Quantum Hopping between Excited Singlet and Triplet States in new 4,4’-(HS)2anti-B18H20.

The tuning of the photophysical properties of the highly fluorescent boron hydride cluster anti-B18H22 (1), by straight-forward chemical substitution to produce 4,4’-(HS)2anti-B18H20 (2), facilitates intersystem crossing from excited singlet states to a triplet manifold.  This subsequently enhances O2(1Δg) singlet oxygen production from a quantum yield of ΦΔ ~ 0.008 in 1 to 0.59 in 2. This contribution describes the synthesis and full structural characterization of the new compound 4,4’-(HS)2anti-B18H20 (2) and uses UV-vis spectroscopy coupled with DFT and ab initio computational studies to delineate and explain its photophysical properties.

Londesborough, M. G. S. et al., Tuning the Photophysical Properties of anti-B18H22: Efficient Intersystem Crossing between Excited Singlet and Triplet States in New 4,4′-(HS)2anti-B18H20. Chem., 52, 9266-9274, (2013).