Chemistry Reference
In-Depth Information
3 Sumanene . . .................................................................................. 97
3.1 Sumanene and Simple Sumanene Derivatives . . ..................................... 97
3.2 Naphthosumanenes . . . ................................................................. 104
3.3 Hemifullerene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4 Mixed Type Buckybowls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
4.1 Acenaphtho[3,2,1,8-
ijlkm
]diindeno[4,3,2,1-
cdef
:1
0
,2
0
,3
0
,4
0
-
pqra
]triphenylene . . . . . 106
4.2 Acenaphth[3,2,1,8-
fghi
j]-
as
-indaceno[3,2,1,8,7,6-
pqrstuv
]picene .................. 106
4.3 Circumtrindene . . . ..................................................................... 108
5 Other Bulkybowls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.1
as
-Indaceno[3,2,1,8,7,6-
pqrstuv
]picenes . . . . . . ....................................... 108
5.2 Tetrabenzopyracylene . . . .............................................................. 109
5.3 Tetraindenopyrene . . . ................................................................. 110
5.4 Highly Curved Fragment of C
70
and Higher Fullerenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5.5 Hexabenzocoronene-Based Buckybowl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6 The Smallest Carbon Nanotube ............................................................. 112
7 A Warped Nanographene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8 Molecular Packing of Bowls in the Solid State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
9 Conclusion and Outlooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
1
Introduction
Introduction of five-membered rings into sp
2
-networks
enables formation of aromatic bowls, exemplifying the so-called Euler's rule
[
1
]. Corannulene (1) and sumanene (2) are representative examples. Extending the
curvature of such Euler's surfaces results in the formation of molecular carbon
spheres or buckyballs. These architectural features are clearly seen in the icosahedral
cage structure of buckminsterfullerene (3), which consists of 20 six-membered rings
and 12 five-membered rings [
2
]; the five-membered rings provide the curvature.
A related class of three-dimensional carbon surfaces, namely single-walled carbon
nanotubes (SWNTs) [
3
], can be regarded as tubular polyhexagonal sheets with two
Eulerean-curved end caps.
Compared to planar polycyclic aromatic hydrocarbons (PAHs), the curved struc-
ture of buckybowls endows them with additional interesting physical properties.
For example, a bowl-shaped molecule has a dipole moment and a self compli-
mentary shape that could lead to the formation of polar crystals. Moreover, bucky-
balls and carbon nanotubes are well known for their (potential) applications as
electro-optical organic materials. Studies of buckybowls can provide fundamental
information on buckyballs and carbon nanotubes.
The chemistry of corannulene-based [
4
-
12
] and sumanene-based buckybowls
[
4
,
12
-
15
] has been described in several review articles. In 2006 we published a
review article focusing on the solution-phase synthesis of buckybowls, and the
structures and physical properties of compounds thus prepared [
7
]. Since then, this
research field has expanded dramatically and many important results have
appeared; we update the contents herein, and introduce some important compounds,
which are not furnished by solution-phase synthesis. Due to page limitations, some
carbon hexagonal
π
