• MRITTIKA CHAKRABORTY

      Articles written in Journal of Chemical Sciences

    • Kinetics and mechanism of formation of nickel(II)porphyrin and its interaction with DNA in aqueous medium

      AHSAN HABIB SALMA SERNIABAD MOHAMMAD SHAMIM KHAN ROKAYEA ISLAM MRITTIKA CHAKRABORTY AKLIMA NARGIS MD EMRAN QUAYUM MD ASHRAFUL ALAM VALENTINA RAPOZZI MASAAKI TABATA

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      Kinetics between 5,10,15,20-tetrakis(N-methylpyridium-4-yl)porphyrin and Ni2+ species wereinvestigated in aqueous solution at 25 ±1 °C in I = 0.10 M (NaNO3). Speciation of Ni2+ was done in I = 0.10M (NaNO3) for knowing distribution of Ni2+ species with solution pH. Experimental data were comparedwith speciation diagram constructed from the values of hydrolysis constants of Ni2+ ion. Speciation datashowed that hexaaquanickel(II) ions took place in hydrolysis reactions through formation of [Ni(OH2)6-n(OH)n]2-n species with solution pH. According to speciation of Ni2+ and pH dependent rate constants, rateexpression can be written as: d[Ni(TMPyP)4+]/dt = (k1[Ni2+(aq)] + k2[Ni(OH)+(aq)] + k3[Ni(OH)2o(aq)] + k4[Ni(OH)3-(aq)])[H2TMPyP4+], where k1, k2, k3 and k4 were found to be k1 = (0.62 ± 0.22) ˟ 10-2; k2 = (3.60± 0.40) ˟ 10-2; k3 = (2.09 ± 0.52) ˟ 10-2, k4 = (0.53 ± 0.04) ˟ 10-2 M-1s-1 at 25 ±1 °C, respectively.Formation of hydrogen bonding between [Ni(H2O)5(OH)]+ and [H2TMPyP]4+ causes enhanced reactivity.Rate of formation of [Ni(II)TMPyP]4+ complex was to be 3.99 ˟ 10-2 M-1s-1 in I = 0.10 M, NaNO3 (25 ±1 °C). UV-Vis and fluorescence data suggested that [Ni(II)TMPyP]4+ and [H2(TMPyP)]4+ interact with DNA via outside binding with self-stacking and intercalation, respectively.

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