Fabrication of hierarchical architectures of Tb-MOF by a “green coordination modulation method” for the sensing of heavy metal ions

Abstract

A green coordination modulation method has been successfully exploited to fabricate lanthanide coordination polymer Tb(BTC)(H₂O) via environmentally friendly ethanol and alkaline additive. Fascinating hierarchical architectures, including rod-like crystals, dual-core shelled peanut-like crystals and double-head dandelion-like crystals were obtained through exploring the reaction parameters. The structures of the samples were confirmed by powder X-ray diffraction, and the morphologies were characterized by SEM. Furthermore, details of the formation mechanism of the resulting crystal morphologies were deduced. The studies of the photoluminescence properties reveal that the hierarchical architectures of these coordination polymers exhibit green emission, corresponding to the ⁵D₄/⁷F_J (J = 6, 5, 4, 3) transitions of the Tb³⁺ ions under UV light excitation. Outstandingly, double-head dandelion-like crystals with the strongest photoluminescence intensity display highly sensitive and selective sensing for heavy metal ions, and the probable sensing mechanism was discussed.