• Subrata Mandal

      Articles written in Journal of Chemical Sciences

    • Reactivity of some cuprous salts towards tenmembered macrocyclic disulphides: A new route to the synthesis of Cu(II)-thiolates

      Subrata Mandal Parimal K Bharadwaj

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      Cuprous ion is found to be quite reactive towards disulphide present in a macrocycle. Thus, when [Cu(MeCN)4] BF4 or [Cu(MeCN)4]ClO4 is allowed to reflux in acetonitrile with a ten-membered macrocycle containing two amino nitrogens and one disulphide donor in an atmosphere of nitrogen, electron transfer takes place from the metal centre to the disulphide group. As a result, copper is oxidised to the + 2 state and the disulphide reduced to thiolates. The thiolates then bind the Cu(II) and form discrete and neutral CuN2S2 complexes. Syntheses of two new CuN2 S2 complexes have been achieved following this route. The reactions take place smoothly and give the desired product in excess of 25% yield with respect to the macrocycle. Electronic absorption spectral results are consistent with a nearly square planar geometry. Each of the two complexes isolated exhibits quasireversible Cu(II)/Cu(I) couple with Ef near — 0.3 V vs SCE. Both the complexes are further characterised by room temperature magnetic susceptibility, EPR spectroscopy at 298 and 77 K and elemental analyses.

    • Palladium(II) complex bearing benzothiazole based O,N,S donor pincer ligand: Study of in-vitro cytotoxicity, interaction with CTDNA and BSA protein


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      A new palladium(II) complex, [Pd(LSEt)Cl] (C1) with benzothiazole based ONS donor pincerligand (HLSEt) was synthesized (where, HLSEt = 2-(benzothiazol-2-yl)-6-(((2-(ethylthio)phenyl)imino)methyl)phenol). Interaction of C1 with CT DNA was investigated, and its binding constant was found to be 4.0˟105 M-1. The proficiency of ethidium bromide (EB) displacement from its EBCT DNA complex by C1 was performed by the fluorescence quenching method, and Stern-Volmer quenchingconstant (Ksv) was found to be 4.3˟105 M-1. Similarly, the interaction of C1 with BSA protein was investigated by UV-Vis and fluorescence methods. The apparent association constant (Ka) and Ksv weredetermined (Ka = 2.8˟104 M-1 and Ksv = 5.5˟104 M-1). In vitro cytotoxicity of the complex, [Pd(LSEt)Cl](C1), towards human gastric cancer cell lines (AGS) was assessed by the MTT assay method. The halfmaximal inhibitory concentration (IC50) of C1 (9.55 ± 1.23 μM) towards AGS cancer lines was found to belower than cisplatin (23.13 ± 1.03 μM).

      Herein, new palladium(II) complex, [Pd(LSEt)Cl] (C1) with benzothiazole-based ONS donor pincer ligand (HLSEt) was synthesized and characterized by several spectroscopic techniques. Interaction of C1 with CT DNA and BSA protein was investigated by UV-Vis and fluorescence methods. In vitro cytotoxicity of the complex toward human gastric cancer cell lines (AGS) was evaluated by the MTT assay method. The half maximal inhibitory concentration (IC50) of the palladium(II) complex (9.55±1.23 µM) was found to be less compared to cisplatin (23.13±1.03 µM) towards AGS cancer lines.

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