Pairing manganese with an off-the-shelf ligand yields a low-cost complex that mimics precious-metal photocatalysts

The photoinduced accumulation of redox equivalents is a challenging requirement for artificial photosynthesis. Now a molecule has been developed in which the sequential absorption of photons results i...

Nearly all photochemical transformations known to date follow Kasha’s rule, implying that reactions occur only from the lowest electronically excited state of a given spin multiplicity due to the fast...

Triplet–triplet annihilation photon upconversion (TTA-UC) provides a milder alternative to traditional UVB/UVC photochemistry. However, suitable sensitizer-annihilator pairs are scarce, in particular…

Investigating the migration of excited-state energy in DNA is crucial for a deep understanding of protection mechanisms and light-induced DNA damage. While numerous reports focused on single electron transfer and Förster-type energy transfer in DNA, studies on the Dexter-type triplet–triplet energy transfer are scarce, in particular, those with direct detection of photoexcited triplet states. Herein, we present direct measurements of the distance-dependent triplet–triplet energy transfer rates through DNA by using transient absorption spectroscopy. This was achieved through the synthetic incorporation of thioxanthone as an energy donor and naphthalene as an energy acceptor into a DNA double strand at defined positions. The energy transfer rates strongly depend on the number of A-T base pairs (up to four) separating the energy donor from the energy acceptor. We observed a fast energy transfer rate with a time constant of 17 ns for the DNA sample in which the donor and acceptor are directly adjacent in the DNA. By analyzing two additional donor–acceptor distances, a steep exponential distance dependence with an attenuation factor of 1.15 Å–1 could be obtained. Our results demonstrate that DNA acts as a poor conductor of triplet energy when energy donors with triplet energies below 2.7 eV are used, complementing more indirect studies on sensitized DNA damage.

The 32nd International Conference on Photochemistry will take place from July 13 (Sunday) to July 18 (Friday), 2025 in Aachen (Germany). The event is jointly organized by the RWTH Aachen University…