Enhancement of Anion Binding in Lanthanide Optical Sensors

In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the “lock-and-key”. Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability, and dynamics.In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, fi...