Facile preparation of neutral monoporphyrinate lanthanide complexes with strong near-infrared emission

Ytterbium (III) acetylacetonate reacts with 5,10,15,20-tetraphenylporphyrin (H2TPP) and 5,10,15,20-tetra(4-bromophenyl)porphyrin (H2TBrPP) in 1,2,4-trichlorobenzene and forms unexpected acetate-bridged dimer and propionate-coordinated monomer of monoporphyrinate ytterbium (III) complexes, respectively, whereas interaction of ytterbium (III) acetate with H2TPP gives stable acetate-coordinated monomer with two labile methanol binding directly to metal center. This compound reacts readily with 1,10-phenanthroline derivatives to give eight-coordinate monoporphyrinate ytterbium (III) complexes with strong near infrared emission efficiency.

Refluxing of porphyrin free base with ytterbium (III) acetate hydrate in 1,2,6-trichlorobenzene gives complex A with two solvent molecules coordinating directly to central metal ion. The efficient substitution of solvents by bidentate ligand in A leads to the formation of eight-coordinate complexes B with intense emission in 980 nm.Figure optionsDownload as PowerPoint slide