对称性和配合物的构型——Ⅱ.混合配体配合物

从库仑定律出发,采用最优化法,计算了MLaL_b′型配合物各种几何异构体的几何构型稳定化能。在计算中考虑了配体L、L′的相对电荷。 计算结果表明,对称性是决定构型的首要因素。具体构型与配体的相对电荷有关。 在若干配合物中,中心原子的dⁿ构型决定其构型的骨架。 配体对构型的作用也应予考虑。对共价性程度大的配合物,应考虑轨道重叠对构型的影响。     

Acidichromism in the Mixed Langmuir—Blodgett Films of Stearic Acid with a Carbazole—containing Schiff Base

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｖｅｒｓｉｂｌｅｃｏｌｏｒｃｈａｎｇｅｓｕｐｏｎｅｘｔｅｒｎａｌｏｒｉｎｔｅｒｎａｌｓｔｉｍｕｌａｔｉｏｎｓｈａｖｅｂｅｅｎａｔｔｒａｃｔｉｎｇｍｕｃｈａｔｔｅｎｔｉｏｎｄｕｅｔｏｔｈｅｉｒｕｔｉｌｉｔｙａｓｆｕｎｃｔｉｏｎａｌｍａｔｅｒｉａｌｓ .Ｆｏｒｅｘａｍｐｌｅ ,ｐｈｏ ｔｏｃｈｒｏｍｉｓｍｄｅｓｃｒｉｂｅｓｔｈｅｃｏｌｏｒｃｈａｎｇｅｓｉｎｄｕｃｅｄｂｙｐｈｏ ｔｏｉｒｒａｄｉａｔｉｏｎａｎｄｃａｎｂｅｕｓｅｄａｓｐｈｏｔｏ ｒｅｃｏｒｄｉｎｇｍａｔｅｒｉ ａｌｓ…     

Complete immiscibility in binary cholesteryl-n-carboxylic acid ester/stearic acid monolayers at the water/air interface

Applying different surface and spreading techniques to form binary monolayers in a different mixing state, the mixing behavior of the three binary systems cholesteryl formiate/stearic acid, cholesteryl acetate/stearic acid, and cholesteryl-n-propionate/stearic acid were investigated and compared.Analyzing the force ()/area (a) isotherms and the equilibrium spreading pressures (^e of the binary monolayers, it can be concluded that the components of the three binary systems do not mix within the whole concentration range. The lipids in the binary monolayers are completely immiscible.     

Electrochemical properties and state of paramagnetic centers in copper-modified complex vanadium and titanium oxides

Complex vanadium and titanium oxides modified by copper ions are studied by the electrochemical and ESR methods. Oxides Cu _x V_2?y Ti _y O_5?δ·nH₂O (0<y<1.33) have a layered structure and oxides Cu _x Ti_1?y V _y O_5+δ·nH₂O (0<y<0.25), an anatase structure. The intercalation of cations Cu²⁺ into the hydrates leads to oxidation of V⁴⁺. According to ESR data, V⁴⁺ exists in the oxides in the form of VO²⁺ and an octahedral surround of oxygen (V⁴⁺?O₆), respectively. The electroreduction of ions of d-elements and chemisorbed oxygen in the oxides is analyzed. The intercalation of cations Cu²⁺ alters the content of V⁴⁺ and the chemisorption ability of the oxides. Possible reasons for this phenomenon are discussed.     

酸性化合物在十二胺-N,N-二亚甲基膦酸改性氧化锆固定相上的分离

酸性化合物在十二胺-N; N-二亚甲基膦酸改性氧化锆固定相上的分离;氧化锆;色谱固定相;十二胺-N; N-二亚甲基膦酸     

锆基纤维素手性固定相直接拆分萘普生衍生物

萘普生是一种消炎镇痛药 ,其 S对映体的抗炎作用是 R构型的 2 8倍 ,萘普生及其衍生物的拆分具有重要意义 .手性固定相 HPLC直接拆分 [1～ 4 ] 是最简便的分析方法 .氧化锆是近年来备受关注的色谱载体 [5,6 ] .Carr等 [7] 对碱性药物快速拆分表明氧化锆在手性分离Scheme1　 Structuresof chiral naproxen and its derivatives中的独特选择性 .萘普生及其衍生物在锆基手性固定相上的分离未见文献报道 .本组利用自制的球形氧化锆制备了涂敷型纤维素 -三 ( 3,5 -二甲基苯基氨基甲酸酯 ) -Zr O2 手性固定相 ( CDMPC- Zr O2 - CSP) ,在正…     

An FT-IR study of adsorption of sulfur dioxide on alpha- and gamma-alumina

In the Claus process hydrogen sulfide reacts to elemental sulfur. Because the Claus reaction is thermodynamically limited, sulfur compounds are still present in Claus tailgas. To avoid air pollution, the tailgas has to be treated.Alfa- and gamma-alumina are being used either as a catalyst or as a support for an active component in the Claus process and some tailgas treatment processes. In order to elucidate the mechanism of the Claus reaction, the adsorption of sulfur dioxide on both of the above aluminas was investigated using Fourier transform infrared spectroscopy.Different adsorbed species displaying a different heat of adsorption were detected. A broad band near 3500 cm^–1 is associated with the basic hydroxyl groups. This band is assigned to a hydrogen bond between the surface of alumina and a bisulfite species. As bisulfite species are reactive towards hydrogen sulfide, we assume that bisulfite species are active intermediates on alumina in the Claus reaction.     

锂离子电池锡氧化物基负极材料的湿化学合成与电化学性质

采用新兴的湿化学方法合成了锡氧化物基粉末材料。用X-射线衍射、扫描电镜和电化学方法对材料的微观结构、形貌和电化学性能进行了详细的研究。结果表明，经400 ℃热处理4 h的锡氧化物基材料的颗粒大小均匀，平均粒径约为200 nm。这种材料的可逆充电容量超过570 mAh·g^-1，30次循环后平均每次循环的容量衰减只有0.15%。良好的电化学性能表明锡氧化物基材料有望作为新一代锂离子电池的负极材料。     

Solidification of metallic tin in dispersed phase

Differential scanning calorimetry (DSC) and particle size measurements were carried out on disproportionation products of pure SnO to investigate the fusion and solidification behaviour of Sn droplets and their catalytic nucleation on Sn oxides. If disproportionation reaction takes place at T ≥ 798 K, the products are metallic Sn and SnO₂; but for 523 < T < 798 K, SnO₂ is replaced by an intermediate oxide (IO) Sn_xO_(1+x). On melting, samples with IO show a drop of melting point of metallic tin due to Gibbs–Thomson effect; no lowering of melting point was observed in samples with SnO₂. On the other hand, if solidification occurs in the presence of IO, Tin droplets always displayed three distinct exothermic solidification peaks, but if it takes place in the presence of SnO₂, only one exothermic peak is observed. Undercooling values and contact angles were determined for each of the heterogeneous nucleation processes. The different behaviour of metallic Tin droplets was related to the different lattice symmetry of SnO₂ and IO, which act as nucleation catalysts.