Saccharide Chemosensors Based on Boronic Acid‐Appended Heavy‐Metal Complexes

Boronic acids ( BA s) have long attracted attention as building blocks for designing simple chemosensors for saccharides. In the molecular design of BA ‐based chemosensors, the incorporation of a signaling unit to visualize the target is essential. Heavy‐metal complexes are among the basic structures of the signaling units used to date. Owing to their excellent luminescence and electrochemical properties, numerous heavy‐metal complex‐based chemosensors have been reported over several decades. Nevertheless, studies on the development of saccharide chemosensors using BA ‐appended heavy‐metal complexes are limited and have not advanced as rapidly as the development of conventional chemosensors using organic compounds as signaling units. This review mainly covers BA ‐appended heavy‐metal complex‐based saccharide chemosensors, reported from 1998 to 2025, with a particular focus on iridium, ruthenium, rhenium, platinum, osmium, and related systems. The designed chemosensors exhibit a variety of signals, mainly phosphorescence or related luminescence responses, while a smaller number of systems exploit electrochemical and electrochemiluminescent responses. These properties enable saccharide recognition through diverse signal transduction mechanisms, although selective recognition of specific saccharides, especially D‐glucose, remains challenging in many cases. Some of these properties are difficult to achieve with conventional organic dyes but can be accessed in heavy‐metal complex‐based chemosensors through metal complexation and ligand design. This review also highlights the difficulties currently faced, compares the reported systems in terms of signal mode, selectivity, and sensing conditions, and ends with suggestions for future directions in this research area.