A New Generation of Sumanene‐Based AIEgens for the Effective Recognition of Metal Cations in Solutions Containing 95 vol % of Water

In recent years, the application of sumanene derivatives for the optical detection of metal cations was demonstrated. Unfortunately, known sumanene-based receptors enable the detection process in purely organic solutions or in aqueous media containing not lower than 50 vol % of organic solvent. Designing easy-to-synthesize sumanene-based optical receptors able to effectively recognize metal cations in aqueous solutions containing a slight volume fraction of organic solvent remained an important and vital challenge. In this work, we show that water-insoluble sumanene receptors composed of only carbon and hydrogen atoms enable the effective detection of cesium (Cs⁺) or lithium (Li⁺) cations in solutions containing 95 vol % of water. Their key feature is related to the exhibition of an aggregation-induced emission (AIE) effect. We discovered that the designed sumanene receptors exhibit excellent detection parameters expressed by Stern-Volmer constant values at the level from 10⁸ to 10¹⁰ M^-1. This work also shows that by simple modification of the sumanene receptor structure, it is possible to drastically change its detection preference from large Cs⁺ cations to small Li⁺ cations. The highest sensitivity of the designed receptors was concluded for Na⁺ or Li⁺, depending on the receptor structure. This work opens new avenues in designing sumanene-based optical receptors.