Thermostable 1D Lanthanide 4-Phenylbenzoate Polymers [Ln(4-phbz)3]n(Ln = Sm, Eu, Gd, Tb, Dy, Ho) with Isolated Metal Chains: Synthesis, Structure, Luminescence, and Magnetic Properties

New 1D polymers with general formula [Ln(4-phbz)3]n, where Ln = Sm, Eu, Gd, Tb, Dy, Ho, and 4-phbz is the 4-phenylbenzoate anion, were synthesized by the reaction of Ln(NO3)3∙xH2O, 4-phenylbenzoic acid and dry KOH. Thermal analysis shows that [Eu(4-phbz)3]n is thermally stable in an inert atmosphere up to 350 oC and melts at 297 oC. It was shown that the 4-phenylbenzoate anion (E(T1) ~ 22500 cm-1) in [Ln(4-phbz)3]n can play the role of an antenna and sensitize the luminescence of Eu3+ and Tb3+ ions. Analysis of magnetic data of the [Gd(4-phbz)3]n complex reveals weak antiferromagnetic coupling between Gd3+ ions (J = -0.053 cm-1). The [Dy(4-phbz)3]n compound shows noticeable frequency-dependent χ'' signals indicating slow magnetic relaxation and single-molecule magnet behavior with the energy barrier of ΔEeff/kB = 5 K.