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21.
A convenient route to new 3-quinolinonyl-pyrazoles and isoxazoles is described through cyclization of 3-[(E)-3-(dimethylamino)-2-propenoyl]-4-hydroxy-1-methyl-2(1H)-quinolinone. The phototoxicity as well as the cytotoxic activities of the title compounds are evaluated against leukemia- and adenocarcinoma-derived cell lines in comparison to the normal human keratinocytes. 相似文献
22.
Giovannelli Tommaso Liuzzi Giampaolo Lucidi Stefano Rinaldi Francesco 《Computational Optimization and Applications》2022,82(2):293-327
Computational Optimization and Applications - In this paper, mixed-integer nonsmooth constrained optimization problems are considered, where objective/constraint functions are available only as the... 相似文献
23.
Some results on configurations realizing minimum blocking sets of a finite projective plane are obtained by introducing a suitable attraction property.Dedicated to Professor M. Scafati Tallini on the occasion of her 65th birthday 相似文献
24.
Copper(II) complexes with the herbicide N-(phosphonomethyl)glycine (glyphosate) have been investigated in aqueous solution by means of pH-metric measurements at different temperatures, 5 = T = 45 degrees C, calorimetry and visible spectrophotometry. Potentiometric data, at all the considered temperatures in the range 2.5 = pH = 10.5, can be explained assuming the formation of the species CuLH(0), CuL(-), CuLH(2 -)(- 1), CuL(4 -)(2) and Cu(2)L(+). By using thermodynamic data and calculated electronic spectra for each complex a structural definition is proposed for the different species. Copper(II)-glyphosate complexes are quite stable and must be taken into account in the speciation of natural fluids. 相似文献
25.
Carlo Mealli Stefano Midollini Simonetta Moneti Thomas A. Albright 《Helvetica chimica acta》1983,66(2):557-569
The reaction of [(C3Ph3)Ni(PPh3)2]ClO4 with P(CH2CH2PPh2)3(pp3) and NaBPh4 yields the [(C3Ph3)Ni(pp3)]BPh4-complex. After long exposure of the solution of this compound in acetone/butanol to the air a new derivative [(C3Ph3)-Ni(pp2po)]BPh4· 0.5 C4H9OH, where pp2po is (Ph2PCH2CH2)2P(CH2 CH2POPh2), is obtained. Complete X-ray analysis has been carried out for the latter complex: a=18.303 (5); b=29.445 (6), c=13.305 (5) Å, β=112.70 (9)°; space group monoclinic, P21/a, Z=4. Disorder problems were encountered in the refinement of the structure. The best R is 0.093. One of the arms of the parent pp3-molecule, not coordinated to the metal, undergoes oxidation. The Ni-atom, coordinated by the three remaining P-atoms of the ligand, is also linked in a roughly η3-mode to the cyclopropenium ligand. The geometry of the molecule is examined in detail. Extended HMO-calculations were performed to interpret how the variation of P? Ni? P angles affects the bonding between the NiP3- and C3H3-fragments. The conclusion is that the overall energy of the complex may be lowered in spite of a weakening of the Ni-cyclopropenium linkage. Extensions are made to other systems containing a linkage between a metal and a X3-ring (X=P,As). 相似文献
26.
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28.
Riccò M Shiroka T Carretta S Bolzoni F Femoni C Iapalucci MC Longoni G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(9):2856-2861
The magnetic behaviour of the even-electron [Ni16Pd16(CO)40]4- cluster, in its [NnBu4]+ salt, has been investigated by magnetometry and muon spin rotation/relaxation (muSR) spectroscopy. The susceptibility measurements show an exceptionally high magnetic moment corresponding to a total spin value J=2. This suggests a Hund filling of a quadruplet ground state, quite unique in carbonyl-metal clusters. SQUID magnetometry shows a departure from the Curie-Weiss law, for T>150 K, and strong deviation from a Brillouin behaviour of the magnetisation curves. muSR spectroscopy in zero applied field shows a temperature independent decay of the muon spin polarisation, similar to that of a purely paramagnetic system. The observed muon spin repolarisation in a moderate external longitudinal field, however, invalidates this simple picture and suggests the presence of a local anisotropy field acting on the cluster's magnetic moment. A consistent interpretation of magnetometry and muSR results implies the occurrence of an additional interaction of the cluster spin with an effective crystalline field. The inclusion of this interaction in a model Hamiltonian allows us to successfully reproduce both the susceptibility and magnetisation data. 相似文献
29.
The low-temperature NMR spectra of 1,4-bis(mesitoyl)durene, 1, and of 1,4-bis(mesitylethenyl)durene, 2, reveal the presence of syn and anti rotamers at the equilibrium, their relative proportions depending on the dielectric constant of the solvent. In solution the more stable rotamer of 1 is the anti whereas, in the case of 2, the more stable is the syn. Depending on the crystallization solvent employed the more (anti) and the less stable (syn) rotamers were both observed (X-ray diffraction) in the solid state of 1. On the other hand, only the less stable rotamer (anti) was found to be present in the solid state of 2. As shown by MM calculations, the syn-to-anti interconversion occurs via a correlated process (cogwheel pathway) involving the mesityl-C and durene-C bond rotations: the dynamic NMR technique yields an experimental barrier of 8.2 kcal mol(-)(1) for 1 and 13.1 kcal mol(-)(1) for 2. In the case of derivative 2 a second barrier, due to a second type of correlated rotation process (torsion), was also determined (8.6 kcal mol(-)(1)). As a consequence of the restriction of this second torsional motion the anti rotamer of 2 displays two distinguishable NMR spectra at -133 degrees C, corresponding to a pair of conformers with different symmetry (anti C(i)() and anti C(2)). 相似文献
30.
Alessandro?De?Robertis Concetta?De?Stefano Demetrio?Milea Silvio?SammartanoEmail author 《Journal of solution chemistry》2005,34(10):1211-1226
Complex formation constants were determined potentiometrically (by a ISE-H+, glass electrode) in the systems, M2+ – Lz – H+ [M2+ = (C2H5)2Sn2+, Lz = malonate, glycinate and ethylenediamine] at t = 25 ∘C and 0.1 mol-L−1≤ I/ ≤ 1 mol-L−1 in NaClaq (0.1 mol-L−1 ≤ I ≤ 0.75 mol-L−1 for the ethylenediamine system). Thermodynamic values of formation constants, at infinite dilution, are [± 95% confidence
interval, Tβpqr refer to the equilibrium, pM2+ + qLz + rH+ = MpLqHr(2+z+r)]: for malonate, log10 Tβ110 = (5.47 ± 0.10); for glycinate, log10 Tβ110 = (9.54 ± 0.08), log10 Tβ111 = (12.97 ± 0.10); and for ethylenediamine, log10 Tβ110 = (10.47 ± 0.10), log10 Tβ120 = (16.17 ± 0.12) and log10 Tβ111 = (15.46 ± 0.10). The dependence on ionic strength of the formation constants was modeled by a simple Debye–Hückel type equation
and by the SIT approach. By analyzing the stability of the species in the three different systems we found a simple additivity
rule that can be expressed by the relationship: log10 K = 6.46 nN + 3.96 nO − 0.60 (nN2+ nO2), with a mean deviation, ε(log10 K) = 0.15 (K = equilibrium constant for the interaction of the organometal cation with the unprotonated or protonated ligand, nN = number of amino groups and nO = number of carboxylic groups of the ligand(s) involved in the formation reaction of complex species). 相似文献