Normal and Reversed-Phase TLC Determination of Rosmarinic and Valerenic Acids

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic properties of valerenic and rosmarinic acids have been studied by normal- and reversed-phase TLC with eight...     

Effect of Temperature on the Retention of Aromatic Hydrocarbons with Polar Groups in Binary Reversed-Phase TLC

JPC – Journal of Planar Chromatography – Modern TLC - RM (log[(1 - RF)/RF]) values at different temperatures have been compared for aromatic hydrocarbons with different functional...     

Comparison of Normal and Reversed-Phase TLC for Separation of Selected Pesticides

JPC – Journal of Planar Chromatography – Modern TLC - Fifteen urea pesticides have been separated on RP-18WF254 plates with methanol-water and mixed organic (acetonitrile-methanol, 1:1...     

四苯基卟啉金属螯合物的反相高效液相色谱保留行为研究

 研究了四苯基卟啉金属螯合物(TPP)的高效液相色谱保留行为。在C18柱上试验以各种有机溶剂洗脱金属螯合物,最终选择了甲醇-丙酮的非 水体系作流动相。各螯合物的保留顺序为：ZnTPP＜TPP＜NiTPP＜CuTPP。运用Horvath的疏溶剂理论解释了这种保留行为。文中采用电负性与离子半径之比（EN／ri）作为静电场强的量度,提出 EN／ri值作为四苯基卟啉金属螯合物保留值参数。实验发现,在不同的流动相配比条件下,lnk′与 EN／ri均呈良好的线性关系。     

Separation of Aminoglycosides by Normal- and Reversed-Phase TLC

JPC – Journal of Planar Chromatography – Modern TLC - The normal-phase (NP) and reversed-phase (RP) thin-layer chromatographic separations of aminoglycosides (streptomycin, kanamycin,...     

Effect of Temperature on the Chromatographic Behavior of Epirubicin and its Analogues on High Purity Silica Using Reversed-Phase Solvents

The influence of temperature on the retention behavior of epirubicin and its analogues on high purity silica with reversed-phase solvents has been systematically investigated. It was found that temperature effects on retention are highly dependent on the type and concentration of organic modifier, as well as the pH of the mobile phase. In organic-rich mobile phases, the type of organic modifier plays an important role. With an aprotic solvent as modifier, retention times show anomalous increases with elevated temperature. At the same time, both efficiency and resolution are significantly improved but this is not the situation with a protic solvent as modifier. In addition, temperature shows different effects on retention time and selectivity when the pH is changed, and temperature-dependent selectivity reversal is found at higher pHs. In aqueous-rich mobile phases, regardless of the nature of the organic solvent and pH, retention of solutes drops as temperature is raised. It seems that the effect of temperature on chromatographic behavior of the solutes on bare silica using mobile phases containing various organic modifiers or pHs, results from a number of different retention mechanisms.     

The Effect of Metal Salts on the Separation of Carbohydrates by TLC

JPC – Journal of Planar Chromatography – Modern TLC - Carbohydrates have been examined by TLC on layers modified with metal ions, in the form of salts, by dipping commercial plates in...     

Interpretation of the Mechanisms of Chromatographic Separation on CN-Silica. Part I: TLC of Metal Complexes

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of four mixed tris(β-diketonato) complexes of the type [Co(acac)3-n(phacphac)n] (n = 0-3), three...     

Chromatographic Analysis of New Antidepressant Drugs by Normal- and Reversed-Phase TLC

JPC – Journal of Planar Chromatography – Modern TLC - The selectivity of the TLC separation of six new antidepressant substances has been investigated on silanized silica gel C18 and on...     

Analysis of Thiabendazole Via its Metal Complexes

Abstract

A new spectrophotometric method for the determination of thiabendazole has been developed. The method depends on the reaction of thiabendazole with copper (II), mercury (II) and silver (I) to form 1:1 complexes having maximum absorption at 317 nm, 318 nm and 324 nm, respectively. These absorption bands were used for the spectrophotometric determination of thiabendazole in pure form, in raw material and in pharmaceutical formulations.     

Spectrophotometric Determination of Diphenadione Via its Metal Complexes

Abstract

Spectrophotometric procedure is described for the quantitative determination of diphenadione [2-(diphenylacetyl)-1,3-indandione], based on direct spectrophotometric measurements of the absorbances of its iron (III), iron (II) and cobalt (II), metal complexes at 488 nm, 505 nm and (334 nm, 372 nm), respectively. The drug reacts with metals in the ratio of 3:1 and 2:1 for iron (III) and for both iron (II) and cobalt (II) respectively. The obtained complexes have apparent molar absorptivities of 1.48 × 10³ 1 mol^?1 cm^?1, 0.714 × 10³ 1 mol^?1cm^?1 and (1.70 × 10³ 1 mol^?1cm^?1, 1.93 × 10³ 1 mol^?1cm^?1) for iron (III), iron (II) and cobalt (II) complexes, respectively. The procedure is suggested for the determination of 51–400 μg.ml^?1 diphenadione via the iron (II) complex and 35–170 μg.ml^?1 diphenadione via both cobalt (II) and iron (III) complexes. The suggested procedure has accuracies of 99.79 ± 0.67%, 99.64 ± 0.37% and (100.09 ± 0.53%, 99.99 ± 0.42%) for the metal complexes of iron (III), iron (II) and cobalt (II), respectively.     

D-氨基葡萄糖Schiff碱及其金属配合物的抗菌活性

The effects of D-glucosamine schiff base and its metal complexes on the growth of Aerobacter aerogenes were investigated by the microcalorimetry. Among the substances tested. Zn-SG was shown to be the most bacteriostasic, followed by Zn-o-VG and SG (with the Ic50 of 242, 287 and 320 μg•mL-1, respectively). Cu(Ⅱ)-SG showed less inhibitory effect on Aerobacter aerogenes over the concentration rang of 50~300μg•mL-1.     

席夫碱及其金属配合物的合成及生物活性研究进展

席夫碱及其金属配合物具有独特的抗菌、抗肿瘤和抗氧化等生物活性.为筛选高效低毒的药物,人们合成了大量不同类型的席夫碱及其金属配合物并对其生物活性进行了研究.本文综述了近年来席夫碱及其金属配合物的合成,以及在抗菌、抗氧化、抗肿瘤等方面生物活性的研究进展,并为进一步研究其在医药领域的应用提供了信息支持.     

Polymer Effect on Catalysis by Macromolecules/Transition Metal Complexes

The present status of research in the field of macromolecules/transition metal complexes is critically reviewed on the basis of selected examples both from the authors′ laboratories and other laboratories around the world. The substantial lack of inertness of the polymeric ligand (the polymer effect) is examined and shown to occur in most cases during preparation of the macromolecule/transition metal complex as well as during its catalytic use. This behavior is attributed and confirmed as due to the polydentate ligand character of the macromolecules and to the effect of physical and chemical parameters which can be varied over large ranges. Future work is duscussed for the development of the field in suitable directions.     

Effect of Metal Alkoxide Complexes on Condensation Reactions of Hydrolyzed Phenyltriethoxysilane

Metal alkoxide complexes, in which alkoxy groups were substituted with ethyl acetoacetate (EAcAc), were found to accelerate condensation reactions of hydrolyzed phenyltriethoxysilane (PTES) and affect the structure of phenylsiloxane networks. The ²⁹Si NMR study revealed that the acceleration effect increased in the order Al(O-sec-C₄H₉)_3–x (EAcAc) _x < Ta(OC₂H₅)_5–x (EAcAc)_x < Ti(OC₂H₅)_4–x (EAcAc) _x . However, the GPC study revealed that the solution contained the high molecular weight species in the order Al(O-sec-C₄H₉)_3–x (EAcAc) _x < Ti(OC₂H₅)_4–x (EAcAc) _x < Ta(OC₂H₅)_5–x (EAcAc) _x . In the case of Ti(OC₂H₅)_4–x (EAcAc) _x , the smaller size of phenylsiloxane networks with a low content of silanol groups was formed in the solution. In the case of Ta(OC₂H₅)_5–x (EAcAc) _x , the larger size of phenylsiloxane networks with a high content of silanol groups was formed in the solution. In the case of Al(O-sec-C₄H₉)_3–x (EAcAc) _x , the small size of phenylsiloxane networks with a high content of silanol groups was formed in the solution. During gelation, the catalytic effect of the metal alkoxide complexes on the development of phenylsiloxane networks was also found. However, the average molecular weight of the gels increased in the order Ta(OC₂H₅)_5–x (EAcAc) _x < Ti(OC₂H₅)_4–x (EAcAc) _x Al(O-sec-C₄H₉)_3–x (EAcAc) _x . The metal alkoxide complexes were hydrolyzed and finally incorporated into the phenylsiloxane networks of gels to form M—O—Si bonds, which were indicated by the results of FT-IR analysis.     

Effect of Temperature on the Nucleation and Growth of Precious Metal Nanocrystals

Understanding the effect of physical parameters (e.g., temperature) on crystallisation dynamics is of paramount importance for the synthesis of nanocrystals of well‐defined sizes and geometries. However, imaging nucleation and growth is an experimental challenge owing to the resolution required and the kinetics involved. Here, by using an aberration‐corrected transmission electron microscope, we report the fabrication of precious metal nanocrystals from nuclei and the identification of the dynamics of their nucleation at three different temperatures (20, 50, and 100 °C). A fast, and apparently linear, acceleration of the growth rate is observed against increasing temperature (78.8, 117.7, and 176.5 pm min^?1, respectively). This work appears to be the first direct observation of the effect of temperature on the nucleation and growth of metal nanocrystals.     

cAMP及其衍生物金属离子铬合物的核磁共振研究

本文报导用核磁共振谱研究了有重要生理意义的二价金属离子与cAMP及其衍生物双丁酰cAMP的相互作用,比较了环苷酸与金属络合时各谱线的化学位移值和谱线宽度。     

阳离子交换色谱中色谱柱温度对碱金属与碱土金属离子保留的影响

研究了非抑制型阳离子交换色谱中色谱柱温度(25~50℃)对碱金属离子(Li+、Na+、K+、Rb+)和碱土金属离子(Mg2+、Ca2+、Sr2+)以及NH4+保留的影响。在Shim-pack IC-C1磺酸型阳离子交换柱上,以硝酸为流动相分离碱金属离子,以乙二胺或乙二胺-草酸(柠檬酸)为流动相分离碱土金属离子,随着色谱柱温度的升高,碱金属和碱土金属离子的保留时间均增长,其范特霍夫曲线具有良好的线性关系,斜率为负值,表明在此条件下碱金属和碱土金属离子的保留为吸热过程。在Shim-pack IC-SC1羧酸型阳离子交换柱上,以硫酸为流动相同时分离碱金属和碱土金属离子,随着色谱柱温度的升高,Mg2+、Ca2+的保留时间增长,而K+、Rb+的保留时间缩短,Li+、Na+、NH4+的保留时间基本不变。在此条件下,Mg2+、Ca2+、K+和Rb+的范特霍夫曲线具有良好的线性关系,其中Mg2+和Ca2+的曲线斜率为负值,K+和Rb+的曲线斜率为正值,表明Mg2+和Ca2+的保留表现为吸热过程,K+和Rb+的保留表现为放热过程。研究表明在不同固定相和流动相条件下,色谱柱温度对碱金属和碱土金属离子保留行为的影响不同。     

Effect of Linear Benzannelation on the Spectral Appearance of Octaaza Substitution in Phthalocyanine and Its Metal Complexes

The effect of linear benzannelation on the spectral appearance of peripheral octaaza substitution in phthalocyanine molecules in going from tetrapyrazinoporphyrazines to tetra-2,3-quinoxalinoporphyrazines in protic and aprotic solvents, such as H₂SO₄, high-percentage oleum, DMSO, and DMF) is intricate and does not allow the contribution of such ligand modification to be assigned exclusively to decreased electron-acceptor power of its periphery.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1221–1224.Original Russian Text Copyright © 2005 by Korzhenevskii, Markova, Efimova, Koifman.     

Activation of P4 and P2 by Transition Metal Complexes at Room Temperature

The first complex with P ₂ as an eight-electron donor diphosphinidene ligand is 1 , which forms at room temperature from [Cp*(OC)₂Re]₂ and P₄ (Cp*=C₅Me₅). The by-product of this reaction, which has a Re₂P₂ butterfly structure, reacts with [W(CO)₅(thf)] at room temperature to give two multinuclear complexes—one with a ReWP₂ tetrahedrane framework and 2 , whose six atoms Re₂P₂W₂ form a plane and in which the P₂ ligand of the butterfly complex is converted into two µ-P ligands.