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 H 2 TMP ( I ) with bismuth nitrate pentahydrate, Bi(NO 3 ) 3 ·5H 2 O in dry pyridine. The spectroscopic data demonstrates the existence of a binuclear moiety [Bi(TMP)NO 3 ] 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 Bi 3+ 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 K 562 strains have been further demonstrated. • A sitting-atop (SAT) macro molecule of Tetrakis-4-methoxyphenylporphyrinato Bi(III) has been synthesized. • Due to hypervalent nature of Bi 3+ centre, the bismuth porphyrin tends to exists as binuclear moiety. • TEM images reflect mutilayered nanosheets of synthesized complex. • Bismuth complex exhibit high antitumor activity against leukaemia K 562 strains relative to its free base ligand. • Due to out of plane coordination mode, the synthesized complex have low thermal stability.