Faculty Publications

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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.
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.
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.
Synthesis and application of Zr-metal–organic framework for simultaneous detection and rapid adsorption of p-nitrophenol from water
(Institute for Ionics, 2023) Nimbalkar, M.N.; Badekai Ramachandra, B.R.
The p-nitrophenol is a prime raw material in the manufacturing of pharmaceutical drugs, fungicides and insecticides. The effluents from these industries contain p-nitrophenol and are harmful to human and aquatic life. Hence, development of fast detection and efficient disposal process of p-nitrophenol in wastewater is a major concern. In this study, fluorescent active smart metal–organic framework (MOF) was employed for the simultaneous detection and adsorptive removal of p-nitrophenol from water. Photoluminescence active zirconium-based metal–organic framework having isostructural with UiO-66 framework was synthesized by using mixed ligand strategy with the replacement of BDC (1,4-Benzenedicarboxylic acid) ligand from 10 to 30 mol% with H3ntb ligand (4,4ʼ,4ʼʼ-Nitrilotrisbenzoic acid, in house synthesised fluorescence active trifunctional ligand). The powder X-ray diffraction (PXRD), analysis of the synthesised MOF confirms face centred cubic (FCC) crystal structure similar to pristine UiO-66. From Fourier transform infrared spectroscopy (FTIR), the peak at 1251 cm−1 for the tertiary amine group validated the presence of H3ntb ligand. The obtained MOFs have the surface area from 1039 m2g−1 to 949.1 m2g−1 and pore volume ranging from 0.04973 cm3g−1 to 0.05160 cm3g−1. Experimental results indicated that MOF was able to detect p-nitrophenol at low concentration (≈35 μM) and to remove rapidly (< 10 min) it from the aqueous solution. The adsorption process obeys Langmuir isotherm (monolayer adsorption capacity is 62 mgg−1) and kinetics by Elovich model indicating adsorption nature as chemisorption on a heterogeneous surface. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.

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