1O2 Generating Luminescent Lanthanide Complexes with 1,8-Naphthalimide-Based Sensitizers.

Lanthanide ion (LnIII) complexes with two new 1,8-naphthalimide-based ligands, Nap-dpe and Nap-cbx, were isolated, and their photophysical properties were explored. Upon excitation at 335 nm, Nap-dpe and Nap-cbx sensitize visible and near-infrared emitting LnIII ions (LnIII = EuIII, NdIII, and YbIII) and generate singlet oxygen (1O2). The quantum yields of EuIII luminescence for [Eu(Nap-cbx)3]3+ and [Eu(Nap-dpe)3]3+ are 16.7% and 8.3%, respectively, with 1O2 generation efficiencies of 41% and 59%, respectively. The efficiencies of 1O2 generation for the NIR emitting complexes [Ln(Nap-dpe)3]3+ are 59% and 56%, respectively, and those for [Ln(Nap-cbx)3]3+ (LnIII = NdIII, YbIII) are 64% and 61%, respectively. In an oxygen-free environment, the quantum yields of EuIII luminescence for [Eu(Nap-cbx)3]3+ and [Eu(Nap-dpe)3]3+ increase to 20% and 18%, respectively.