Anion-activated, thermoreversible gelation system for the capture, release, and visual monitoring of CO(2)

Carbon dioxide (CO(2)) is an important green house gas. This is providing an incentive to develop new strategies to detect and capture CO(2). Achieving both functions within a single molecular system represents an unmet challenge in terms of molecular design and could translate into enhanced ease of use. Here, we report an anion-activated chemosensor system, NAP-chol 1, that permits dissolved CO(2) to be detected in organic media via simple color changes or through ratiometric differences in fluorescence intensity. NAP-chol 1 also acts as a super gelator for DMSO. The resulting gel is transformed into a homogeneous solution upon exposure to fluoride anions. Bubbling with CO(2) regenerates the gel. Subsequent flushing with N(2) or heating serves to release the CO(2) and reform the sol form. This series of transformations is reversible and can be followed by easy-to-discern color changes. Thus, NAP-chol 1 allows for the capture and release of CO(2) gas while acting as a three mode sensing system. In particular, it permits CO(2) to be detected through reversible sol-gel transitions, simple changes in color, or ratiometric monitoring of the differences in the fluorescence features.