we have evaluated the nmr shielding tensors for a:t,g:c,a:u in watson-crick, and u-quartet. we have computed nmr shielding tensors at b31yp level by using 6-31g(d) basis set. we have compute anisotropy and asymmetry in a:t,g:c,a:u and u-quartet. the nmr shielding tensors were calculated using the giao method. the natural bonding orbital analysis (nbo) were performed. nbo calculation have been ...

The change in (1)H NMR chemical shifts upon hydrogen bonding was investigated using both experimental and theoretical methods. The (1)H NMR spectra of a number of phenols were recorded in CDCl(3) and DMSO solvents. For phenol, 2- and 4-cyanophenol and 2-nitrophenol the OH chemical shifts were measured as a function of concentration in CDCl(3). The plots were all linear with concentration, the g...

compound (n,n-bis (salicylidene) 1,2-diaminophenylene) was prepared by condensation of ethanolsolution of 2-hydroxybanzaldehyde and 1,2-diaminophenylene. the compound was characterized by1h nmr, infrared spectroscopy (ft-ir) data and analytical data. the geometrical parameters andenergies have been obtained from density functional theory (dft) b3lyp method and hartree-fock (hf) method with 3-21...

A theory ~MPL! to compute the NMR chemical shifts in condensed matter systems using periodic boundary conditions was presented by F. Mauri, B. Pfrommer, and S. G. Louie @Phys. Rev. Lett. 77, 5300 ~1996!#. The MPL method has been implemented so far within a pseudopotential formulation in which the wave functions are expanded in plane waves. In this paper, we compare analytically the MPL approach...

A series of monocyclic planar inorganic compounds have been optimized at the B3LYP/6-311+G* level. GIAO-B3LYP nucleus-independent chemical shifts (NICS) profiles calculated in the perpendicular direction of each ring show that the series of analyzed compounds can be classified in three groups according to their aromatic, non-aromatic or antiaromatic character. Our results suggest exercising cau...

p53 is one of the gene that has important role in human cell cycle and in the human cancers too.models of codon substitution make it possible to separate mutational biases in the dna fromselective constraints on the protein, and offer a great advantage over amino acid models forunderstanding the evolutionary process of proteins and protein-coding dna sequences. in thiswork, we investigated abou...

The fluxional barrier of (dicarbonyl)[dihydrobis(3,5-dimethylpyrazol-1-yl)borato][eta-(1,2,3)-2-methylpropen-1-yl]-molybdenum (1) has been measured and a complete assignment of its (1)H, (13)C and (15)N NMR signals has been carried out. Theoretical calculations at the B3LYP/LANL2DZ level including GIAO absolute shieldings (sigma) have allowed to analyze the molecular contributions to the barrie...

A series of oxonium and carboxonium ions and their corresponding protonated dications were investigated by ab initio/IGLO/GIAO-MP2 methods. The calculated 17O and 13C NMR chemical shifts were compared with the solution phase experimental data for the monocations. The structures and energies of a number of oxonium and carboxonium dications and the effect of diprotonation on the 17O and 13C NMR c...

Văn xuôi Ngọc Giao đã tái hiện một hình ảnh làng quê vừa truyền thống pha chút đại, êm đềm xao động, đáng yêu, sống sợ, phải đổi thay. Tuy nhiên, đây vẫn là vấn đề chưa được nghiên cứu tìm hiểu thấu đáo. Qua khảo sát, kê, phân tích, so sánh về trong văn Giao, chúng tôi bước đầu nhận thấy: Đó yên bình, nặng nghĩa tình nhưng nghèo đói, bế tắc; Làng tiêu điều, đau thương vùng giặc chiếm đóng và dầ...

Density functional theory (DFT) calculations at the B3LYP/6-311G* theoretical level have been performed to study the 1,3-dipolar cycloaddition (1,3-DC) reactions between indenone (1) and different 1,3-dipoles (diazomethane and N-methyl C-methoxy carbonyl nitrilimine, compounds 2 and 3, respectively). The geometrical and energetic properties were analysed for the different reactives, transition ...