Various optical luminescence spectroscopic techniques were used to characterize the high T_c superconductor YBa_2Cu_3O_x.The emission bands reveal that Cu^(3+) coexist with Cu^(2+) and Cu^+ in this material.
Two distinct copper coordination polymers, namely [Cu^Ⅱ2（2,5-pydc）2（bpp）2]·H2O（1） and Cu2^ⅠCu^Ⅱ（2,5-pydc）2（bpp）2（2）（2,5-pydc = pyridine-2,5-dicarboxylic acid, bpp = 1,3-bi（4-pyridyl）propane）, h...Two distinct copper coordination polymers, namely [Cu^Ⅱ2（2,5-pydc）2（bpp）2]·H2O（1） and Cu2^ⅠCu^Ⅱ（2,5-pydc）2（bpp）2（2）（2,5-pydc = pyridine-2,5-dicarboxylic acid, bpp = 1,3-bi（4-pyridyl）propane）, have been successfully synthesized through hydrothermal conditions under different temperatures. Single-crystal X-ray structural analysis revealed that both complexes 1 and 2 are 3D frameworks. Complex 1 is an 8-connected 2-fold interpenetrating network based on [Cu（2,5-pydc）]4 molecular building block（MBB）, and also can be simplified as a 4-connected net if the Cu（Ⅱ） ion is regarded as an independent node, whereas 2 shows a（4,4）-connected non-interpenetrated framework which contains mixed valence Cu（Ⅰ/Ⅱ） centers. The results demonstrate that temperature plays a significant role in the final structures of the complexes.展开更多
Cu/SiO2 catalysts prepared by different methods have been investigated focusing on the influence of Cu^＋on the catalytic performance.The composition,structure and copper valence state were characterized by means of B...Cu/SiO2 catalysts prepared by different methods have been investigated focusing on the influence of Cu^＋on the catalytic performance.The composition,structure and copper valence state were characterized by means of BET,XRD,XPS,FTIR,N2O-titration.It was found that the Cu/SiO2 prepared by ammoniaevaporation（AE） method had much higher TOF value than that prepared by wetness-impregnation（WI）with the same THF selectivity.The higher TOF value was attributed to the coexistence of Cu^＋ and Cu^0species in the activated AE-Cu/SiO2.while only Cu° species existing in the activated Wl-Cu/SiO2.Researches suggest that Cu^＋ can adsorb and polarize the C=0 bond of DMM.It is concluded that Cu°could be the main active site and the synergistic effect between Cu^0 and Cu^＋ could contribute to hydrogenation of DMM to THF.展开更多
文摘Various optical luminescence spectroscopic techniques were used to characterize the high T_c superconductor YBa_2Cu_3O_x.The emission bands reveal that Cu^(3+) coexist with Cu^(2+) and Cu^+ in this material.
基金supported by the application basis research key project of Yunnan Province science and technology department(201401CB00299)the major project of Qujing Normal University(2012ZD002)
文摘Two distinct copper coordination polymers, namely [Cu^Ⅱ2（2,5-pydc）2（bpp）2]·H2O（1） and Cu2^ⅠCu^Ⅱ（2,5-pydc）2（bpp）2（2）（2,5-pydc = pyridine-2,5-dicarboxylic acid, bpp = 1,3-bi（4-pyridyl）propane）, have been successfully synthesized through hydrothermal conditions under different temperatures. Single-crystal X-ray structural analysis revealed that both complexes 1 and 2 are 3D frameworks. Complex 1 is an 8-connected 2-fold interpenetrating network based on [Cu（2,5-pydc）]4 molecular building block（MBB）, and also can be simplified as a 4-connected net if the Cu（Ⅱ） ion is regarded as an independent node, whereas 2 shows a（4,4）-connected non-interpenetrated framework which contains mixed valence Cu（Ⅰ/Ⅱ） centers. The results demonstrate that temperature plays a significant role in the final structures of the complexes.
基金Funding for the present study from the National Key Basic Research Program of China(973 Program,No.2011CB710800)National Natural Science Foundation of China(No.NSFC21406199)
文摘Cu/SiO2 catalysts prepared by different methods have been investigated focusing on the influence of Cu^＋on the catalytic performance.The composition,structure and copper valence state were characterized by means of BET,XRD,XPS,FTIR,N2O-titration.It was found that the Cu/SiO2 prepared by ammoniaevaporation（AE） method had much higher TOF value than that prepared by wetness-impregnation（WI）with the same THF selectivity.The higher TOF value was attributed to the coexistence of Cu^＋ and Cu^0species in the activated AE-Cu/SiO2.while only Cu° species existing in the activated Wl-Cu/SiO2.Researches suggest that Cu^＋ can adsorb and polarize the C=0 bond of DMM.It is concluded that Cu°could be the main active site and the synergistic effect between Cu^0 and Cu^＋ could contribute to hydrogenation of DMM to THF.
