Structural and optical properties of C-70 fullerenes in aqueous solution

The simple method of preparation of highly stable and purified C-70 fullerene aqueous solution (C(70)FAS) is proposed. The features of structural stabilization of C-70 fullerenes in an aqueous solution by studying their structural and optical properties using Raman, photoluminescence, infrared reflection-absorption, UV-VIS absorption, and dynamic light scattering spectroscopy methods were analyzed. The experimental results showed that the most likely mechanism for C-70 fullerenes stabilization in water is surface hydroxylation with covalent attachment of water hydroxyls to C-70 fullerene carbons. Raman and infrared absorption spectra of C(70)FAS showed characteristic vibrational bands of C-70 fullerenes with a slight broadening and low-frequency shift of & SIM;1 cm(-1), indicating the attachment of water hydroxyls to the C-70 fullerene carbons. The photoluminescence spectra showed excitonic emission bands of C-70 molecules with intensity depending on their content. UV-VIS absorption spectra demonstrate the absorption bands typical for monomeric C-70 fullerene. Finally, the dynamic light scattering data confirmed that C(70)FAS is a typical colloidal fluid containing both individual C-70 molecules and their nano aggregates up to 100 nm. These findings provide insights into the stabilization mechanism of C-70 fullerenes in water and may have implications for their potential application in nanobiotechnology.