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<正> 7 解的唯一性 如果不考虑非平衡态和不可逆性,则等能密度理论中的基本命题与经典弹性理论中的在形式上完全相同。无论整个系统的动能是大还是小,图6中(sumform)_o上的面力T_i和在(sumform)_c和在的位移u_i将始终在空间坐标系x_i和时刻i下给出。与一般力学中相同,必须知道有关位移u_i及其时间导数的初始条件。它们的影响则可通过(38)和(39)向等能面转化,从而得到 相似文献
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Alberto Cassol Plinio Di Bernardo Pier Luigi Zanonato Sergio Tamburini Patrizia Tomasin Pietro Alessandro Vigato 《Supramolecular chemistry》2013,25(3):469-488
Abstract The asymmetric compartmental macrocycles containing one N2O2 or N3O2 Schiff base and one O2O3 or O2O4 crown-ether like chamber, have been obtained by condensation reaction of the formyl precursors 3,3′-(3-oxapentane-1, 5-diyldioxy) bis (2-hydroxybenzaldehyde) or 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)-bis(2-hydroxybenzaldehyde) with ethyl ethylenediamine (H2LA, H2LC), 1,5-diamino-3-azamethylpentane(H2LB, H2LD), also in the presence of metal ions as templating agents. These ditopic ligands, with dissimilar coordination sites, have been designed and used for the selective complexation of “d” and/or “s” metal ions, respectively into the Schiff base and the crown ether chamber. The selectivity of these processes strongly depends on the size and on the donor atom sets of the sites. The possibility to obtain mononuclear M(L)·nH2O (M = Ni2+, Cu2+, Co2+), Mn(L)(CH3COO)·nH2O or Na(L) and hetero-dinuclear MNa(L)(CH3COO) (M = Ni2+, Cu2+, Co2+) and MnNa(L)(CH3COO)2·nH2O complexes has been successfully tested. The ligands and complexes have been characterized by ir, nmr, mass spectrometry and magnetic susceptibility measurements. Two of the ligands used for the preparation of the solid samples, i.e., to H2LA and H2LB, have been employed to study complexation reactions of Co(II) and Na(I) in solution. In order to obtain information on the ligand preorganization effect toward the complex stabilities, a simpler open chain parent compound of H2LB (H2LE) has been also prepared and studied. FT-IR spectra show that H2LA is unable to complex Na+ in DMSO while the complexation reactions of Na+ by H2LB and of Co2+ by H2LA take place with slow kinetics. Therefore, thermodynamic data have been obtained only for the systems Co2+/H2LB and Co2+/H2LE. The thermodynamic parameters obtained for the complexation reactions show that the pre-organization of the donor atoms in H2LB does not add a significant contribution to the stabilities of the complexes. Both H2LB and H2LE form in DMSO 1:1, 1:2 and 1:3 = M:L complexes with very similar stabilities and almost equal enthalpies of formation. Physico-chemical studies suggest besides that the slow reaction of Na+ with H2LB is probably due to the formation of a 1:1 complex where the metal cation, initially occupying the O3 cage of the ligand, slowly binds also the oxygens of the phenolic moieties. Spectral and calorimetric data on solutions containing H2LB and different Co2+: Na+ ratios evidence that in DMSO no stable heterodinuclear complexes form when the neutral ligand is considered. 相似文献
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Sergio Tamburini Pietro A. Vigato Pietro Traldi 《Journal of mass spectrometry : JMS》1986,21(4):183-192
The 70 eV electron impact mass spectra of some macrocyclic and acyclic aldimines, together with that of their synthon, are described and discussed with the aid of exact mass measurements, linked scans, deuterium labelling experiments and collisional experiments. The mass spectrometric behaviour of the acyclic compounds, not directly related to their structure, has been studied in detail with the aid of differential thermal analysis, which demonstrates the occurrence of pyrolysis. 相似文献
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D. Fregona S. Sitran P. A. Vigato U. Casellato R. Graziani 《Journal of heterocyclic chemistry》1986,23(3):817-823
The pathway of the reaction between 2,4,6-heptanetrione and 1,5-diamine-3-aza-pentane was studied and some products identified by ir, uv, mass spectra and x-ray diffractometry. This reaction is not a simple condensation with the formation of a Schiff base but a more complicated process. The structure of the final compound was determined by x-ray crystallography and refined to R = 0.047. Crystals are triclinic, space group Pl, with a = 11.795(5), b = 9.779(5), c = 7.801(5) Å, α = 101.74(3), β = 90.93(3), γ = 110.65(3), Dx = 1.27 g. cm?3 for Z = 2. The structure is essentially formed by three heterorings two of which have a common edge. Only the 4-pyridone ring is planar. As expected 1,5-diamino-3-thiapentane reacts with the same triketone, in 1:1 or 1:2 molar ratios, to give the acyclic or macrocyclic Schiff bases. 相似文献
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