Synthesis of a Eu complex based on benzonitrile hydrolysis as the first luminescent probe for clinafloxacin

Hydrolysis of benzonitrile to benzoate was realized for constructing a zero-dimensional dinuclear europium complex [Eu2(pip)2(PhCOO)6] via a hydrothermal reaction, where pip denotes 2-phenylimidazo[4,5-f][1,10]phenanthroline. This complex is very insoluble and stable in water from pH 3 to 10. It exhibits strong characteristic Eu(III) red photoluminescence, which could be significantly quenched by clinafloxacin without remarkable disturbance by other common salts or fluoroquinolone antibiotics. The luminescence quenching might be the result of photoinduced electron transfer from excited pip or benzoate to clinafloxacin. This complex is the first convenient luminescent sensor for clinafloxacin and the limit of detection is determined to be 0.21 μM.