C60(CO2)x, where x = 0.2 or 0.95, has been synthesized from solutions of C60 in conventional organic solvents using antisolvent precipitation with supercritical CO2. The technique requires much lower pressures and temperatures than current routes to C60(CO2)x and, for small quantities, is quicker. Products were characterized by SEM, IR, 13C solid-state NMR, and powder XRD. Reitveld refinement of the powder XRD shows CO2 to be located in the octahedral interstitial sites of the C60 lattice. The cell lattice parameter is observed to increase for higher occupancies of CO2. Experimental conditions can be varied to generate radically different morphologies of C60(CO2)x. Using rapid antisolvent precipitation, irregular aggregates of ca. 200 nm particles are formed, where x = 0.2. With slower, diffusion-controlled precipitation, regular, highly crystalline; octahedral-shaped particles (1-70 μm) can be formed, where x = 0.95. All products were precipitated completely free from the original organic solvent, and we conclude that CO2 has entered the lattice during crystallization.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry