Ruthenium-Based Sensors

In the periodic table of the elements, ruthenium occupies an excellent position, just below iron. And like iron, it possesses several oxidation states, with +2 and +3 being the most common. Accordingly, ruthenium chemistry is extremely rich and well developed, and ruthenium complexes show excellent catalytic aptitude, tremendous redox capacity, and intriguing biological activity. However, in the design of sensors, the use of ruthenium complexes can be better exploited, as they possess valuable electro- and photochemical properties. Therefore, there is an opportunity here, and ruthenium-based complexes might become, one day, key players in sensing technology. Starting a new research project with ruthenium-based sensors ourselves, writing this review was essential to see the current state of research in the field, to better identify opportunities and to have an overview of state-of-the-art examples.