A hypervalent Bismuth(III) derivative of Tetrakis-4-methoxyphenyl porphyrin: Synthesis, spectroscopic characterisation and morphological investigations

Abstract In this study, we aimed to synthesize as well as spectroscopically characterize a sitting-atop (SAT) macro molecule of Tetrakis-4-methoxyphenylporphyrinato Bi(III). The bismuth porphyrin was prepared by the reaction of free base macrocycle, 5, 10, 15, 20-Tetrakis-4-methoxyphenylporphyrin H2TMP (I) with bismuth nitrate pentahydrate, Bi(NO3)3·5H2O in dry pyridine. The spectroscopic data demonstrates the existence of a binuclear moiety [Bi(TMP)NO3]2 (II) in the solid state and even in solution in which two bismuth porphyrins are interlinked by a bridging bidentate nitrate. Self dimerisation of bismuth porphyrin is expected to arise due to strong tendency of Bi3+ ions to become hypervalent. The electronic absorption as well emission bands in complex (II) are bathochromically shifted relative to compound (I) with emission bands significantly quenched in the metal chelate. At pH ∼5, complex (II) is demetallized to form the dicationic analogs of I which tend to undergo prominent J-type supramolecular aggregation. Demetallation is also followed when a dichloromethane solution of metal chelate (II) is kept for a long period at room temperature. The macro rings were also studied by nano technology like SEM, TEM, EDX and powder XRD. Thermal analysis and invitro cytotoxicity screening of the macro rings against leukaemia K562 strains have been further demonstrated.