The outside knows the difference inside: Trapping helium by immediate reduction of orifice size of an open-cage fullerene and NMR investigations of the effect of encapsulated helium and hydrogen to the proton directly attached to the open-cage fullerene sphere

ORGN 802

Shih-Ching Chuang, scchuang@gmail.com, Yasujiro Murata, yasujiro@scl.kyoto-u.ac.jp, Michihisa Murata, and Koichi Komatsu. Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
Helium can enter and escape at room temperature from open cage fullerene 1 based on previously reported kinetic results. Its equilibrium constant Keq at 50 oC was measured to be 3.1×10–4 atm–1 with overall uncertainty of 40%. This result predicts the incorporation ratio is ca. 20% at a pressure of 800 atm. A high pressure helium gas of 322580 atm will be necessary to achieve nearly 100% incorporation of helium at 50 oC! In this paper, we present an approach to entrap helium within the cage by instant reduction of the opening size after helium was inserted into the cage of 1, based on the reactivity of the two carbonyl and imine functional groups of compound 1. We further discuss the effect of encapsulated helium and hydrogen on the chemical shift of a proton that is directly attached to the fullerene skeleton.

 

Combinatorial, Parallel and Process Chemistry, Heterocycles, Aromatics, New Reactions and Methodology
8:00 PM-10:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Organic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007