Synthesis and Photoluminescence Properties of Nonanuclear Tb(III) Clusters with Long Alkyl Chain Group

Abstract

Series of nonanuclear Tb(III) clusters with ligands of different length of alkyl chain groups and their photophysical properties are demonstrated. The nonanuclear Tb(III) clusters (Tb₉ clusters) are composed of nine oxygen-bridged Tb(III) ions and sixteen alkyl salicylate ligands, where alkyl chain are ethyl (Tb₉-Et), propyl (Tb₉-Pr), butyl (Tb₉-Bu), and hexyl (Tb₉-Hex) groups. The luminescence properties of the Tb₉ clusters are characterized by absorption spectra, emission quantum yields, and emission lifetimes. The radiative (k_r) and nonradiative (k_nr) rate constants were calculated from their photophysical properties. Tb₉-Hex have shown the highest k_r (859 s^-1) and lowest k_nr (137 s^-1), owing to the tight packing due to CH-π interaction by long alkyl chains. [DOI: 10.1380/ejssnt.2015.27]