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1.
M. Al-Amin A. A. Islam M. C. Sheikh M. S. Alam E. Zangrando M. A. Alam M. T. H. Tarafder R. Miyatake 《Transition Metal Chemistry》2014,39(2):141-149
Transition metal complexes ML2 (2–6) [where M = Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and HL = allyl-2-(4-benzyloxyphenylmethylene)hydrazine carbodithioate (1)] have been prepared by the reaction of the ligand with metal ions in 2:1 molar ratio and characterized by physicochemical techniques and spectroscopic methods. The crystal structures of the free ligand and its nickel(II) complex 2 have been determined by X-ray diffractometry. The ligand exists in its thione tautomeric form both in solution and in the solid state. In complex 2, square-planar coordination of nickel(II) was achieved by two chelating ligand moieties coordinating through the azomethine nitrogen and the deprotonated thione sulphur atom. Based on the crystal structures of analogous dithiocarbazate species, a square-planar geometry was assumed for the copper(II) and palladium(II) complexes, and a tetrahedral coordination sphere for the zinc(II) and cadmium(II) derivatives. The in vitro bactericidal activity suggests that the palladium(II) complex is strongly active against two bacteria. The cadmium(II) complex is moderately cytotoxic with an LC50 value of 409 μg/ml, but less active than gallic acid, LC50 = 78 μg/ml. 相似文献
2.
2,3-Dihydroxynaphthalene forms a strong chelate with titanium over the pH range 4 to 9. At pH 4–5, titanium is extracted into ethyl acetate along with iron, leaving behind V, Nb, Mo, and a host of elements present in complex matrices of rock samples. In the extract, titanium is easily separated from iron after raising the pH of the medium and re-extracting. The method is free from any interference. The sensitivity of the method is 3.2×104 L·mol–1cm–1. The method has been applied to a number of diverse samples including rocks and minerals. The precision of the Ti method is excellent. This method has been compared with tiron, chromotropic acid, diantipyrilmethane (DAM) and other existing spectrophotometric methods used in the analysis of rocks, ores and minerals. The proposed method has definite advantages over most spectrophotometric methods in terms of sensitivity, selectivity, reproducibility and simplicity. 相似文献
3.
Tarafder M. Tofazzal H. Asmadi A. Talib Siti M. S. Ali A. M. Crouse K. A. 《Transition Metal Chemistry》2001,26(1-2):170-174
Complexes of S-benzyldithiocarbazate (SBDTC) with lighter and heavier metals, viz., CrIII, FeIII, SbIII, ZrIV, ThIV and UVI have been prepared and characterized by elemental analyses, conductivity measurements, and spectral studies. The complexes: [Cr(SBDTCA)3],** [Fe(SBDTCA)3], [Sb(SBDTCA)3], [Sb(SBDTCA)2Cl · H2O], [Zr(O)(SBDTCA)2 · H2O], [Th(SBDTCA)(NO3)3 · H2O)], and [U(O)2(SBDTCA)2] were all prepared in alkaline media. They were all hexa-coordinated with bidentate, uninegative chelation of the ligand. [Fe(SBDTCA)3], [Sb(SBDTCA)3] and [Sb(SBDTCA)2Cl · H2O] were strongly effective against bacteria giving clear inhibition zones with Pseudomonas aeruginosa and Bacillus cereus. The compounds showed poor antifungal activity. The antimony complexes were strongly cytotoxic against leukemic cells with CD50 values of 3.2–6.7 g cm–3 as compared to the CD50 value of 14.5 g cm–3 of the free SbCl3 molecule. 相似文献
4.
Ivana Kraiselburd Laura Moyano Analía Carrau Josefina Tano Elena G. Orellano 《Photochemistry and photobiology》2017,93(3):666-674
Light is an important environmental signal for almost all living organisms. The light perception is achieved by photoreceptor proteins. As can be observed from the great number of bacterial genomes sequenced, plant pathogenic bacteria encode for a large number of photoreceptor proteins. The physiological implications of these photoreceptors are still poorly characterized. However, recent studies revealed the participation of these photosensory proteins in the pathogenic process. Here, we summarize what is known about these proteins and their role during the virulence process, concluding that the light environment modulates the plant–pathogen interaction. 相似文献
5.
Reenamoni Saikia Chaliha K. Annapurna Anal Tarafder V.S. Tiwari P.K. Gupta Basudeb Karmakar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):243-250
Precursor glass of composition 25K2O–25Nb2O5–50SiO2 (mol%) doped with Er2O3 (0.5 wt% in excess) was isothermally crystallized at 800 °C for 0–100 h to obtain transparent KNbO3 nanostructured glass–ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass–ceramics. The crystallite size of KNbO3 estimated from XRD and TEM is found to vary in the range 7–23 nm. A steep rise in the dielectric constant of glass–ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO3 phase. The measured visible photoluminescence spectra have exhibited green emission transitions of 2H11/2, 4S3/2 → 4I15/2 upon excitation at 377 nm (4I15/2 → 4G11/2) absorption band of Er3+ ions. The near infrared (NIR) emission transition 4I13/2 → 4I15/2 is detected around 1550 nm on excitation at 980 nm (4I15/2 → 4I11/2) of absorption bands of Er3+ ions. It is observed that photoluminescent intensity at 526 nm (2H11/2 → 4I15/2), 550 nm (4S3/2 → 4I15/2) and 1550 nm (4I13/2 → 4I15/2) initially decrease and then gradually increase with increase in heat-treatment time. The measured lifetime (τf) of the 4I13/2 → 4I15/2 transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er3+ ions gradually enter into the KNbO3 nanocrystals. 相似文献
6.
The role of ion-pairing in peak deformations in overloaded reversed-phase chromatography of peptides
Abhijit Tarafder Lars Aumann Massimo Morbidelli 《Journal of chromatography. A》2010,1217(45):7065-7073
The paper reports a study on the role of ion-pairing behind peak deformations, e.g. peak splitting and even peak disappearance, during the elution of a peptide at highly overloaded conditions in reversed-phase chromatography. Deformation of component peaks is not uncommon in chromatography. There are reports which discuss their occurrence, but mostly at analytical scale, while their occurrence is quite common also in the preparative scale, as in the case discussed in this work. This paper first describes the conditions leading to peak splitting and peak disappearance of an industrial peptide, then explains the plausible reasons behind such behaviour, and finally with experimental analysis demonstrates the role of ion-pairing in causing such behaviour. 相似文献
7.
Pranab Kumar Tarafder Susanta Kumar Pradhan Shaswati Roychowdhury 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):527-534
An extractive pellet fluorimetry determination of trace uranium in thorium rich samples has been developed. This is based upon a solvent extraction system which completely separates both the elements uranium and thorium from each other. Thorium as a neutral complex with 2,3-dihydroxynaphthalene at pH 4–6 is extracted into ethylacetate and then uranium-2,3-dihydroxynaphthalene anionic complex is extracted into another batch of ethylacetate at pH 11–12 under the influence of a counter cation, cetyltrimethylammonium ion. This method has been applied for the determination of trace uranium in synthetic nuclear grade thorium oxide and thorium rich mineralized rock with high degree of accuracy and precision. 相似文献
8.
A highly sensitive method for extractive spectrophotometric determination of titanium in silicate rocks is described. Titanium in the range 0-10 microg as TiO2 is extracted into benzene or toluene by the formation of a ternary complex of the metal with thiocyanate (SCN-) and cetyltrimethylammonium bromide (CTA) in the ratio 1:2:2. A deep yellowish-orange ternary complex thus formed is suitable for the determination of titanium at wavelength 421 nm. The optimum colour intensity of this ternary complex was attained when the complex was extracted from an aqueous solution having concentrations of thiocyanate and HCl, in the range, 1.5-2.5 and 1-5 mol L(-1), respectively. The molar absorptivity and Sandell's sensitivity of the extracted species were found to be 1.1-1.0x10(5) L mol(-1) cm(-1) and 0.47 ng cm(-2) (referred to titanium), respectively, at lambda(max) of 421 nm. Except Fe3+, Nb5+ and V5+, no interference was encountered in the estimation of titanium. While up to 10 mg L(-1) Nb and V did not interfere in the determination of titanium, the interference of Fe(3+) was eliminated by reducing it to Fe2+ using SnCl2 solution. The method is highly sensitive and selective. The results obtained for titanium estimation in a host of silicate rock samples have been found to be highly reproducible, accurate and favourably comparable with certified values of reference materials and those obtained from standard methods. 相似文献
9.
With significant advancement in the upstream processing technology, downstream processing of large bio-molecules is becoming the bottle-neck in the production chain. To face this challenge, design and development of efficient separation processes has become crucial. As a step towards boosting the performance of a chromatographic separation process through improved design, we investigated the potential of recycling as a process option. The most important advantage of recycling is that it can be implemented in an existing batch system without any major investment and consultation. Although impure products are recycled in industries, it is done as additional batch, and only then, when the recoverable product is valuable enough to surpass the loss of productivity in running the additional batches. In our study, on the other hand, it was found that a well-designed recycle can not only improve the yield, but also the productivity of a multi-component purification. A series of multiobjective optimization studies were carried out on multi-component separation to comprehend the role of recycling with reference to an industrially relevant problem, i.e. the chromatographic purification step of the production process of calcitonin. 相似文献
10.
Tarafder M. Tofazzal H. Ali Manaf A. Saravanan N. Weng Wong Y. Kumar Saravana Umar-Tsafe N. Crouse Karen A. 《Transition Metal Chemistry》2000,25(3):295-298
Two tridentate Schiff bases having ONS and NNS donor sequences were prepared by condensing S-benzyldithiocarbazate (NH2NHCSSCH2Ph) (SBDTC) with pyridine-2-carboxaldehyde and salicylaldehyde, respectively. Complexes of these ligands with NiII, ZnII, CrIII, CoII, CuII, and SnII were studied and characterized by elemental analyses and various physico-chemical techniques. NiII, CuII, ZnII and SnII complexes were four-coordinate while the CrIII, SrIII and CoIII complexes were six-coordinate. The ONS Schiff base was moderately active against leukemia, while its zinc, antimony and cobalt complexes were strongly active against leukemic cells with DC50 = 0.35–5.00. 相似文献