Faculty Publications

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Author: search.filters.author.Vasudeva Adhikari, A.V.Subject: search.filters.subject.synthesis

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Now showing 1 - 6 of 6
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    Synthesis and nonlinear optical characterization of copolymers containing alternating 3,4-dialkoxythiophene and 1,3,4-oxadiazolydbenzene units
    (2007) Udayakumar, D.; Kiran, A.J.; Vasudeva Adhikari, A.V.; Chandrasekharan, K.; Shashikala, H.D.
    We report the synthesis and linear and third-order nonlinear optical (NLP) characterization of two novel copolymers containing alternating 3,4-dialkoxythiophene and 1,4-bis(1,3,4-oxadiazolyl)benzene units. The copolymers were synthesized with a precursor polyhydrazide route. Both copolymers exhibited fluorescence around 430 nm under the irradiation of UV light. The NLO measurements were made with the single-beam Z-scan technique with Nd:YAG nanosecond laser pulses at 532 nm. The nonlinear refractive index of the investigated copolymers was negative, and the magnitude was as high as 10 -10 esu. The samples exhibited strong reverse saturation absorption and very good optical limiting properties at the wavelength used. The concentration dependence of third-order NLO parameters was studied. ©2007 Wiley Periodicals, Inc.
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    Design and synthesis of some new quinoline-3-carbohydrazone derivatives as potential antimycobacterial agents
    (Elsevier Ltd, 2010) Eswaran, S.; Vasudeva Adhikari, A.V.; Pal, N.K.; Chowdhury, I.H.
    A series of 26 new quinoline derivatives carrying active pharmacophores has been synthesized and evaluated for their in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv (MTB), Mycobacterium smegmatis (MC2), and Mycobacterium fortuitum following the broth micro dilution assay method. Compounds 13e, 13i, 13k, 14a, 14c, 14i, and 14k exhibited significant minimum inhibition concentrations, when compared with first line drugs isoniazid (INH) and rifampicin (RIF) and could be ideally suited for further modifications to obtain more efficacious compounds in the fight against multi-drug resistant tuberculosis. © 2009 Elsevier Ltd. All rights reserved.
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    Nonlinear optical studies on new conjugated poly{2,2 l-(3,4- dialkoxythiophene-2,5-diyl) bis[5-(2-thienyl)-1,3,4-oxadiazole]}s
    (2010) Hegde, P.K.; Vasudeva Adhikari, A.V.; Manjunatha, M.G.; Suchand Sandeep, C.S.; Philip, R.
    Three new donor-acceptor type poly{2,2 1-(3,4-dialkoxythiophene- 2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]}s (P1, P2, and P3) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting properties of the polymers were investigated by UV-visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish-green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1, P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to "effective" three-photon absorption. Values of the effective three-photon absorption (3PA) coefficients, thirdorder nonlinear susceptibilities (? (3)), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc.
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    Trihydrazone functionalized cyanopyridine discoids: Synthesis, mesogenic and optical properties
    (2014) Ahipa, T.N.; Vasudeva Adhikari, A.V.
    A new series of trihydrazone functionalized cyanopyridine derivatives (CPTH-Dm) carrying 3,4-dialkoxyphenyl groups was designed and synthesized successfully as discotic columnar liquid crystals. These new discoid mesogens display hexagonal columnar phase with a wide mesophase range from ambient temperature to 110 C and the observed columnar assembly is due to the presence of intermolecular hydrogen bonds and ?-? interactions in them. Their optical studies reveal that the compounds are good blue light emitters and hence they are potential candidates for OLED device fabrication. © 2013 Elsevier Ltd. All rights reserved.
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    New luminescent 2-methoxy-6-(4-methoxy-phenyl)-4-p-tolyl-nicotinonitrile: Synthesis, crystal structure, DFT and photophysical studies
    (2014) Ahipa, T.N.; Kamath, P.R.; Kumar, V.; Vasudeva Adhikari, A.V.
    In the current communication, we report the synthesis, spectroscopic, crystal structure, DFT and photophysical studies of a new nicotinonitrile derivative, viz. 2-methoxy-6-(4-methoxy-phenyl)-4-p-tolyl-nicotinonitrile (2) as a potential blue light emitting material. The compound 2 was synthesized in good yield via a simple route. The acquired spectral and elemental analysis data were in consistent with the chemical structure of 2. The single crystal study further confirms its three dimensional structure, molecular shape, and nature of short contacts. Its DFT calculations reveal that compound 2 possesses a non-planar structure and its theoretical IR spectral data are found to be in accordance with experimental values. In addition, its UV-visible and fluorescence spectral measurements prove that the compound exhibits good absorption and fluorescence properties. Also, it shows positive solvatochromic effect when the solvent polarity was varied from non-polar to polar. © 2014 Elsevier B.V. All rights reserved.
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    2-Methoxypyridine derivatives: Synthesis, liquid crystalline and photo-physical properties
    (Royal Society of Chemistry, 2014) Ahipa, T.N.; Vasudeva Adhikari, A.V.
    We herein report the design and synthesis of fourteen new bent shaped luminescent mesogens carrying a pyridine core substituted with various polar groups. They possess a slightly non-planar bent conformation with various intermolecular interactions, as evidenced by their single crystal X-ray diffraction study, and exhibit an ambient to elevated temperature liquid crystalline phase (N or Colr), which has been confirmed by differential scanning calorimetry, polarized optical microscopy, and powder X-ray diffraction techniques. In these compounds, the nature of polar substituents influences significantly the formation of the mesophase over a wide thermal range. The appearance of the nematic phase is due to the presence of the lateral CN group attached to the pyridine core and the terminal F or Cl substituent. The formation of a rectangular columnar phase is attributed to the absence of the lateral CN group in the pyridine core and the presence of the terminal Br, NO2 or 4-pyridyl group. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.