Synthesis, characterization, and DNA-binding and -photocleavage properties of water-soluble lanthanide porphyrinate complexes

A series of cationic lanthanide porphyrinate complexes of the general formula [(Por)Ln(H2O)3]+ (Ln 3+=Yb3+ and Er3+) were synthesized in moderate yields through the interaction of meso-pyridyl-substituted porphyrin free bases (H2Por) with [Ln{N(SiMe3)2}3] ·x [LiCl(thf)3], and the corresponding neutral derivatives [(Por)Ln(LOMe)] (LOMe-= [(η5-C5H5)Co{P(=O)(OMe) 2}3]-) were also prepared from [(Por)Ln(H 2O)3]+ by the addition of the tripodal anion, LOMe-, an effective encapsulating agent for lanthanide ions. Furthermore, the water-soluble lanthanide(III) porphyrinate complexes-including [(cis-DMPyDPP)Yb(H2O)3]Cl3 (cis-DMPyDPP=5,10-bis(N-methylpyridinium-4′-y1)-15,20-di(phenyl)porphyrin) , [(trans-DMPyDPP)Yb(H2O)3]Cl3 (trans-DMPyDPP=5,15-bis(N-methylpyridinium-4′-y1)-10,20-di(phenyl) porphyrin), [(TMPyP)Yb(LOMe)]I4, and [(TMPyP)Er(L OMe)]I4 (TMPyP=tetrakis(N-methylpyridinium-4-y1)porphyrin) -were obtained by methylation of the corresponding complexes with methyl iodide and unambiguously characterized. The binding interactions and photocleavage activities of the water-soluble lanthanide(III) porphyrinate complexes towards DNA were investigated by UV-visible, fluorescence, and near-infrared luminescence spectroscopy, as well as circular dichroism and gel electrophoresis.