Sorption of Polymethine Dyes on Nanographites and Carbon Nanotubes

The sorption of functional molecules is a simple rather effective way of modification of nanostructures. The goal of this work is to study the sorption of various polymethine dyes on nanographites and carbon nanotubes. A simple technique affording the preparation of macroscopic amounts (tens of grams) of nanographite from an available starting material has been implemented. The chemical functionalization of the obtained nanographite has been carried out in order to modify its binding properties. Stable suspensions of nanographite and its modifications are obtained in water and organic solvents. It is found that the cationic, anionic and neutral (merocyanine) polymethine dyes do not bind efficiently with the surface of the studiednanographites. Carbon nanotubes of different types (single-, double-, and multiwall) under the same conditions form stable associates with polymethine dyes, what is primarily manifested by a decrease in the absorption intensity of dyes in time, as well as by the additional stabilization of the nanotube suspension. The DFT calculations demonstrate that the studied dyes do not bind strongly, indeed, with nanographites, but they can form more stable aggregates with carbon nanotubes.