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Item SYNTHESIS, CHARACTERIZATION, THERMAL, THEORETICAL AND ANTIMICROBIAL STUDIES OF SCHIFF BASE LIGAND AND ITS CO(II) AND CU(II) COMPLEXES (Article)(Serbian Chemical Society, 2020) Palaniswamy, Radha Venkittapuram; Dhandapani, Mahalakshmi; Suyambulingam, Jonekirubavathy; Subramanian, ChitraA Schiff base ligand L was synthesized by condensation of 1,2-diaminoethane with creatinine. The reaction of the ligand with metal chloride salt gives Co(II) and Cu(II) complexes. The synthesized ligand and its metal complexes were characterized by elemental analysis, FT-IR, NMR, UV-Vis, conductivity and magnetic susceptibility measurements as well as thermal analyses. Based on spectral data, tetrahedral geometries have been proposed for the Co(II) and Cu(II) complexes. The molar conductivity data show that the complexes are non-electrolytic in nature. In DFT studies, the geometry of the Schiff base ligand and its Co(II) and Cu(II) complexes were fully optimized using the B3LYP functional together with 6-31g(d,p) and LANL2DZ basis sets. The ligand and its metal complexes were tested against four bacterial species and two fungal species. The results revealed that the metal complexes are more potent against the microbes than the parent ligand.Item EFFECT OF FORMAZANS ON THE CORROSION INHIBITION OF MILD STEEL IN 1M SULFURIC ACID(Bulletin of Electrochemistry, 2005-06) Selvaraj, A; Anuradha, R; Sudha, K; Subramanian, ChitraThe effect of formazans as a new class of corrosion inhibitors on the corrosion of mild steel in H2SO4 has been investigated by various techniques. The results obtained reveal that all the compounds gave a maximum inhibition efficiency of 98-99% at 0.5-10.0 mM concentrations of the inhibitors. Potentiodynamic polarization studies showed that the inhibition was under mixed control. Adsorption on the mild steel surface followed the Langmuir adsorption isotherm. Values of the activation and free energy of adsorption are presented.Item STUDY ON THE INHIBITION OF MILD STEEL CORROSION BY BENZOISOXAZOLE AND BENZOPYRAZOLE DERIVATIVES IN H2SO4 MEDIUM(Portugaliae Electrochimica Acta, 2010) Parameswari, K; Rekha, S; Subramanian, Chitra; Kayalvizhy, EFour heterocyclic compounds, namely 4- phenyl-5-acetyl/carbethoxy-3-methyl-6-hydroxyl-6-methyl-4,5,6,7-tetrahydro-2,1-benzoisoxazole and benzopyrazole (BIS1, BP1and BIS2, BP2), were synthesized and their influence on the inhibition of corrosion of mild steel in 1 M H2SO4 was investigated by means of weight loss, potentiodynamic polarization, electrochemical impedance (EIS) and scanning electron microscopy (SEM). The values of activation energy and free energy of adsorption of these compounds were also calculated. Adsorption obeys Langmuir adsorption isotherm. The IE of the compounds was found to vary with concentration and temperature. Synergistic effect was also investigated for the four compounds at 0.05 mM concentration by weight loss method in 1 M H2SO4 medium in presence of KI, KBr and KCl. Results obtained revealed that all the four compounds performed excellently as a corrosion inhibitor for mild steel in 1 M H2S04 and their efficiency attains more than 90% at 0.6 mM at 298 K. Polarisation studies showed them to be mixed type inhibitors.Item LIRIOPE PLATYPHYLLA EXTRACT AS A GREEN INHIBITOR FOR MILD STEEL CORROSION IN SULFURIC ACID MEDIUM(Taylor & Francis Online, 2021) Ill-Min, Chung; Venkatesan, Hemapriya; Seung-Hyun, Kim; Kanchana, Ponnusamy; Natarajan, Arunadevi; Subramanian, ChitraThe phytochemical components of the methanol extract of Liriope platyphylla (L. platyphylla) leaves were identified using UHPLC, and their antioxidant activities were studied. The impact of the L. platyphylla extract on the corrosion of mild steel by 1 M H2SO4 was assessed using electrochemical and gravimetric techniques. L. platyphylla exhibited concentration-dependent corrosion protection activity through a mixed-mode adsorption process, as revealed by polarization studies. Impedance measurements indicated the development of a protective film of the inhibitor, which was confirmed by morphology studies at the micro level with scanning electron microscopy (SEM) and at the nano level with atomic force microscopy (AFM). Fourier transform infrared (FT-IR) studies also confirmed the adsorption of the inhibitor film onto the mild steel surface.Item SYNTHESIS, CHARACTERIZATION, THERMAL, THEORETICAL AND ANTIMICROBIAL STUDIES OF SCHIFF BASE LIGAND AND ITS CO(II) AND CU(II) COMPLEXES(Journal of the Serbian Chemical Society, 2020) Venkittapuram, Palaniswamy Radha; Dhandapani, Mahalakshmi; Suyambulingam, Jonekirubavathy; Subramanian, ChitraA Schiff base ligand L was synthesized by condensation of 1,2-diaminoethane with creatinine. The reaction of the ligand with metal chloride salt gives Co(II) and Cu(II) complexes. The synthesized ligand and its metal complexes were characterized by elemental analysis, FT-IR, NMR, UV–Vis, conductivity and magnetic susceptibility measurements as well as thermal analyses. Based on spectral data, tetrahedral geometries have been proposed forthe Co(II) and Cu(II) complexes. The molar conductivity data show that the complexes are non-electrolytic in nature. In DFT studies, the geometry of the Schiff base ligand and its Co(II) and Cu(II) complexes were fully optimized using the B3LYP functional together with 6-31g(d,p) and LANL2DZ basis sets. The ligand and its metal complexes were tested against four bacterial species and two fungal species. The results revealed that theItem TRANSITION METAL COMPLEXES OF NOVEL BINUCLEAR SCHIFF BASE DERIVED FROM 3,3′-DIAMINOBENZIDINE: SYNTHESIS, CHARACTERIZATION, THERMAL BEHAVIOR, DFT, ANTIMICROBIAL AND MOLECULAR DOCKING STUDIES(Taylor & Francis Online, 2020-03-21) Venkittapuram, Palaniswamy Radha; Subramanian, Chitra; Suyambulingam, Jonekirubavathi; Ill-Min, Chung; Seung-Hyun, Kim; Mayakrishnan, PrabakaranA series of binuclear Co(II), Ni(II), Cu(II), and Zn(II) complexes were prepared with a novel bidentate Schiff base ligand derived by condensation of 3,3′-diaminobenzidine with creatinine. The prepared compounds were characterized by elemental analysis, magnetic susceptibility measurements, molar conductivity, FT-IR, UV-vis, 1H NMR, 13C NMR and mass spectra and thermal analysis (TGA/DTG). From spectral analysis, an octahedral geometry was proposed for the complexes except Zn(II) complex which had tetrahedral geometry. The microcrystalline nature of the complexes has been confirmed by powder XRD and SEM analyses. The molecular structures of the Schiff base L and its Zn(II) complex were fully optimized and also their quantum chemical parameters were calculated. The synthesized ligand and their metal complexes were screened against two gram-positive, gram-negative bacterial and fungal species. The results revealed that the metal complexes exhibited higher antimicrobial activity than the free ligand. The antioxidant activity of the synthesized ligand and their metal complexes was carried out by DPPH method.Item FLOXACINS: AS MEDIATORS IN ENHANCING THE CORROSION INHIBITION EFFICIENCY OF NATURAL POLYMER DEXTRIN(Springer Link, 2020-01-11) Gowraraju, Nirmala Devi; Chan, Basha Nusrath Unnisa; Selvaraj, Mohana Roopan; Venkatesan, Hemapriya; Subramanian, Chitra; Ill-Min, Chung; Seung-Hyun, Kim; Mayakrishnan, PrabakaranThree different floxacins (Ciprofloxacin, Levofloxacin, and Norfloxacin) were used to enhance the inhibition property of Dextrin (Dex) against the dissolution of mild steel in acid medium. Substantial increase in the inhibition property was observed against mild steel dissolution by the addition of floxacins than with pure Dex. Weights loss experiments proved the potential of Fluoroquinolones (FQs) in enhaning the corrosion inhibition property of Dex on metal by proving its best ability at lower concentrations. Adsorption of Dex and floxacins on metal surface was observed to accept with Langmuir adsorption isotherm. The results from EIS studies add to the enhancing property of floxacins on Dex. While the mixed type behavior of inhibitors were confirmed by polarization studies, images from SEM, EDS and AFM gathers strength to propose the formation of protective layer.Item ANTI-CORROSIVE POTENTIAL OF CYPERUS ROTUNDUS AS A VIABLE CORROSION INHIBITOR FOR MILD STEEL IN SULPHURIC ACID(Emerald Publishing Limited, 2020-06-05) Rajan, Anitha; Chan Basha, Nusrath Unnisa; Venkatesan, Hemapriya; Selvaraj, Mohana Roopan; Subramanian, Chitra; Chung, ll-Min; Seung-Hyun, Kim; Prabakaran, MayakrishnanOver the past decade, plant extracts are ultimate green candidatures to substitute the expensive and noxious synthetic corrosion inhibitors. In this regard, this study aims to focus on evaluating anti-corrosion properties of green inhibitor Cyperus rotundus (C. rotundus), a perennial herb found throughout India.Item SYNTHESIS, CHARACTERIZATION, BIOLOGICAL AND PHOTOLUMINESCENCE STUDY OF CO(II) COMPLEXES OF FUSED HETEROCYCLIC RING SYSTEMS(Indian Journal of Pharmaceutical Education and Research, 2020-08) Suyambulingam, Jone Kirubavathy; Subramanian, ChitraTo synthesize and characterize the transition metal complexes of fused heteroccylic ring systems. Background: Many of the fused ring heterocyclic compounds were found to be biologically active in the literature like anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant and so on. The present work focus on the synthesis of the biologically active compounds. Materials and Methods: Synthesis of the ligands and the complexes are done using the standard procedures in earlier reports. Melting points were found using open glass capillaries on a Raaga melting point apparatus and are uncorrected. The percentage of C, H, N , infra-red and UV-Visible spectra of the compounds were recorded using Elementar Vario EL III CHN analyser, Shimadzu spectrophotometer (4000-400 cm-1) and Elico SL 159 UV-Vis spectrophotometer respectively. The antimicrobial activity of the compounds was carried out by well diffusion method. The anticancer activity of the compounds were carried out for the MCF-7 cell line (breast Cancer) using MTT assay. Discussion and Conclusion: Structural elucidation of newly synthesized Co(II) metal complexes of fused heterocyclic ring systems were done using various spectral techniques like FT-IR, 1H-NMR, Electronic and TGA-DTA studies. The anti-microbial activity of the prepared complexes and the DNA Cleavage studies were screened for various test pathogens and explained. The photoluminescence property of the fused heterocyclic ligand and their complexes were studied and compared. Fluorescence enhancement is observed in these complexes which is contradictory to the normal Fluorescence quenching phenomena by added organic derivatives, paved way for photochemical applications.Item UTILIZATION OF BIOWASTE AS AN ECO-FRIENDLY BIODEGRADABLE CORROSION INHIBITOR FOR MILD STEEL IN 1 MOL/L HCL SOLUTION(Elsevier, 2020-12) Venkatesan, Hemapriya; Mayakrishnan, Prabakaran; Subramanian, Chitra; Manoharan, Swathika; Seung-Hyun, Kim; Ill-Min, ChungThis report focuses on the application of a biodegradable biowaste [human hair-(HHR)], to produce a mild steel corrosion inhibitor. The performance of HHR extract in inhibiting metallic corrosion in 1 mol/L HCl was investigated. The analysis of the metal corrosion behavior using electrochemical and weight loss techniques revealed that HHR exhibits an efficient corrosion-mitigating effect via adsorption on the metal surface following a Langmuir isotherm. Tafel-plot results revealed the mixed-mode corrosion protection behavior of HHR. Surface analysis using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and Fourier transform infrared (FT-IR) spectroscopy provided evidence for the precipitation of a protective HHR film on the metal surface.