Inclusion of cresols by β cyclodextrin in DHO has been investigated by 1H NMR spectra. Although chemical shifts of the same proton are different in the cavity of empty and enclosed β cyclodextrin, only a time averag...Inclusion of cresols by β cyclodextrin in DHO has been investigated by 1H NMR spectra. Although chemical shifts of the same proton are different in the cavity of empty and enclosed β cyclodextrin, only a time average peak has been detected for a proton in the spectra. The value of chemical shift corresponds to enclosed degree of cresol by β cyclodextrin. The average structure of inclusion has been determined based on 1H NMR data, it describes dynamic depth of cresol in the cavity of β cyclodextrin.展开更多
A zinc complex, [Zn(iso)_2(H_2O)_4](iso=C_6H_4NO_2^-), was synthesized and characterized by elemental analysis, thermal analysis and IR spectrum studies. The crystal structure of the complex was determined by X-ray di...A zinc complex, [Zn(iso)_2(H_2O)_4](iso=C_6H_4NO_2^-), was synthesized and characterized by elemental analysis, thermal analysis and IR spectrum studies. The crystal structure of the complex was determined by X-ray diffraction. The crystal crystallizes in the triclinic system, molecular formula ZnC12H16N2O8, Mr=381.64, space group P with a = 6.338(1), b =6.919(1), c=9.277(1), α=96.28(1), β=104.91(1), γ=112.85(1)°, V=352.12(9)?3, Z=1, Dc=1.80g?cm-3 and F(000)=196, μ =1.791mm-1. The crystal structure was solved by direct methods for final R=0.0204 and Rw=0.0542 for 1258 observed reflections with [Fo>4σ(Fo)]. The crystal structure reveals that zinc ion is trans-octahedral with two pyridyl nitrogens and two aque oxygens at the equational positions and two aqua oxygens at the axial positions. The complex forms a three-dimensional network through intermolecular hydrogen bonds.展开更多
K_2NiF_4 type compounds Sm_(2-x)Sr_x CuO_4 (0 ≤ x ≤ 1.2) were prepared.Rietveld refinement of powder diffraction data shows that the crystal system of these compoundsbelongs to T' type tetragonal structure of sp...K_2NiF_4 type compounds Sm_(2-x)Sr_x CuO_4 (0 ≤ x ≤ 1.2) were prepared.Rietveld refinement of powder diffraction data shows that the crystal system of these compoundsbelongs to T' type tetragonal structure of space group I4/mmm , and the addition of Sr causes adramatic shift of the O(Ⅰ) ions along the c axis from Sm (Sr) toward Cu while scarcely affectingthe Cu―O (Ⅱ) bond in basal CuO_4 plane. From XRD data, it can be seen that when 0.0 ≤ x ≤ 0.6,Sm_(2-x)Sr_xCuO_4 belongs to a single-phase K_2NiF_4 type structure, while at x ≥ 0.7, both thefree SrO phase and the CuO phase exist in these compounds. From the results of XPS and Rietveldrefinement, it can be seen that after replacing Sm^(3+) with Sr^(2+) of lower valence, the valenceof Cu and Sm does not change apparently, and thus some defect must be formed at the oxygen ionpositions and/or position A on A_2BO_4 to keep charge balance and to stabilize the structure.展开更多
文摘Inclusion of cresols by β cyclodextrin in DHO has been investigated by 1H NMR spectra. Although chemical shifts of the same proton are different in the cavity of empty and enclosed β cyclodextrin, only a time average peak has been detected for a proton in the spectra. The value of chemical shift corresponds to enclosed degree of cresol by β cyclodextrin. The average structure of inclusion has been determined based on 1H NMR data, it describes dynamic depth of cresol in the cavity of β cyclodextrin.
文摘A zinc complex, [Zn(iso)_2(H_2O)_4](iso=C_6H_4NO_2^-), was synthesized and characterized by elemental analysis, thermal analysis and IR spectrum studies. The crystal structure of the complex was determined by X-ray diffraction. The crystal crystallizes in the triclinic system, molecular formula ZnC12H16N2O8, Mr=381.64, space group P with a = 6.338(1), b =6.919(1), c=9.277(1), α=96.28(1), β=104.91(1), γ=112.85(1)°, V=352.12(9)?3, Z=1, Dc=1.80g?cm-3 and F(000)=196, μ =1.791mm-1. The crystal structure was solved by direct methods for final R=0.0204 and Rw=0.0542 for 1258 observed reflections with [Fo>4σ(Fo)]. The crystal structure reveals that zinc ion is trans-octahedral with two pyridyl nitrogens and two aque oxygens at the equational positions and two aqua oxygens at the axial positions. The complex forms a three-dimensional network through intermolecular hydrogen bonds.
基金theNaturalScienceFoundationofZhejiangProvince (No .2 92 0 33)
文摘K_2NiF_4 type compounds Sm_(2-x)Sr_x CuO_4 (0 ≤ x ≤ 1.2) were prepared.Rietveld refinement of powder diffraction data shows that the crystal system of these compoundsbelongs to T' type tetragonal structure of space group I4/mmm , and the addition of Sr causes adramatic shift of the O(Ⅰ) ions along the c axis from Sm (Sr) toward Cu while scarcely affectingthe Cu―O (Ⅱ) bond in basal CuO_4 plane. From XRD data, it can be seen that when 0.0 ≤ x ≤ 0.6,Sm_(2-x)Sr_xCuO_4 belongs to a single-phase K_2NiF_4 type structure, while at x ≥ 0.7, both thefree SrO phase and the CuO phase exist in these compounds. From the results of XPS and Rietveldrefinement, it can be seen that after replacing Sm^(3+) with Sr^(2+) of lower valence, the valenceof Cu and Sm does not change apparently, and thus some defect must be formed at the oxygen ionpositions and/or position A on A_2BO_4 to keep charge balance and to stabilize the structure.
