The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A s...The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight（TOF） mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg^＋ （CH3OH）n（ n = 0-5） and weak H^＋ （CH3OH）n（ n = 0-5 ） cluster ions were observed with relatively small cluster sizes ; in the middle part of the molecular beam, the main cluster ions were H^＋ （ CH3OH）n （ n = 6-17 ） and H^＋（ H2O） 2 （ CH3OH）n（ n = 6-17 ） with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO^＋ （ H2O） （ CH3 OH）n（ n = 6-10 ） and MgOCH3^＋ （ CH3OH）n（ n = 6-10）, were obtained and accompanied by weak H^＋（CH3OH）n（n = 4-7） and H^＋（ H2O）2 （CH3OH）n（ n = 3-6）. The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.展开更多
The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herei...The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herein,we report a novel Cd/TiO_(2) catalyst exhibiting a methanol selectivity of 81%,a CO_(2) conversion of 15.8%,and a CH_(4) selectivity below 0.7%.A combination of experimental and computational studies revealed that the unique electronic properties exhibited by the Cd clusters supported by the TiO_(2) matrix were responsible for the high selectivity of CO_(2) hydrogenation to methanol via the HCOO*pathway at the interfacial catalytic sites.展开更多
A discrete centrosymmetric （H2O）20（CH3OH）4 binary cluster was confined in the cavity of a metaMigand hybrid [Ag4（bpda）2（bpp）4＂ 14H2O.2CH3OH], （1） （where bpp = 1,3-bis（4-pyridyl）propane and H2bpda = 2,2＇...A discrete centrosymmetric （H2O）20（CH3OH）4 binary cluster was confined in the cavity of a metaMigand hybrid [Ag4（bpda）2（bpp）4＂ 14H2O.2CH3OH], （1） （where bpp = 1,3-bis（4-pyridyl）propane and H2bpda = 2,2＇-biphenyldicarboxylic acid） The novel mixed water-methanol cluster consists of one grail-shaped hexadecameric cluster, four dangling water and four hanging methanol molecules. The （H2O）16 cluster is composed of two pairs of edge-sharing （H2O）5 rings attached to one （H2O）4 core with twenty hydrogen bonds. Alternatively, the （H2O）16 cluster is structurally similar to a complicated hydrocarbon generated by undergoing [2＋2] cycloaddition of 1,2,3,4,5,6-hexahydropentalene, which reveals the resemblance between water clusters and organic compounds.展开更多
Density functional theory （DFT） calculations are reported for the structures of neutral and zwitterionic glycine-（CHaOH）n where n=1-6. Initial geometries of the clusters of neutral and zwitterionic glycine with 1-...Density functional theory （DFT） calculations are reported for the structures of neutral and zwitterionic glycine-（CHaOH）n where n=1-6. Initial geometries of the clusters of neutral and zwitterionic glycine with 1-6 methanol molecules are fully optimized at B3LYP/6-31＋G^＊ level of theory. The lowest energy configurations are located and their hydrogen bond structures are analyzed. Theoretical prediction reveals that the methanols prefer to locate near the carboxylic acid group for the small clusters （n_〈3） with the neutral form while the configurations with the methanols bridging the acid and the amino group are favorite in the zwitterionic form clusters. When the number of the methanol molecules in the clusters reaches five and six, the two forms tend to be isoenergetic.展开更多
A new tetranuclear cluster [Co4（bm）6C12]＇（H20）2-（CH3OH） （1, Hbm is （1H-benzi- midazol-2-yl）-methanol） has been synthesized by solvothermal method and structurally determined by IR, elemental analysis, and s...A new tetranuclear cluster [Co4（bm）6C12]＇（H20）2-（CH3OH） （1, Hbm is （1H-benzi- midazol-2-yl）-methanol） has been synthesized by solvothermal method and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. Complex 1 belongs to monoclinie space group P21/n with a = 21.1713（5）, b = 12.7948（3）, c = 24.0195（9） А, β = 95.309（3）°, V = 6478.6（3） A3, Z = 4, F（000） = 2568, Dc = 1.289 g.cm-3, Mr = 1257.63,μ= 9.096 mm-I, S = 1.000, the final R = 0.0861 and wR = 0.2552 for 4956 observed reflections with 1 〉 20（/）. Two connected face-sharing cubes are observed in the framework of 1, each with one vertex missing. Complex 1 forms a 2-D network through N-H...O hydrogen bonds. The apparent holes can be observed.展开更多
基金Supported by the Doctoral Startup Foundation from Qufu Normal University.
文摘The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight（TOF） mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg^＋ （CH3OH）n（ n = 0-5） and weak H^＋ （CH3OH）n（ n = 0-5 ） cluster ions were observed with relatively small cluster sizes ; in the middle part of the molecular beam, the main cluster ions were H^＋ （ CH3OH）n （ n = 6-17 ） and H^＋（ H2O） 2 （ CH3OH）n（ n = 6-17 ） with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO^＋ （ H2O） （ CH3 OH）n（ n = 6-10 ） and MgOCH3^＋ （ CH3OH）n（ n = 6-10）, were obtained and accompanied by weak H^＋（CH3OH）n（n = 4-7） and H^＋（ H2O）2 （CH3OH）n（ n = 3-6）. The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.
文摘The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herein,we report a novel Cd/TiO_(2) catalyst exhibiting a methanol selectivity of 81%,a CO_(2) conversion of 15.8%,and a CH_(4) selectivity below 0.7%.A combination of experimental and computational studies revealed that the unique electronic properties exhibited by the Cd clusters supported by the TiO_(2) matrix were responsible for the high selectivity of CO_(2) hydrogenation to methanol via the HCOO*pathway at the interfacial catalytic sites.
基金supported by the National Natural Science Foundation of China(50971063,21053001)the Natural Science Foundation of Fujian Province(2011J01047,2010J01042)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Education of Ministrythe Startup Package Funding of Huaqiao University (10BS210)
文摘A discrete centrosymmetric （H2O）20（CH3OH）4 binary cluster was confined in the cavity of a metaMigand hybrid [Ag4（bpda）2（bpp）4＂ 14H2O.2CH3OH], （1） （where bpp = 1,3-bis（4-pyridyl）propane and H2bpda = 2,2＇-biphenyldicarboxylic acid） The novel mixed water-methanol cluster consists of one grail-shaped hexadecameric cluster, four dangling water and four hanging methanol molecules. The （H2O）16 cluster is composed of two pairs of edge-sharing （H2O）5 rings attached to one （H2O）4 core with twenty hydrogen bonds. Alternatively, the （H2O）16 cluster is structurally similar to a complicated hydrocarbon generated by undergoing [2＋2] cycloaddition of 1,2,3,4,5,6-hexahydropentalene, which reveals the resemblance between water clusters and organic compounds.
基金VI. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （（No.20973067） and Guangdong-Natural Science Foundation （No.7005823）, the Scientific Research Foundation for the Returned Overseas Chinese scholars, the State Education Ministry and the Foundation for Introduction of Talents by the Universities in Guangdong Province. Initial computation contributed by Mr. Xiting Zhang is gratefully acknowledged.
文摘Density functional theory （DFT） calculations are reported for the structures of neutral and zwitterionic glycine-（CHaOH）n where n=1-6. Initial geometries of the clusters of neutral and zwitterionic glycine with 1-6 methanol molecules are fully optimized at B3LYP/6-31＋G^＊ level of theory. The lowest energy configurations are located and their hydrogen bond structures are analyzed. Theoretical prediction reveals that the methanols prefer to locate near the carboxylic acid group for the small clusters （n_〈3） with the neutral form while the configurations with the methanols bridging the acid and the amino group are favorite in the zwitterionic form clusters. When the number of the methanol molecules in the clusters reaches five and six, the two forms tend to be isoenergetic.
基金financially supported by the National Natural Science Foundation of China(No.21161006)Program for Excellent Talents in Guangxi Higher Education Institutions(Gui Jiao Ren[2012]41)Program of the first session backbone teacher of Guangxi of China
文摘A new tetranuclear cluster [Co4（bm）6C12]＇（H20）2-（CH3OH） （1, Hbm is （1H-benzi- midazol-2-yl）-methanol） has been synthesized by solvothermal method and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. Complex 1 belongs to monoclinie space group P21/n with a = 21.1713（5）, b = 12.7948（3）, c = 24.0195（9） А, β = 95.309（3）°, V = 6478.6（3） A3, Z = 4, F（000） = 2568, Dc = 1.289 g.cm-3, Mr = 1257.63,μ= 9.096 mm-I, S = 1.000, the final R = 0.0861 and wR = 0.2552 for 4956 observed reflections with 1 〉 20（/）. Two connected face-sharing cubes are observed in the framework of 1, each with one vertex missing. Complex 1 forms a 2-D network through N-H...O hydrogen bonds. The apparent holes can be observed.
