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921.
Wei-Jia Wang Yan Wang Qian Xu Huan-Xin Ju Tao Wang Zhi-Jie Tao Shan-Wei Hu Jun-Fa Zhu 《中国化学快报》2017,28(8):1760-1766
The interaction of Co with ceria thin films and its influence on the sintering behavior of Au were investigated by scanning tunneling microscopy(STM), synchrotron radiation photoemission spectroscopy(SRPES) and X-ray photoelectron spectroscopy(XPS). The strong interaction between Co and CeO_2(111) leads to oxidation of Co to Co~(2+) at 300 K, accompanied by partial reduction of ceria surface at low Co coverages. Subsequent Co deposition results in an increasing fraction of metallic Co. Annealing to high temperatures induces Co~(2+)ions diffuse into the CeO_2 film, while the small metallic Co islands agglomerate into larger ones. The bimetallic Co–Au particles were prepared by deposition of Au on the existing Co particles on ceria surfaces. The sintering behavior of Co–Au bimetallic surfaces is found to be highly determined by the stoichiometry of ceria supports. The addition of Co to the Au/CeO_2 surface suppresses the sintering of Au particles at high temperatures in comparison with that of pure Au particles. However, Au particles are less stable on the Co/CeO_(1.82) layer than on CeO_(1.82) surface. 相似文献
922.
Vladimir A. Dyakonov Gulnara N. Kadikova Ramil N. Nasretdinov Usein M. Dzhemilev 《Tetrahedron letters》2017,58(19):1839-1841
The cycloaddition reaction between conjugated diynes and 1,3,5-cyclooctatriene in the presence of the catalyst Co(acac)2/dppe/Zn/ZnI2, led to the selective formation of tricyclo[4.2.2.02,5]deca-7,9-diene derivatives in 72–85% yield. 相似文献
923.
Yizheng Geng Junyu Chen Haiwei Zhao Hongjian Sun Benjing Xue Xiaoyan Li Olaf Fuhr Dieter Fenske 《无机化学与普通化学杂志》2017,643(11):712-716
Three η4‐(C=C–C=O) coordination cobalt(I) complexes 1 – 3 were synthesized by the reactions of cinnamaldehyde, p‐fluorocinnamaldehyde, and p‐chlorocinnamaldehyde with CoMe(PMe3)4. Complex 4 as η2‐(C=C) coordination was prepared by the reaction of chalcone with Co(PMe3)4. The structures of complexes 1 – 4 were confirmed by single‐crystal X‐ray diffraction. Although the reactions didn't undergo C–H bond activation and decarbonylation, the formation of complexes 1 – 4 deepens our understanding of the reactions between α,β‐unsaturated aldehyde or ketone with low‐valent central cobalt atom. 相似文献
924.
Synthesis,Crystal Structure,and Catalytic Properties of Porous 3d‐4f Heterometallic Coordination Polymers Constructed from Pyrazine‐2,3‐dicarboxylic Acid
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Reactions of pyrazine‐2,3‐dicarboxylic acid (H2pzdc), cobalt nitrate and lanthanide (Ln) oxide under hydrothermal conditions result in four new 3d‐4f heterometal coordination polymers, namely, [Ln2Co(pzdc)4(H2O)6] · 2H2O [Ln = La ( 1 ), Pr ( 2 ), Eu ( 3 ) and Gd ( 4 )]. All compounds were characterized by elemental analysis, infrared spectroscopy, thermal gravimetric analysis, and X‐ray diffraction. The compounds exhibit a three‐dimensional (3D) brick‐like structure with rectangular‐shaped nano‐scale channels along a axis direction, made up of wave‐like layers containing [Ln(pzdc)]+ units, which are connected by one‐dimensional (1D) chain of [Co(pzdc)2]2–. The catalytic properties of compounds 1 and 3 were investigated in the synthesis of cyanohydrins at room temperature under solventless conditions. They showed similar catalytic activities with very high conversions of benzaldehyde and high selectivity towards cyanohydrin. The control experiment without addition of the coordination polymers only reached 16 % conversion. Other aldehydes could also be converted totally under shorter reaction times also with very high selectivities for the corresponding cyanohydrins. Compound 1 could also be recycled in another catalytic cycle. 相似文献
925.
Synthesis,Structure, and Magnetic Properties of a Random Bimetallic One‐dimensional CoII‐MnII Coordination Polymer with Mixed Azide‐carboxylate Bridges
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The 3d–3d random bimetallic compound [Co2.28Mn0.72(N3)6(mpc‐3)2(CH3OH)2] ( 1 ) (mpc‐3 = N‐methylpyridinium‐3‐carboxylate) was synthesized by partly substituting the CoII ions in the homometallic compound by MnII. Complex 1 was structurally and magnetically characterized. It consists of one‐dimensional chains with the neighboring metal ions being linked alternatively by [(μ‐EO‐N3)2(μ‐COO)] (EO = end‐on) triple bridges and double EO azide bridges. Hydrogen‐bonding interactions and π–π interactions are involved in the formation of a three‐dimensional supramolecular network. Magnetic measurements revealed that complex 1 exhibits slow relaxation, which is similar to the homometallic CoII parent compound whereas the TB is lower than that of the CoII analog. 相似文献
926.
927.
Metal‐ and Substituent‐Dependent Structural Diversity in Cobalt and Nickel Isophthalate Coordination Polymers with Bis(4‐pyridylformyl)piperazine Tethers
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Hydrothermal reactions of nickel or cobalt nitrate with the dipyridylamide ligand bis(4‐pyridylformyl)piperazine (4‐bpfp) and either 5‐methoxyisophthalate (H2omeip) or 5‐methylisophthalate (H2mip) afforded a series of coordination polymers that were structurally characterized by single‐crystal X‐ray diffraction. Different synthetic conditions afforded the 1D chain phase {[Ni(Homeip)2(H2omeip)(bpfp)] · 2H2O}n ( 1 ) or the mutually inclined interpenetrated (4, 4) grid system in {[Ni(omeip)(bpfp)(H2O)] · 2H2O}n ( 2 ). The analogous cobalt phase {[Co(omeip)(bpfp)] · 3H2O}n ( 3 ) lacks bound water molecules, which enforces a non‐interpenetrated (4, 4) grid structure based on {Co2(OCO)2} dinuclear clusters. Similar clusters are seen in {[Co(mip)(bpfp)(H2O)2] · 3.5H2O}n ( 4 ), which manifests a 1D ribbon structural motif. Its nickel congener {[Ni(Hmip)2(bpfp)(H2O)2] · 2H2mip}n ( 5 ) also shows a 1D chain motif. A variable temperature magnetic susceptibility study indicates antiferromagnetic coupling within the dimeric units in 3 and 4 concomitant with single ion effects. Additionally, thermal degradation properties of these new materials are described. 相似文献
928.
Syntheses,Crystal Structures,and Magnetic Properties of Two Cobalt Coordination Polymers Constructed From 1,3‐Bis(2,4‐dicarboxyphenyl) Benzene and Bis(imidazole) Linkers
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Abstract. The 3D cobalt(II) coordination polymers [Co1.5(HDDB)(1,4‐bib)1.5(H2O)]n ( 1 ), and {[Co2(DDB)(1,3‐bib)2(μ2‐H2O)] · H2O}n ( 2 ) were assembled by mixed‐ligand synthetic strategy [H4DDB = 1,3‐bis(2,4‐dicarboxyphenyl) benzene, 1,3‐bib = 1,3‐bis(1H‐imidazol‐4‐yl)benzene, and 1,4‐bib = 1,4‐bis(1H‐imidazol‐4‐yl)benzene]. Their structures were determined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses (EA), IR spectroscopy, powder X‐ray diffraction (PXRD), and thermogravimetric (TG) analyses. Single X‐ray diffraction analysis reveals that complex 1 is an interestingly 3D (3,3.6)‐connected (63)4(65 · 88 · 102) net, and complex 2 is an unprecedented dinuclear [Co2(COO)(μ2‐H2O)] SBUs based 3D (3,6)‐connected (3 · 6 · 7)(32 · 43 · 54 · 63 · 7 · 82) net. Additionally, the magnetic properties of 2 were investigated. 相似文献
929.
930.
In this paper, a composite of reduced graphene oxide decorated by Co3O4 hollow spheres (Co3O4/RGO composite) has been synthesized by a one-pot solvothermal method. The samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR), Raman spectra and so on. The results demonstrate that the Co3O4 hollow spheres with good purity and homogenous size are absorbed onto the reduced graphene oxide sheets as spacers to prevent the aggregation of the graphene oxide sheets. Furthermore, the well electrochemical properties demonstrate that the Co3O4/RGO composite might have potential applications as electrode materials for supercapacitors. 相似文献