Jeremy Kintigh

Hydrogenation of Single-Wall Carbon Nanotubes Using Polyamine Reagents : Combined Experimental and Theoretical Study

We combine experimental observations with ab initio calculations to study the reversible hydrogenation of single-wall carbon nanotubes using high boiling polyamines as hydrogenation reagents. Our calculations characterize the nature of the adsorption bond and identify preferential adsorption geometries at different coverages. We find the barrier for sigmatropic rearrangement of chemisorbed hydrogen atoms to be approximately 1 eV, thus facilitating surface diffusion and formation of energetically favored, axially aligned adsorbate chains. Chemisorbed hydrogen modifies the structure and stability of nanotubes significantly and increases the inter-tube distance, thus explaining the improved dispersability in solvents like methanol, ethanol, chloroform, and benzene.

Fulleranes produced via efficient polyamine hydrogenations of [60]fullerene, [70]fullerene and giant fullerenes

All fullerenes including [60]fullerene, [70]fullerene and giant fullerenes are hydrogenated in excellent yield using polyamines like diethylenetriamine (DET), triethylenetetramine (TET), tetraethylenepentamine (TEP) or pentaethylenehexamine (PEH) at elevated temperatures. The resulting hydrogenated fullerenes or fulleranes have been characterized by a combination of NMR spectroscopy and mass spectrometry. The addition of elemental cobalt promotes formation of more highly hydrogenated fulleranes. Hydrogenation reaction times can be reduced to minutes using a microwave reactor. The mechanism of polyamine hydrogenation is discussed in terms of successive electron transfer–protonation cycles as evidenced by deuterium labeling studies.