Mechanism of Chelation Enhanced Fluorescence in Complexes of Cadmium(ii), and a Possible New Type of Anion Sensor

The Cd(II) complex of adpa (N-(9-anthracenylmethyl)-N,N-di-(picolyl)amine) in MeOH-H2O has increased fluorescence intensity with [Cl(-)], a new type of anion sensor. The structure of [Cd(adpa)(NO3)2] has a proposed fluorescence-quenching π-contact between Cd and the fluorophore, while the Cl in [Cd(adpa)Cl2] disrupts the π-contact, restoring fluorescence.