ABSTRACT
This chapter describes the ion binding properties of the ruthenium complexes containing host receptor(s) R onto their organic moiety and their optical responses, with particular attention to the changes in their luminescence properties upon addition of these analytes in solution. In comparison to the organic fluorophores, the excited state properties of ruthenium complexes are complicated and can include metal-to-ligand charge-transfer, ligand-to-ligand charge transfer, intra-ligand charge-transfer, ligand-to-metal charge transfer, metal–metal-to-ligand charge-transfer, ligand-to-metal metal charge transfer and metal-to-ligand–ligand charge-transfer states. Ruthenium complexes are playing a sharply increasing role in inorganic and medicinal chemistry not only due to its abundant uses as a potential sensing agent for metal cations, anions and gases but also it has promising sensing capability towards different neutral molecules including amino acids, DNA, drug molecules and hazardous compounds. The luminescence of the ruthenium complex is monitored by changes in the apparent lifetime using a phase shift measurement or by intensity methods.
