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

Unlabelled: Kinetics between 5,10,15,20-tetrakis(N-methylpyridium-4-yl)porphyrin and Ni species were investigated in aqueous solution at 25 ±1 °C in = 0.10 M (NaNO). Speciation of Ni was done in = 0.10 M (NaNO) for knowing distribution of Ni species with solution pH. Experimental data were compared with speciation diagram constructed from the values of hydrolysis constants of Ni ion. Speciation data showed that hexaaquanickel(II) ions took place in hydrolysis reactions through formation of [Ni(OH)(OH)] species with solution pH. According to speciation of Ni and pH dependent rate constants, rate expression can be written as: d[Ni(TMPyP)]/dt = ( [Ni ] + [Ni(OH) ] + [Ni(OH) ] + [Ni(OH) ])[HTMPyP], where , , and were found to be = (0.62 ± 0.22) × 10; = (3.60 ± 0.40) × 10; = (2.09 ± 0.52) × 10, = (0.53 ± 0.04) × 10 Ms at 25 ±1 °C, respectively. Formation of hydrogen bonding between [Ni(HO)(OH)] and [HTMPyP] causes enhanced reactivity. Rate of formation of [Ni(II)TMPyP] complex was to be 3.99 × 10 Ms in = 0.10 M, NaNO (25 ± 1 °C). UV-Vis and fluorescence data suggested that [Ni(II)TMPyP] and [H(TMPyP)] interact with DNA outside binding with self-stacking and intercalation, respectively. .

Supplementary Information: The online version contains supplementary material available at 10.1007/s12039-021-01945-y.