Synthesis and spectroscopic characterization of Ni, Zn, Pd and Pt tetra(pentafluorophenyl)porpholactone with comparisons to Mg, Zn, Y, Pd and Pt metal complexes of tetra(pentafluorophenyl)porphine

Abstract

Ni , Zn , Pd and Pt tetra(pentafluorophenyl)porpholactone (TFPL) were synthesized and identified by their optical and mass spectra. The lactone ring was produced from the parent free-base porphyrin using silver nitrate and oxalic acid with a yield of 73%, and the metals were inserted by standard procedures from metal salts. The compounds show intense Soret Bands in the region 390-420 nm. The longest wavelength visible absorbance peaks, in the region 572-608 nm, are weaker than the Soret peaks by a factor of only ~3 for the Ni , Pd , and Pt complexes but a factor of ~10 for the free-base and Zn complexes. As found with other metalloporphyrins the Ni complex is dark, Zn shows fluorescence and Pd and Pt complexes show strong phosphorescence. The Pd complex also shows a weak fluorescence not quenched by oxygen. The phosphorescence lifetimes of Pd and Pt complexes of TFPL in 3-methylpentane at 77 K are, respectively, ~1 ms and ~70 μs, about 60% that of the TFPP complexes. The wavelengths of phosphorescence emission, 733 nm and 758 nm for PtTFPL and PdTFPL, respectively, are sufficiently red-shifted so that these pressure sensitive luminophors can be included in the same pressure sensitive paint (PSP) as Eu complexes, whose emission at ~615 nm can serve as a temperature sensor. The fluorescences of Mg , Zn , and Y(TFPP) show weak origin bands, making them suitable as unquenched references for PSP.