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Artificially Produced UV Light and Challenging Photoreactions Enabled by Upconversion in Water

submitted on 28.02.2020, 18:10 and posted on 02.03.2020, 13:11 by Björn Pfund, Debora M. Steffen, Mirjam R. Schreier, Maria-Sophie Bertrams, Chen Ye, Karl Börjesson, Oliver S. Wenger, Christoph Kerzig
Sensitized triplet-triplet annihilation is the most promising mechanism for pooling the energy of two visible photons, but its applications in solution were so far limited to organic solvents, with a current maximum of the excited-singlet state energy of 3.6 eV. By combining tailor-made iridium complexes with naphthalenes, we demonstrate blue-light driven upconversion in water with unprecedented singlet-state energies approaching 4 eV. The annihilators have outstanding excited-state reactivities enabling challenging photoreductions driven by sTTA. Specifically, we found that an aryl-bromide bond activation can be achieved with blue photons, and we obtained full conversion for the very energy-demanding decomposition of a persistent ammonium compound as typical water pollutant, not only with a cw laser but also with an LED light source. These results provide the first proof-of-concept for the usage of low-power light sources for challenging reactions employing blue-to-UV upconversion in water, and pave the way for the further development of sustainable light-harvesting applications.


See acknowledgements section of the manuscript.


Email Address of Submitting Author


University of Basel



ORCID For Submitting Author


Declaration of Conflict of Interest

There are no conflicts to declare.

Version Notes

Version 1 including Supplementary Information (SI)