A Ratiometric Multimode Optical Sensor for Highly Selective and Sensitive Detection of Ammonia by Hydrogen Bonding Interaction Regulation

Ammonia, as one of the most important industrial chemicals and a promising energy carrier, plays an important role in our daily lives. However, the high ammonia content discharged in water will not only affect the growth of aquatic organisms and the safety of aquatic products but also threaten the surrounding environment and destroy the ecosystem. Therefore, conveniently but accurately monitoring aqueous ammonia is always significant and imperative. Here, an unusual self-calibrated multimode ratiometric optical sensor Al-TCPP@MR for convenient and accurate aqueous ammonia detection was elaborately fabricated, and its high stability, sensitivity, selectivity, and fast response properties were then estimated. The detection limits for ratiometric fluorometry, ratiometric absorbance-based colorimetry, and smartphone-based ratiometric RGB analysis were as low as 19.9, 12.2, and 37.0 nM, respectively. This sensitive sensing only takes 5 min for fast ammonia level evaluation, and the recovery of ammonia in different actual samples was 97.3–102.8%. In addition, the mechanism of this sensing via the effective regulation of multiple hydrogen bond sites was supported by DFT calculations. These results not only open up a promising way for effective, rapid, and self-calibrated ammonia detection in complex samples but may also provide a highly efficient method for the development of a class of multimode sensors based on effectively regulated multiple hydrogen bond units.