Synthesis and trivalent lanthanide ion complexation studies of new macrocyclic receptors based lactam ionophores

This study is the first report on the design, synthesis and photophysical properties of three new macrocyclic receptors based receptors containing two amide bridges. Their binding properties towards trivalent lanthanide ions such as La³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Er³⁺ and Yb³⁺ were investigated by using spectroscopic techniques. With respect to emission intensity changes upon trivalent lanthanide ion complexation, macrocyclic receptors based lactam ionophores showed higher selectivity towards Yb³⁺ and/or Er³⁺ ion over other ions. Presence of proximal two amide groups in macrocyclic lactam receptors having different cavity size were observed to play an important role in exhibiting its lanthanide ion binding.