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1.
Cr. Simionescu Tatiana Lixandru Lucia Tǎtaru I. Mazilu M. Vâţǎ 《Journal of organometallic chemistry》1982,238(4):363-381
The synthesis and study of some polyenes, polýiminoimides and Schiff polybases with ferrocene obtained by either polymerization or polycondensation are reported.The following monomers were used: ethynylferrocene, 1-chloro-1′-ethynyl-ferrocene, α-chloro-β-formyl-p-ferrocenylstyrene, p-ferrocenylphenylacetylene, p-ferrocenylacetophenone, 1,1′-diacetylferrocene and 1,1′-bis[β-(2-furyl)acryloyl]ferrocene which were characterized by spectral and thermodifferential analyses and Hückel MO calculations. The polymerization was performed in the presence of benzoyl and lauroyl peroxides, triisopropylboron and complex catalysts of [P(C6H5)3]2 NiX2 type. The ferrocene derivatives were polycondensed with biuret, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl thioether, 4,4′-diamino-2,2′-dinitrodiphenyl disulphide in the presence of metallic salts and p-toluene sulphonic acid as catalysts.Polymers with either linear or tridimensional structure showing good thermal stability and semiconducting properties have been obtained. Some polymers show catalytical activity in the polymerization of chloroformylated vinylic derivatives. 相似文献
2.
Polyaddition reactions of aliphatic and aromatic diamines to N,N′-bismaleimide and model compounds have been investigated in order to establish some properties of this imide. Glacial acetic acid has a catalytic effect when used as solvent in the preparation of aspartimide compounds. Aromatic diamines show a much smaller reactivity than aliphatic, the former giving polydisuccinimides and the latter polyamides under the same reaction conditions. Addition reactions of N,N′-bismaleimide proceed either by an ionic mechanism in polar solvents or by a homolytic process in solvents precluding ion formation. The thermal stability and the infrared spectra of the new polymers are discussed. 相似文献
3.
Attempts to construct structural models of glassy CdGeAs2 are described. Microcrystal models with normal and appropriately distorted crystallites gave poor fits with the experiment. Relaxed random network models, in which force constants and equilibrium distances and angles obtained by an energy relaxation of the crystal were used to minimize their free energy, provided excellent agreement with experiment if only even-numbered rings and, therefore, no wrong bonds were allowed to form. 相似文献
4.
The gas phase infrared spectrum of monoisotopic H3Si37Cl has been reinvestigated in the ν1/ν4 region near 2200 cm−1, using a Fourier transform spectrometer, with a nominal resolution of 0.0027 cm−1. The rovibrational analysis confirms, besides the weak Coriolis x, y resonance between the (v1 = 1) and (v4 = 1) levels, the existence of two strong local perturbations in the ν4 band. These are caused by rotational (Δk = Δl = ±1) type resonances with and , respectively. Another local perturbation of the 12 ? KΔK ? 14 subbands of the ν4 band, probably due to a (Δk = Δl = ±1) interaction with , was detected and analyzed. All these local perturbations have been studied individually using a simple model of two interacting sublevels. Without the transitions involved in the local perturbations, more than 2000 lines of the ν1/ν4 band system were used to obtain a complete set of vibration-rotation parameters set for the v1 = 1 and v4 = 1 states. By means of a band contour simulation, both the transition moment ratio ∣M4:M1∣ = 1.25 and a positive sign of the Coriolis intensity perturbation were determined.The present results, together with the accurate existing data for ν2, ν3, ν5, and ν6 bands, allowed us to derive the experimental values, Ae = 2.8722945(37) cm−1 and Be = 0.2182248(22) cm−1, which are compared with those of ab initio calculations. 相似文献
5.
I. Spǎnulescu I. Dima Mohamed Ismail Abd El-Ati N. Bǎlţǎţeanu Talal Khalass 《辐射效应与固体损伤》2013,168(3-4):299-303
The influence of 8 MeV electrons on the crystalline structure of HgTe and Hg1-xCdxTe thin films was studied. HgTe and Hg1-xCdxTe layers were obtained by thermal evaporation and condensation in vacuum on optically flat silica glass substrates heated at different temperatures. One finds that the results of irradiation of HgTe and Hg1-xCdxTe thin films with 8 MeV electrons depend on the preparation conditions of the samples, and therefore on the level of perfection of the crystalline structure and the quantity of nonstoichiometric atoms. 相似文献
6.
The high-resolution infrared spectrum of deuterated fluoroform (DCF3) was studied in the 700 and 1200 cm−1 regions, with the aim of assigning and analyzing the ν4 CF3 asymmetric stretching vibration. The Fermi-type anharmonic coupling between the ν4 = 1 and ν3 = ν6 = 1 rovibrational levels, already mentioned in an early work of Ruoff et al. [Spectrochimica Acta Part A 31A (1975) 1099-1100], was studied here for the first time under high resolution. Assignments in the ν3 + ν6/ν4 band system were confirmed and extended by the identification of the ν3 + ν6 − ν6 and ν4-ν6 bands in the 700 cm−1 region, the latter being enhanced near the Fermi crossings of the studied levels. Data from both the hot and difference bands were included in the analysis. The close separation of the studied vibrational levels of about 14.8 cm−1 produces a large variety of resonance crossings which involve levels with . Besides the Fermi () and Coriolis () resonances, they were accounted for by inclusion of additional higher-order ( and ) interaction terms between the vibrational states. The least-squares fit of more that 16,000 vibration-rotation transitions provides a quantitative reproduction of data in all bands. 相似文献
7.
C. Zǎlinescu 《Journal of Mathematical Analysis and Applications》1983,95(2):344-374
In this paper we study uniformly convex functions and uniformly convex functions at a point, giving some properties and characterizations of them. Further, we give some examples and applications of these types of functions. 相似文献
8.
Abstract Elevated plasma cholesterol is now well established as a major risk factor for cardiovascular diseases. It has also been shown that the oxidation of low density lipoproteins leads to the formation of foam cells which contribute to the deposition of cholesterol in arteries. 相似文献
9.
The purpose of this paper is to provide a new, unified and complete study for uniform dichotomy and exponential dichotomy
on the half-line. First we deduce conditions for the existence of uniform dichotomy, using classes of function spaces over
_+{\mathbb {R}_+} which are invariant under translations. After that, we obtain a classification of the main classes of function spaces over
\mathbb R+{\mathbb {R}_+}, in order to deduce necessary and sufficient conditions for the existence of exponential dichotomy, emphasizing on the main
technical qualitative properties of the underlying spaces. We motivate our approach by illustrative examples and show that
the main hypotheses cannot be dropped. We provide optimal methods regarding the input space in the study of dichotomy and
deduce as particular cases some interesting situations as well as several dichotomy results published in the past few years. 相似文献
10.
Adina I. Ciuciu Dr. Lucia Flamigni Dr. Roman Voloshchuk Prof. Dr. Daniel T. Gryko 《化学:亚洲杂志》2013,8(5):1004-1014
An assembly consisting of three units, that is, a meso‐substituted corrole ( C3 ), 1,8 naphthaleneimide ( NIE ), and a Zn porphyrin ( ZnP ), has been synthesized. NIE is connected to C3 through a 1,3‐phenylene bridge and to the ZnP unit through a direct C? C bond. The convergent synthetic strategy includes the preparation of a trans‐A2B‐corrole possessing the imide unit, followed by Sonogashira coupling with a meso‐substituted A3B‐porphyrin. The photophysical processes in the resulting triad ZnP-NIE-C3 are examined and compared with those of the corresponding C3-NIE dyad and the constituent reference models C3 , NIE , and ZnP . Excitation of the NIE unit in C3-NIE leads to a fast energy transfer of 98 % efficiency to C3 with a rate ken=7.5×1010 s?1, whereas excitation of the corrole unit leads to a reactivity of the excited state identical to that of the model C3 , with a deactivation rate to the ground state k=2.5×108 s?1. Energy transfer to C3 and to ZnP moieties follows excitation of NIE in the triad ZnP-NIE-C3 . The rates are ken=7.5×1010 s?1 and ken=2.5×1010 s?1 for the sensitization of the C3 and ZnP unit, respectively. The light energy transferred from NIE to Zn porphyrin unit is ultimately funneled to the corrole component, which is the final recipient of the excitation energy absorbed by the different components of the array. The latter process occurs with a rate ken=3.4×109 s?1 and 89 % efficiency. Energy transfer processes take place in all cases by a Förster (dipole–dipole) mechanism. The theory predicts quite satisfactorily the rate for the ZnP/C3 couple, where components are separated by about 23 Å, but results in calculated rates that are one to two orders of magnitude higher for the couples NIE/ZnP (D/A) and NIE/C3, which are separated by distances of about 14 and 10 Å, respectively. 相似文献