Terrylene-Based Probe in Selective Colorimetric and Fluorometric Sensing of Toxic Heavy Metal Ions and Nitroaromatic...

The ongoing quest for developing new chromophores or fluorophores capable of detecting heavy metal ions and explosive nitroaromatic compounds remains a critical challenge. Higher rylene dyes, particularly terrylene and its structural derivatives are renowned for their exceptional photophysical properties, characterized by remarkably high molar extinction coefficient and fluorescence emission. Inspired by the distinct photophysical characteristics of terrylene, herein, for the first time, we synthesized a novel pyridine-substituted terrylene small molecule (TERPy), which emerged as a highly selective probe for colorimetric and fluorometric sensing of mercuric ion (Hg^{2 +}) and nitroaromatic explosives like 2,4,6-trinitrophenol (TNP). TERPy exhibited an impressive limit of detection (LOD) at 140 nM with an exceptionally high binding constant (logK = 11.4), indicating remarkable sensitivity and strong molecular interaction with Hg²⁺. Morphological evolution upon addition of Hg²⁺ indicated a successful complex formation between TERPy and Hg²⁺. Moreover, a reversible unbinding of Hg²⁺ from the complex by EDTA in both solution and solid-state enables their future optoelectronic device applications. Additionally, TERPy displayed remarkable selectivity for TNP, achieving a detection limit of 360 nM and demonstrated strong molecular affinity with a high binding constant (logK) of 0.92, reflecting excellent analytical performance.