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81.
Z. Latajka H. Ratajczak K. Romanowska Z. Tomczak 《Journal of organometallic chemistry》1977,139(2):129-133
A systematic CNDO/2 study has been carried out on the molecular complexes formed between dimethylberyllium and aliphatic amines. It has shown that the calculated molecular properties of these complexes, viz. the interaction energy, amount of charge transferred and the enhancement of the dipole moment are related to the ionization potential of the amine. The results are discussed in terms of the Mulliken's charge transfer theory. 相似文献
82.
Janina Kuduk-Jaworska Maria Kubiak Tadeusz Gŀowiak Henryk Mastalarz 《Transition Metal Chemistry》1994,19(4):403-405
Summary A new platinum complex of 1-methyl-5-nitroimidazole has been obtained and characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The structure of [PtI2-(C4 H5N3O2)2] has been determined by single-crystal X-ray diffraction. The crystals are triclinic: P1, a = 15.640(3), b = 12.617(2), c = 6.701(1) , = 102.77(5), = 101.15(5), = 100.71(5)°, V = 1228.6(3) 3, Z = 3, Dx = 2.851(6) Mg m–3, (MoK
) = 0.71069 , = 12.85 mm–, F(000) = 948, final R = 0.038 for 2859 reflections. The complex consists of monomeric PtI2(1-methyl-5-nitroimidazole)2 units. The coordination geometry is square-planar. The two 1-methyl-5-nitroimidazole ligands are trans coordinated to platinum. 相似文献
83.
An analysis of the influence of I? ions on radiative and radiationless transitions from the lowest triplet state of aromatic hydrocarbons is presented. The distance dependence in the external heavy atom effects and the dependence of the enhancement of the T1→S0 radiative transition on the triplet energy is discussed in terms of perturbation theory. 相似文献
84.
Z. Latajka M. M. Szczniak H. Ratajczak W. J. Orville-Thomas 《Journal of computational chemistry》1980,1(4):417-419
The hydrogen-bonded complex between nitric acid and ammonia molecules has been studied by the ab initio molecular orbital method using the 4-31G basis set. The calculated interaction energy for the complex (ΔE = ?91.4 kJ mole?1) indicates that one is dealing with the strongest “nonionic” H-bonded complex considered hitherto by theoretical methods. Other properties of the hydrogen-bonded complex such as geometrical parameters, dipole moment, amount of charge transfer, and stretching force constants of the O? H and (OH)… N bonds are calculated and discussed. 相似文献
85.
Conjugates of 3′-azido-2′,3′-dideoxythymidine (AZT) and 2′,3′-didehydro-2′,3′-dideoxythymidine (D4T) with the hydroxyl group of tyrosine containing boranephosphate and boranephosphorothioate moieties were prepared via the oxathiaphospholane and dithiaphospholane methodology as a mixture of P-diastereomers. Their structures were confirmed by MS analysis and 1H, 31P NMR spectroscopy. It has been shown that the boranephosphorothioate linkage is unstable under acidic conditions. The first nucleoside-alanine conjugates connected through a boranephosphoramidate linkage were also obtained. 相似文献
86.
Janina Baraniak Renata Kaczmarek Ewa Wasilewska Wojciech J. Stec 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1667-1670
Based upon 1,3,2-oxathiaphospholane chemistry, 5'-O-derivatization of nucleosides with the O-methyl esters of amino acids was performed and corresponding conjugates were obtained in satisfactory yield. 相似文献
87.
88.
Bloemhoff - Kerling's method of L-homohistidine synthesis was modified by employing formamidine acetate in liquid ammonia for imidazole ring formation. The improved procedure significantly shortened the synthetic pathway and resulted in enhanced yield. 相似文献
89.
We discuss recent developments for studying plasmonic metal nanostructures. Exploiting photons and electrons opens up new capabilities to probe the complete plasmon spectrum including bright and dark modes and related local optical fields at subnanometer spatial resolution. This comprehensive characterization of plasmonic properties of metal nanostructures provides new basic insight into the fundamental physics of “surface enhanced” spectroscopy in hottest hot spots and enables us to optimize plasmon supported processes and devices. 相似文献
90.
Janina Kneipp Burghardt Wittig Henrik Bohr Katrin Kneipp 《Theoretical chemistry accounts》2010,125(3-6):319-327
Sensitive and detailed molecular structural information plays an increasing role in molecular biophysics and molecular medicine. Therefore, vibrational spectroscopic techniques, such as Raman scattering, which provide high structural information content are of growing interest in biophysical and biomedical research. Raman spectroscopy can be revolutionized when the inelastic scattering process takes place in the very close vicinity of metal nanostructures. Under these conditions, strongly increased Raman signals can be obtained due to resonances between optical fields and the collective oscillations of the free electrons in the metal. This effect of surface-enhanced Raman scattering (SERS) allows us to push vibrational spectroscopy to new limits in detection sensitivity, lateral resolution, and molecular structural selectivity. This opens up exciting perspectives also in molecular biospectroscopy. This article highlights three directions where SERS can offer interesting new capabilities. This includes SERS as a technique for detecting and tracking a single molecule, a SERS-based nanosensor for probing the chemical composition and the pH value in a live cell, and the effect of so-called surface-enhanced Raman optical activity, which provides information on the chiral organization of molecules on surfaces. 相似文献