ABSTRACT
A luminescent 1D coordination polymer (CP) [Zn2L2(H2O)4]·H2O (1, H2L = 1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid) was prepared by a solvothermal method. 1 shows excellent fluorescence properties and has an obvious fluorescence "turn-on" phenomenon for saccharin (SAC), 2-thiazolidinethione-4-carboxylic acid (TTCA), and periodate (IO4-). Between 0 and 60 µM concentration range of SAC, the fluorescence enhancement efficiency (KEC) of 1 reaches 1.00 × 105 M-1 with the limit of detection (LOD) of 90 nM. 1 is the first CP-based sensing material for SAC detection. For TTCA detection, the KEC is 2.73 × 105 M-1 at the 25-80 µM concentration range, and the LOD is 33 nM, the lowest LOD among the sensors that detect TTCA at present. For IO4- ion detection, when the IO4- ion concentration ranges from 0 to 10 µM, the KEC is 2.34 × 105 M-1 and the LOD is as low as 39 nM. In order to better understand the sensing phenomenon, we also discuss in detail the sensing mechanisms for SAC, TTCA, and IO4- ions.
ABSTRACT
By the solvothermal assembly of Gd3+ and 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H4adip), an anthracene-based lanthanide coordination polymer (CP), [Gd2(adip)(H2adip)(NMP)2]·DMF·3H2O (1; NMP = N-methylpyrrolidone; DMF = N,N-dimethylformamide), has been prepared. It possesses a 3D framework and a strong ligand-based blue emission. 1 could be applied as a multifunctional chemical sensor for UO22+, PO43-, and 2-thiazolidinethione-4-carboxylic acid (TTCA) with excellent selectivity, sensitivity, and anti-interference. In the 0-20 µM concentration range of UO22+, the quenching constant (KSV) is 4.05 × 104 M-1 with a detection limit of 1.42 µM. Fluorescence enhancement was observed when PO43- was added to the 1-H2O suspension. The slope of the linear relationship between the PO43- concentration in the 0-35 µM concentration range and I/I0 is 3.70 × 104 M-1 with a detection limit of 1.55 µM. When the TTCA concentration is lower than 20 µM, the fluorescence quenching constant KSV is 1.77 × 104 M-1 with a detection limit of 3.25 µM, which approaches the values reported of the best CP-based sensing materials for TTCA up to now. Moreover, the fluorescence quenching or enhancement mechanism was also investigated.
ABSTRACT
Reports about the detection of antibiotic aztreonam (ATM) are very rare. Herein, a fluorescent "turn-on" sensing coordination polymer 1 for ATM is described. The good linear relationship between the luminescence intensity and ATM concentration (0-0.135 mM) gave the slope of 20 380 M-1 and detection limit of 4.44 × 10-7 M. This work is of great significance, not only because 1 is a sensing material for ATM with excellent selectivity, sensitivity, anti-interference ability and recoverability, but also because it expands the catalogue of antibiotics detection.
Subject(s)
Anti-Bacterial Agents , Polymers , Aztreonam , Fluorescent Dyes , LuminescenceABSTRACT
Powerful explosive sensors play a key role in public security and environmental protection. Herein, we report a series of isostructural lanthanide coordination polymers [Ln2L1.5(NMP)2] n (LnL: Ln = Eu, Gd, Tb, Dy, Ho, and Er; H4L = [1,1':4',1â³-terphenyl]-2',4,4â³,5'-tetracarboxylic acid; NMP = N-methyl-2-pyrrolidone) and mixed-Ln LnL (Eu xTb1- xL, Eu xGd1- xL, Tb xGd1- xL, and Eu xTb0.02- xGd0.98L). Luminescence studies show that both H4L and GdL emit strong fluorescence and phosphorescence at 77 K while only fluorescence at room temperature, and TbL exhibits strong Tb3+ characteristic emission, although the energy difference between the triplet excited state of H4L (20661 cm-1) and the 5D4 energy level of Tb3+ (20500 cm-1) is very small. By doping Eu3+ and Tb3+ into GdL, we obtained Eu xTb0.02- xGd0.98L emitting warm white light. For TbL and Tb0.01Gd0.99L showing dual emission, upon addition of picric acid (PA) into their suspensions in Tris-HCl buffer, Tb3+ emission decreases slowly; however, the ligand-based emission is sharply quenched, rendering TbL and Tb0.01Gd0.99L excellent single-lanthanide and mixed-lanthanide ratiometric luminescence PA sensor materials, respectively.