Magnetic properties and sensitized visible and NIR luminescence of Dy-III and Eu-III coordination polymers by energy transfer antenna ligands

Abstract

Two coordination polymers, {[Ln(2-stp)(4,4 '-bipy)(H2O)]center dot(H2O)}, [Ln = Dy (1) and Eu (2), 2-stp = 2-sulfoterephthalate and 4,4 '-bipy = 4,4 '-bipyridine] have been characterized by solid state UV-vis, FTIR spectra, X-ray single crystal diffraction and solid state photoluminescence. Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field is also studied for both complexes. After ligand-mediated excitation, both complexes show the characteristic visible and NIR luminescence of the corresponding Ln(III) ions (Ln = Dy, Eu) which is due to efficient energy transfer from the ligands to the central Ln(III) ions via an antenna effect. The indirect energy transfer in both complexes has been investigated and discussed in detail.