Terbium-macrocycle as a narrow-range pH fluorescence probe for detection and discrimination of carboxylic diacid isomers

It is a very challenging work to discriminate their isomers of aliphatic or aromatic carboxylic diacids for potential needs by the design and synthesis of conventional chemical receptors. Herein, we implement the efficient discrimination of selected carboxylic diacids based on the comprehensive analysis of sensing signals, associated with several fluorescent channels. A mononuclear terbium-macrocycle Tb - 2 a is synthesized by the template method, and it is used as a fluorescent probe to provide multi-channel responses for carboxylic diacids. Upon its narrow-range pH-responsive behaviors, complex Tb - 2 a exhibits differential fluorescence on three emission bands which are statistically analyzed. As a result, complex Tb - 2 a can efficiently distinguish carboxylic diacid isomers from each other by their visual fingerprints and determine p -PA contents by a linear equation. Further explorations also verify that this complex Tb - 2 a has good capability of identifying mixed carboxylic diacids and monitoring p -PA in the real sample. This multi-channel response strategy should be potentially referable for not only analogue discrimination of other isomers but also more multianalyte detection methods.