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

• Published in: European journal of inorganic chemistry Vol. 2017; no. 22; pp. 2892 - 2904
• Main Authors: Evstifeev, Igor S., Efimov, Nikolay N., Varaksina, Evgenia A., Taydakov, Ilya V., Mironov, Vladimir S., Dobrokhotova, Zhanna V., Aleksandrov, Grygory G., Kiskin, Mikhail A., Eremenko, Igor L.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 16-06-2017
• Subjects: Antennas; Antiferromagnetism; Chains (polymeric); Chemical synthesis; Coordination polymers; Coupling; Coupling (molecular); Drying; Dysprosium; Inorganic chemistry; Lanthanides; Luminescence; Magnetic induction; Magnetic properties; Magnetic relaxation; Melts; Polymers; Rare gases; Samarium; Thermal analysis; Thermal stability
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201700089

New 1D polymers, with the 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 under an inert gas up to 350 °C, and it melts at 297 °C. It is 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 the 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 an energy barrier of ΔEeff/kB = 5 K.
The 1D polymers [Ln(4‐phbz)3]n (Ln = Sm, Eu, Gd, Tb, Dy, Ho), stable up to 297 °C, are the first examples of structurally characterized lanthanide complexes with 4‐phenylbenzoato ligands. The Tb complex shows the strongest luminescence, with high quantum yield (66 %); the Dy complex shows distinct frequency‐dependent χ′′ signals in a zero dc field, indicating slow magnetic relaxation below 5 K.