Recent progress in the design and applications of fluorescence probes containing crown ethers

Crown ethers, discovered by the winner of the Nobel Prize Charles Pedersen, are cyclic chemical compounds that consist of a ring or multiple rings containing several ether groups that are capable of binding alkali ions. A smart fluorescent probe containing a crown ether moiety could be developed as a sensor for metal ions, anions and other bio-molecules and be further applied to monitor the relevant biological process in vivo. This review highlights recent advances which can be divided into seven parts: (i) fluorescent probes containing a simple crown ether or an aza-crown ether structure; (ii) fluorescent probes containing an azathia crown ether; (iii) fluorescent probes containing a cryptand; (iv) fluorescent probes containing two or more binding sites; (v) crown ether derivatives-metal complex assisted chemosensing of bioactive species; (vi) crown ether-based chemosensors for bioactive molecular detection; and (vii) efforts to improve biological relevance.