A molecular boron cluster-based chromophore with dual emission

Abstract

Bromination of the luminescent borane, anti-B₁₈H₂₂, via electrophilic substitution using AlCl₃ and Br₂, yields the monosubstituted derivative 4-Br-anti-B₁₈H₂₁ as an air-stable crystalline solid. In contrast to the unsubstituted parent compound, 4-Br-anti-B₁₈H₂₁ possesses dual emission upon excitation with UV light and exhibits fluorescence at 410 nm and phosphorescence at 503 nm, with Φ_total = 0.07 in oxygen-free cyclohexane. Increased oxygen content in cyclohexane solution quenches the phosphorescence signal. The fluorescent signal intensity remains unaffected by oxygen, suggesting that this molecule could be used as a ratiometric oxygen probe.