A Red‐Emitting Luminescent Material Capable of Detecting Low Water Content in Organic Solvents

A new red‐emitting luminescent material was prepared from a gel formed by simply mixing EuCl 3 ⋅ 6 H 2 O and 4′‐ para ‐phenylcarboxyl‐2,2′:6′,2′′‐terpyridine (Hcptpy) in a molar ratio of 1:2 in anhydrous ethanol at room temperature. It shows bright red luminescence dominated by the 5 D 0 → 7 F 2 transition of Eu 3+ , a long lifetime (1.16 ms), a high absolute quantum yield (48.2 %), and good thermostability (stable up to 500 °C). In addition, the luminescence of the material can be easily quenched by contact with water, which makes it suitable for detecting low contents of water (0.1–1.5 vol %) in common organic solvents such as diethyl ether and THF.