Functional Three-Dimensional Ce-Based Coordination Polymer: Synthesis, Structure, and Selective Sensing of Lysine and Arginine Based on the Luminescence Turn-On Effect

A new cerium(III)-based coordination polymer, Ce(HCOO)(2,5-pydc) (where 2,5-pydc = 2,5-pyridinedicarboxylate), 1, has been fruitfully synthesized using the solvothermal method. A single-crystal X-ray diffraction study established the three-dimensional structure of compound 1. Ce3+ ions are in a tricapped trigonal prismatic geometry. The phase purity of 1 has been confirmed by powder X-ray diffraction, thermogravimetric analysis, and IR spectroscopic studies. Aqueous dispersion of compound 1 gives a luminescence emission at 350 nm upon excitation at 270 nm. We have observed a 17 nm shift in emission spectra in the presence of two amino acids (AAs), e.g., l-lysine (Lys) and l-arginine (Arg), in an aqueous medium. The compound also displays huge luminescence turn-on behavior in the presence of Lys and Arg with high sensitivity. The limits of detections are 0.72 and 1.03 μM for Lys and Arg, respectively. The selectivity experiments show that the detection of these AAs is highly selective in the presence of other AAs. Time-correlated single photon counting (TCSPC) studies show that the excited-state lifetime increases with the increase in addition of AAs. Detailed experimental studies propose that the superior interaction of basic AAs with CP is probably favored by the positive charge on these two amino acids.