Controllable Regulation of Emissive Excimers with Alkyl Chains for Highly Sensitive Perchlorate Analysis

Performing fast and accurate analysis of perchlorate in the environment is crucial for environmental and public safety. In this work, a novel strategy for modifying 4,4′-(3′,4′,5′,6′-tetrakis(4-(pyridin-4-yl)phenyl)-[1,1′:2′,1″-terpheny]-4,4″-diyl)dipyridine (TPD) with varied alkyl chains to realize bright monomer and excimer emissions simultaneously and fine-tune their emission properties was proposed. The excimer emission was thoroughly characterized via regulating the concentration of the luminophore and the length of the alkyl chain. It was found that the monomer emission and excimer emission could be optionally designed via regulating alkyl chains. Benefiting from the excellent dual-mode emission characteristics, the hypersensitive and ultraselective analysis of perchlorate (ClO₄^–) in real water samples was performed due to the strong electrostatic interaction between ClO₄^– and luminophore triggered excimer emission. The limit of detection was down to 21 ng·g^–1, which was a magnitude below the limit in drinking water set by the United States Environmental Protection Agency (60 ng·g^–1). Practical application showed the concentrations of ClO₄^– in construction wastewater samples were four-folds higher than the local river water. As a result, it is necessary to take control measures for ClO₄^– in construction wastewater. This study presents a reliable and convenient method for creating fluorescent probes toward target applications.