Design and synthesis of chiral spirobifluorenes.

Chiroptical spectroscopic methods serve as a practical tool for the structural characterization of chiral systems based on the interaction with polarized light. The higher sensitivity of these methods, compared with their achiral counterparts, not only enables the determination of absolute configuration and conformational preferences, but also supramolecular interactions may be monitored. In order to expand the applicability of chiroptical systems, the development of functional materials exhibiting intense chiroptical responses is essential. As a proof of principle, we previously constructed chiroptical interfaces via thioacetate-derivatized allenes. Because of the photoisomerization issues associated with allenes, we have recently proposed their replacement by spirobifluorenes to achieve robust chiroptical systems. Thus, we hereby present the design and synthesis of chiral spirobifluorenes bearing thioacetates suitable for suface functionalization.