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891.
Banerjee S Madhusudanan KP Khanuja SP Chattopadhyay SK 《Biomedical chromatography : BMC》2008,22(3):250-253
The applicability of a new mass spectrometric technique, DART (direct analysis in real time) has been studied in the analysis of the calli of Taxus wallichiana. The intact callus samples were directly analyzed by holding them in the gap between the DART source and mass spectrometer for measurements. Five C-14 oxygenated taxoids were characterized from the analysis of the calli of the Taxus wallichiana almost instantaneously. The confirmation of the structures of the identified taxoids was made through their accurate molecular formula determinations. 相似文献
892.
Subhra Basak Soma Sen C. Marschner J. Baumgartner Stuart R. Batten David R. Turner Samiran Mitra 《Polyhedron》2008
Two new Cd(II) complexes, having one binuclear structure [Cd2(L)2(Cl)2] (1) and another azido bridged one-dimensional zig-zag polynuclear network [Cd3(μ1,1-N3)4(L)2{H2N(CH2)2N(C2H5)2} · H2O]n (2) have been synthesized from a tridentate N2O donor Schiff base ligand LH, [LH = (OCH3)(OH)C6H3CHN(CH2)2N(C2H5)2], which is the condensation product of 2-hydroxy-4-methoxybenzaldehyde and 2-diethylaminoethylamine. Both the complexes 1 and 2 have been characterized by elemental analyses, IR & 1H NMR spectroscopy, TGA and fluorescence studies. Finally their structures have been established by single crystal X-ray diffraction method. Structural study reveals that in the complex 1, two Cd(II) centers are held together by two μ2-phenolato oxygen atoms and the terminal chlorine atom occupies the apical site of the square pyramidal environment of each metal center. In case of complex 2, the trinuclear asymmetric unit contains octahedral Cd(II) centers which are further held together by doubly end-on azido bridging to form a zig-zag polynuclear structure. It also displays intraligand 1(π–π∗) fluorescence and can potentially serve as photoactive material. 相似文献
893.
A simple procedure for the synthesis of substituted (E)-2-alkene-4-ynecarboxylic esters has been achieved using hydroxyapatite-supported palladium as efficient catalyst surface. The catalyst is recycled, and the turnover number (TON) based on Pd is 16000. A naphthyl-substituted derivative gives very intense fluorescence emission. 相似文献
894.
Graphite epoxide 总被引:1,自引:0,他引:1
Chattopadhyay J Mukherjee A Hamilton CE Kang J Chakraborty S Guo W Kelly KF Barron AR Billups WE 《Journal of the American Chemical Society》2008,130(16):5414-5415
Oxidation of graphite may be carried out by reaction with meta-chloroperoxybenzoic acid to yield graphite epoxide. Scanning tunneling microscopy (STM) showed that the functionalization occurs at the edges rather than on the basal plane of the graphite. Quantification of the epoxide content is possible through the deepoxidation reaction using MeReO3/PPh3. 相似文献
895.
Sanpui P Pandey SB Ghosh SS Chattopadhyay A 《Journal of colloid and interface science》2008,326(1):129-137
Purified recombinant green fluorescent protein (GFP) expressed in E. coli was used for single-step synthesis of gold nanoparticles (Au NPs) with extraordinary size specificity in aqueous medium. The fluorescence of GFP offered a probe for concomitant changes in the protein during the course of synthesis, in addition to the monitoring of the time-dependent formation of Au NPs by the surface plasmon resonance. Reaction of AuCl−4 with the protein produced spherical Au NPs having diameters ranging from 5–70 nm. Remarkably, addition of 1.0×10−5 M AgNO3 in the medium produced uniform spherical Au NPs with particle diameter of 2.2±0.5 nm. Fluorescence spectroscopic measurements suggest that during synthesis of Au NPs in absence of AgNO3, partial denaturation of the protein occurred resulting in the lowering of fluorescence intensity. On the other hand, when the NPs were synthesized in the presence of AgNO3 complete denaturation of the protein with complete loss of fluorescence could be observed, which was further confirmed by native and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). However, use of AgNO3 only resulted neither in the formation of NPs nor had any significant effect on the fluorescence of GFP. 相似文献
896.
We introduce a simple and efficient strategy to enhance the efficiency of a quenching-based fluorosensor for metal ions by several orders of magnitude by using commercially available anionic surfactants varying hydrophobic chain length. Anionic surfactants with a proper choice of hydrophobic chain length at their optimum concentrations are efficient to boost up the efficiency of copper ion sensor dramatically. This simple and convenient strategy is, in general, applicable to quenching-based fluorosensors, new or established, in aqueous solution. It is powerful enough to transform a virtually non-sensor fluorophore to a sensor with a commendable efficiency with the help of proper surfactant. Thus, in this communication, light has been thrown on the application of surfactants toward increasing fluorosensing efficiency of a quenching based sensor. 相似文献
897.
Aurkie Ray Sambuddha Banerjee Soma Sen Ray J. Butcher Georgina M. Rosair Maria T. Garland Samiran Mitra 《Structural chemistry》2008,19(2):209-217
Three new coordination complexes of Zn(II) and Mn(II) have been synthesised using two different tridentate N,N,O donor hydrazone ligands, Hpbh and Hacpbh respectively. The complexes [Zn(pbh)2] (1) and [Zn(acpbh)2] (2) have been synthesized by the treatment of ZnSO4 · 7H2O with Hpbh and Hacpbh hydrazone ligands, respectively. The Mn(II) complex [Mn(acpbh)2] (3) was obtained on reacting Mn(NO3)2 · 4H2O with the ligand Hacpbh. The ligands Hpbh and Hacpbh were prepared by condensing pyridine-2-carboxaldehyde and 2-acetylpyridine with benzhydrazide respectively. Inspite of varying the carbonyl functionality attached to the pyridine moiety present in the hydrazone ligands in both the Schiff bases, we obtained three mononuclear complexes 1, 2, and 3 which were clearly characterized from single crystal X-ray diffraction studies. Spectroscopic investigations like IR and UV/Vis have been carried out for 1, 2, and 3. Fluorescence studies have been performed for 1 and 2. For 3 cyclic voltammetry, room temperature magnetic study and EPR measurements have been recorded. 相似文献
898.
Effect of surfactant chain length on the binding interaction of a biological photosensitizer with cationic micelles 总被引:1,自引:0,他引:1
Chakrabarty A Das P Mallick A Chattopadhyay N 《The journal of physical chemistry. B》2008,112(12):3684-3692
Steady-state and time-resolved fluorometric techniques have been exploited to study the photophysical and distribution behavior of an efficient cancer cell photosensitizer, norharmane (NHM), in well-characterized, biomimicking nanocavities formed by cationic micelles with varying surfactant chain length. Amphiphiles like dodecyl trimethyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB), and cetyl trimethyl ammonium bromide (CTAB) have been used for the purpose. Emission behavior of NHM is very much dependent on the surfactant concentration as well as their hydrophobic chain length. The binding constant (K) and free-energy change (DeltaG) for the interaction of NHM with the cationic micelles have been determined from the fluorescence data. Polarity of the microenvironment around the probe has been determined in the cationic micellar environments from a comparison of the variation of fluorescence properties of the two-prototropic species of the probe in water/dioxane mixture with varying composition. Experimental results demonstrate that the variation in the cationic surfactant chain length plays an important role in promoting a specific prototropic form of the probe molecule. Fluorescence decays are biexponential in all the micelles indicating that the probe molecules are distributed between the two distinct regions of the micelles. The population of the component with a longer lifetime corresponds to the probe in the head group site, while the short-lived component comes from the probe bound to the core region of the micelles. On the basis of the lifetime measurements, the partitioning behavior of the chromophore in the head group and in the core regions in the micelles has been determined. 相似文献
899.
Armstrong DS Arvieux J Asaturyan R Averett T Bailey SL Batigne G Beck DH Beise EJ Benesch J Bimbot L Birchall J Biselli A Bosted P Boukobza E Breuer H Carlini R Carr R Chant N Chao YC Chattopadhyay S Clark R Covrig S Cowley A Dale D Davis C Falk W Finn JM Forest T Franklin G Furget C Gaskell D Grames J Griffioen KA Grimm K Guillon B Guler H Hannelius L Hasty R Allen AH Horn T Johnston K Jones M Kammel P Kazimi R King PM Kolarkar A Korkmaz E Korsch W Kox S Kuhn J Lachniet J Lee L Lenoble J 《Physical review letters》2007,99(9):092301
900.
Basu AK Chattopadhyay P Roychoudhuri U Chakraborty R 《Bioelectrochemistry (Amsterdam, Netherlands)》2007,70(2):375-379
The development of a cholesterol biosensor by co-immobilization of cholesterol esterase (ChEt) and cholesterol oxidase (ChOX) on oxygen electrode is described. The electrode consists of gold cathode and Ag/AgCl anode. The enzymes were immobilized by cross-linking with glutaraldehyde and Bovine Serum Albumin (BSA). The immobilized enzymatic membrane was attached to the tip of the electrode by a push cap system. The optimum pH and temperature of the sensor was determined, these are 6 and 25 degrees C respectively. The developed sensor was calibrated from 1-75 mg/dl of cholesterol palmiate and found linear in the range of 2-50 mg/dL. The calibration curve was drawn with V(i) (ppm/min)(initial velocity) vs different concentrations of cholesterol palmiate (mg/dL). The application of the sensor to determine the total cholesterol in different real food samples such as egg, meat was investigated. The immobilized enzymatic layer can be reused over 30 times and the stability of the enzymatic layer was studied up to 9 weeks. 相似文献