Aqueous Eu^II-Containing Complex with Bright Yellow Luminescence

EuII-containing materials
have unique luminescence, redox, and magnetic properties that have
potential applications in optoelectronics, sensors, and imaging. Here,
we report the synthesis and characterization of EuII-containing
aza-222 cryptate that displays yellow luminescence and a quantum yield
of 26% in aqueous media. The crystal structure reveals a staggered
hula-hoop geometry. Both solid-state and solution-phase data are presented
that indicate that the high quantum yield is a result of the absence
of OH oscillators in the inner sphere of the complex. We expect that
EuII-containing aza-222 cryptate is a step toward EuII-containing luminescent materials that can be used in a variety
of applications including biological imaging.