Near-infrared luminescent xerogel materials covalently bonded with ternary lanthanide [Er(III), Nd(III), Yb(III), Sm(III)] complexes

A beta-diketone ligand 4,4,5,5,5-pentafluoro-1-(2-naphthyl)-1,3-butanedione (Hpfnp), which contains a pentafluoroalkyl chain, was synthesized as the main sensitizer for synthesizing new near-infrared (NIR) luminescent Ln(pfnp)(3)phen (phen = 1,10-phenanthroline) (Ln = Er, Nd, Yb, Sm) complexes. At the same time, a series of lanthanide complexes covalently bonded to xerogels by the ligand 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (phen-Si) were synthesized in situ via a sol-gel process. [The obtained materials are denoted as xerogel-bonded Ln complexes (Ln = Er, Nd, Yb, Sm).] The single crystal structures of the Ln(pfnp) 3phen complexes were determined. The properties of these complexes and the corresponding xerogel materials were investigated by Fourier-transform infrared (FTIR), diffuse reflectance (DR), and field-emission scanning electron microscopy (FE-SEM). After ligand-mediated excitation of these complexes and the corresponding xerogel materials they all show the characteristic NIR luminescence of the corresponding Ln(3+) ion. This is attributed to efficient energy transfer from the ligands to the Ln(3+) ion (the so-called "antenna effect").