Browsing by Author "Karvembu, Ramasamy"

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    Crystal structures of the Schiff base derivatives (E)-N′-[(1H-indol-3-yl)methylidene]isonicotinohydrazide ethanol monosolvate and (E)-N-methyl-2-[1-(2-oxo-2H-chromen-3-yl)ethylidene]hydrazinecarbothioamide
    (International Union of Crystallography, 2017-03-24) Saranya, Sivaraj; Haribabu, Jebiti; Bhuvanesh, Nattamai S.P.; Karvembu, Ramasamy; Gayathri, Dasararaju
    The crystal structures of two title Schiff base derivatives, C15H12N4O·C2H6O (1·EtOH) and C13H13N3O2S (2), were determined at 110 and 100K, respectively. In the crystal of compound 1·EtOH, the (E)-N′-[(1H-indol-3-yl)methylidene]isonicotinohydrazide and ethanol molecules are linked by O-H⋯O, N-H⋯O and N-H⋯N hydrogen bonds, forming a tape structure running along the b-axis direction. The tapes are weakly linked via a C-H⋯N interaction. In the crystal of compound 2, (E)-N-methyl-2-[1-(2-oxo-2H-chromen-3-yl)ethylidene]hydrazinecarbothioamide molecules are linked via N-H⋯O and C-H⋯O hydrogen bonds, forming a helical chain along the b-axis direction. The chains are further linked into a layer expanding parallel to (102) through C-H⋯S interactions.
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    Crystal structures of two hydrazinecarbo­thio­amide derivatives: (E)-N-ethyl-2-[(4-oxo-4H-chromen-3-yl)methyl­­idene]hydrazinecarbo­thio­amide hemi­hydrate and (E)-2-[(4-chloro-2H-chromen-3-yl)methyl­­idene]-N-phenyl­hydrazinecarbo­thio­amide
    (International Union of Crystallography, 2015-02-21) Gangadharan. Rajeswari; Haribabu, Jebiti ; Karvembu, Ramasamy ; Sethusankar, K
    The title compounds, C13H13N3O2S·0.5H2O, (I), and C17H14ClN3OS, (II), are hydrazinecarbothioamide derivatives. Compound (I) crystallizes with two independent molecules (A and B) and a water molecule of crystallization in the asymmetric unit. The chromene moiety is essentially planar in molecules A and B, with maximum deviations of 0.028 (3) and 0.016 (3) Å, respectively, for the carbonyl C atoms. In (II), the pyran ring of the chromene moiety adopts a screw-boat conformation and the phenyl ring is inclined by 61.18 (9)° to its mean plane. In the crystal of (I), bifurcated N - H⋯O and C - H⋯O hydrogen bonds link the two independent molecules forming A-B dimers with two R 12(6) ring motifs, and R 22(10) and R 22(14) ring motifs. In addition to these, the water molecule forms tetrafurcated hydrogen bonds which alternately generate R44(12) and R66(22) graph-set ring motifs. There are also π-π [inter-centroid distances = 3.5648 (14) and 3.6825 (15) Å] interactions present, leading to the formation of columns along the c-axis direction. In the crystal of (II), molecules are linked by pairs of N - H⋯S hydrogen bonds, forming inversion dimers with an R22(8) ring motif. The dimers are linked by C - H⋯π interactions, forming ribbons lying parallel to (210).
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    Effect of morphology and (Sn, Cr) doping on in vitro antiproliferation properties of hydrothermally synthesized 1D GaOOH nanostructures
    (Elsevier B.V., 2024-03-15) Pilliadugula, Rekha; Haribabu, Jebiti; Mohamed Subarkhan, Mohamed Kasim; Echeverria, Cesar; Karvembu, Ramasamy; Gopalakrishnan, N
    GaOOH powders of submicron dimensions were synthesized through a simple, surfactant-free hydrothermal synthesis at pH values of 7 and 14. Sn and Cr at concentrations of 2 mol% and 1 mol%, respectively, were successfully incorporated into a GaOOH lattice at pH = 7. The synthesized powders were characterized through XRD, SEM, UV-Vis spectroscopy, XPS, and PL spectroscopy to untangle their structural, morphological, optical, elemental, and compositional- and defect-level analyses, respectively. All samples were individually tested for their in vitro anti-proliferation activities against three human cancer cell line profiles, namely, lung carcinoma (A549), colon adenocarcinoma (LoVo), and hepatocellular carcinoma (HuH-7). The samples showed obtrusive anti-proliferation activity against the three cancer line profiles. An apoptotic cell killing mechanism was found in the studied samples after a successful analysis of various staining assays and flowcytometric analyses in the A549 cancer cell profile. Cr loading at 1 mol% enhanced the cancer cell inhibition property of GaOOH against all cancer cells investigated. Also, the morphology and doping levels were observed to have a collective effect on the anti-proliferation activity of GaOOH with specificity in treating certain cancer cells. © 2021 The Authors
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    Heterostructure of two different 2D materials based on MoS2 nanoflowers@rGO: an electrode material for sodium-ion capacitors
    (Royal Society of Chemistry, 2018-09-05) Ramakrishnan, Kiruthiga; Nithya, Chandrasekaran; Karvembu, Ramasamy
    Sodium ion capacitors are under extensive investigation as companionable pre-existing lithium ion batteries and sodium ion batteries. Finding a suitable host for sodium ion storage is still a major challenge. In this context, here we report a MoS2 nanoflowers@rGO composite produced via a hydrothermal method followed by an ultra sonication process as a sodium ion symmetric hybrid supercapacitor. The structural and electrochemical performances of the electrode material were investigated to establish its applicability in sodium ion capacitors. The electrochemical performance was evaluated using metallic sodium in a half cell configuration which delivered a maximum specific capacitance of 226 F g−1 at 0.03 A g−1. When examined as a symmetric hybrid electrode (full cell) it delivered a maximum capacitance of 55 F g−1 at 0.03 A g−1. This combination may be a new gateway for upcoming research work which deals with sodium ion storage applications. The results confirmed that the as-synthesized MoS2 nanoflowers@rGO heterostructure electrode exhibited notable electrochemical behaviour.
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    Spectroscopic, anticancer and antioxidant studies of fluxional trans-[PdCl2(S-acylthiourea)2] complexes
    (Elsevier B.V., 2021-07-19) Dorairaj, Dorothy Priyanka; Haribabu, Jebiti; Chithravel, Vadivalagan; Vennila, Kailasam N; Bhuvanesh, Nattamai; Echeverria, Cesar; Hsu, Sodio C.N.; Karvembu, Ramasamy
    A library of palladium(II) acylthiourea complexes (1–6) of the type [PdCl2{C8H13N2OS(R)}2] [where R = C6H4CH3(o) (1), C6H5 (2), C6H4OCH3(p) (3), C6H4OC2H5(p) (4), C10H7 (5) or C6H5Cl(p) (6)] was synthesized and characterized by UV–Visible, FT-IR, 1H NMR, 13C NMR and ESI-Mass spectroscopy, and elemental analysis. Single crystal X-ray structure of complex 4 revealed the monodentate coordination of acylthiourea ligand through sulphur atom to the palladium ion in a trans fashion. In addition, variable-temperature (VT) NMR studies were performed to analyze the fluxional nature of complexes. The interaction of complexes with calf thymus (CT) DNA and BSA (bovine serum albumin) was analyzed by spectroscopic and molecular docking studies. The results inferred intercalation binding mode of the complexes with DNA. All the complexes exhibited good binding with BSA as well. Further, the complexes were found to act as good scavengers of DPPH as deduced from the antioxidant assay. In vitro cytotoxicity of the compounds against A549 (lung) cancer and HEK293 (human embryonic kidney) normal cell lines was investigated by MTT assay. Among the six complexes, complex 5 bearing a napthyl substitution in acylthiourea exhibited a remarkable activity against A549 cell line with an IC50 value of 14.8 µM and was more active than cisplatin (IC50 = 17.8 µM). On the other hand, it showed less toxicity on HEK293 cell line. The cell death mechanism was analyzed by AO/EB and DAPI staining, flow cytometry and Western blot investigations, which revealed that complex 5 could initiate cell death through apoptosis.
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    Synthesis of sulfanyl derivatives of 1,2,4-triazoles via an acid catalyzed intramolecular cyclization of isothiosemicarbazones: structural characterization, E/Z isomerism, mechanistic insights and in vitro cytotoxicity
    (Royal Society of Chemistry, 2026-03-10) Snisha, Kallivalappil; Karthikeyan, Mano Chitra; Bhuvanesh, Nattamai; Arockiam, Antony Joseph Velanganni; Karvembu, Ramasamy
    Sulfanyl derivatives of 1,2,4-triazoles (CL1–CL3) were synthesized via a Lewis or Brønsted acid catalyzed intramolecular cyclization of corresponding isothiosemicarbazones (TL1–TL3). All the synthesized isothiosemicarbazones and their cyclized sulfanyl 1,2,4-triazole derivatives were well characterized by spectroscopic techniques and single crystal XRD analyses. The E/Z isomerism of the isothiosemicarbazones was elucidated using NMR spectroscopy and single crystal XRD analysis. Mechanistic investigations, supported by controlled experiments and spectroscopic evidence, revealed that the cyclization proceeded via an ionic pathway with the evolution of hydrogen. The cytotoxic effect of the cyclized sulfanyl 1,2,4-triazole derivatives (CL1–CL3) was evaluated by MTT assay against MDA-MB-231 (breast), MCF-7 (breast), and HeLa (cervical) cancer cell lines, as well as HEK-293 (kidney) normal cell line, taking 5-fluorouracil (5-FU) as a reference drug. All the substituted sulfanyl-1,2,4-triazoles showed higher cytotoxicity toward MDA-MB-231 and HeLa cells than 5-FU, while exhibiting low toxicity toward HEK-293 cells, indicating good selectivity toward cancer cells. Substituted compounds [CL2 (p-OCH3) and CL3 (p-NO2)] displayed enhanced activity compared to the unsubstituted one (CL1), indicating the influence of the substituents on cytotoxicity. Fluorescence staining assays (AO/EB, Hoechst 33342, Rhodamine 123 and DCFH-DA) further supported the observed cytotoxic effects, and suggested that the compounds promoted apoptotic cell death via intracellular reactive oxygen species (ROS) generation, depletion of mitochondrial membrane potential (MMP) and damage to nuclear material.
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    Tris-(2-pyridyl)-pyrazolyl Borate Zinc(II) Complexes: Synthesis, DNA/Protein Binding and In Vitro Cytotoxicity Studies
    (MDPI, 2021-12-03) Narwane, Manmath; Dorairaj, Dorothy Priyanka; Chang, Yu-Lun; Karvembu, Ramasamy; Huang, Yu-Han; Chang, Hsueh-Wei; Hsu, Sodio C. N.
    Abstract Zn(II) complexes bearing tris[3-(2-pyridyl)-pyrazolyl] borate (Tppy) ligand (1–3) was synthesized and examined by spectroscopic and analytical tools. Mononuclear [TppyZnCl] (1) has a Zn(II) centre with one arm (pyrazolyl-pyridyl) dangling outside the coordination sphere which is a novel finding in TppyZn(II) chemistry. In complex [TppyZn(H2O)][BF4] (2) hydrogen bonding interaction of aqua moiety stabilizes the dangling arm. In addition, solution state behaviour of complex 1 confirms the tridentate binding mode and reactivity studies show the exogenous axial substituents used to form the [TppyZnN3] (3). The complexes (1–3) were tested for their ability to bind with Calf thymus (CT) DNA and Bovine serum albumin (BSA) wherein they revealed to exhibit good binding constant values with both the biomolecules in the order of 104–105 M−1. The intercalative binding mode with CT DNA was confirmed from the UV-Visible absorption, viscosity, and ethidium bromide (EB) DNA displacement studies. Further, the complexes were tested for in vitro cytotoxic ability on four triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, MDA-MB-468, HCC1937, and Hs 578T). All three complexes (1–3) exhibited good IC50 values (6.81 to 16.87 μM for 24 h as seen from the MTS assay) results which indicated that these complexes were found to be potential anticancer agents against the TNBC cells.