Bend and twist intramolecular charge transfer and emission for selective metal ion sensing

© 2015 Optical Society of America. Zn2+ and Cu2+ complexation of cyclam-triazolyl-naphthalimide fluoro-ionophores lead to increased and decreased fluorescence respectively. The differences between the two metals are accounted for by their Lewis acid and base properties. This difference means the system can be described as an optical diode with characteristics that suggest measurable differences in fluorescence rise and decay times for the mechanical suppression of bend- and/or twist-induced emissions from intramolecular charge transfer. Different fluorescence evolution profiles are observed offering a new way of distinguishing metal ions for applications in biomedical and environmental sensing.