Faculty Publications
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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 Cobalt Schiff Base Immobilized on a Graphene Nanosheet with N, O Linkage for Cross-Coupling Reaction(American Chemical Society, 2019) Saroja, A.; Badekai Ramachandra, B.R.A simple and direct pathway to synthesize heterogeneous catalyst by covalently immobilizing a cobalt Schiff base complex on the surface of amino functionalized graphene oxide for the cross coupling of aryl halides and arylboronic acids is reported. The as synthesized samples were characterized using various spectroscopic techniques and thermal analysis to attain their structural and functional features. The analysis confirmed that the Co bounded to the ligand using bi(N, O) linkage and the Co Schiff base complex immobilized onto the functionalized graphene oxide through its amino moiety. The catalytic investigation confirmed the product yield up to 96.5% for the Suzuki cross coupling using gas chromatography. ICP analysis shows that the central active metal is 85% in its catalyst even after the fifth iteration. High product yield, environmentally benign, easy workup, easy filtration of catalyst, and mild reaction conditions are the main facets of this catalyst. © Copyright 2018 American Chemical Society.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 Polypyrrole functionalized Cobalt oxide Graphene (COPYGO) nanocomposite for the efficient removal of dyes and heavy metal pollutants from aqueous effluents(Elsevier B.V., 2021) Anuma, S.; Mishra, P.; Badekai Ramachandra, B.R.A cobalt oxide graphene nanocomposite functionalized with polypyrrole (COPYGO) having a heterogenous porous structure was synthesized using hydrothermal method. Microscopic imaging of the COPYGO surface revealed its highly porous and ordered features. The adsorption performance of the COPYGO composite was systemically investigated for Methylene Blue (MB), Congo red (CR) dyes and toxic lead (Pb(II)) and Cadmium (Cd(II)) metals. These were selected as they are the common pollutants in industrial wastewater. The COPYGO was found to be thermally stable up to 195 oC with a specific surface area of 133 m2 g?1. Experimental data indicates that the COPYGO follows Langmuir and Temkin adsorption isotherm. The COPYGO was efficient in removing MB (92.8%), CR (92.2%), Pb(II) (93.08%) and Cd(II) (95.28%) pollutants at pH 7.2, 5.0, 5.5 and 6.1 respectively from the simulated effluents. The maximum adsorption capacity (Qmax) observed for MB 663.018 mg g-1, CR 659.056 mg g-1, Pb(II) 780.363 mg g?1 and Cd(II) 794.188 mg g?1 pollutants. The thermodynamic analysis of the COPYGO indicates that the adsorption is endothermic and spontaneous in nature. COPYGO showed very high efficient removal rate for the pollutants in simulated effluents which guaranteed its benefits and efficacy in industrial wastewater treatment. © 2021 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.Item Significance of transition metal (Co, Ni and Zn) doping on the nano MnSe for high-performance supercapacitor electrode(Elsevier Ltd, 2024) Mascarenhas, F.J.; Rodney, J.D.; Kim, B.C.; Badekai Ramachandra, B.R.The demand for electrode materials in supercapacitors necessitates designs with exceptional performance, superior structure, and environmental sustainability, all while remaining affordable and abundantly available. This study introduces an economical hydrothermal synthesis method for producing MxMn1-xSe (M=Co / Ni / Zn) nanomaterials at varying concentrations (x = 0.0, 0.01, 0.02, and 0.03). Diverse characterization methods confirm the successful formation of nanomaterials. Among the materials studied, Co0.01Mn0.99Se nanoclusters exhibit superior performance as electrode materials for supercapacitors, delivering a specific capacitance of 421 F/g at 5 mV/s and 377 F/g at 1 A/g in a 5 M KOH solution. A two-electrode symmetric configuration was established utilizing Co0.01Mn0.99Se as the active material in a 5 M KOH electrolyte, yielding a notable specific capacitance of 73 F/g at 0.5 A/g. The maximum energy density and power density achieved are 20.44 Wh/kg and 2838 W/kg respectively. This configuration demonstrates the exceptional electrochemical performance and energy storage capabilities of Co0.01Mn0.99Se in a two-electrode system. Impressively, the symmetric cell maintains a significant 70% capacitance retention even after 5000 charge-discharge cycles. Considering these findings, the developed Co0.01Mn0.99Se emerges as a pivotal advancement, providing a robust framework for the development of cutting-edge energy conversion and storage technologies. © 2024 Elsevier B.V.Item Electrochemical insights into manganese-cobalt doped ?-Fe2O3 nanomaterial for cholesterol detection: a comparative approach(Royal Society of Chemistry, 2025) Sushmitha, S.; Ray, S.; Rao, L.; Nayak, M.P.; Carva, K.; Badekai Ramachandra, B.R.Herein, a self-assembled hierarchical structure of hematite (?-Fe2O3) was synthesized via a one-pot hydrothermal method. Subsequently, the nanomaterial was doped to obtain MxFe2?xO3 (M = Mn-Co; x = 0.01, 0.05, and 0.1) at precise concentrations. An electrode was fabricated by coating the resulting nanocomposite onto a nickel foam (NF) substrate. Electrochemical characterization demonstrated the excellent performance of cobalt-doped ?-Fe2O3, among which Co0.05Fe0.95O3 (CF5) exhibited a superior performance, showing a two-fold increase in sensitivity of 1364.2 ?A mM?1 cm?2 (±0.03, n = 3) in 0.5 M KOH, a limit of detection (LOD) of ?0.17 mM, and a limit of quantification (LOQ) of ?0.58 mM. The Density Functional Theory (DFT) was performed to understand the doping prompting in the reduced bandgap. The fabricated electrode displayed a rapid response time of 2 s and demonstrated 95% stability, excellent reproducibility, and selectivity, as confirmed by tests with several interfering species. A comprehensive evaluation of the electrode's performance using human blood serum highlighted its robustness and reliability for cholesterol detection in clinical settings, making it a promising tool for clinical and pharmaceutical applications. © 2025 The Royal Society of Chemistry.Item Electrochemical determination of ascorbic acid using carbon paste electrode modified with cobalt oxide nanoparticles(Elsevier Ltd, 2025) G, B.A.; Bhat, R.S.; Hegde, S.S.; Badekai Ramachandra, B.R.The present work introduces a cobalt oxide nanoparticle-modified carbon paste electrode (Co2O3/CPE) as a simple, low-cost, and efficient platform for the electrochemical determination of ascorbic acid. This study shows the excellent selectivity of the electrode against common interferents, linear detection range, low detection limit, and reproducibility, making it a promising substitute to expensive noble-metal-based sensors for real-sample ascorbic acid analysis. An eco-friendly novel electrochemical study is carried out to detect ascorbic acid (ACA) using a Congo red (CR) modified cobalt oxide nanoparticle (Co3O4) composite carbon paste electrode (CRMCCCPE). This CRMCCCPE significantly enhanced the electrochemical performance for the selective and sensitive analysis of ACA. The elemental analysis of the synthesised Co3O4 by EDX (energy-dispersive X-ray spectroscopy), the phase structure through XRD (X-ray diffraction), and the absorbance peaks by Raman spectrometry with 37.41 nm. The surface topography by FESEM (field emission scanning electron microscopy). Voltammetric techniques and EIS (electrochemical impedance spectroscopy) are investigated for the electrochemical redox response of ACA in phosphate buffer (PB) of 0.1 M concentration across the various ranges of pH at a 0.1 V/s scan rate. The ACA detection through the impact of pH, impact of scan rate, concentration, interference, simultaneous detection, and real sample analysis, indicating CV at 0.2 ?M to 2.4?M, DPV at 0.2 ?M to 2.6?M and LSV at 0.2 ?M to 2.4?M, with a lower limit of detection (LOD) were CV is 1.4 ??, DPV is 0.7 ?M, and LSV is 1.5 µ? and quantification (LOQ) was CV is 4.8 ?M, DPV is 2.6 µM, and LSV is 5.0 ?M. The fabricated CRMCCCPE exhibits the novelty of excellent stability, reproducibility, and repeatability, suggesting its potential application for the electrochemical recognition of ACA in complex matrices. The results indicate that CRMCCCPE is a reliable and effective platform for voltammetric sensing of ACA, offering promising applications in food quality control and medicinal diagnostics. © 2025 Elsevier Ltd.