Showing papers by "Emma Jakab published in 2005"
TL;DR: It is shown that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane.
Abstract: Cubane (C8H8) and fullerene (C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes.
116 citations
TL;DR: The thermal decomposition of carbon black composites with polyethylene (PE), polypropylene (PP) and polyisobutylene (PIB) has been studied in this paper.
63 citations
TL;DR: The presence of formamide decomposition products, as well as CO2 and various carbonates identified by DRIFT spectroscopy, indicates the formation of superactive centers as a result of mechanochemical activation and heat treatment (thermal deintercalation).
48 citations
TL;DR: In this article, the carbon nanotubes were prepared in liquid ammonia and THF and reacted with a series of alkyl and aryl halogenides, as well as methanol.
Abstract: We present sidewall functionalization of carbon nanotubes via various dissolving metal reduction methods. Carbanion complexes of lithium were prepared in liquid ammonia and THF and reacted with a series of alkyl and aryl halogenides, as well as methanol resulting in the formations of alkylated, arylated, and hydrogenated nanotube derivatives, respectively. The hydrogenation reactions were also performed on graphite. Thermal stabilities and chemical compositions were determined by thermogravimetry‐mass spectrometry (TG‐MS). Characteristic decomposition peaks, observed in the range of 350–600°C, suggest the formation of covalent derivatives upon functionalization. The compositions are 0.01–0.25 side group/carbon depending on the materials. NMR and Raman spectroscopic characterizations show the structural changes due to functionalization.
19 citations
TL;DR: In this article, the compositions and chemical identities of compounds formed in silver-permanganate-pyridine-water systems, as well as of their recrystallization products obtained from benzene-acetone solutions, have been elucidated.
Abstract: Compositions and chemical identities of compounds formed in silver–permanganate–pyridine–water systems, as well as of their recrystallization products obtained from benzene–acetone solutions, have been elucidated. Three compounds: Agpy2MnO4(1), 7Agpy2MnO4*Agpy4MnO4 (Agpy2.25MnO4) (2) and Agpy2MnO4 * 0.5py (Agpy2.5MnO4) (3) were isolated. The compositions of the products obtained by a method described previously [1] for the preparation of ‘Agpy2MnO4’ (1*) and ‘Agpy2.5MnO4’ (2*) were determined and the constituent compounds identified. It has been established that the instability of compound (3) is due to the presence of the benzene, substituting for pyridine at the solvate sites. The benzene, however, is released at room temperature, disrupting the crystal lattice of (3), and the whole process leads to the loss of the solvate pyridine and to the formation of (1).
6 citations