Synthesis and spectroscopic studies of lanthanide monoporphyrinates with meso-tetra-aryl porphyrinate bearing bromines on the β-pyrrole positions of fluorines on phenyl groups

Abstract

The metal derivatives of octabromotetraphenyl porphyrin with lanthanide (Sm to Lu) ions have been synthesized via the acetylacetonates and characterized by UV-vis, IR and ESR spectroscopies. These lanthanide complexes exhibit interesting electronic features compared with all the previously reported lanthanide monoporphyrinates. The stability of the complexes is discussed in terms of the already known related complexes. The meso-fluoro-aryl-substituted porphyrin with Sm III has been synthesized and its spectroscopic behaviour compared with the above β-pyrrole octabromotetraphenyl complexes. IR studies indicate that the axial ligand is the acetylacetonate as has been observed for lanthanide monoporphyrinates synthesized by the acetylacetonate method. ESR spectroscopy of Ln(obp)acact exhibit one intense peak with g ∼ 2.00 and hyperfine splitting for Ln  Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu. The ESR spectrum of Gd(obp)acac exhibits an isotropic g-factor with a value of 2.3099 and it compared with the analogous complex of Gd(tpp)acac.