A high-nuclearity Cd(ii)–Nd(iii) nanocage for the rapid ratiometric fluorescent detection of quercetin†
A NIR luminescent Cd(II)–Nd(III) nanocage 1 was synthesized from a new long-chain Schiff base ligand. The cage dimensions are about 2.4 × 2.4 × 2.4 nm, which allow direct visualization by TEM. 1 exhibits rapid and stable ratiometric fluorescent response to Que with high sensitivity. The quenching constants of Que to the ligand-centered and lanthanide emissions of 1 are 1.7 × 105 M−1 and 8.1 × 104 M−1, respectively. The detection limits to Que are 1.8 μM for the ligand-centered emission and 3.7 μM for the lanthanide luminescence. The response behavior of 1 to Que is not influenced by some potential interferents such as biomolecules and ions.