Harry C. Dorn

A stable non-classical metallofullerene family.

In the evolving field of fullerenes, nanotubes and endohedral metallofullerenes, the isolated-pentagon rule (IPR) is sacrosanct — exceptions have been predicted, but no bare carbon cages with adjacent pentagons have been characterized. Small organic molecules with metal-stabilized fused five-membered rings (pentalenes) have been created, however, and here we describe a family of non-classical endohedral metallofullerenes with the general structure AxSc3−xN@C 68 (where x = 0–2, A is a rare-earth metal, Sc is scandium and N is nitrogen) that has a non-IPR cage of only 68 carbon atoms containing annelated five-membered rings. This internal ring network is metal-stabilized and is accessible for external organic reaction chemistry.

Characterization of fullerenes and doped fullerenes

Abstract The results of a variety of experiments used to characterize fullerenes, metallofullerenes and alkali-metal intercalated C 60 are reported. It is shown that differential scanning calorimetry and NMR characterization of the orientational phase transition in C 60 provide sensitive means to assess the purity and crystallinity of fullerene samples. The results of a mass-spectrometric investigation of metallofullerene samples produced by co-vaporization of carbon and metals are described. An account is given of some electron paramagnetic resonance results obtained for LaC 82 and solid-state NMR results obtained on an alkali-intercalated fullerite, Rb 3 C 60 , which show for the first time the presence of magnetically inequivalent carbons in underivatized C 60 . Together these experiments yield a great deal of information about the phase purity, molecular dynamics and structure of a variety of fullerene materials.

Conditions for quantitative flow FT-1H NMR measurements under repetitive pulse conditios

Abstract The problem of quantitation in continuous-flow FT-NMR is treated in detail. The application discussed is continuous-flow liquid chromatography-proton NMR (LC-1H NMR). Much of the discussion is also applicable to other flow FT-NMR measurements including kinetic studies. A simplified analysis of magnetization under steady-state repetitive pulse conditions including the influence of flow is presented. This analysis illustrates how quantitation errors can arise. A method for calculating molar quantities from integrated LC-1H NMR spectra is also presented. If signal to noise is adequate, relative quantitation is accurate to ±3% under the recommended conditions.

Photovoltaic cells based on ionically self-assembled nanostructures

We use the technique of ionically self-assembled monolayers (ISAMs) to produce photovoltaic devices of well-controlled thickness and composition. The ISAM nanostructure fabrication method simply involves the alternate dipping of a charged substrate into aqueous cationic and anionic solutions at room temperature. We have employed several approaches to combine the tetrahydrothiophenium precursor of poly(para-phenylene-vinylene) (PPV) with fullerenes and other organic materials. We apply modulation spectroscopy for the electro-optical characterization of the ISAM-devices. The modulation frequency dependence of the photocurrent can be assigned to the influence of trapped charges taking part in the photovoltaic process.

The Encapsulation of Trimetallic Nitride Clusters in Fullerene Cages

The Kratschmer-Huffman electric-arc generator typically produces endohedral metallofullerenes in low yields with a wide array of different products, but the introduction of nitrogen leads to a new family of encapsulates. A family of endohedral metallofullerenes AnB3−nN@C2n (n=0–3, x=34, 39, and 40) where A and B are Group III and rare-earth metals is formed by a trimetallic nitride template (TNT) process in relatively high yields. The archetypal representative of this new class is the stable endohedral metallofullerene, Sc3N@C80 containing a triscandium nitride cluster encapsulated in an icosahedron (Ih), C80 cage. The Sc3N@C80 is formed in yields even exceeding empty-cage C84. Other prominent scandium TNT members are Sc3N@C68 and Sc3N@C78. The former Sc3N@C68 molecule represents an exception to the well known isolated pentagon rule (IPR). These new molecules were purified by chromatography with corresponding characterization by various spectroscopic approaches. In this paper we focus on the characterizat...

Trimetallic Nitride Template (TNT) Endohedral Metallofullerenes

In this chapter, we review the preparation, separation, and characterization of a new family of trimetallic nitride template (TNT) endohedral metallofullerenes AnB3−nN@C2x (n = 0–3, x = 34, 39, and 40) where A and B are metals (Group III and rare earths) that are formed in relatively high yields. The archetypal representative of this new class is the stable endohedral metallofullerene, Sc3N@C80 containing a triscandium nitride cluster encapsulated in an icosahedron (Ih), C80 cage. Other prominent TNT members are Sc3N@C68 and Sc3N@C78. The former Sc3N@C68 molecule represents an exception to the well known isolated pentagon rule (IPR).