Showing papers by "Badiadka Narayana published in 2019"

Third-order nonlinear optical studies of two novel chalcone derivatives using Z-scan technique and DFT method

Abstract: The present study reports the theoretical and experimental investigations of nonlinear optical properties of two novel chalcone derivatives namely (2E)-1-(Anthracen-9-yl)-3-(4-methoxyphenyl) prop-2-en-1-one (methoxy-ANC) and (2E)-1-(Anthracen-9-yl)-3-(4-ethoxyphenyl)prop-2-en-1-one (ethoxy-ANC). The theoretical calculations performed by density functional theory have been supported by the obtained experimental results. The FT-IR, FT-Raman and UV–visible absorption spectra were recorded and analysed. The optimized geometry, vibrational wavenumbers, HOMO-LUMO energy gap, Natural Bond Orbital (NBO) analysis, Natural Population Analysis (NPA) were computed by B3LYP level of theory with 6-311++G (d,p) basis set. The theoretical second-order hyperpolarizability were calculated using B3LYP and CAM-B3LYP hybrid functional. The third-order nonlinear optical properties, along with the optical limiting behaviour and laser damage threshold studies were carried out by Z-scan technique using Q-switched Nd: YAG laser with 5 ns pulses at 532 nm.

Synthesis of anisotropic silver nanoparticles using silk fibroin: characterization and antimicrobial properties

Abstract: In the present investigation, anisotropic silver nanoparticles (AgNPs) were synthesized using silk fibroin (SF) obtained from Bombyx mori silk without any reducing agent under UV-B environment. The...

Design and fabrication of environmentally benign cellulose based hydrogel matrix for selective adsorption of toxic dyes from industrial effluvia

Abstract: The present study investigates the use of agri-waste derived superabsorbent graft copolymer for effective removal of hazardous dye from industrial effluents. The hydrogel was synthesized via free radical graft copolymerization of poly (3-acrylamidopropyl)-trimethylammonium chloride copolymer N,N-Dimethylacrylamide (APTAC-co-DMA) onto banana pseudo-stem carboxymethyl cellulose (BPCMC) backbone. The reaction was initiated by ammonium per sulfate (APS) whereas the polymer cross linking was achieved by the addition of N,N-methylene-bis-acrylamide (MBA). The hydrogel was evaluated for its structure, morphology and thermal behavior using FT-IR, FESEM and TGA analyses respectively. The parameters affecting the hydrogel’s swelling capacity in distilled water were optimized and the optimum condition was used to perform pH sensitivity test on the hydrogel. The maximum swelling as high as 559 g/g was obtained at the optimized condition of 0.0657 mol/L, 0.0972 mol/L and 0.5 mol for APS, MBA and APATAC/DMA respectively. The pH sensitivity test revealed maximum swelling under pH 7 for 570 min. Furthermore, the hydrogel was evaluated for removal of Rhodamine B. (RhB) and Eriochrome black T (EBT) dyes. The respective maximum dye adsorption capacity to the tune of 434 and 714 mg/g for RhB and EBT was obtained. The adsorption was modeled for isotherm studies and the Freundlich isotherm model was found to be the most favored models befitting the adsorption of both dyes.

Spectrophotometric Determination of Citalopram Hydrobromide in Pharmaceuticals

Abstract: Simple, rapid and sensitive methods are described for the spectrophotometric determination of citalopram hydrobromide (CIT) in pharmaceuticals. The method A is based on the oxidation of citalo- pram by a known excess of bromate-bromide mixture in hydrochloric acid medium, reduction of the residual oxidant by a fixed amount of iron(II) and the formation of iron(III)-thiocyanate-complex which is measured at 480 nm. In the method B, 1,10-phenanthroline is used as a complexing agent and the formation of iron(II)-1,10-phenanth- roline, which is measured at 510 nm. The system obeys Beer's law in the concentration range of 1.0-7.0 µg mL -1 of CIT for method A and 0.6-6.2 µg mL -1 of CIT for method B. No interference observed from common pharmaceutical adjuvants. Both methods are equally precise as shown by the relative standard deviation values less than 2%. The apparent molar absorptivities and Sandell's sensitivity for method A and B are found to be 2.10 × 10 4 L mol -1 cm -1 , 0.019 µg cm -2 , 7.30 × 10 4 L mol -1 cm -1 and 5.5 × 10 -3 µg cm -2 , respectively. The methods

Donor-π-Acceptor-π-Donor class of 2,5-dibenzylidenecyclopentan-1-one analogues as efficient third order nonlinear optical and photoluminescent materials – An experimental investigation

Abstract: In the present work, nonlinear optical (NLO) and optoelectronic investigations of four 2,5-dibenzylidenecyclopentan-1-one (bischalcone) analogues 1 (4-F), 2(4-Cl), 3(4-Br) and 4(3-NO2) with push-pull substituents (Donor-π-Acceptor-π-Donor) are studied. The third-order nonlinear optical measurements of bischalcone analogues carried out by Z-scan technique, which revealed that these compounds possess strong third-order nonlinear absorption (NLA), negative nonlinear refraction (NLR) and optical limiting behaviour under the illumination at 532 nm continuous wave laser beam (200 mW). The magnitude of third order NLA coefficient β, NLR index n2, and effective susceptibility χ(3) are found to be in the order of 10−5 cm/W, 10−12 cm2/W, and 10−7 e.s.u respectively. The β value varied with substitution at the phenyl ring which contributed immensely on the variation. Even though the deactivating effect of 4-F, 4-Cl, 4-Br and 3-NO2 groups contributed on polarization, the presence of electron rich cyclopentanone ring ameliorated the effect of deactivation. Hence these molecules are found to possess moderate NLA and NLR properties. In addition, photoluminescence activity of these flourophores(1–4) is observed as emission spectra in the range of 307–554 nm on shining at 279 nm with relative quantum yield of 1.81%, 3.8%, 1.62% and 0.89% respectively with reference to tryptophan. The HOMO-LUMO analysis for optical band gap ranged between 2.89 eV and 3.13 eV indicating polarizing nature varied with substituents.

Spectroscopic investigation, molecular orbital studies, frequency and solvent dependent NLO properties of (2E)-1-(4-bromophenyl)-3-phenylprop-2-en-1-one

Abstract: The structure and the vibrational frequencies of the fundamental modes of the optimized geometry of (2E)-1-(4-bromophenyl)-3-phenylprop-2-en-1-one (BP3PP) have been determined. A detailed v...

Biosynthesis of spherical gold nanoparticles and their characterization

Abstract: Colloidal gold nanoparticles (AuNPs) were synthesized by the reduction of chloroauric acid (HAuCl4.H2O) using silk sericin (SS) extracted from Bombyx mori silk as a biotemplate. Synthesized AuNPs were characterized by using the various analytical techniques. UV-visible (UV-vis) study confirms the formation of AuNPs in aqueous SS solution showing the surface plasmon resonance (SPR) band at λ = 530 nm. The X-ray diffraction (XRD) study revealed the crystalline phase of gold nanoparticles with face centered cubic (FCC) structure. Transmission electron microscopy (TEM) images showed the formed AuNPs are spherical in shape with diameter around 8 nm. Dynamic light scattering (DLS) experiment also confirmed the formation of AuNPs in SS solution with average size 10 nm.