Fluorescent Bis-Calix[4]arene-Carbazole Conjugates: Synthesis and Inclusion Complexation Studies with Fullerenes C₆₀...

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Supramolecular chemistry is vital in biomedical applications, especially for stimuli-responsive devices.
• Fullerenes and their assemblies are increasingly used in biomedical sciences and engineering.
• Sensitive methods are needed to study fullerene inclusion complexes.

Purpose of the Study:

• To design and synthesize novel fluorescent bis-calix[4]arene-carbazole conjugates.
• To investigate the host-guest complexation ability of these conjugates with fullerenes C60 and C70.
• To characterize the optical properties and stability of the resulting supramolecular assemblies.

Main Methods:

• Synthesis of bis-calix[4]arene-carbazole conjugates.
• UV-Vis and fluorescence spectroscopy (steady-state and time-resolved) for optical property analysis.
• Fluorescence titration, low-temperature NMR spectroscopy, and Density Functional Theory (DFT) modeling for complex characterization.

Main Results:

• Two novel fluorescent bis-calix[4]arene-carbazole conjugates (4 and 5) were synthesized.
• Compounds 4 and 5 demonstrated selective host-guest complexation with fullerenes C60 and C70.
• The C70 fullerene formed a more stable supramolecular complex with host 4 (Ka = 5.6 × 10^4 M^-1).
• NMR and DFT studies confirmed the formation of true inclusion complexes.

Conclusions:

• Novel fluorescent bis-calix[4]arene-carbazole conjugates serve as effective hosts for fullerenes.
• The C70@4 supramolecule exhibits enhanced stability, indicating potential for advanced applications.
• Spectroscopic and computational methods provide robust evidence for inclusion complex formation.