Progress of Synthesis and Separation of Regioisomerically Pure 5(6)-Substituted Rhodamine

Regioisomerically pure 5(6)-substituted rhodamine is an outstanding molecular platform for functional probes and a very useful material for fluorescent labels. However, 5(6)-substituted rhodamine is difficult to be synthesized by general methods, which limits the application of the dye. This review highlights the progress regarding the methods for the synthesis and separation of regioisomerically pure 5(6)-substituted rhodamine, which are categorized by the four different protocols for acquiring 5(6)-substituted rhodamine. The advantages and disadvantages of each protocol are also discussed.