Extension of Novel Lanthanide Luminescent Mesoporous Nanostructures to Detect Fluoride

Abstract

A novel polydentate type ligand derived from <i>N</i>²,<i>N</i>⁶-bis­(4,4-diethoxy-9-oxo-3-oxa-8,10-diaza-4-siladodecan-12-yl)­pyridine-2,6-dicarboxamide (<b>L</b>) has been designed, and it played essential roles in the assembly of new organic–inorganic functional materials. First, its multiple amide groups would coordinate to lanthanide ions firmly and transfer the absorbed energy to both Eu­(III) and Tb­(III) simultaneously. Second, the hydrogen-bond donor units showed strong affinity to guest anion (F^–). Third, the two silylated arms could induce the formation of sol–gel derived siloxane hybrid materials. Following this idea, two lanthanide luminescent amorphous particles (<b>ASNs-Eu</b> and <b>ASNs-Tb</b>) have been prepared for the recognition of fluoride ions. Further modification of the synthesis method and transformation to mesoporous network (<b>MSNs-Eu</b> and <b>MSNs-Tb</b>) led to much enhanced thermostabilities, larger specific surface area (from 78.5 to 515 m² g^–1 for Eu­(III); 89.6 to 487 m² g^–1 for Tb­(III)), and lower detection limits (2.5 × 10^–8 M for <b>MSNs-Eu</b> and 3.4 × 10^–8 M for <b>MSNs-Tb</b>) for the fluoride ion