Self-inclusion properties of C60-linked calix[5]arene
摘要:
C-60-linked calix[5]arenes were synthesized and their intramolecular binding properties were investigated. The self-inclusion ratio of the C-60 moiety was determined by using UV-vis spectroscopy, and the ratio depends on chain length, temperature, and solvent. Influence of temperature and solvent was explained by the thermodynamic data of the intramolecular complex formation process. (C) 2005 Elsevier Ltd. All rights reserved.
Metal-induced regulation of fullerene complexation with double-calix[5]areneElectronic supplementary information (ESI) available: spectroscopic and titration data. See http://www.rsc.org/suppdata/cc/b1/b108121g/
A self-assembled fullerene receptor based on calix[5]arene has been developed. Silver cation complexation held together the two calix[5]arenes with bipyridine units providing a large enough cavity to take up C(60) or C(70). The formation of the supramolecular complex with C(60) or C(70) was established by using the electrospray mass spectrometry. (C) 2001 Elsevier Science Ltd. All rights reserved.
This paper presents the synthesis of the fullerene hosts based on the calix[5]arenes and their binding properties. Calix[5]arenes la, 2, 3a bind C-60 or C-70 in organic solvents. The solvent effect of the fullerene complexation was clearly observed; the association constant decreases in a solvent with high solubility for C-60. Covalently linked double-calix[5]arenes 4-6 were also investigated on their binding properties for fullerenes in organic solvents. Their binding abilities for both C-60 and C-70 are extremely high in toluene solution. Higher binding selectivity toward C-70 is observed by all the double-calix[5]arenes. The selectivity of 5a toward C-70/C-60 is highest in toluene with a value of 10. The structures of the supramolecular complexes of the calix[5]arene hosts and C-60 or C-70 were investigated by using H-1 and C-13 NMR studies. The molecular mechanics calculation and X-ray structure reveal that the interior of the calix[5]arene is complementary to the exterior Of C-60 molecule. In contrast, the host-guest complexes Of C-70 With the simple calix[5]arenes take many conformational options due to its less symmetric shape. The molecular mechanics calculation and our chemical shift simulation nicely worked to estimate the reliable structures; the calix[5]arene cavity takes up C-70 molecule, and the C-70 molecule tilts significantly from the C5 axis of the calix[5]arene. In the case of the host-guest complex Of C-70 with the double-calix[5]arene, the molecular dynamics simulation of the host-guest complex represented the realistic movement of the bound C-70 inside the cavity. The combination of the molecular dynamics simulation and the chemical shift simulation of the host-guest complex suggested that the C-70 molecule rapidly moves inside the cavity. (c) 2005 Elsevier Ltd. All rights reserved.