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941.
对近期发展的固体圆二色(CD)光谱测试方法进行了概述、评价和比较, 着重探讨了“浓度效应”的存在使固体CD光谱失真的原因. 通过对本课题组和其他作者已报道的四种化合物的固体CD谱再测试的反思, 强调了依手性化合物的手性光谱学性质不同, 根据浓度梯度实验选择其合适测试浓度的必要性. 对固有手性的阻转异构化合物(S)-1,1'-联二萘酚(S-BINOL)进行了成膜法固体CD谱浓度梯度测试, 发现所得固体薄膜CD谱中也存在着“浓度效应” 相似文献
942.
Nobuyuki Akai Satoshi Kudoh Masao Takayanagi Munetaka Nakata 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):93-100
Rotational isomerization of 2-chlorobenzaldehyde in low-temperature rare-gas matrices has been investigated by vibrational and electronic spectroscopies with aids of the density functional theory (DFT) and configuration interaction single (CIS) calculations. Infrared spectrum of the less stable O-cis isomer, produced from the more stable O-trans isomer upon UV irradiation, is measured with an FT-IR spectrophotometer. The enthalpy difference between the O-cis and O-trans isomers is estimated to be 9.7±0.2 kJ mol−1 from the temperature dependence of the infrared band intensities. Analyses of the infrared and electronic absorption spectral changes after UV irradiation and the phosphorescence spectra measured at various excitation wavelengths suggest that the rotational isomerization occurs via the intersystem crossing from S1 to T1. 相似文献
943.
D. P. Krutko M. V. Borzov E. N. Veksler A. V. Churakov 《Russian Chemical Bulletin》2005,54(1):117-123
The intracomplex conversion of (2-diphenylphosphanoethyl)cyclopentadienyl zirconium and titanium complexes into the corresponding 2-phosphinothioyl and 2-phosphinoyl derivatives, viz., (η5-C5H5)[η 5-C5H4CH2CH2P(S)Ph2]ZrCl2, [η5-C5H4CH2CH2P(S)Ph2]ZrCl3, [η5:η1C5H4CH2CH2P(O)Ph2]ZrCl3·THF, and [η5:η 1-C5H4CH2CH2P(O)Ph2]TiCl3 (7), was performed. The NMR spectroscopy data revealed the following order of the coordination ability of the functional groups with respect to the Zr center: Ph2P=O > Ph2P > Ph2P=S. An analogous order was found for the monodentate ligands (Ph3P=O > Ph3P > Ph3P=S) with respect to (η5-C5H5)ZrCl3. The molecular structure of complex 7 was established by X-ray diffraction analysis. Coordination of the Ph2P=O group to the titanium atom was found retained both in the crystalline state and solution.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 116–122, January, 2005. 相似文献
944.
Marco Arfelli Giovanni Cossu Giulia Mattogno Carla Ferragina Maria Antonietta Massucci 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(2):161-170
X-ray photoelectron spectroscopy provides evidence that when [Cu(phen)2]2+(phen = 1,10-phenanthroline) is diffused between the layers of -zirconium phosphate, the complex species does not remain intact after intercalation, but some Cu-N bonds are broken, replaced with Cu-O bonds and the released nitrogen atoms can now interact with the PO3-OH groups of the host. XPS also provides evidence for coordination of the Cu2+ ions when they are diffused by ion exchange in the phenanthroline--zirconium phosphate intercalation compound. Although Cu2+ and phen are in a 1 : 1 molar ratio in the interlayer region of the host, so that a 1 : 1 coordination could be expected between the two species, the characteristic peaks of the uncoordinated phenanthroline, even though at a low intensity, are still present. The differences between the two Cu(II)-intercalation compounds are discussed. 相似文献
945.
I. I. Chuev S. M. Aldoshin E. G. Atovmyan D. B. Frolov A. N. Utenyshev 《Russian Chemical Bulletin》1996,45(4):851-855
N-Thenylidene- andN-(o-nitrobenzylidene)hydrazides of isonicotinic acid have been studied by X-ray structural analysis and IR spectroscopy. In the crystalline state, these molecules are linked through intermolecular N—H ... Npy hydrogen bonds. Carbonyl groups are not involved in intermolecular hydrogen bonds. However, it was found that the C=O group participates in an attractive interaction with the sulfur atom of the thiophene group. The energy of this interaction is comparable with the energies of intermolecular C=O ... H—N hydrogen bonds in amides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 896–900, April, 1996. 相似文献
946.
The solid state structures of three nitroformate (NF) salts were determined using single crystal X‐ray crystallography. The NF anion was found to be a non‐planar moiety which adopts either the commonly observed C2v conformation or distorted propeller conformation (D3) in the case of the silver salts, or, a C2 conformation in the case of the potassium salt. This latter C2 conformation has been uniquely observed for potassium nitroformate. All structures exhibit cation‐anion interactions that influence the structure of the anion. The 13C and 14N NMR spectra of the NF anion show broad singlets, which indicates the equivalence of the nitro groups in solution within the NMR time‐scale. In addition, the vibrational and mass spectra of potassium nitroformate and silver nitroformate monohydrate were recorded. Furthermore, the gaseous decomposition products of potassium nitroformate at 25 °C were detected using IR spectroscopy and mass spectrometry. 相似文献
947.
A slab optical waveguide (SOWG) has been used for study of adsorption of both methylene blue (MB) and new methylene blue (NMB) in liquid–solid interface. Adsorption characteristics of MB and NMB on both bare SOWG and silanized SOWG by octadecyltrichlorosilane (ODS) were compared. Effect of pH on adsorption on MB and NMB was investigated. Binding rate constant analysis showed that both MB and NMB on bare SOWG demonstrates larger association constants than those on ODS-SOWG. Interactions of MB and NMB on bare SOWG and ODS-SOWG were analyzed by molecular mechanics calculation method. The binding energy change was in the following order: ENMB–bare > EMB–bare > ENMB–ODS > EMB–ODS. 相似文献
948.
Jorge Pavez Maritza Páez Armelle Ringuedé Fethi Bedioui José H. Zagal 《Journal of Solid State Electrochemistry》2005,9(1):21-29
We studied the electrocatalytic activity of cobalt tetra-aminophthalocyanine (CoTAPc) for the reduction of molecular oxygen (O2) on adsorbed monomeric and on electropolymerized films of different thicknesses on glassy carbon (GC) electrode. The polymeric films, denoted poly-CoTAPc, were first characterized by electrochemical impedance spectroscopy and it appears that the types of phenomena revealed to be occurring depend less on the film thickness in basic than in acid media. For O2 reduction, the results showed that poly-CoTAPc is more active than the monomeric CoTAPc adsorbed on GC. Indeed, rotating ring-disk electrode data showed that polymeric CoTAPc promotes the four-electron reduction of O2 to water in parallel to a two-electron reduction to give peroxide. On monomeric and thin films of poly-CoTAPc, a two-electron reduction mechanism predominates. In basic media the activity increases very slightly with thickness, whereas in acid media this increase is more pronounced. This parallels the observed behavior revealed by electrochemical impedance spectroscopy. 相似文献
949.
The high-resolution 1H and 13C NMR spectra of 1-vinylimidazole complexes with iron group metals were recorded. The contact coupling in these systems was
established in the 1H and 13C NMR spectra. The applicability of the NMR spectra transformed by long-range hyperfine coupling for elucidating the molecular
structure of the ligand was shown.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1430–1433, June, 2005. 相似文献
950.
A.?R.?MustafinaEmail author L.?S.?Kuznetsova A.?S.?Michailov V.?E.?Kataev A.?I.?Konovalov W.?D.?Habicher 《Journal of solution chemistry》2004,33(10):1257-1276
The complexation of a macrocycle containing thiopyrimidine and uracil moieties (M) with amino acids and some dicarboxylic acids was studied by pH-metric, UV-VIS, 1H NMR spectroscopy methods in chloroform, methanol, aqueous 1,4-dioxane, and biphasic water–chloroform media. The complexation of M with acids is too weak to solubilize them from the solid state into chloroform solutions containing M. The 1H NMR spectra and pH-metric data of aqueous 1,4-dioxane (80 vol.%) reveal the pH-dependent 1:1 binding between M and the acids studied. The protonation of M is not a prerequisite for binding of fumaric, succinic, o-phtalic acids and the series of amino acids, whereas binding of maleic acid requires the protonation of both thiopyrimidine moieties of M. Therefore,M·(H+)2 exhibits strong selectivity towards maleic acid in aqueous 1,4-dioxane and in biphasic water–chloroform media. 相似文献