Photoluminescent Lanthanide Coordination Polymers for Ammonia Gas Detection at Ambient Temperature and Humidity

Aiming at ammonia gas detection at ambient temperature,phenoxyaceticacid (Hpoa) and 2,5-pyridinedicarboxylic acid (H(2)pydc)were employed to construct the isostructural [Ln(III)(poa)(2,5-pydc)(H2O)(2)]& BULL;3H(2)O (Ln(III) = Eu-III (I), Gd-III (II), andTb(III) (III)). Their single crystal structuresand photophysical properties as well as the triplet state energiesof the sensitizers were characterized. Robustness and responses of I and its composite film with poly(vinyl alcohol) (I/PVA) toward water, ammonia, and common volatile organic compoundswere examined. The substantial quenching of Eu-III:D-5(0) & RARR; F-7( J ) by only ammonia was disclosed, and the underlying mechanismwas postulated based on experimental and computational studies. Referringto Eu-III:D-5(0) & RARR; F-7(2), the response R parameter was defined.Under ambient temperature (25-35 & DEG;C) and humidity (45-55%RH), a linear dependence of R on ammonia concentration(0.50-10.0 ppm) was obtained from I/PVA. Basedon the calibration method, the sensitivity (4.04%& BULL;ppm(-1)), detection limit (0.14 ppm), percentage recoveries (103-111%for 3.50, 6.50, and 8.50 ppm), and relative standard deviation (1.5-8.2%)were determined. The reuse of the film for at least 10 cycles wasdemonstrated with 95-97% repeatability. Limitation of the detectionby extreme humidity was presented. Performanceof new photoluminescent lanthanide coordinationpolymers (as powder and film) in ammonia gas detection at ambienttemperature is presented.