Synthesis, Structure, and Luminescent Properties of Lanthanide Complexes with 1,8-Naphthalenediboronic Acid Anhydride

Complexes of trivalent lanthanides La (1), Sm (2), Er (3), Yb (4) are prepared by the reaction of Cp3Ln with 1,8-naphthalenediboronic acid anhydride. The structures and photoluminescent properties of obtained compounds are described. The tetranuclear structure of the Sm4Cp2L2(μ-O)2(THF)4 complex is determined by XRD (L is the product of self-condensation of three 1,8-naphthalenediboronic anhydride molecules). According to the elemental analysis, IR spectroscopy, and time-of-flight MALDI mass spectrometry data, all the prepared compounds have a similar composition. At room temperature, all of these complexes exhibit ligand-centered photoluminescence (PL). The PL spectra of Sm, Er, and Yb complexes show narrow bands of metal-centered emission of the corresponding ions in visible and near-IR ranges. The lanthanum complex exhibits phosphorescence at 77 K with an excited state lifetime of 6.2 ms.