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A study was conducted to investigate the double Diels-Alder cycloaddition of two tethered isobenzofurans to the fullerene [C.sub.60]. The method helps to easily perform the saturation of two of the three C=C double bonds within a six-membered ring of [C.sub.60] and provides the means of saturating the remaining double bond of a six-membered ring of [C.sub.60] via the side chains of the isobenzofurans with suitably reactive functional groups.

A study was conducted to examine the reactions of 1,3-disubstituted isobenzofurans with the fullerene [C.sub.60] in the context of an approach to open a large orifice on the fullerene framework. The thermal stability of the adducts toward retro-Diels-Alder fragmentation differs greatly in solution from that in the solid state which suggest that they could be stored at room temperature in the solid state for several weeks without significant decomposition but have to be handled within several hours in solution.

The photophysical properties of a novel 1,2,3,4,5,6-hexasubstituted fullerene derivative are examined, aong with its triplet-triplet absorption spectrum. It is seen that disruption of the [pi] system of a single six-member ring results in significant changes in triplet state properties, including a systematic decrease in the triplet state lifetime, triplet quantum yield and singlet oxygen quantum yield.

Research concerning reaction of phosphites with dimethyl acetylenedicarboxylate and C (sub)60 to produce phosphite ylides has been conducted. Hydrolysis of these ylides used to introduce phosphonate ester, phosphine oxide and phosphonic acid to a fullerene moiety is described.

Research has been conducted on the C (sub)60 and acetylenes reaction with phosphines. Introduction of phosphorus substituents onto C (sub)60 is discussed.

The efficient conversion of one allotrope of hydrogen into another when both are incarcerated in the interior space of a [C.sub.60] molecule dispersed on a zeolite surface is demonstrated. Enriched p[H.sub.2]@[C.sub.6], which is nonvolatile, readily soluble in common solvents is seen as a versatile probe than p[H.sub.2] for examining magnetic effects in condensed media or on surfaces.

A general term is presented for easy estimation of relative orifice size by defining an index K(orifice) for open-cage fullerene. The correlation between the index K with the effective areas A has helped in estimating K(orifice) index and/or relative rate k of hydrogen release through computing activation energy Ea-(calcd) for a designed open-cage fullerene.

Research has been conducted on methanofullerenes with alpha-ylidic ester. The authors report the study of acid-catalyzed ring-expansion of these compounds.

Fullerenes are unparalleled among carbon-based molecules in their combination of structural, topological, and electronic features. The methodology is described which allows a straightforward insertion of a C(sub 2) unit onto the framework of C(sub 60) giving stable C(sub 62) derivatives in a one-pot synthesis.

Inverted carbenoid species, generated from attack of phosphines at the α(δ′)-carbon of hex-2-en-4-ynedioic acid dialkyl esters, react with aldehydes to give γ-lactones possessing an α-phosphorus ylide moiety. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed heteroannulation of N-substituted benzamides with [60]fullerene, which proceeds through direct sp2 C—H bond activation to form 7-membered ring pallada-intermediate with C60, led to formation of [60]fulleroisoquinolinones in moderate to good yields (8-64% based on recovered C60). A plausible reaction pathway is proposed. [ABSTRACT FROM AUTHOR]

In a quest to form wider openings within the cage of the fullerene C60 through controlled bond-breaking reactions, we have examined the double saturation of adjacent CC bonds within a six-membered ring of C60. We have investigated the double Diets-Alder cycloaddition of two tethered isobenzofurans to the fullerene C60. We obtained cis-1 adducts in good yields after reacting the methylene- or quinoxaline-tethered bis(isobenzofuran) precursors 2a-k with parent 3,6-dihydro-1,2,4,5-tetrazine (3b). The X-ray structure of the methylene-tethered bis(isobenzofuran)-C60 adduct 4b has been obtained; four-eclipsed substituents are held rigidly by the bicyclic addends. The cis-1 bis(isobenzofuran) bisadducts 4b and 4e-j are kinetically far more stable toward thermal retro-Diels-Alder fragmentation than are mono- (isobenzofuran) adducts of C60, in solution and in the solid state as determined by ¹H NMR spectroscopy or thermogravimetric analysis. A methodology for the reversible solubilization of other fullerene derivatives based on this work is also presented. [ABSTRACT FROM AUTHOR]

A novel acid-catalyzed ring expansion of methanofullerenes bearing an α-ylidic ester has been investigated. Treatment of dialkyl acetylenedicarboxylate and tricycloalkylphosphine with C[sub 60] led to the isolation of a methanofullerene ylide after passing the reaction mixtures through a basic alumina column. If the reaction mixture was passed through a silica gel column, a cyclopentanofullerene was isolated instead. These new cyclopentanofullerenes consisted of a fused cyclopentanone ring bearing an α-hydroxy ester and a phosphonium ylide and were confirmed by their NMR, mass, and X-ray diffraction data. The cyclopentanofullerenes were formed by the ring expansion of the corresponding methanofullerenes in the presence of silica gel. The ring expansion also proceeded by treating methanofullerene with acetic acid in chloroform. On the other hand, the methanofullerenes from RO[sub 2]CCCCO[sub 2]R, PAr[sub 3], and C[sub 60] were stable in silica gel. However, upon heating with acetic acid at 50 °C, they underwent ring expansion and dephosphination to give cyclopentenofullerenes. An implicit vinyl cyclopropane ring expansion mechanism was proposed to account for this novel acid-catalyzed rearrangement. [ABSTRACT FROM AUTHOR]

Describes a methodology that allows a straightforward insertion of a C[sub 2] unit onto the framework of C[sub 60] giving stable C[62] derivatives in a one-pot synthesis. Generation of the parallel fullerene in a gas phase from a designed precursor in a laser-induced pyrolytic extrusion; Formation of the four-membered ring; Description of the sequential rearrangement of cyclohexadienofullerenes.

In a quest to form wider openings within the cage of the fullerene C60 through controlled bond-breaking reactions, we have examined the double saturation of adjacent CC bonds within a six-membered ring of C60. We have investigated the double Diets-Alder cycloaddition of two tethered isobenzofurans to the fullerene C60. We obtained cis-1 adducts in good yields after reacting the methylene- or quinoxaline-tethered bis(isobenzofuran) precursors 2a-k with parent 3,6-dihydro-1,2,4,5-tetrazine (3b). The X-ray structure of the methylene-tethered bis(isobenzofuran)-C60 adduct 4b has been obtained; four-eclipsed substituents are held rigidly by the bicyclic addends. The cis-1 bis(isobenzofuran) bisadducts 4b and 4e-j are kinetically far more stable toward thermal retro-Diels-Alder fragmentation than are mono- (isobenzofuran) adducts of C60, in solution and in the solid state as determined by ¹H NMR spectroscopy or thermogravimetric analysis. A methodology for the reversible solubilization of other fullerene derivatives based on this work is also presented. [ABSTRACT FROM AUTHOR]

The article describes the demonstration of a chemical transformation inside the fullerene with reversible conversion of the allotropes. In the process of the study, the allotropes provide an opportunity to explore the intriguing possibility of performing chemical transformations of hydrogen incarcerated in the spin catalyzed forward conversion. Physicist Werner Heisenberg had created the quantum mechanics that led to the discovery of the allotropic forms of hydrogen.