Progress Towards Colorimetric and Fluorescent Detection of Carbonyl Sulfide

We report here that a fluorescent benzobisimidazolium salt (TBBI) can be used for the fluorescent and colorimetric detection of carbonyl sulfide (COS) over related heterocumulenes including CO₂ and CS₂ in wet MeCN. The reaction between TBBI and COS in the presence of fluoride yields a highly fluorescent (l_em = 354 nm) and colored product (l_ex = 321 nm), that is readily observed by the naked eye. We view these results as a first step toward developing activity-based probes for COS detection.