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Effect of Structure of Monocyclic Aromatic Solvents on the Packing Density of Fullerene Solvation Shell

DOI: 10.5402/2012/906976

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Fullerene C60 solutions in various monocyclic aromatic solvents (AS) diluted by tetrahydrofurane (THF) were studied using UV spectroscopy. An algorithm was proposed which made it possible to obtain the data from the UV spectra of (C60+AS) solutions in THF which pointed to the difference between the packing density of AS molecules in solvation shell of C60 and that in the pure AS solvent. The presence of asymmetrical substituents in the AS molecule has been shown to result in loosening of solvent structure in the solvation shell, while the absence of the substituents or presence of symmetrical substituents leads to compacting of solvent structure. 1. Introduction Donor-acceptor interactions of fullerene C60 with solvent molecules are responsible for its good solubility in numerous organic solvents due to formation of strong solvation shells [1]. Fullerene C60 manifests itself mainly as a π-acceptor [1–3], which predominates its high solubility in aromatic solvents due to formation of fullerene-solvent molecular complexes. The presence of substituents in the aromatic solvent (AS) molecule may be expected to result in the appearance of additional interactions between the AS and C60 during solvation. For example, the spectroscopic study of fullerene solutions in various solvents [4, 5] pointed to the possibility of C60 solvation by o-dichlorobenzene owing to both π-π interactions of the benzene ring of AS with the π-system of fullerene and partial charge transfer from the chlorine atom to fullerene. The presence of methyl group as a substituent in the AS molecule may open the way to formation of additional hydrogen-bonding complexes [6]. Interaction of some organic donors with C60 has been shown to result in their coordination with fullerene C60 [7]. The structure of solvation shell would be dependent on the forced coordination of solvent molecules by fullerene. The fullerene ability to structure a solvent was shown in [8]. It seems quite obvious that the coordination of monocyclic AS molecules by C60 during solvation would depend on the presence of substituents in AS which may interact with fullerene. The forced coordination of solvent molecules by C60 may be proposed to result in the difference between the packing density of AS molecules in the C60 solvation shell and that in the pure AS. The examination of this idea was the aim of the work. 2. Experimental Part 2.1. Materials, Experimental Procedure, and Equipment Fullerene C60 (purity 99.5?wt%) (Fullerene Technologies, St. Petersburg) was used for preparation of its solutions with specified

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