Expanding Luminescence Horizons in Macropolyhedral Heteroboranes

Luminescence is observed in three novel macropolyhedral nineteen- and eighteen-vertex chalcogenaboranes: Se₂B₁₇H₁₇ (1), SeB₁₇H₁₉ (3) and SeB₁₈H₂₀ (4). This led us to the recognition that previously published macropolyhedral heteroborane species might also exhibit luminescence. Thus, the known nineteen- and eighteen-vertex dithiaboranes S₂B₁₇H₁₇ (2), n-S₂B₁₆H₁₆ (5) and i-S₂B₁₆H₁₆ (6) were synthesised and also found to exhibit a range of luminescent properties. These macropolyhedral species are very different from the previously unique fluorescent binary borane B₁₈H₂₂ in terms of their structural architectures, by the presence of borane cluster hetero atoms, and, as in the cases of 5 and 6, that their synthetic origins are not derived simply through the modification of B₁₈H₂₂ itself. They consequently greatly expand the possibilities of finding new luminescent inorganic borane species.