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131.
Moloy Sarkar Raghavendra Yellampalli Bhaswati Bhattacharya Ravi Kumar Kanaparthi Anunay Samanta 《Journal of Chemical Sciences》2007,119(2):91-97
Fluorescence behaviour of 4-benzoylamido-N-methylphthalimide (1), designed and developed for selective detection of fluoride ions, is reported. 1 displays F−-induced colour change that allows its detection with the naked eye. The F− specificity of the sensor system is evident from the fact that unlike F−, other halides do not affect the absorption characteristics of 1. Apart from the colorimetric response, the fluorescence output of 1 is also modulated by F− in a manner that permits ratiometric fluorescence signalling of F− as well. It is found that the system can detect F− in the concentration range of 10–60 μM. The results of the experiments and theoretical calculations unambiguously suggest that the changes of the electronic absorption
and fluorescence behaviour of 1, which have been exploited for signalling purpose, are due to F−-induced deprotonation of the 4-amido moiety of the sensor system. 相似文献
132.
L.A. Farina X. Bai . Kurdak S. Chakrabarti P. Bhattacharya M.Shayegan 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):187
We have fabricated devices on GaAs/AlGaAs heterostructures, containing two-dimensional electron gases, that consist of three point contacts surrounding an etched antidot with an Al/AlOx/Al single electron transistor. The single electron transistor measurement shows rearrangement of neighboring charged impurities with a characteristic stability time scale of 20 s in one device and greater than 1 h in a second device. We also measured the resistance of the point contact–antidot constriction versus magnetic field. In a device with a 20 s stability time, we see a high noise level and poor reproducibility. In a device with a long stability time, much greater than 1 h, we are able to see reproducible features including Aharonov–Bohm oscillations. 相似文献
133.
Salicylaldehyde thiosemicarbazone (H2saltsc) reacts with [M(PPh3)3X2] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh3)2(Hsaltsc)2], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered
chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh3)3X2] also affords complexes of similar type, viz. [M(PPh3)2(bztsc-R)2], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming
a four-membered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)2X2] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)2(bztsc-R)]+, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure
of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason
for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)2X2] to afford the [M(bpy)2(actsc)]ClO4 complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donorformingafive-membered chelate ring. Reaction
of H2saltsc has been carried out with [Ru(bpy)2Cl2] to prepare the [Ru(bpy)2(Hsaltsc)]ClO4 complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [Ru(bpy)2(saltsc-H)4Ni4](ClO4)4. 相似文献
134.
Madhuri Mukhopadhyay Debi Banerjee Aleksander Koll Aleksander Filarowski Samaresh Mukherjee 《Chemical physics letters》2006,420(4-6):316-320
The effect of neutral, cationic and anionic micellar environments on the ground and excited state proton transfer reactions of salicylidine-3,4,7-methyl amine (SMA) in water has been studied by steady state and time resolved fluorescence spectroscopy. In the ground state, the formation of the primary form of SMA is enhanced at the expense of the zwitterionic species due to micellization. In the excited state, anion formation decreases both in the presence of Triton-X and cetyl trimethyl ammonium bromide (CTAB). However, in the presence of sodium dodecyl sulphate (SDS), the anionic emission increases after reaching a certain micellar concentration. The lifetime of the anion is significantly reduced in CTAB compared to that in the bulk water and also in the presence of Triton-X. It is proposed that the destabilization and modification of SMA anion occurs due to the different electrostatic environments produced by micellization. 相似文献
135.
136.
As in the case of reinforcing filler-induced increase in hysteresis in rubbers, placement of aluminum (A1) foil to the surface of a rubber blend of epichlorohydrin rubber and carboxylated nitrile base induces increased hysteresis of the rubber due to adhesion between Al and the rubber blend. Changes in hysteresis loss due to Al foil can be correlated with the peel strength of Al-rubber-Al joints. © 1995 John Wiley & Sons, Inc. 相似文献
137.
In this paper, we propose a scheme for the generation of low phase noise tunable mm-wave signal by beating two lightwaves in a photodiode. These two lightwaves are made phase coherent by an optoelectronic phase locked loop.Calculated mm-wave power at a frequency of 60 GHz is found to be -4 dBm. 相似文献
138.
139.
A. Gulyani R. Srinivasa Gopalan G. U. Kulkarni S. Bhattacharya 《Journal of Molecular Structure》2002,616(1-3)
9-Anthryl and 1-pyrenyl terpyridines (1 and 2, respectively), key precursors for the design of novel fluorescent sensors have been synthesized and characterized by 1H NMR, mass spectroscopy and X-ray crystallography. Twisted molecular conformations for each 1 and 2 were observed in their single crystal structures. Energy minimization calculations for the 1 and 2 using the semi-empirical AM1 method show that the ‘twisted’ conformation is intrinsic to these systems. We observe interconnected networks of edge-to-face CHπ interactions, which appear to be cooperative in nature, in each of the crystal structures. The two twisted molecules, although having differently shaped polyaromatic hydrocarbon substituents, show similar patterns of edge-to-face CHπ interactions.The presently described systems comprise of two aromatic surfaces that are almost orthogonal to each other. This twisted or orthogonal nature of the molecules leads to the formation of interesting multi-directional ladder like supramolecular organizations. A combination of edge-to-face and face-to-face packing modes helps to stabilize these motifs. The ladder like architecture in 1 is helical in nature. 相似文献
140.