Journal Article

Molecular and Polymer Ln 2 M 2 (Ln = Eu, Gd, Tb, Dy; M = Zn, Cd) Complexes with Pentafluorobenzoate Anions: The Role of Temperature and Stacking Effects in the Structure; Magnetic and Luminescent Properties

Sidorov, Alexey A, Korshunov, Vladislav M, Eremenko, Igor L, Gogoleva, Natalia V, Shmelev, Maxim A, Kiskin, Mikhail A, Babeshkin, Konstantin A, Varaksina, Evgenia A, Voronina, Julia K, Taydakov, Ilya V, Efimov, Nikolay N

2020

Overview

Varying the temperature of the reaction of [{Cd(pfb)(H O) } · (pfb) ], [Ln (pfb) (H O) ]·H O (Hpfb = pentafluorobenzoic acid), and 1,10-phenanthroline (phen) in MeCN followed by crystallization resulted in the isolation of two type of products: 1D-polymers [LnCd(pfb) (phen)] 1.5 MeCN (Ln = Eu (I), Gd (II), Tb (III), Dy (IV)) which were isolated at 25 °C, and molecular compounds [Tb Cd (pfb) (phen) ] (V) formed at 75 °C. The transition from a molecular to a polymer structure becomes possible because of intra- and intermolecular interactions between the aromatic cycles of phen and pfb from neighboring tetranuclear Ln Cd fragments. Replacement of cadmium with zinc in the reaction resulted in molecular compounds Ln Zn [Ln Zn (pfb) (phen) ]·4MeCN (Ln = Eu (VI), Tb (VIII), Dy (IX)) and [Gd Zn (pfb) (H O) (phen) ]·4MeCN (VII). A new molecular EuCd complex [Eu Cd (pfb) (phen) ]·4MeCN (X)] was isolated from a mixture of cadmium, zinc, and europium pentafluorobenzoates (Cd:Zn:Ln = 1:1:2). Complexes II-IV, VII and IX exhibit magnetic relaxation at liquid helium temperatures in nonzero magnetic fields. Luminescent studies revealed a bright luminescence of complexes with europium(III) and terbium(III) ions.