Hybridization of near-infrared emitting erbium(iii) and ytterbium(iii) monoporphyrinate complexes with silica xerogel: synthesis, structure and photophysics

Abstract

The new erbium(III) and ytterbium(III) monoporphyrinate complexes were synthesized and hybridized into silica xerogel frameworks though the coordination of 5-(N,N-bis(3-propyl)ureyl-1,10-phenanthroline to the lanthanide ions. The complexes are eight-coordinate with strong emissions in solution in the near-infrared region. The resulting silica films are transparent, homogenous, and exhibit strong mechanical strength. The scanning electron microscope and atomic force microscope study reveals that the surface of the film is porous with the silica in particulate or rod shapes. Upon visible light excitation, the fluorescence of the porphyrin at ∼ 649 nm with lifetimes of ∼ 3.4 and 3.8 ns for erbium(III) and ytterbium-hybridized films were observed, respectively. The erbium- and ytterbium-hybridized films gave characteristic emissions at 1538 nm with a lifetime of 0.6 μs and at 980 nm with a lifetime of 6.6 μs, respectively. They exhibited a 50 to 70% decrease in lifetime compared to their parent complexes in toluene.