Luminescent Zinc Phosphonates for Ratiometric Sensing of 2,4,6-Trinitrophenol and Temperature

Three new luminescent zinc phosphonates, [Zn(H2L)(H2O)(2)]center dot H2O (1), [Zn(H2L)] (2), and [Zn(H3L)(2)(H2O)(2)]center dot 3H(2)O (3), have been hydrothermally synthesized based on 1-hydroxy-2-(imidazo(1,2-a)pyridin-3-yl)ethylidene-1,1-diphosphonic acid (H4L). Single-crystal X-ray diffraction reveals that compounds 1-3 are a binuclear cluster, two-dimensional polar sandwich-like framework, and mononuclear unit, respectively. Compounds 1-2 exhibit remarkable capabilities to detect the trace of 2,4,6-trinitrophenol rapidly and quantitatively through luminescent quenching. It is worth to note that compounds 1-2 can be readily recovered and reused. On the other hand, compound 1 features dual emissions which facilitates it to serve as a useful self-calibrated ratiometric luminescent thermometer in the temperature range of 77-243 K, as well as a more reliable and sensitive intensity -based luminescent thermometer in the temperature range of 10-60 degrees C. Furthermore, compound 1 has good stability under simulated physiological conditions, indicating that it can be potentially utilized as a luminescent thermometer for biological applications.