Enhanced luminescence and tunable magnetic properties of lanthanide coordination polymers based on fluorine substitution and phenanthroline ligand

Abstract

A family of highly stable lanthanide coordination polymers incorporating fluorine-substituted carboxylate tectonics and the rigid ligand phenanthroline, namely, {[Ln _<i>m</i> (Tfbda) _<i>n</i> (Phen)₂·2H₂O]·2H₂O} _<i>z</i> , (Ln = Pr (1), Ho (4) and Gd (7), <i>m</i> = 2, <i>n</i> = 3); {[Ln₃ (Tfbda) _{<i>m</i> ₁} (Tfba) _{<i>m</i> ₂} (Phen) _<i>n</i> ·2H₂O]·H₂O} _<i>z</i> (<i>z</i> > 1, Ln = Dy (3), Er (5) and Yb (6), <i>m</i> ₁ = 4, <i>m</i> ₂ = 1, <i>n</i> = 3); [Ln₂(H₂Tfbda)₄(Phen)₂·(H₂O)₂]·Phen (Ln = Nd (2)), Tfbda = 3,4,5,6-tetrafluoro-benzene-1,2-dioic acid, Tfba = 2,3,4,5-tetrafluorobenzoic acid have been afforded under hydrothermal conditions. The series of coordination polymers exhibited diverse structural motifs, from dinuclear cluster to 1-D chain arrary, displaying efficiently sensitized luminescence over a spectral range from visible to near-infrared (NIR) region and a long lifetime, due to efficient energy transfer from fluorine-substituted ligands to Ln(iii) centers in solid state. Slow relaxation magnetization and significant frequency- and temperature-dependent peaks were observed in trinuclear Dy(iii)-based coordination polymer 3. DC magnetic susceptibility studies reveal the existence of weak ferromagnetic interaction within 7.