A New Fluorescent Calixarene Dimer: Synthesis, Optical Properties, and Sensory Applications

Abstract

A new fluorogenic bis-calix[4]arene-carbazole compound (3) with an enlarged intramolecular cavity able to be involved in host:guest chemistry with large organic guests was designed. Its synthesis was accomplished for the first time using a Sonogashira-Hagihara crosscoupling reaction in the final step. The calixarene receptor was structurally characterized by FTIR and 1 H/ 13 C/2D NMR techniques and its photophysical properties evaluated. The ability of 3 to form supramolecular complexes with fullerenes (C60 and C70) was evaluated through fluorimetric titration experiments. The value of the binding constants (K3:C60 = 1.39x10 5 M −1 and K3:C70= 6.88x10 4 M −1), and the free energy changes for the inclusion complexation (G3:C60 = −29.33 kJ/mol and G3:C70 = −27.60 kJ/mol), revealed a high sensitivity of the calixarene-carbazole host for both fullerenes. The host molecule shown to be particularly selective towards fullerene C60.