Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Excited State Prototropic Activities in 2-Hydroxy 1-Naphthaldehyde

Abstract: Excited state proton transfer in 2-hydroxy 1-naphthaldehyde (HNL) has been reported on the basis of steady state absorption and emission, time-resolved emission, and semiempirical quantum chemical calculations. The existence of open and closed ring conformers in the ground state gives rise to different emissions upon excitation in hydroxylic and hydrocarbon solvents, respectively. Formation of the ground state HNL ion in open conformer was observed with addition of base. Excitation of the closed conformer leads to intramolecular proton transfer across the preexisting intramolecular hydrogen bond to give excited zwitterion in hydrocarbon solvents. On excitation of the open ring conformer in hydroxylic solvents, emission from the neutral excited state could be observed for the first time apart from the emission of ionic intermolecular proton transfer species. An increase or decrease in pH results in enhancement or a decrease of emission from the ionic conformer with parallel dwindling or intensification of ...

Tuning of Organic Reversible Switching via Self‐Assembled Supramolecular Structures

Abstract: Single-layer devices based on Rose Bengal show large conductance switching between the on and off states (on/off ratio =10 4 ) in the pristine form. Rose Bengal molecules have been incorporated into different water soluble "host" polymer-based supramolecular matrices by layer-by-layer electrostatic self-assembly. Different ionic groups in the supramolecular structures tune the leakage current and the on/off ratio by several orders of magnitude. The switching devices may be used in random-access and read-only memory applications.

A New Facile Synthesis of Tungsten Oxide from Tungsten Disulfide: Structure Dependent Supercapacitor and Negative Differential Resistance Properties.

Abstract: Tungsten oxide (WO3 ) is an emerging 2D nanomaterial possessing unique physicochemical properties extending a wide spectrum of novel applications which are limited due to lack of efficient synthesis of high-quality WO3 . Here, a facile new synthetic method of forming WO3 from tungsten sulfide, WS2 is reported. Spectroscopic, microscopic, and X-ray studies indicate formation of flower like aggregated nanosized WO3 plates of highly crystalline cubic phase via intermediate orthorhombic tungstite, WO3. H2 O phase. The charge storage ability of WO3 is extremely high (508 F g-1 at current density of 1 A g-1 ) at negative potential range compared to tungstite (194 F g-1 at 1 A g-1 ). Moreover, high (97%) capacity retention after 1000 cycles and capacitive charge storage nature of WO3 electrode suggest its supremacy as a negative electrode of supercapacitors. The asymmetric supercapacitor, based on the WO3 as a negative electrode and mildly reduced graphene oxide as a positive electrode, manifests high energy density of 218.3 mWhm-2 at power density 1750 mWm-2 , and exceptionally high power density, 17 500 mW m-2 , with energy density of 121.5 mWh m-2 . Furthermore, the negative differential resistance (NDR) property of both WO3 and WO3 .H2 O are reported for the first time and NDR is explained with density of state approach.

In2S3 Micropompons and Their Conversion to In2O3 Nanobipyramids: Simple Synthesis Approaches and Characterization

Abstract: In2S3 micropompons composed of randomly oriented flakes of ∼10 nm thickness were synthesized in high yield by a facile hydrothermal process. When the product was thermally oxidized at 600 °C, single crystalline well-faceted body-centered cubic (bcc) In2O3 bipyramids of sizes between 50 and 300 nm were obtained. It was proposed that the growth of the In2S3 nanoflakes was initially controlled by the Ostwald ripening process, and finally the aggregation of the flakes led to the development of the micropompons. The growth of the In2O3 bipyramids from the In2S3 micropompons started with the formation of In2O3 nulclei at the surface of the micropompons causing the destruction of the flakelike structure to produce In2O3 bipyramids. The micropompons showed good optical properties due to a strong quantum confinement effect. In2O3 bipyramids showed near-band-edge (NBE) UV emission, which was mainly attributed to the high crystal quality of the bipyramids. The study may provide guidance for the morphology controllab...

Optical absorption by nanoparticles of Cu2O

Abstract: Cuprous oxide (Cu2O) particles coated with polyacrylamide having diameters in the range from 4.8 to 8.6 nm were prepared by a chemical method. The optical absorption of these particles was found to be characterized by excitons with corresponding energies varying from 2.6 to 2.25 eV in the particle size range mentioned above. A second optical-absorption maximum signifying surface states within the band gap is exhibited by the specimens with relevant energies varying from 2.6 to 1.77 eV in this particle size range.