Somobrata Acharya | Indian Association for the Cultivation of Science (original) (raw)

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Papers by Somobrata Acharya

Journal of Physics: Conference Series, 2017

Graphene is a promising material in the field of solid-state gas sensors due to the unique twodim... more Graphene is a promising material in the field of solid-state gas sensors due to the unique twodimensional structure. Here, we have shown by fabricating graphene/ZnS-CdS heteronanowire structure, the gas sensor sensitivity has a twofold increase to 20% under 15 ppm gaseous concentration compared to a 10% response in pristine graphene. Spectroscopy and microscopy analysis indicate that the semi-conducting ZnS-CdS hetero-nanowires are 2 nm wide and densely packed on top of graphene. By combining UV illumination, the device approaches a fast response/recovery and high gas sensitivity, thus has a potential to be used in a detection of wide range of gases.

Journal of Materials Chemistry C, 2021

We report on colloidal synthesis of quaternary alloyed I–II–VI2 copper cadmium sulfide selenide q... more We report on colloidal synthesis of quaternary alloyed I–II–VI2 copper cadmium sulfide selenide quantum dots (QDs) with bright, stable photoluminescence. We fabricate transparent, flexible optical waveguide to transmit photoluminescence of the QDs.

Because of the emergence of multidrug-resistant pathogenic bacteria, there is a growing interest ... more Because of the emergence of multidrug-resistant pathogenic bacteria, there is a growing interest for the development of an efficient alternative to antibiotics. Gold nanoparticles (AuNPs) are promising candidates due to their inherent non-toxicity and can be used as effective carriers of drugs. Cholera caused by Gram-negative Vibrio cholerae is still a potential threat in many developing countries. Virstatin, a small molecule, has been reported to inhibit virulence regulation in V. cholerae. Herein, we report an efficient synthesis of virstatin-conjugated gold nanoparticles (VL-AuNPs) and their antibacterial efficacy against the El Tor biotype of V. cholerae (VcN16961). The spherical-shaped NPs have an average diameter of ∼17 nm. The uniqueness of VL-AuNPs relies in the enhanced antibacterial efficacy compared to virstatin, as evidenced from the inhibitory concentration obtained from growth kinetics, and attributed to the inhibition of ATPase activity and DNA damage. More importantly, the expression of cholera toxin, the most important virulence factor of V. cholera, is reduced to a far greater extent than by any of the component molecules. The effect of VL-AuNPs on VcN16961 was monitored using various assays such as confocal microscopy, FACS, fluorescence spectroscopy, and so on. Overall, VL-AuNPs could be a potential candidate for the use as an effective agent for combating diarrheal diseases caused by V. cholera.

Nanoscale, 2020

Fully transparent perovskite microwire arrays passivated with supramolecular assembly for stable ... more Fully transparent perovskite microwire arrays passivated with supramolecular assembly for stable and high-performance photodetectors.

Macromolecules, 2018

Efficient light emitting diodes (LEDs) derived from organic π-conjugated polymers are in the cent... more Efficient light emitting diodes (LEDs) derived from organic π-conjugated polymers are in the center of light generating research. Facile fabrication of true color blue LEDs is challenging. Herein, for the first time, we report the synthesis of highly soluble new π-conjugated polymers 1,4-polynaphthalenes with high molecular weight following a Ni(0)-mediated Yamamoto coupling reaction. The designed polymer shows a color pure blue luminescence with a high quantum yield of ∼80% in solution and ∼34% in thin film. We demonstrate solution-processed fabrication and ambient condition operation of LEDs using 1,4polynaphthalene as the active layer. True color blue electroluminescence from the LEDs with CIE coordinates (0.16, 0.08) meets the criteria of the National Television Standards Committee (NTSC) for efficient displays.

The Journal of Chemical Physics, 2008

We have examined the electronic structure and bonding of the Mn2 molecule through multireference ... more We have examined the electronic structure and bonding of the Mn2 molecule through multireference variational calculations coupled with augmented quadruple correlation consistent basis sets. The Mn atom has a 6S(4s23d5) ground state with its first excited state, 6D(4s13d6), located 2.145 eV higher. For all six molecular states 1Sigmag+, 3Sigmau+, 5Sigmag+, 7Sigmau+, 9Sigmag+, and 11Sigmau+(1) correlating to Mn(6S)+Mn(6S), and for six

Journal of Solid State Chemistry, 2020

Aggregation behavior of luminophores is a subject of great interest over more than half a century... more Aggregation behavior of luminophores is a subject of great interest over more than half a century. Aggregation generally causes quenching of luminescence of luminophores, which is detrimental for the solid state electroluminescence device fabrication. In oppose to the aggregation caused quenching, aggregation-induced emission phenomenon leads to highly luminescence state of luminophores upon aggregate formation. However, aggregation-induced emission behavior of the luminophores is commonly observed in irregular bulk solids, by adding antisolvents into a solution or in the biological cells, where the state of aggregation remains uncontrolled. Here we report on the synthesis of a new tailor made luminogen, 4 0 ,4 000-(2,2-bis(4-methoxyphenyl)ethene-1,1diyl)bis([1,1 0-biphenyl]-4-carbaldehyde) (TPE 2) using Suzuki coupling reaction with high yield. We form the well-controlled supramolecular aggregates of TPE 2 at the airÀwater interface of a Langmuir trough. As a consequence, the mono-and multilayer LangmuirÀBlodgett films of TPE 2 show a large enhancement of luminescence in comparison to the solution phase owing to the aggregation-induced emission phenomenon. We reveal inherent interaction of TPE 2 complexes within the supramolecular aggregates using density functional theory. This unique feature of luminescence enhancement is utilized for the fabrication of light-emitting diodes with low threshold voltage using TPE 2 as active layer. This study opens up the advantage of ordered supramolecular assembly to achieve optimal luminescence performances.

New Journal of Chemistry, 2005

We study Langmuir and Langmuir Blodgett (LB) films of several strong NLO (nonlinear optical) acti... more We study Langmuir and Langmuir Blodgett (LB) films of several strong NLO (nonlinear optical) active amphiphilic derivatives of 1,3-indandione-5,6-dicarboxylic acid. The surface pressure-area (π-A) isotherms at the air-water interface are investigated at different temperatures and pH values. Non-centrosymmetric Z-type LB films are deposited. UV-visible spectra indicate a uniform film transfer. The orientation of the molecular transition moments is calculated from the polarized UV-visible spectra. Packing within the LB films is observed by UV-visible absorption and fluorescence spectroscopy. The morphology of the LB films is examined by AFM and compared to ellipsometric measurements, and the nature of the films is studied by contact angle measurements. Significant second harmonic generation (SHG) by the LB films is observed. Alternate layer Y-type LB films of two different dyes are fabricated to achieve enhanced stability and SHG.

Nano Letters, 2007

Ultranarrow (1.8 nm) PbS nanowires are synthesized in a single step, under benchtop conditions at... more Ultranarrow (1.8 nm) PbS nanowires are synthesized in a single step, under benchtop conditions at relatively low temperature (90°C). The nanowires exhibit a nearly perfect crystal lattice, high width uniformity, and tight side-by-side registry. Two-dimensional (2D) assembly over large areas (>15 µm 2) is achieved using the Langmuir Blodgett method. The wire width can be readily controlled in the range 1.8−10 nm by a surface pressure-induced coalescence reaction, as monitored by transmission electron microscopy and Raman spectroscopy. The fluorescence of the 2D assembly shows strong polarization dependence along the long axis of the wires, making the system potentially suitable for orientationsensitive devices.

The Journal of Physical Chemistry Letters, 2019

Materials Research Express

Journal of Nanoscience and Nanotechnology

Materials Horizons

Self-assembled mesoporous fullerene C70 cube-shaped crystals with crystalline frameworks displaye... more Self-assembled mesoporous fullerene C70 cube-shaped crystals with crystalline frameworks displayed enhanced PL intensity (around 15 times higher intensity compared to bulk C70) due to the high degree of crystallinity in their pore walls.

Angewandte Chemie International Edition

Small, 2017

Aggregation-induced emission (AIE) is commonly observed in irregular bulk form. Herein, unique ag... more Aggregation-induced emission (AIE) is commonly observed in irregular bulk form. Herein, unique aggregation properties of an AIE-active complex into branched supramolecular wires are reported for the first time. Mono-cyclometalated Ir(III) complex shows in-plane J-aggregation at the air-water interface owing to the restriction of intramolecular vibration of bidentate phenylpyridinato and intramolecular rotations of monodentate triphenylphosphine ligands at air-water interface. As a consequence, a large enhancement of luminescence comparable to the solid state is obtained from the monolayers of supramolecular wires. This unique feature is utilized for the fabrication of light-emitting diodes with low threshold voltage using supramolecular wires as active layer. This study opens up the need of ordered assembly of AIE complexes to achieve optimal luminescence characteristics.

The Journal of Physical Chemistry C, 2016

RSC Adv., 2016

A facile strategy to synthesize polymer based conjugation of methylglyoxal which demonstrated inh... more A facile strategy to synthesize polymer based conjugation of methylglyoxal which demonstrated inhibition against malignant cells with desired selectivity can revolutionize the cancer treatment via minimizing the human health risks.