Anthryl-functionalized cyanide-bridged Fe/Co cubes

Abstract

Two anthryl-functionalized cyanide-bridged [Fe₄Co₄] cube complexes, [(pzTp)Fe(CN)₃Co(TpEtOAn)]₄[OTf]₄·8MeCN·7Et₂O (1) and [NEt₄]₃[(pzTp)Fe(CN)₃Co(TpEtOAn)]₄[OTf]₇·5MeCN·2Et₂O (2) (pzTp⁻ = tetrapyrazolylborate, TpEtOAn = 2,2,2-tris-(pyrazol-1-yl)ethoxy(9-methyl-anthracene)), were synthesized and characterized. The crystallographic study revealed that the [Fe₄Co₄] cubes are arranged into a linear supramolecular chain through significant anthryl–anthryl π–π stacking interactions in complex 1, whereas a zigzag supramolecular 1D assembly is observed in 2. The magnetic measurements showed that both compounds exhibited incomplete transitions from the paramagnetic {Fe^III_LS(μ-CN)Co^II_HS} state to the diamagnetic {Fe^II_LS(μ-CN)Co^III_LS} state at about 200 K. The luminescence measurement of 1 in solution revealed an enhancement of the emission upon dilution or addition of perfluoronaphthalene (PFN) molecules, which could be attributed to the suppression of the aggregation-caused quenching (ACQ) effect, suggesting possible aggregation of the cube units in the solution.