Photochemistry of supramolecular species involving anionic coordination compounds and polyammonium macrocyclic receptors

Polyammonium macrocyclic receptors can bind anionic coordination compounds, namely those containing cyanide ligands. The driving force to maintain the adduct is essentially the coulombic attraction, but the possibility of formation of hydrogen bonds is also important to define the geometry of the structure. The second coordination sphere that results from the binding of the polyammonium macrocycle can change several physico-chemical properties of the metal coordination compound, such as spectroscopic, redox and photophysical properties as well as the photochemical reactivity. These changes permit to infer, in some favourable cases, details of the supramolecular structure in solution.