Recent advances in H₂PO₄^- fluorescent sensors

Dihydrogen phosphate (H₂PO₄^-) plays an essential role in a number of chemical and biological processes. The sensitive and selective detection of H₂PO₄^- is of great interest to many scientific fields, ranging from supramolecular chemistry to life sciences. For the detection of H₂PO₄^-, fluorescent methods have plenty of distinct advantages, for example they are simplistic and allow low levels of determination. Therefore, this review will focus on the current progress in the development of H₂PO ₄^- fluorescent sensors based on organic scaffolds, for sensing in both organic and aqueous solutions. Three main types of fluorescent probes will be categorized in this review: (i) intensity-based "turn-off" fluorescent sensors; (ii) intensity-based "turn-on" fluorescent sensors; and (iii) ratiometric fluorescent sensors that involve a ratio of two emission outputs. This review should provide a comprehensive description of this research area to date and be instructive for the design and synthesis of new fluorescent sensors for H₂PO ₄^-. In addition, the principles and mechanisms employed in the design of H₂PO₄^- sensors will be thoroughly described.