Faculty Publications
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Publications by NITK Faculty
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Item The ultrafast nonlinear optical response and multi-photon absorption of a new metal complex in the near-infrared spectral range(Institute of Physics Publishing, 2010) Kiran, A.J.; Lee, H.W.; Sampath Kumar, H.C.; Rudresha, B.J.; Badekai Ramachandra, B.; Yeom, D.-I.; Kim, K.; Rotermund, F.A new coordination compound, chloro(1,10-phenanthroline-N, N ?)(triphenylphosphine)copper(I) dichloromethane, incorporated in poly(methyl methacrylate) exhibits superior nonlinear optical properties in the near-infrared spectral region. Its nonlinear response time and third-order nonlinear optical susceptibility at 800nm are ? 90fs and 1.8 × 10 -10esu, respectively. Considerable nonlinear absorption is observed with this sample, near 800 and 1250nm. The contribution of the excited states to the total nonlinear absorption process is discussed. The results reveal the potential of this newly designed compound for multi-photon absorption-based photonic applications. © 2010 IOP Publishing Ltd.Item Synthesis, characterization, and biological activity of metal complexes of 4-ethyl vanillideneamino-3-methyl-5-mercapto-1,2,4-triazole(2010) Ramasubramanian, A.S.; Badekai Ramachandra, B.; Ramakrishna, D.A series of transition metal-triazole derivatives have been synthesized and characterized by microanalytical, thermal, magneto-chemical, and spectral studies. The synthesized complexes were screened for biological activities. The complexes of Co(II) and Ni(II) emerged as a good antibacterial agent against Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Bacillus subtilis, and Shigella flexneri. © 2010 Taylor & Francis.Item Synthesis and characterization of schiff base metal complexes and reactivity studies with malemide epoxy resin(Korean Chemical Society sunlee@kcsnet.or.kr, 2012) Lakshmi, B.; Shivananda, K.N.; Prakash, G.A.; Isloor, A.M.; Mahendra, K.N.A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, 1H NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.Item Octupolar metal complexes for third order nonlinear optical studies(2012) Rudresha, B.J.; Manjunatha, K.B.; Umesh, G.; Badekai Ramachandra, B.R.The octupolar metal complexes [Zn(bpy)(L)] (1), [Cd(bpy)(L)] (2), [Hg(bpy)(L)] (3) (bpy = 2,2?-bipyridyl, L = 4-dimethylamino-?- cyanocinnamic acid) have been synthesized. The third-order nonlinear optical properties of complexes were studied using Z-scan technique at 532 nm with nanosecond laser pulses. The complexes show optical limiting behavior. The values of the effective two-photon absorption (2PA) coefficients (?), third-order nonlinear susceptibilities (? (3)) and two-photon absorption cross sections (? 2) are calculated. Results show, lewis acidity of metal center and molecular symmetry are two important factors for observed large TPA cross-section of metal complexes. © 2012 Elsevier B.V. All rights reserved.Item Optical nonlinearity, limiting and switching characteristics of novel ruthenium metal-organic complex(Elsevier B.V., 2017) Manjunatha, K.B.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.R.; Poornesh, P.We report the nonlinear optical properties of Ruthenium metal complex a promising organic material for use in scientific and technological applications. The thin films of newly synthesized ruthenium metal–organic complex were fabricated using spin coating technique. Z-scan and degenerate four wave mixing (DFWM) techniques used to extract the third-order nonlinear optical (NLO) parameters. The data reveals the investigated material exhibited relatively large NLO properties. The pump–probe experiments shows that the switch-on and off times of the material were in the order of ?s at different pump intensities and the energy dependent transmission studies reveal good limiting property of the material in nanosecond regime. © 2017 Elsevier B.V.Item Air-Stable Cobalt(II) and Nickel(II) Complexes with Schiff Base Ligand for Catalyzing Suzuki–Miyaura Cross-Coupling Reaction(Pleiades journals, 2018) Ansari, R.M.; Kumar, L.M.; Badekai Ramachandra, B.R.The Co(II) complex [Co{C6H4–1,2-(N=CH–C6H4O)2}] (I) and Ni(II) complex [Ni{C6H4–1,2-(N=CH–C6H4O)2}] (II) with Schiff base of o-phenylenediamine and salicylaldehyde have been synthesized. The structure of the ligand and its complexes were derived on the basis of various techniques such as elemental analysis, mass, FT-IR, electronic spectra and magnetic susceptibility. From the Singal crystal X-ray diffraction (SCXRD) analysis techniques (CIF file CCDC no. 1498772 (II)), it has been confirmed that the Schiff base ligand (L), coordinates to the metal ion in a tetradentate fashion through the nitrogen and oxygen atom. In addition, the square planar geometry of Ni(II) complex also has been confirmed from SCXRD. Electronic spectra, mass spectra, and magnetic susceptibility measurements reveal square planar geometry for the Co(II) complex. Synthesized complexes were used in cross-coupling of arylhalides with phenylboronic acid. The transformation offers products in good yields using 0.02 mmol catalysts loading, thereby proving the efficiency of the complexes as catalysts for Suzuki–Miyaura reaction. © 2018, Pleiades Publishing, Ltd.Item Nanographene sheet immobilized transition metal complexes for C-C coupling reactions(Science Publishing Corporation Inc ijet@sciencepubco.com, 2018) Anuma, S.; Badekai Ramachandra, B.R.Transition metal Schiff base complexes covalently immobilized on the surface of amino functionalized graphene sheet to catalyze C-C coupling reaction is reported. Graphene sheet which synthesized using mechanical exfoliation and then by differential oxidative reduction phenomenon of graphite. The schiff base ligand is prepared using aldehyde and amino groups containing compounds which further treated with metal salts to form metal complexes. The as-synthesized metal complexes was then incorporated into amino functionalized nanosheets which are characterized using different spectrochemical techniques. The catalytic investigation of the asprepared catalyst were done by the cross coupling of aryl halides and aryl boronic acids to form biaryls as product in C-C cross coupling reaction. The yield of the products were high and selective which were analyzed using Gas chromatography technique. The advantage of this catalyst is high stability, recyclability easy recovery of catalyst, environmentally benign and mild reaction condition. © 2018 Authors.Item Enhanced photostability and optical nonlinearity of nickel and cobalt organometallic complexes(Elsevier B.V., 2019) Manjunatha, K.B.; Rajarao, R.; Poornesh, P.; Rudresha, B.J.; Umesh, G.; Badekai Ramachandra, B.R.Nonlinear optical and limiting properties of nickel, cobalt metal-organic complexes and ligand (L) {L = N,N?-o-phenylenebis (4-hyrdoxy-salicylideneimine)} were studied using Z-scan technique using Q-switched Nd: YAG laser with nanosecond pulses at 532 nm. The results reveal that metal complexes exhibit large negative nonlinear refractive index (n2) of the order of 10?11 esu. The metal complexes displays large nonlinearity than the ligand due to effective charge delocalization between metal ion and ligand. The magnitude of ground state absorption cross section is small compared to the effective excited-state absorption cross section implying the observed nonlinearity is due to reverse saturable absorption. Further, metal-organic complexes exhibit enhanced optical limiting behaviour at nanosecond laser pulses. © 2019 Elsevier B.V.Item Thermally stable complexes of Fe(III), Co(II), Ni(II) and Cu(II) with Schiff base derived from 4-aminoacetophenone and salicylaldehyde(Springer, 2022) Ansari, R.M.; Ramakrishna, D.; Badekai Ramachandra, B.R.The Schiff base ligand 1-(4-((2-hydroxybenzylidene)amino)phenyl)ethan-1-one, obtained from 4-aminoacetophenone and salicylaldehyde, and its complexes with Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized. These complexes were characterized by FTIR spectroscopy, elemental, and SCXRD analysis. FTIR spectra of complexes show the bidentate coordination of metal ions with ligands where O and N are electron-donating sites of the azomethine group. The electronic absorption spectra of these complexes show the characteristics of absorption bands involved in the Fe, Co, and Ni complexes due to their π→π*, n→π* transitions. Further, the geometry of the complexes was deduced from the calculated magnetic moment values and single crystal XRD analysis. Graphical abstract: A Schiff base derived from the condensation reaction between 2-aminoacetophenone and salicylaldehyde was involved in the formation of four different metal complexes, i.e., with Nickel, Cobalt, Iron, and Copper. The synthetic route to forming these complexes followed an easy process, and the complexes were obtained in good yields.[Figure not available: see fulltext.] © 2022, Indian Academy of Sciences.