Spectroscopic Characterization of Nanohybrids Consisting of Single-walled Carbon Nanotubes and Fullerodendron

<div><p>Hydrogen gas, which can be used in fuel cells to generate electricity, is considered the ultimate clean energy source. Recently, it was reported that a photo-induced electron transfer system consisting of single-walled carbon nanotubes (SWCNTs) and fullerodendrons shows photo-catalytic activity with a very high quantum yield for splitting water under visible light irradiation. However, the mechanism of high efficiency hydrogen generation is not yet clearly understood. We report here the spectroscopic characterizations of the SWCNT-fullerodendron composites. The results indicate two important fundamental properties of the composite system. First, fullerodendrons preferentially interact with the semiconducting SWCNTs instead of with their metallic counterparts. Second, the photo-induced electron transfer process from the C₆₀ moiety of fullerodendrons to SWCNTs occurs more efficiently with an increasing tube diameter.</p> </div

A Convenient Route to Synthetic Analogues of the Oxidized Form of High-Potential Iron–Sulfur Proteins

An amide-bound [Fe₄S₄]³⁺ cluster, [Fe₄S₄{N­(SiMe₃)₂}₄]⁻ (<b>1</b>), was found to serve as a convenient precursor for synthetic analogues of the oxidized form of high-potential iron–sulfur proteins. Treatment of <b>1</b> with 4 equiv of bulky thiols led to replacement of the amide ligands with thiolates, giving rise to a series of [Fe₄S₄(SR)₄]⁻ clusters (R = Dmp (<b>2a</b>), Tbt (<b>2b</b>), Eind (<b>2c</b>), Dxp (<b>2d</b>), Dpp (<b>2e</b>); Dmp = 2,6-di­(mesityl)­phenyl, Tbt = 2,4,6-tris­[bis­(trimethylsilyl)­methyl]­phenyl, Eind = 1,1,3,3,5,5,7,7-octaethyl-<i>s</i>-hydrindacen-4-yl, Dxp = 2,6-di­(<i>m</i>-xylyl)­phenyl, Dpp = 2,6-diphenylphenyl). These clusters were characterized by the mass spectrum, the EPR spectrum, and X-ray crystallography. The redox potentials of the [Fe₄S₄]^3+/2+ couple, −0.82 V (<b>2a</b>), −0.86 V (<b>2b</b>), −0.84 V (<b>2c</b>), −0.74 V (<b>2d</b>), and −0.63 V (<b>2e</b>) vs Ag/Ag⁺ in THF, are significantly more negative than that of [Fe₄S₄(SPh)₄]^−/2– (−0.21 V)