title: Dimeric capsules with a nanoscale cavity for [60]fullerene encapsulation.
abstract: The acid-assisted and guest-induced formation of superstructures was achieved by the addition of haloacetic acids to a toluene solution of the resorcin[4]arene derivatives 1 and [60]fullerenes. The formation of dimeric superstructures that encapsulated a nanosized guest molecule was observed when appropriate acids, such as haloacetic acids, and suitable guest molecules, such as [60]fullerenes, were co-added to a toluene solution of cavitand 1 that has four pyridine units, whereas a complicated equilibrium between several species was detected without [60]fullerenes, and the formation of discrete superstructures was not monitored in the absence of haloacetic acids. The spectroscopic data indicate that the formed [60]fullerene-encapsulated complexes have the structure of 2. These complexes are self-assembled through pyridinium-anion-pyridinium interactions and by pi-pi and van der Waals interactions. The rate of decomplexation of 2 is estimated to be 3.1 s(-1) from a 2D exchange NMR spectrum. The [60]fullerene encapsulation process can be controlled by modifying the amounts of acids used, changing the temperature of the system, altering the ratio of acid/base, and even through varying the solvent polarity. Moreover, the fluorescence spectra show band-narrowing spectral changes and a retardation of the relaxation characteristics of isolated and isotropic [60]fullerenes, which indicates that the environmental change around [60]fullerene is induced upon its encapsulation.
authors.affiliation: Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, Korea.
authors.forename: Seong Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Oh-Hoon
authors.initials: OH
authors.lastname: Kwon
authors.forename: Kyung-Sik
authors.initials: KS
authors.lastname: Lee
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Du-Jeon
authors.initials: DJ
authors.lastname: Jang
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Hong
mesh_terms: D002214:Capsules / Q000737:chemistry; D002247:Carbon Isotopes; D019281:Dimerization; D005021:Ethylamines / Q000737:chemistry; D037741:Fullerenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D014269:Trifluoroacetic Acid / Q000737:chemistry
chemical_list: D002214:Capsules; D002247:Carbon Isotopes; D005021:Ethylamines; D037741:Fullerenes; D012997:Solvents; D014269:Trifluoroacetic Acid; C069837:fullerene C60; C016162:triethylamine