共查询到20条相似文献,搜索用时 15 毫秒
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Stoichiometric determination of complexes of La (III) with some derivatives of salicylic acid by monovariation and Job's method of continuous variation have shown formation of 1:3 complex in each case. The dissociation constants of these complexes have been determined by conductometric and spectrophotometric methods. 相似文献
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J. E. Schmidtund J. C. Krantz Jr und D. Henville 《Fresenius' Journal of Analytical Chemistry》1936,106(1-2):79
Ohne Zusammenfassung 相似文献
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《Analytical letters》2012,45(3):573-583
Abstract A procedure based on a spot test for salicylate is presented. The method is simple, rugged and is based on the salycilate native fluorescence measurement on the surface of a filter paper by using optical fibers for light conduction. The fluorescence was linear at concentration range of 0.01–0.4 mmol l?1. The relative standard deviation of 5% (n=10) was observed. Detection and quantification limits were 4 and 14 µmol l?1, respectively. The results obtained in pharmaceutical salicylate determinations showed that practically no statistical difference existed with the pharmacopeical method (95% confidence level). The recovery studies in biological samples spiked with salicylic acid at overdose concentration levels showed that the matrix sample did not interfere in the method. 相似文献
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Ultrasoft pseudopotential was generated for uranium and the plane waves pseudopotential formalism was used to study its crystal structures at zero temperature as a function of pressure. The alpha phases of uranium were fully relaxed. The zero-pressure zero-temperature equilibrium volumes and bulk moduli are consistent with previous calculations, and in excellent agreement with the experiment. This is also the case for cell parameters and pressure-induced phase transitions. In the calculation of NaCl and CaF2 structure type of compound of uranium, the difference of theoretical lattice constant and the experimental value is less than 3%. For UO2+x the trend of the lattice shinking with the x value increase is in accord with the experiment. For large U2C3 and U2N3 complex cells the difference of theoretical lattice constant and the experimental value is less than 3%, and the difference of coordination of atom is less than 5%. 相似文献
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Kabir-ud-Din Nahid Parveen Andleeb Z. Naqvi 《Journal of Dispersion Science and Technology》2013,34(10):1500-1505
It is well known that, like surfactants aggregating at a certain concentration (called critical micelle concentration, CMC), hydrotropes also have minimum hydrotrope concentration (MHC). However, unlike surfactant CMC, this MHC value is usually very high, thereby reducing their application. In this paper we report the results of conductivity and viscosity measurements with a well known hydrotrope sodium salicylate (NaSal) solutions in presence and absence of additives (propanol, PrOH; butanol, BuOH; pentanol, PeOH and tetrabutylammonium bromide, Bu4NBr). We have found that MHC value of NaSal decreases in presence of additives. Alcohols increase the hydrophobic interactions and decrease the MHC while Bu4NBr, in addition to ameliorating the hydrophobic interactions, reduces the charge on head groups and MHC decreases more steeply in its presence. Increased solubility of riboflavin in NaSal containing the above additives corroborates the results. 相似文献
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考察了阳离子、非离子和阴离子表面活性剂存在下水杨酸-2′-乙基己基酯(EHS)的吸收光谱和激发态分子内质子转移(ESIPT)荧光光谱.结果表明,EHS可增溶在胶束中,2′-乙基己基碳链朝向胶束内核,而水杨酸基朝向胶束-水界面;胶柬环境有利于EHS分子对紫外光的吸收和分子内氢键的形成,从而使ESIPT荧光显著增强,激发态分子以发射可见光和非辐射去活化方式衰减;并根据EHS和表面活性剂分子的结构和大小,解释了EHS分子在胶束中的结合位点,荧光猝灭和酯水解的光谱测量进一步为此结合位点提供了佐证. 相似文献
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Moritz K. Jackl Hyeonglim Seo Johannes Karges Mark Kalaj Seth M. Cohen 《Chemical science》2022,13(7):2128
Metalloenzyme inhibitors typically share a common need to possess a metal-binding pharmacophore (MBP) for binding the active site metal ions. However, MBPs can suffer from physicochemical liabilities, impeding the pharmacological properties and drug-likeliness of inhibitors. To circumvent this, problematic features of the MBP can be identified and exchanged with isosteric replacements. Herein, the carboxylic and hydroxyl group of the salicylic acid MBP were replaced and a total of 27 salicylate metal-binding isosteres (MBIs) synthesized. Of these 27 MBIs, at least 12 represent previously unreported compounds, and the metal-binding abilities of >20 of the MBIs have not been previously reported. These salicylate MBIs were examined for their metal-binding features in model complexes, physicochemical properties, and biological activity. It was observed that salicylate MBIs can demonstrate a range of attractive physicochemical properties and bind to the metal in a variety of expected and unexpected binding modes. The biological activity of these novel MBIs was evaluated by measuring inhibition against two Zn2+-dependent metalloenzymes, human glyoxalase 1 (GLO1) and matrix metalloproteinase 3 (MMP-3), as well as a dinuclear Mn2+-dependent metalloenzyme, influenza H1N1 N-terminal endonuclease (PAN). It was observed that salicylate MBIs could maintain or improve enzyme inhibition and selectivity. To probe salicylate MBIs as fragments for fragment-based drug discovery (FBDD), an MBI that showed good inhibitory activity against GLO1 was derivatized and a rudimentary structure–activity relationship was developed. The resulting elaborated fragments showed GLO1 inhibition with low micromolar activity.Metal-binding isosteres (MBIs) of salicylic acid have been developed for metalloenzyme drug development. 相似文献
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《Analytical letters》2012,45(3):425-442
ABSTRACT A microbiosensor is proposed for a quick and easy amperometric determination of salicylate. The methodology involves the use of the enzyme salicylate hydroxylase (SH) to convert salicylate to catechol, which is then oxidised at the carbon fibre electrode. The covalent immobilisation of the enzyme onto a carbon fibre electrode via carbodiimide results in an amperometric biosensor with high sensitivity, low detection limit and good stability. The response of the biosensor is linearly proportional to the salicylate concentration between 1.0 10?7 and 2.0 10?6 mol L?1, at an applied potential of 300 mV vs SCE, with a response time of 3.5 s and a detection limit of 3.3 10?8 mol L?1. The relative standard deviation for the determination was 4.1% for n=10. The biosensor was applied to determine salicylate in urine and pharmaceutical samples and compared to the reference method with a good correlation. 相似文献
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考察了阳离子、非离子和阴离子表面活性剂存在下水杨酸-2’-乙基己基酯(EHS)的吸收光谱和激发态分子内质子转移(ESIPT)荧光光谱. 结果表明, EHS可增溶在胶束中, 2’-乙基己基碳链朝向胶束内核, 而水杨酸基朝向胶束-水界面; 胶束环境有利于EHS分子对紫外光的吸收和分子内氢键的形成, 从而使ESIPT 荧光显著增强, 激发态分子以发射可见光和非辐射去活化方式衰减; 并根据EHS和表面活性剂分子的结构和大小, 解释了EHS分子在胶束中的结合位点, 荧光猝灭和酯水解的光谱测量进一步为此结合位点提供了佐证. 相似文献
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Acetylpyridine thiosemicarbazone, HAPTSC ( 1 ), reacts with uranyl nitrate in MeOH under formation of (H2APTSC)[UO2(NO3)2(μ‐OH)]2 ( 2 ) or [ UO2(APTSC)(MeOH)(MeO)]2 ( 3 ) depending on the experimental conditions applied. Protonation of 1 and precipitation of the [UO2(NO3)2(μ‐OH)]22— dianion as acetylpyridinium thiosemicarbazone salt is observed when the reaction is performed without the addition of a base. The metal atoms are situated in the centres of distorted hexagonal bipyramids. The U—U distance is 3.892(1)Å. Addition of triethylamine results in deprotonation of HAPTSC and the formation of 3 which is an unusual dimer with four methanol/methanolato ligands of two metal sites sharing two protons. The U—U distance in this dimer is 5.313(1)Å. (Bu4N)[UO(APTSC)Cl2] ( 4 ) is obtained when (Bu4N)2[UO2Cl4] is used as precursor. The uranium atoms in 3 and 4 are seven co‐ordinate. Their co‐ordination polyhedra can best be described as pentagonal bipyramids. Compounds 3 and 4 represent the first examples of thiosemicarbazone complexes with actinide elements which haven been studied by X‐ray analysis. 相似文献
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The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the (5s4p3d4f)/[3s3p2d2f] contraction basis sets, and the cores are approximated with the relativistic effective core potential. The results show that the ground electronic state is X9∑+g . The pair potential data are fitted with a Murrell-Sorbie analytical potential function. The U-U embedded atom method (EAM) interatomic potential is deter-mined based on the generalized gradient approximation calculation within the framework of the density functional theory using Perdew-Burke-Ernzerhof exchange-correlation functional at the spin-polarized level. The physical properties, such as the cohesive energy, the lattice constant, the bulk modulus, the shear modulus, the sc/fcc relative energy, the hcp/fcc rela-tive energy, the shear modulus and the monovacancy formation energy are used to evaluate the EAM potential parameters. The U-U pair potential determined by the first principle calculations is in agreement with that defined by the EAM potential parameters. The EAM calculated formation energy of the monovacancy in the fcc structure is also found to be in close agreement with DFT calculation. 相似文献