Development of functionalized cyclotriveratrylene analogues: introduction of withdrawing and π-conjugated groups

Cyclotriveratrylene analogues (CTVs) are supramolecular bowl-shaped molecules known for their ability to complex organic and organometallic guests, to form liquid crystals, polymers, or nanostructures. In this Article, we report the synthesis of new cyclotriveratrylene analogues with fluorescence properties in which various electron-withdrawing or π-extended conjugated groups are appended to the wide rim ortho to the methoxy-donating groups. Synthetically, these functionalized CTVs cannot be obtained as CTVs with electron-rich functions by the typical method (i.e., the trimerization of the corresponding benzyl alcohol) but are prepared from a common key intermediate, the C(3)-triiodocyclotriveratrylene (CTV-I(3)), in good yields. Despite the synthetic difficulties encountered due to the presence of three reactive centers, we have demonstrated the possibility of performing Sonogashira coupling and Huisgen cycloaddition reactions directly to the CTV core for the first time. CTVs with π-extended conjugated groups reveal interesting fluorescence profiles. More broadly, this study utilizes CTV-I(3) to introduce novel functionalities into CTVs to keep exploring their potential applications.