Near-IR Luminescent Lanthanoid Materials

Near-IR luminescence (ca. 800-2500nm) is a very interesting physical property which many technologically important applications, e.g. in optical telecommunication, spectral conversion for solar energy, or in biomedical optical imaging.


Lanthanoid-based luminophores provide a very unique set of optical properties as near-IR luminophores, for example very sharp emission lines, long luminescence lifetimes or great robustness toward photobleaching. Unfortunately, the luminescence of lanthanoid complexes is highly susceptible to quenching by high-energy and highly anharmonic molecular oscillators such as C-H stretching vibrations in organic ligands.We use the strategy of selective deuteration to avoid C-H quenching. Deuteration reduces the energy of the oscillator which then needs to attain a higher vibrational overtone to bridge the electronic gap between the excited state and a lower-lying state on the metal center. This process is much more unlikely and provides much higher luminescence efficiencies.


Using this strategy, we have realized very brightly near-IR luminescent lanthanoid materials which are often the most efficient systems known to date. For example, the following molecular lanthanoid complexes show typically luminescence enhancement up to one order of magnitude after deueration and in some cases more than two orders of magnitudes in comparison to typically known luminophores in the literature.