A NIR luminescent “tetra-decker” Nd(III) salen nanocluster for rapid ratiometric fluorescence detection of quercetin

Two NIR luminescent “bi-decker” and “tetra-decker” Cd(II)-Yb(III) and Nd(III) clusters 1 and 2 were synthesized from a new salen-type Schiff base ligand. 2 exhibits rapid ratiometric fluorescence response to Que with high sensitivity. The quenching constants of Que to the ligand-centered and lanthanide emissions of 2 are 2.9 × 104 M−1 and 3.8 × 104 M−1, respectively. The detection limits to Que are 6.75 μM for the ligand-centered emission and 2.03 μM for the lanthanide luminescence. The response of 2 to Que is not influenced by some potential interferents such as biomolecules and ions.