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1.
Abstract

Potentiometric and spectrophotometric studies of Ni(II) coordination to β-alaninehydroxamix acid (β-Alaha) have shown 4N coordination of β-Alaha for 1:2 species and their planar geometry. The geometry of the species formed in the nickel(II)-β-Alaha below ca. pH 7 is octahedral. The differences between the stabilities of zinc(II)-β-Alaha and zinc(II)-α-alaninehydroxamic acid complexes can be explained by the terdentate coordination of the β-alaninehydroxamic acid.  相似文献   

2.
Three new diterpenoids,named esquirolin B(1),C(2),D(3)respectively,and two known cemocundseariocal(4)and taraxerol were isolated from Coleus esquirolii(Levl).The structure elucidation was achieved byspectroscopic means  相似文献   

3.
A new rhodium(Ⅱ)porphyrin complex was isolated by chromatography from the photochemical reac-tion of(μ—tetraphenylporphyrinato)bis[dicarbonylrhodium(Ⅰ)]with pyridine in benzene and has been charac-terized.From the results,the reaction mechanism is proposed.  相似文献   

4.
Abstract

The coordination mode of complexes formed in the systems Cu(II)/NMP/PA; (NMP =adenosine 5′-monophosphate, cytidine 5′-monophosphate; PA = 1,4-diaminopropane (putrescine, Put), 1,7-diamino-4-azaheptane (3,3-tri) and 1,11-diamino-4,8-diazaundekane (3,3,3-tet)) was determined on the basis of the equilibrium and spectroscopic studies. The presence of the following mixed complexes was established: Cu(CMP)H(Put), Cu(AMP)H2(3,3-tri) and Cu(CMP)H2(3,3-tri), Cu(CMP)H4(3,3-tri) and coordination compounds of MLL′ type-Cu(CMP)(3,3,3-tet), Cu(AMP)(3,3,3-tet). A significant influence of the polyamine length on the solution structure of the complexes was observed. In mixed-ligand complexes Cu(NMP)(3,3,3-tet) a {N4, O} chromophore is formed, and metallation involves all nitrogen atoms from 3,3,3-tet. In the analogous system with 3,3-tri, protonated complexes occur. Non-covalent intramolecular interaction between the protonated amine groups and donor atoms from the purine ring from the nucleotide results in an increase of complex stability.  相似文献   

5.
We report here a first series of ~(10)Be measurements on loess samples covering the last 750,000 years. The close correlation of the ~(10)Be data with δ~(18)O variations from deep sea cores allows for establishing a preliminary time scale. Based on this time scale accumulation rates and ~(10)Be fluxes can be calculated. The accumulation-evolution of loess is also discussed in terms of a simple qualitative model of ~(10)Be.  相似文献   

6.
Abstract

Complexes having the compositions [LMCl2], [L2MCl2], [L2Cu][PF6], [L′MCl2] and [L′(MCl2)2] of 4,5-diazafluorene, L, and 9,9′-bis(4,5-diazafluorenyl), L′, have been prepared from MCl2 (M = Ni, Cu, Zn) and characterised. Steric strain or the bite angle of the pro-ligand has no recognisable effect on its coordination chemistry with smaller 3d-metals.  相似文献   

7.
Average aggregate number of coaggregates(N_co)of CE-n or BL-n and the fluoresc-ence probe(Np-16)have been determined by using time-resolved fluorescence spectroscopy.Chain-length,hydroxy-group and chain-foldability effects on the N_co have been discussed.  相似文献   

8.
The impact of axiasymmetric structure of tropical cyclone, beta effect and the environmentalflow field on tropical cyclone motion have been investigated in terms of theoretical analysisand numerical modelling. The sudden change of tropical cyclone (TC) motion has also beenstudied. The analysis and modelling results indicate that the impact of axiasymmetric struc-ture of TC on its motion cannot be underestimated in the certain stage of TC development.Under the specified conditions, it may lead to snakelike or loop motion of TC. The movingdirection and speed of TC will change suddenly when the interaction of environmental flowfield, beta effect and axiasymmetric wind and pressure fields reach a critical state.  相似文献   

9.
THESTUDYOFTHESYNTHESESOFTHEDERIVATIVESOFPOLYPHENYLENEANDTHEIRCONDUCTIVITY¥YinKuiLl;QingZiLIU;SanHUANG;TieFengWEN;ShangYouZHOU...  相似文献   

10.
The crystal-growing conditions and the results of preliminary X-ray crystallographic analysis of (L-Try)~(A1)-insulin and (D-Try)~(A1)-insulin are reported. The single crystals of this pair of insulin analogue suitable for X-ray diffraction analysis have been grown in the citrate buffer system by still-setting method. They both belong to the trigonal system with space group R3. The parameters of the unit cell (L-Trp)~(A1)-insulin are αH= 80.31, cH= 37.45 and those of (D-Trp)~(A1)-insulin αH = 79.48, cH = 43.81. There are two molecules in an asymmetric unit. The obtained results are discussed.  相似文献   

11.
Six coordination compounds of Pt(Ⅱ)L_2 and Ir(Ⅲ)L_3 type(where L is PT~-,3Me-PT~-or 4Me-PT~-)are reported here.Four coordination compounds of the lattertwo ligands have never been reported before,while PT~-'s were synthesized withH_2PtCl_6 and(NH_4)_3IrCl_6 respectively,which were different from the methods ofDavidson et al.~1 and Sterinbrech~2.They were characterized by elemental analysis,UV,IR,~1HNMR and molar conductance.Their structural formulas have beendetermined,and the mechanism of synthetic reaction has been discussed.  相似文献   

12.
Abstract

Fe(II)T(p-X)PP(NH2Bu n )2 (X = H, Cl, CH3, OCH3, TPP = dianion of meso-tetraphenylporphyrin) complexes have been prepared by the reduction of Fe(III) porphrins with n-butylamine in antiformin/dichloromethane in air, and by sodium borohydride reduction. The complexes were characterized by electronic and IR spectra and elemental analysis.  相似文献   

13.
THE development of the theory of molecular structure and thenature of the chemical bond are discussed.Particular atten-tion is given to the theory of hybrid bond orbitals.  相似文献   

14.
Abstract

Infrared assignments (4000 - 50 cm?1) are presented for the complexes [M(quinO)n](ClO4)2(quinO = quinoline N-oxide; n = 6 for Mn, Co, Ni; n = 5 for Zn, and n = 4 for Cu) and their perdeuterated analogues. The spectra are consistent with octahedral structures for the 6-coordinate complexes, a trigonal bipyramidal structure for the Zn(II) complex and a square planar structure for the Cu(II) complex, with some distortion from idealised symmetry evident for each complex. In the Mn(II) complex, strong coupling occurs between the vM-O of lowest frequency and the ligand vibration, xN-O (mode 45). In the Cu(II) complex, the single vCu-O is strongly coupled with the ring torsion (mode 28).  相似文献   

15.
傅强 《高分子科学》2002,(2):143-154
Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystallinelayered structure. Whether or not a chain disentangles may result in different crystallization mechanism. When compared tothe crystal thickness (d_c), the volume occupied by the chain in the melt, i.e., the radius of gyration (R_g), plays a veryimportant role in polymer crystallization. When d_c≤R_g, crystallization does not necessitate a chain disentangling. Theentanglements are just shifted into the amorphous regions. However, as d_c>R_g, i.e., as the crystal thickness ges larger thanthe radius of gyration of the chain in the melt, it becomes necessary for a chain to disentangle. Then a change ofcrystallization mechanism occurs. Such change has been experimentally observed in the crystallization of poly(1-butene). Achange in the crystal morphologies from spherulite to quadrangle, is seen via PLM, as crystalliation temperatures increase.Even more, such a change is molecular weigh dependent and shifts to lower temperature as molecular weigh decreases.There exists a jump of crystal thickness and crystallinity associated with morphological change, as seen via SAXS. A changeof crystallization kinetics and crystallinity is further evidenced via dilatometry. The unique feature of P1b crystallization hasbeen discussed based on the radius of gyration of chain in the melt (R_g), and very good agreement is obtained.  相似文献   

16.
We have now succeeded in preparing a partially purified antigen (Fr. 1). The positive rates of the indirect ELISA were 100% both for sera of proved human cases and dogs infected with Paragonimus westermani when Fr. 1 was used, whereas the positive rates of the test were 71.4% and 75% on sera from patients and infected dogs respectively when crude antigen was used. Moreover, it is also better than the crude antigen in specificity, so a more reliable test in immunodiagnosis of paragonimiasis is available in our laboratory.  相似文献   

17.
The one plus one (1 + 1) mode of hydrosilation reaction of ladderlike cis-isotatic polyallylsilsesquioxane (Allyl-T)and polyhydrosilsesquioxane (H-T) using dicyclopentadienylplatinumdichloride (Cp_2PtCl_2) as the catalyst leads to theformation of a new polyorganosiloxane (POS). The presence of nanoscale tubular structure in the product POS waspreliminarily proved by IR, ~1H-NMR, differential scanning calorimetry (DSC), X-ray diffraction (XRD), gel permeationchromatography (GPC), atomic force microscopy (AFM) and molecular simulation.  相似文献   

18.
Abstract

The synthesis, conventional characterisations and x-ray structures of the following monomeric complexes are given for 2,9-diaminophenanthroline-bisacetate-cobalt(II) ( A ) and 6,6′-diaminobipyridine-bisacetate-M(II) (M = nickel( C ) and copper( B )). Complex A crystalizes in the monoclinic, C2/c space group with a=12.813(6), b = 10.218(3), c= 13.811(5), Å; β= 118.17(2)°; Z=4; V=1549(2) Å3. A total of 1787 unique reflections with F > 6σ(F) were refined to values of R and Rw 0.0461 and 0.0774, respectively. Complex B crystallizes in the triclinic, P-1 space group with a=10.099(5), b=10.257(5), c=8.015(11), Å; α=112.98(2), β=93.13(2), γ=92.960(2),°; Z=2; V = 761(1), Å3. A total of 2603 unique reflections with F > 3.00σ(F) were refined to values of R and Rw 0.0764 and 0.1022, respectively. Complex C crystallizes in the monoclinic, P21/n space group with a=8.124(5), b=10.343(6), c=18.724(11), β=98.36(2),°; Z=4; V=1556(1), Å3. A total of 2537 unique reflections with F > 3.00σ(F) were refined to values of R and Rw 0.0689 and 0.0975, respectively. The structures consist of six-coordinate [M(CH3COO)2(L)] (L=2,9-diaminophenanthroline or 6,6′-diaminobipyridine) discrete monomeric neutral species, although in the Cu(II) compound the elongation of two long Cu—O bonds, due to the Jahn-Teller effect, makes the metal essentially four-coordinate. In the Ni and Co compounds the acetate acts as a bidentate ligand. The diamino ligands are coordinated by the pyridine nitrogen atoms. The IR spectra of the complexes have been recorded and are discussed in relation to the crystal structure and the acetate coordination mode.  相似文献   

19.
Thirteen observed heat flow values in combination with relevant geological and geophysical information are employed in the current paper to conduct a model study by means of direct inversion. The modeling demonstrates the tectono-thermal evolution of the Tibetan Plateau during the last 40 Ma since the continent-continent collision. The authors stress the fact that the tectonic deformations of terranes are usually the inducing factors for the deep-seated thermal activities in the crust and upper mantle. On this basis a series of kinematic equations of 3-D deformations of terranes in forms of shortening-thickening-uplifting-erosion-mass sliding were deduced using the principle of plate kinematics. These equations are further used as systematically defined initial and boundary conditions for simulating the integrated processes of tectono-thermal evolution, The results of the model study suggest that there exist sharp differences in the tectono-thermal evolution between the old northern terranes and the new  相似文献   

20.
THE STACKING INERACTION OF TERNARY COMPLEXES OF Zn(ATP)~(2-)AND PYRIDINE-LIKELIGANDSTHESTACKINGINTERACTIONOFTERNARYCOMPLEXESO?..  相似文献   

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