TY - JOUR
T1 - Highly curved bowl-shaped fragments of fullerenes
T2 - Synthesis, structural analysis, and physical properties
AU - Chen, Min Kuan
AU - Hsin, Hsin Ju
AU - Wu, Tsun Cheng
AU - Kang, Bo Yan
AU - Lee, Yen Wei
AU - Kuo, Ming Yu
AU - Wu, Yao-Ting
PY - 2014/1/7
Y1 - 2014/1/7
N2 - Highly curved buckybowls 3, 4, and 5 were synthesized from planar precursors, fluoranthenes 8, benzo[k]- fluoranthenes 10 and naphtho[1,2-k]- cyclopenta[cd]fluoranthenes 12, respectively, using straightforward palladium-catalyzed cyclization reactions. These fluoranthene-based starting materials were easily prepared from 1,8-bis(arylethynyl)- naphthalenes 6. Both buckybowls 3 and 4 are fragments of C60, whereas 5 is a unique subunit of C70. The curved structures were identified by X-ray crystallography, and they are deep bowls. The maximum p-orbital axis vector (POAV) pyramidalization angle in both 3 and 4 is 12.88. Such a high curvature is very rarely obtained. Buckybowls 5 are less curved than the others because they have a lower density of fivemembered rings, analogous to the tube portion of C70. Cyclopentaannulation increases the bowl depths of 3 and 4, but not the maximum POAV pyramidalization angle. Among the eight buckybowls studied herein, five form polar crystals. The bowl-to-bowl inversion dynamics of these buckybowls can be classified into two types; one has a planar transition structure, whereas the other has an S-shaped transition structure. A larger longitudinal length of these buckybowls corresponds to a stronger preference for the latter. The photophysical properties of these buckybowls were examined and compared with those of C60 and C70. Buckybowls 5 have absorption bands at wavelengths greater than 450 nm, which are similar to those of C70. The chiral resolution of the mono-substituted buckybowl 4ac was also studied by using HPLC with a chiral column.
AB - Highly curved buckybowls 3, 4, and 5 were synthesized from planar precursors, fluoranthenes 8, benzo[k]- fluoranthenes 10 and naphtho[1,2-k]- cyclopenta[cd]fluoranthenes 12, respectively, using straightforward palladium-catalyzed cyclization reactions. These fluoranthene-based starting materials were easily prepared from 1,8-bis(arylethynyl)- naphthalenes 6. Both buckybowls 3 and 4 are fragments of C60, whereas 5 is a unique subunit of C70. The curved structures were identified by X-ray crystallography, and they are deep bowls. The maximum p-orbital axis vector (POAV) pyramidalization angle in both 3 and 4 is 12.88. Such a high curvature is very rarely obtained. Buckybowls 5 are less curved than the others because they have a lower density of fivemembered rings, analogous to the tube portion of C70. Cyclopentaannulation increases the bowl depths of 3 and 4, but not the maximum POAV pyramidalization angle. Among the eight buckybowls studied herein, five form polar crystals. The bowl-to-bowl inversion dynamics of these buckybowls can be classified into two types; one has a planar transition structure, whereas the other has an S-shaped transition structure. A larger longitudinal length of these buckybowls corresponds to a stronger preference for the latter. The photophysical properties of these buckybowls were examined and compared with those of C60 and C70. Buckybowls 5 have absorption bands at wavelengths greater than 450 nm, which are similar to those of C70. The chiral resolution of the mono-substituted buckybowl 4ac was also studied by using HPLC with a chiral column.
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U2 - 10.1002/chem.201303357
DO - 10.1002/chem.201303357
M3 - Article
AN - SCOPUS:84895918509
VL - 20
SP - 598
EP - 608
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 2
ER -