New life of ancient pigments: application in high-performance optical sensing materials.

Calcium, strontium, and barium copper silicates are demonstrated to possess valuable photophysical properties which make them particularly attractive for application in optical chemosensors. Several examples of sensing materials based on these phosphors are provided. Particularly, broad excitation and near-infrared emission makes them ideal candidates for the preparation of ratiometric sensors based on absorption-based indicators. Due to their excellent chemical and photochemical stability and high brightness, these phosphors can serve as reference for fluorescent indicators to enable ratiometric intensity or dually lifetime referenced measurements. Finally, the moderate temperature dependence of the luminescence decay time enables intrinsic temperature compensation of the sensing materials at ambient temperatures. The improved sensitivity at temperatures above 100 °C makes these new materials promising candidates for high-temperature thermographic phosphors.