Spectral study on conformation switchable cationic calix[4]carbazole serving as curcumin container, stabilizer and...

A fluorescent 2,7-dimethoxy-substituted calix[4]carbazole (1) is facilely synthesized. The spectral behaviors of both the guest-induced switchable conformation of 1 and its abilities serving as the stabilizer and molecular carrier of curcumin are investigated. UV-vis, fluorescence and NMR spectral results show that upon binding to curcumin, the 1,3-alternate conformation of 1 is converted to be the cone one. The relative high association constant (6.4×10⁶M^-1) of 1 binding to curcumin enables it to stabilize the curcumin, to suppress its degradation, and to sustainably deliver it into the EYPC vesicles within 20h. Moreover, the cytotoxicity assay shows that 1 does not interfere the antiproliferative activities of curcumin. All these properties endow 1 the potential capability of serving as the molecular drug carrier. Our current result may pave the way looking for more efficient fluorescent calixcarbazoles and thereof spectral utilities.