1D-photosensitized lanthanide polymers with flexible 4, 4′-bipyridyl linker

Abstract

Three new ternary lanthanide complexes, [Ln(fod)3(4,4′-bpy)]n (Ln = Nd, Sm and Tb) were synthesized using asymmetric fluorinated β-diketone, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione, as first sensitizer and 4, 4′-bipyridyl, the linker. The structural characterizations were carried out through various techniques viz., 1H NMR, FT-IR, single crystal X-ray diffraction (SC-XRD) and thermal analysis. Single crystal X-ray diffraction (SC-XRD) analysis demonstrates a 1D-polymeric chain structure of [Nd(fod)3(4,4′-bpy)]n in which Nd (III) ions are octa-coordinate with distorted square antiprismatic geometry. The structure of samarium and terbium complexes were optimized by the sparkle PM7 model using MOPAC implemented in LUMPAC and found to be distorted triangular dodecahedron The thermal studies shows that the complexes are thermally stable and acquire volatility without decomposition. The 1H NMR of these complexes are similar. The protons of 4, 4ʹ-bpy are largely shifted upfield in the Tb complex followed by Nd and Sm. The detailed photoluminescence and decay curves of these polymeric complexes have been discussed in solution and solid state. The emission spectra obtained for all the complexes display their characteristic emission peaks. The terbium complex shows pure green luminescence and exhibits a longer lifetime of 406 µs. The [Sm(fod)3(4,4′-bpy)]n displays color tuning during interphase and also with a change in excitation wavelength from turquoise to pure yellow via green. All the synthesized complexes exhibiting remarkable photophysical properties ensures their importance in various fields.