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111.
K. Indira Priyadarsini B. Mishra D. K. Maity Hari Mohan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):985-988
Abstract Reactions of oxidizing radicals like hydroxyl (·OH) radical, specific electron transfer agents like N 3 ·, and I 2 ?. radicals were studied with selenourea (SeU) and compared with thiourea (ThU) using pulse radiolysis technique in microsecond time scales. Both the compounds efficiently react with ·OH radicals, however, SeU undergoes easier oxidation by secondary oxidants as compared to ThU. The results were supported by cyclic voltammetry studies. The radical cations of both SeU and ThU formed on oxidation undergo dimerization with the parent molecule to form two-centered three-electron-hemi bonded radical cations absorbing at 410 and 400 nm respectively with the stabilization energies of 21.1 and 20.5 kcal/mol for SeU and ThU, respectively. Preliminary studies indicated that at low concentration of SeU, the dimerization is prevented and the oxidation reaction produced metallic Se nanoparticles. 相似文献
112.
We report the synthesis of pyrene‐ and carboxyfluorescein labeled Cα‐tetrasubstituted amino acids (TAAs). The fluorescent dye can be coupled to the TAA before or after its incorporation into a peptide sequence using a Suzuki‐type C? C bond formation. 相似文献
113.
Semigroup Forum - We study quasi completely regular semirings through their congruence structures. 相似文献
114.
Chen YH Maity AN Pan YC Frey PA Ke SC 《Journal of the American Chemical Society》2011,133(43):17152-17155
Adenosylcobalamin- and pyridoxal-5'-phosphate-dependent lysine 5,6-aminomutase utilizes free radical intermediates to mediate 1,2-amino group rearrangement, during which an elusive high-energy aziridincarbinyl radical is proposed to be central in the mechanism of action. Understanding how the enzyme participates in stabilizing any of the radical intermediates is fundamentally significant. Y263F mutation abolished the enzymatic activity. With isotope-edited EPR methods, the roles of the Tyr263α residue in the putative active site are revealed. The Tyr263α residue stabilizes a radical intermediate, which most likely is the aziridincarbinyl radical, either by acting as a spin-relay device or serving as an anchor for the pyridine ring of pyridoxal-5'-phosphate through aromatic π-stacking interactions during spin transfer. The Tyr263α residue also protects the radical intermediate from interception by molecular oxygen. This study supports the proposed reaction mechanism, including the aziridincarbinyl radical, which has eluded detection for more than two decades. 相似文献
115.
Supramolecular Interactions of Nonsteroidal Anti‐inflammatory Drug in Nanochannels of Molecular Containers: A Spectroscopic,Thermogravimetric and Microscopic Investigation
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Banibrata Maity Aninda Chatterjee Sayeed Ashique Ahmed Dr. Debabrata Seth 《Chemphyschem》2014,15(16):3502-3514
Supramolecular host–guest complexation between the nonsteroidal anti‐inflammatory drug indomethacin (IMC) and molecular containers were investigated. The weakly fluorescent drug molecule becomes highly fluorescent on complexation with different molecular containers, and time‐resolved fluorescence emission spectroscopy reveals that the lifetime components of IMC significantly increase in the presence of molecular containers, compared with the lifetimes in neat water. The respective solid host–guest complexes were synthesised and characterised by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopic analysis. Microscopy techniques were used to analyse modifications of the surface morphology, owing to the formation of supramolecular complexes. The effect of the molecular container on the optical properties of IMC has also been investigated to determine the effect of nanochannels of different size and structure. 相似文献
116.
Light Harvesting and Directional Energy Transfer in Long‐Lived Homo‐ and Heterotrimetallic Complexes of FeII,RuII, and OsII
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Dinesh Maity Chanchal Bhaumik Sourav Mardanya Srikanta Karmakar Dr. Sujoy Baitalik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13242-13252
A new family of trimetallic complexes of the form [(bpy)2M(phen‐Hbzim‐tpy)M′(tpy‐Hbzim‐phen)M(bpy)2]6+ (M=RuII, Os; M′=FeII, RuII, Os; bpy=2,2′‐bipyridine) derived from heteroditopic phenanthroline–terpyridine bridge 2‐{4‐[2,6‐di(pyridin‐2‐yl) pyridine‐4‐yl]phenyl}‐1H‐imidazole[4,5‐f][1,10]phenanthroline (phen‐Hbzim‐tpy) were prepared and fully characterized. Zn2+ was used to prepare mixed‐metal trimetallic complexes in situ by coordinating with the free tpy site of the monometallic precursors. The complexes show intense absorptions throughout the UV/Vis region and also exhibit luminescence at room temperature. The redox behavior of the compounds is characterized by several metal‐centered reversible oxidation and ligand‐centered reduction processes. Steady‐state and time‐resolved luminescence data show that the potentially luminescent RuII‐ and OsII‐based triplet metal‐to‐ligand charge‐transfer (3MLCT) excited states in the triads are quantitatively quenched, most likely by intercomponent energy transfer to the lower lying 3MLCT (for Ru and Os) or triplet metal‐centered (3MC) excited states of the FeII subunit (nonluminescent). Interestingly, iron did not adversely affect the photophysics of the respective systems. This suggests that the multicomponent molecular‐wire‐like complexes investigated here can behave as efficient light‐harvesting antennas, because all the light absorbed by the various subunits is efficiently channeled to the subunit(s) in which the lowest‐energy excited states are located. 相似文献
117.
Super Sensitization: Grand Charge (Hole/Electron) Separation in ATC Dye Sensitized CdSe,CdSe/ZnS Type‐I,and CdSe/CdTe Type‐II Core–Shell Quantum Dots
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Tushar Debnath Partha Maity Dr. Hirendra N. Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13305-13313
Ultrafast charge‐transfer dynamics has been demonstrated in CdSe quantum dots (QD), CdSe/ZnS type‐I core–shell, and CdSe/CdTe type‐II core–shell nanocrystals after sensitizing the QD materials by aurin tricarboxylic acid (ATC), in which CdSe QD and ATC form a charge‐transfer complex. Energy level diagrams suggest that the conduction and valence band of CdSe lies below the LUMO and the HOMO level of ATC, respectively, thus signifying that the photoexcited hole in CdSe can be transferred to ATC and that photoexcited ATC can inject electrons into CdSe QD, which has been confirmed by steady state and time‐resolved luminescence studies and also by femtosecond time‐resolved absorption measurements. The effect of shell materials (for both type‐I and type‐II) on charge‐transfer processes has been demonstrated. Electron injection in all the systems were measured to be <150 fs. However, the hole transfer time varied from 900 fs to 6 ps depending on the type of materials. The hole‐transfer process was found to be most efficient in CdSe QD. On the other hand, it has been found to be facilitated in CdSe/CdTe type‐II and retarded in CdSe/ZnS type‐I core–shell materials. Interestingly, electron injection from photoexcited ATC to both CdSe/CdTe type‐II and CdSe/ZnS type‐I core–shell has been found to be more efficient as compared to pure CdSe QD. Our observation suggests the potential of quantum dot core–shell super sensitizers for developing more efficient quantum dot solar cells. 相似文献
118.
Satarupa Acharjee Tapan Kumar Maity Subir Samanta Supriya Mana Tania Chakraborty Tanushree Singha 《合成通讯》2013,43(23):3015-3024
AbstractThe present study describes the synthesis of novel chalcone based 1-{3-[3-(substituted phenyl) prop-2-enoyl] phenyl} thioureas (4a-c) using Claisen Schmidt condensation and investigates their protective role in diabetic conditions and associated oxidative stress. Spectral properties for the synthesized compounds were studied. Novel compounds were screened for antihyperglycemic effect in streptozotocin (STZ)-induced diabetic rats in a 6?week study and compound 4b exhibited significant (p?≤?.05) results similar to the standard drug glipizide. Treatment of diabetic animals with compound 4b (10 and 20?mg/kg, body weight) for 12?weeks, reduced the increased blood glucose level significantly (p?≤?.01) and restored attenuated serum biochemical parameters to normal levels. Altered antioxidant enzyme activity was also considerably (p?≤?.01) restored to the standard normal range. β-apoptotic TUNEL assay indicated that compound 4b (AI: 1.2?±?0.05) could prevent further β-cell death in the pancreas of diabetic animals in a dose-dependent manner, which highlights its potentiality as an effective antihyperglycemic agent. 相似文献
119.
Krishnendu B. Sahu Arindam Maity Shyamal Mondal Rupankar Paira Pritam Saha Subhendu Naskar Abhijit Hazra Sukdeb Banerjee Nirup B. Mondal 《Journal of heterocyclic chemistry》2013,50(Z1):E148-E155
A basic alumina‐supported microwave assisted simple methodology has been developed for the synthesis of aryl‐heteroaryl methanes (benzylated quinolones) via transition metal catalyzed cross‐coupling reaction of halo substituted polynuclear oxa‐aza quinolones with benzyl indium, an organometallic reagent easily derived from commercially available benzyl bromide. 相似文献
120.
D. Maity S. SenGupta S. Sur 《The European Physical Journal C - Particles and Fields》2005,42(4):453-460
In this work we explore the geodesic deviations of spinning test particles in a string inspired Einstein-Kalb-Ramond background. Such a background is known to be equivalent to a spacetime geometry with torsion. We have shown here that the antisymmetric Kalb-Ramond field has a significant effect on the geodesic deviation of a spinning test particle. A search for observational evidence of such an effect in astrophysical experiments may lead to a better understanding of the geometry of the background spacetime.Received: 5 April 2005, Revised: 19 May 2005, Published online: 8 July 2005 相似文献