A near-infrared luminescent Cd(II)−Nd(III) nanocluster 1 (molecular dimensions of 1.0 nm × 2.2 nm × 2.2 nm) was obtained using a Schiff base ligand. It can be used as a sensor for the wavelength-dependent detection of rutin even in the presence of other interference, which can be expressed by the third-order equation1 is used to analyze the Rut concentrations quantitatively in CH 3 CN and fetal calf serum (FCS). For the determination of Rut concentrations in FCS, the ranges of recovery and relative standard deviations are 99.06−104.70% and 2.30−4.15%, respectively.■ EXPERIMENTAL SECTION Synthesis of HL. 4,4′-Diaminodiphenylsulfone (10 mmol, 2.48 g) in 30 mL of EtOH was added to a 30 mL EtOH solution of 3methoxysalicylaldehyde (10 mmol, 1.52 g). The mixture was stirred under reflux for 8 h to give a yellow solid product. After cooling, the solid was then filtered and washed with EtOH to give the product HL.