde Schiff base, two nitrogen from 1,10-phenanthroline and one oxygen from water to form a distorted octahedronal coordination geometry.展开更多
Objective: To observe the effect of Xueshuantong injection (XST,血栓通注射液) with its ingredient as Notoginseng saponin, on acute cerebral infarction (ACI) and on blood coagulation and fibri-nolysis, so as to compreh...Objective: To observe the effect of Xueshuantong injection (XST,血栓通注射液) with its ingredient as Notoginseng saponin, on acute cerebral infarction (ACI) and on blood coagulation and fibri-nolysis, so as to comprehensively analyse the mechanism of XST. Methods: Fifty ACI patients were randomly divided into 2 groups, and XST group (30 patients) was treated with XST, and the control group (20 patients) given low molecular dextrose, as well as low molecular heparin calcium. The course of treatment for both groups was 15 days. The changes of effective rate, score of neurologic impairment, tissue-type plasminogen activator (tPA), inhibitor of plasminogen activator (PAI), D-D dimmer, antithrombin-III (AT-III), and fibrinogen (Fbg) were all observed. Results: The total effective rate of XST group was 73.33%, that of the control group 65. 00%. After the therapy, plasma level of tPA, ratio of tPA/PAI, and AT-III content were increased obviously, while the plasma level of PAI and D-D dimmer were decreased significantly (all P<0.01) . But there was only insignificant difference between the 2 groups (P> 0.05).Conclusion: XST injection could be effective to ACI, the mechanism of which is probably related to improving the balance between plasminogen activator and its inhibitory factor, increasing the activity of fi-brinolysin, inactivating thrombin, inhibiting platelet aggregation induced by thrombin, and decreasing blood coagulation.展开更多
Reaction of acetylacetone with 1 mole of dimethylformamide dimethyl acetal (DMFDMA) affords enamine 2a which reacts with cyanothioacetamide to give pyridinethione 3a. Pyridinethione 3a reacts with methyl iodide, halog...Reaction of acetylacetone with 1 mole of dimethylformamide dimethyl acetal (DMFDMA) affords enamine 2a which reacts with cyanothioacetamide to give pyridinethione 3a. Pyridinethione 3a reacts with methyl iodide, halogenated compounds, aromatic aldehyde and malononitrile/elemental sulfur to yiled compounds 7-10 respectively. Reactions of thioether 7 in ethanolic K2CO3, 1 mole DMFDMA and 4-(dimethylamino)benzaldehyde give compounds 11, 13, 14 respectively. Enaminone 12 can be prepared by reaction of compound 11 with DMFDMA. We have demonstrated some reactions in order to show the potential usefulness of the prepared compounds for the preparation of new bipyridyl compounds 15, 16, 18, bicyclic compounds 17 and uncommon tricyclic compounds 20, 21, 22 and 23 respectively using DMFDMA.展开更多
This paper reports that high quality CuGeO3 single crystals were successfully grown by floating-zone technique and the magnetic property was studied. The temperature dependence of magnetic susceptibility below the spi...This paper reports that high quality CuGeO3 single crystals were successfully grown by floating-zone technique and the magnetic property was studied. The temperature dependence of magnetic susceptibility below the spin-Peierls （SP） transition temperature （Tsp） under magnetic fields applying along both the a- and c-axis direction can be fitted well by a model of noninteracting dimmers. The spin gap derived from the fitting is consistent with other reports. There is a very weak anisotropy in the fitting parameters for different directions, which should be expected from a SP system. A small upturn in susceptibility at low temperature due to paramagnetic impurities and/or defects can be observed. A suppression of the upturn by magnetic field is first discovered in this system and the possible origins for this suppression are discussed.展开更多
A novel vanadate decamer, involving all vanadium atoms present in +5 oxidation and one formhydroxamic acid dimer cation readical, has been synthesized. The single-crystal X-ray diffraction shows that the orange crysta...A novel vanadate decamer, involving all vanadium atoms present in +5 oxidation and one formhydroxamic acid dimer cation readical, has been synthesized. The single-crystal X-ray diffraction shows that the orange crystal is formed in the triclinic system, space group Pi, a = 8. 4960 (17), b = 10.447 (2), c = 11.299 (2) A, α= 68. 82 (3)°,β= 87.35 (3)°, γ = 66.97(3)°. V = 855. 3(3) A3, Z = 8, R1 = 0. 0857, wR2=0. 2551. X-ray crystallographic and packing in superlattice studies showed that the crystal structure was constructed by electrostatic attraction of O-H…O hydrogen bonds between formhydroxamic acid dimer cation and decavanadate polyanion. Formhydroxamic acid dimer is got through controlling the condition of the reaction using formhydroxamic acid.展开更多
A novel dimer of the bismuth(Ⅲ) complex with dithiotetrahydropyrrolocarbamate, [Bi(S_2CNC_4H_8)_2·(NO_3)]_2, was synthesized and the crystal structure was determined by X-ray single crystal diffraction. The crys...A novel dimer of the bismuth(Ⅲ) complex with dithiotetrahydropyrrolocarbamate, [Bi(S_2CNC_4H_8)_2·(NO_3)]_2, was synthesized and the crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to a monoclinic system with space group P2_1/n, a=0.64718(13) nm, b=2.6738(6) nm, c=1.0423(2) nm, β=106.384(3)°, Z=4, V=1.730(3) nm^3, D_c=2.163 g/cm^3, μ=10.682 mm^(-1), F(000)=1072, R=0.0329, wR=0.0659. The structure shows a distorted pentagonal bipyramidal configuration with the seven-coordinated central Bi atom. In the crystal, the molecular packing in the unit cell reveals that the two adjacent molecules are symmetrically linked each other in the dimer by virtue of a couple of Bi-S interaction.展开更多
Axially substituted tin phthalocyanines, namely dichloride-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 2, dihydroxy-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 3 and its dimmer di-μ-oxo-tetra-（α-pentyloxy...Axially substituted tin phthalocyanines, namely dichloride-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 2, dihydroxy-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 3 and its dimmer di-μ-oxo-tetra-（α-pentyloxy） tin（Ⅳ） phthalocyanine 4 were synthesized. The catalytic effect of H2O-free CaCl2 in quinoline was used for condensation of dihydroxy tin phthalocyanine 3 to the cofacially array dimmer 4. Their structures were characterized by UV-vis, IR, elemental analysis, MS, as well as ^1HNMR spectroscopy.展开更多
The performance of ion-exchange resin catalysts during isobutene (IB) dimerization was investigated under different IB contents,temperatures and liquid-volume hourly space velocity (LHSV) using a plug flow reactor in ...The performance of ion-exchange resin catalysts during isobutene (IB) dimerization was investigated under different IB contents,temperatures and liquid-volume hourly space velocity (LHSV) using a plug flow reactor in the absence of any selectivity enhancing component.High IB content and temperature resulted in a high conversion and C12 selectivity bu low C8 selectivity.The influence of LHSV was related with the IB content:LHSV had great effect at high IB content,while the performance of ion-exchange resin changed little with LHSV if IB content was low.The effect of water on the stability of resins was also studied.Desulfonation was observed during the C4 dimerization reaction when water was added to the feed.Chlorinated resin was more stable than conventional polystyrene-based resins during the test.展开更多
In the one-color experiment at 193nm, we studied the photodissociation of Si2+ ions prepared by two-photon ionization using the time-sliced ion velocity map imaging method. The Si+ imaging study shows that Si2+ dissoc...In the one-color experiment at 193nm, we studied the photodissociation of Si2+ ions prepared by two-photon ionization using the time-sliced ion velocity map imaging method. The Si+ imaging study shows that Si2+ dissociation results in two distinct channels: Si(3Pg)+Si+(2Pu) and Si(1D2)+Si+(2Pu). The main channel Si(3Pg)+Si+(2Pu)) is produced by the dissociation of the Si2+ ions in more than one energetically available excited electronic state, which are from the ionization of Si2(v=0-5). Particularly, the dissociation from the vibrationally excited Si2(v=1) shows the strongest signal. In contrast, the minor Si(1D2)+Si+(2Pu) channel is due to an avoided crossing between the two 22Πg states in the same symmetry. It has also been observed the one-photon dissociation of Si2+(X4Σg-) into Si(1D2)+Si+(2Pu) products with a large kinetic energy release.展开更多
The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF&#...The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.展开更多
Three optimized geometries of nitromethane dimer have been obtained at the HF/6–31G* level. Dimer binding energies have been corrected for the basis set superposition error (BSSE) and the zero point energy. Computed ...Three optimized geometries of nitromethane dimer have been obtained at the HF/6–31G* level. Dimer binding energies have been corrected for the basis set superposition error (BSSE) and the zero point energy. Computed results indicate that the cyclic structure of (CH3NO2)2 is the most stable of three optimized geometries, whose corrected binding energy is 17.29 kJ·mol?1 at the MP4SDTQ/6–31G*/HF/6–31G* level. In the optimized structures of nitromethane dimer, the inter-molecular hydrogen bond has not been found; and the charge-transfer interaction between CH3NO2 subsystems is weak; and the correlation interaction energy makes a little contribution to the intermolecular interaction energy of the dimer.展开更多
The first example of cyclodextrin dimer appending a macrocyclic polyamine spacer on the primary faces was synthesized via two approaches: 1, a direct reaction of 1,7-bis(2′-aminoethyl)-4,10-dimethyl-1,4,7,10-tetraaza...The first example of cyclodextrin dimer appending a macrocyclic polyamine spacer on the primary faces was synthesized via two approaches: 1, a direct reaction of 1,7-bis(2′-aminoethyl)-4,10-dimethyl-1,4,7,10-tetraazacyclododecane (1) with an excess of 6-deoxy-6-O-tosyl-β-cyclodextrin; 2, a condensation of 1 with two equivalents of 6-deoxy-6-formyl-β-cyclodextrin, which wan followed by a reduction with NaBH4.展开更多
Two imidazolium-bridged cyclodextrin dimers 3a and 3b were prepared by reacting 6-deoxy-6-N-imidazolyl-β-CD (2) with bis(bromomethyl) benzene. The catalytic properties of 2, 3a and 3b in the hydrolytic cleavage of p-...Two imidazolium-bridged cyclodextrin dimers 3a and 3b were prepared by reacting 6-deoxy-6-N-imidazolyl-β-CD (2) with bis(bromomethyl) benzene. The catalytic properties of 2, 3a and 3b in the hydrolytic cleavage of p-nitrophenyl alkanoates, in the form of acetate (PNPA), butanoate (PNPB), hexanoate (WH) and octanoate ( PNPO), were examined. CD dimers showed middling rate enhancements around neutrality. Catalytic rate constants ( kc) in the presence of 3a or 3b did not vary much with chain length of esters. In contrast, dissociation constants (Kd) and selectivity factors (kc/Kd) for “long-chain” esters were much smaller and significantly larger than those for “short-chain” ones respectively, indicating CD dimers 3a and 3b have good dimensional recognition ability and substrate selectivity in the hydrolytic cleavage of p-nitrophenyl alkanoate. Their kinetic consequences are briefly interpreted.展开更多
基金We are grateful for the financial support from the Postdoctoral Foundation of China.
文摘Polyethylene glycol (PEG) supported (diacetoxy)iodobenzene as soluble polymer reagent can smoothly oxidize acid hydrazides into corresponding dimmers in good yields under very mild conditions.
文摘The double bonds in the vegetable oils can be conjungated and Diels-Alder react when they are heated in the existence of the catalyst. The percent of the double bond will decrease and the oxidative stability of the vegetable oils can be ameliorated. Dimmer acid can react with different carbon chain length of alcohols to form dimmer acid esters. A series of dimmer acid esters were synthesized and their rheological characteristics （viscosity, viscosity index, pour point） and tribological characteristics （the coefficient of friction at different load, the characteristic of extreine pressure （ PB ）, the wear scare diameter （ D30min^196N ） were evaluated and analyzed. The results showed that the characteristics of Di-iso-octanol dimmer acid ester were the best among the synthesized dimmer esters. It＇ s a lubricant with good properties（the viscosity is 94.5 mm^2/s, the viscosity index is high up to 141 and the pour point is - 49℃ ）. It is a kind of newly interesthing ester type lubricant. Its rheological and tribological characteristics are even better than those of the slap-up synthesized lubricant--pentaerythritol esters （C7-9 acidate）. The FT-IR spectrophotometer was used to analyze the structure of the synthetic esters. Their IR spectra are the same as the typical IR spectrum of ester. The test indicated that Di-iso-octanol dimmer acid ester could be used as a kind of base lubricant with excellent quantity.
基金Supported by the NSF of Guangxi Province (No. 0339034), the Science Research Foundation of Guangxi Universities and Minister of Education Foundation of Guangxi (No. [2004]20)
文摘The title complex [Ni(TSSB)(phen)H2O]?C2H5OH?0.5H2O (C23H26N3NiO6.5S, TSSB = taurine salicylaldehyde Schiff base, phen = 1,10-phenanthroline) has been synthesized by the reaction of taurine salicylaldehyde Schiff base (TSSB), 1,10-phenanthroline and nickel acetate in water-ethanol. Its single-crystal structure was determined by X-ray diffraction method. The crystal belongs to triclinic, space group P1 with a = 1.0562(2), b = 1.1604(2), c = 2.1170(3) nm, α = 103.257(3), β = 96.958(4), γ = 105.179(3)°, Mr = 539.24, V = 2.3917(6) nm3, Z = 4, Dc = 1.498 g/cm3, μ = 0.945 mm-1 and F(000) = 1124. The compound is a one-dimensional network, infinitely extending with hydrogen bonds. The Ni(Ⅱ) is 6-coordinated by one nitrogen and two oxygen atoms from taurine salicylaldehyde Schiff base, two nitrogen from 1,10-phenanthroline and one oxygen from water to form a distorted octahedronal coordination geometry.
文摘Objective: To observe the effect of Xueshuantong injection (XST,血栓通注射液) with its ingredient as Notoginseng saponin, on acute cerebral infarction (ACI) and on blood coagulation and fibri-nolysis, so as to comprehensively analyse the mechanism of XST. Methods: Fifty ACI patients were randomly divided into 2 groups, and XST group (30 patients) was treated with XST, and the control group (20 patients) given low molecular dextrose, as well as low molecular heparin calcium. The course of treatment for both groups was 15 days. The changes of effective rate, score of neurologic impairment, tissue-type plasminogen activator (tPA), inhibitor of plasminogen activator (PAI), D-D dimmer, antithrombin-III (AT-III), and fibrinogen (Fbg) were all observed. Results: The total effective rate of XST group was 73.33%, that of the control group 65. 00%. After the therapy, plasma level of tPA, ratio of tPA/PAI, and AT-III content were increased obviously, while the plasma level of PAI and D-D dimmer were decreased significantly (all P<0.01) . But there was only insignificant difference between the 2 groups (P> 0.05).Conclusion: XST injection could be effective to ACI, the mechanism of which is probably related to improving the balance between plasminogen activator and its inhibitory factor, increasing the activity of fi-brinolysin, inactivating thrombin, inhibiting platelet aggregation induced by thrombin, and decreasing blood coagulation.
文摘Reaction of acetylacetone with 1 mole of dimethylformamide dimethyl acetal (DMFDMA) affords enamine 2a which reacts with cyanothioacetamide to give pyridinethione 3a. Pyridinethione 3a reacts with methyl iodide, halogenated compounds, aromatic aldehyde and malononitrile/elemental sulfur to yiled compounds 7-10 respectively. Reactions of thioether 7 in ethanolic K2CO3, 1 mole DMFDMA and 4-(dimethylamino)benzaldehyde give compounds 11, 13, 14 respectively. Enaminone 12 can be prepared by reaction of compound 11 with DMFDMA. We have demonstrated some reactions in order to show the potential usefulness of the prepared compounds for the preparation of new bipyridyl compounds 15, 16, 18, bicyclic compounds 17 and uncommon tricyclic compounds 20, 21, 22 and 23 respectively using DMFDMA.
基金supported by the National Natural Science Foundation of China (Grant No 10634030)the Zhejiang Province Natural Science Foundation of China (Grant No Y605106)
文摘This paper reports that high quality CuGeO3 single crystals were successfully grown by floating-zone technique and the magnetic property was studied. The temperature dependence of magnetic susceptibility below the spin-Peierls （SP） transition temperature （Tsp） under magnetic fields applying along both the a- and c-axis direction can be fitted well by a model of noninteracting dimmers. The spin gap derived from the fitting is consistent with other reports. There is a very weak anisotropy in the fitting parameters for different directions, which should be expected from a SP system. A small upturn in susceptibility at low temperature due to paramagnetic impurities and/or defects can be observed. A suppression of the upturn by magnetic field is first discovered in this system and the possible origins for this suppression are discussed.
文摘A novel vanadate decamer, involving all vanadium atoms present in +5 oxidation and one formhydroxamic acid dimer cation readical, has been synthesized. The single-crystal X-ray diffraction shows that the orange crystal is formed in the triclinic system, space group Pi, a = 8. 4960 (17), b = 10.447 (2), c = 11.299 (2) A, α= 68. 82 (3)°,β= 87.35 (3)°, γ = 66.97(3)°. V = 855. 3(3) A3, Z = 8, R1 = 0. 0857, wR2=0. 2551. X-ray crystallographic and packing in superlattice studies showed that the crystal structure was constructed by electrostatic attraction of O-H…O hydrogen bonds between formhydroxamic acid dimer cation and decavanadate polyanion. Formhydroxamic acid dimer is got through controlling the condition of the reaction using formhydroxamic acid.
基金Supported by the Natural Science Foundation of Shandong Province(No.L2 0 0 3B0 1) and the State Key L aboratory ofCrystal MaterialsShandong Universit
文摘A novel dimer of the bismuth(Ⅲ) complex with dithiotetrahydropyrrolocarbamate, [Bi(S_2CNC_4H_8)_2·(NO_3)]_2, was synthesized and the crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to a monoclinic system with space group P2_1/n, a=0.64718(13) nm, b=2.6738(6) nm, c=1.0423(2) nm, β=106.384(3)°, Z=4, V=1.730(3) nm^3, D_c=2.163 g/cm^3, μ=10.682 mm^(-1), F(000)=1072, R=0.0329, wR=0.0659. The structure shows a distorted pentagonal bipyramidal configuration with the seven-coordinated central Bi atom. In the crystal, the molecular packing in the unit cell reveals that the two adjacent molecules are symmetrically linked each other in the dimer by virtue of a couple of Bi-S interaction.
文摘Axially substituted tin phthalocyanines, namely dichloride-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 2, dihydroxy-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 3 and its dimmer di-μ-oxo-tetra-（α-pentyloxy） tin（Ⅳ） phthalocyanine 4 were synthesized. The catalytic effect of H2O-free CaCl2 in quinoline was used for condensation of dihydroxy tin phthalocyanine 3 to the cofacially array dimmer 4. Their structures were characterized by UV-vis, IR, elemental analysis, MS, as well as ^1HNMR spectroscopy.
基金supported financially by the Purolite Company and the Chinese National Natural Science Foundation (20674069)
文摘The performance of ion-exchange resin catalysts during isobutene (IB) dimerization was investigated under different IB contents,temperatures and liquid-volume hourly space velocity (LHSV) using a plug flow reactor in the absence of any selectivity enhancing component.High IB content and temperature resulted in a high conversion and C12 selectivity bu low C8 selectivity.The influence of LHSV was related with the IB content:LHSV had great effect at high IB content,while the performance of ion-exchange resin changed little with LHSV if IB content was low.The effect of water on the stability of resins was also studied.Desulfonation was observed during the C4 dimerization reaction when water was added to the feed.Chlorinated resin was more stable than conventional polystyrene-based resins during the test.
基金supported by the National Natural Science Foundation of China (No.21673047, No.21327901, and No.21322309)the Shanghai Key Laboratory Foundation of Molecular Catalysis and Innovative Materialsthe Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning
文摘In the one-color experiment at 193nm, we studied the photodissociation of Si2+ ions prepared by two-photon ionization using the time-sliced ion velocity map imaging method. The Si+ imaging study shows that Si2+ dissociation results in two distinct channels: Si(3Pg)+Si+(2Pu) and Si(1D2)+Si+(2Pu). The main channel Si(3Pg)+Si+(2Pu)) is produced by the dissociation of the Si2+ ions in more than one energetically available excited electronic state, which are from the ionization of Si2(v=0-5). Particularly, the dissociation from the vibrationally excited Si2(v=1) shows the strongest signal. In contrast, the minor Si(1D2)+Si+(2Pu) channel is due to an avoided crossing between the two 22Πg states in the same symmetry. It has also been observed the one-photon dissociation of Si2+(X4Σg-) into Si(1D2)+Si+(2Pu) products with a large kinetic energy release.
基金Supported by the National Natural Science Foundation of China (Grant No. 20773046)
文摘The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.
基金Project supported by the Foundation of China Academy of Engineering Physics (No. 99050330, 20000552)
文摘Three optimized geometries of nitromethane dimer have been obtained at the HF/6–31G* level. Dimer binding energies have been corrected for the basis set superposition error (BSSE) and the zero point energy. Computed results indicate that the cyclic structure of (CH3NO2)2 is the most stable of three optimized geometries, whose corrected binding energy is 17.29 kJ·mol?1 at the MP4SDTQ/6–31G*/HF/6–31G* level. In the optimized structures of nitromethane dimer, the inter-molecular hydrogen bond has not been found; and the charge-transfer interaction between CH3NO2 subsystems is weak; and the correlation interaction energy makes a little contribution to the intermolecular interaction energy of the dimer.
基金Project (29502010) supported by the National Natural Science Foundation of China
文摘The first example of cyclodextrin dimer appending a macrocyclic polyamine spacer on the primary faces was synthesized via two approaches: 1, a direct reaction of 1,7-bis(2′-aminoethyl)-4,10-dimethyl-1,4,7,10-tetraazacyclododecane (1) with an excess of 6-deoxy-6-O-tosyl-β-cyclodextrin; 2, a condensation of 1 with two equivalents of 6-deoxy-6-formyl-β-cyclodextrin, which wan followed by a reduction with NaBH4.
基金Project supported by the National Natural Science Foundation of China (No. 29632004 and 29772023)the State Education Commission (No. 380)the Research Program of Sichuan University.
文摘Two imidazolium-bridged cyclodextrin dimers 3a and 3b were prepared by reacting 6-deoxy-6-N-imidazolyl-β-CD (2) with bis(bromomethyl) benzene. The catalytic properties of 2, 3a and 3b in the hydrolytic cleavage of p-nitrophenyl alkanoates, in the form of acetate (PNPA), butanoate (PNPB), hexanoate (WH) and octanoate ( PNPO), were examined. CD dimers showed middling rate enhancements around neutrality. Catalytic rate constants ( kc) in the presence of 3a or 3b did not vary much with chain length of esters. In contrast, dissociation constants (Kd) and selectivity factors (kc/Kd) for “long-chain” esters were much smaller and significantly larger than those for “short-chain” ones respectively, indicating CD dimers 3a and 3b have good dimensional recognition ability and substrate selectivity in the hydrolytic cleavage of p-nitrophenyl alkanoate. Their kinetic consequences are briefly interpreted.
