The article discovers that a new family of large, cage-like boron-based molecules called macropolyhedral heteroboranes can emit visible light- a property known as luminescence. Until now, strong luminescence among boranes was considered unique to the molecule anti-B₁₈H₂₂ and its close derivatives. By synthesizing and studying three new compounds containing selenium and boron (Se₂B₁₇H₁₇, SeB₁₇H₁₉, and SeB₁₈H₂₀), as well as revisiting known sulfur-containing analogues, it was found that these structurally diverse clusters also show luminescent behavior in the solid state. Experiments revealed that these new and known macropolyhedral heteroboranes emit light in colors ranging from green to orange when exposed to ultraviolet or blue light, and that their emission properties depend on the specific structure and composition of the cluster. This work significantly broadens the range of boron-based molecules known to be luminescent and suggests that many more such compounds could be discovered, opening new possibilities for their use in technologies like sensors, lasers, and bioimaging. We contributed to this work by structure characterization of one of the compounds using single-crystal X-ray diffraction. A precise atomic arrangement is essential to confirm the compound’s identity and geometry and understand its electronic properties, influencing luminescence behavior.
Figure: Molecular structure of the nineteen-vertex selenaborane Se2B17H17 (1). Displacement ellipsoids for non-hydrogen atoms are drawn at a 50 % probability level. The molecule has crystallographic inversion symmetry at the mid-point of the B(7)-B(8) vector; hence the asymmetric unit is half a molecule and the molecule is disordered. Interatomic distances (Å): Se(9)-B(4) 2.097(15), Se(9)-B(5) 2.056(13), Se(9)-B(8) 2.133(16), Se(9)-B(10) 2.141(13), B(5)-B(6) 1.791(15), B(6)-B(7), B(7)-B(8) 1.823(17), B(7)-B(11) 1.910(18). Se(9’)-B(4’) 1.997(16), Se(9’)-B(8’) 1.864(17), Se(9’)-B(10’) 2.031(16), B(5’)-B(10’) 1.889(18) B(8’)-B(8’) 2.00(2).