1.
NMR and Theoretical Study on the Coordination and Solution Structures - XianYongYu; ShuHuiCai; XinXu; ZhongChen
To simulate the types of coordination and solution structures of the active site of haloperoxidases, the interaction
systems between diperoxovanadate complexes [OV(O2)2L]n- (n ) 1 or 3, L ) oxalate or H2O) and a series of
histidine-like ligands in solution have been studied by using 1D multinuclear (1H, 13C, and 51V) NMR, 2D diffusion
ordered spectroscopy, and variable-temperature NMR in 0.15 mol/L NaCl ionic medium, representing the physiological
conditions of human blood. Some direct NMR data are given for the first time. The reactivity among the histidinelike
ligands is imidazole > 2-methylimidazole > carnosine ? 4-methylimidazole > histidine. Competitive coordination
interactions result in a series of...
2.
Investigation on the complex of diperoxovanadate with 2-(20-pyridyl)-imidazole - XianYongYu; ShuHuiCai; Zhong Chen
A novel diperoxovanadate complex NH4[OV(O2)2{2-(2′-pyridyl)-imidazole}] · 4H2O was synthesized in aqueous solution under physiological conditions. The solution structure of the complex was characterized by multinuclear (1H, 13C, 14N, and 51V) as well as multi-dimensional (DOSY and C-H COSY) NMR techniques in the interaction system of NH4VO3/H2O2/2-(2′-pyridyl)-imidazole at room temperature. The crystal structure of the complex was determined at 173 K by single-crystal X-ray diffraction method. It belongs to the monoclinic space group P21/c with a = 13.048(4), b = 6.984(2), c = 17.814(5) Å, β = 104.695(5), V = 1570.3(8) Å3 and Z = 4. The crystal is composed of...
3.
Suppression of undesired peaks due to residual intermolecular dipolar interactions in liquid NMR - ZhongChen; ShuhuiCai; XiaoqinZhu; JianhuiZhong
Residual intermolecular dipolar interactions may result in undesired spectral features on highly concentrated samples in liquid NMR. Although homonuclear decoupling can be employed to suppress the interactions, it may cause a strong irradiation peak, which obscures the nearby peaks. In order to overcome this shortcoming, a modified CRAZED sequence with three radio-frequency pulses was proposed. The analytical expression derived from the dipolar field treatment was employed to select proper flip angles and phase cycling. Theoretical predictions, experimental observations, and computer simulations demonstrated that the new method effectively suppresses the undesired peaks due to residual dipolar effects.
4.
Theoretical formalism and experimental verification of line shapes of NMR intermolecular multiple-quantum coherence spectra - BingwenZheng; ShuhuiCai; ChaohuiYe; ZhongChen; JianhuiZhong
Although the theories and potential applications of intermolecular multiple-quantum coherences (iMQCs) have been under active investigations for over a decade, discussion of iMQC NMR signal formation was mainly confined in the time domain. In this paper, a full line-shape theory was developed to describe iMQC signals in the frequency domain. Relevant features of the line shape, such as peak height, linewidth, and phase, were investigated in detail. Predictions based on the theory agree well with experimental and simulated results. Since radiation-damping effects always couple with iMQCs in highly polarized liquid-state NMR systems, and strongly radiation-damped signals have many spectral characteristics...
17.
黄铜矿半导体DMS的第一原理计算 - 曾永志; 黄美纯
为了寻找新的高Tc的稀磁半导体(DMS),利用自旋局域密度泛函的第一性原理对 3d过渡金属(TM= V、Cr、Mn、Fe、Co或Ni)掺杂的II IV V2(CdGeP2 和ZnGeP2)以及I III VI2(CuGaS2 和CuGaSe2)黄铜矿半导体的电磁性质进行系统计算.结果发现:V或Cr 掺杂的 II IV V2 将出现铁磁(FM)状态,而 Mn、Fe或者 Co掺杂的 II IV V2 将出现反铁磁(AFM)状态,Ni掺杂时,DMS的磁性非常不稳定;在TM掺杂的 I III VI2 的DMS中,Cr、Mn掺杂的 CuGaS2 和 CuGaSe2将表现为FM状态,而当V、Fe、Co或Ni掺杂时,Cu(Ga,TM)S2 和Cu(Ga,TM)Se2 则表现了AFM性质.Cr掺杂的I IV V 以及 I III VI 黄铜矿半导体将可能出现较高的居里温度(Tc).
1.
