A R T I C L E S
Cheng et al.
by positional order in one, two, or three dimensions. Rodlike
and disklike molecules on the other hand align parallel and give
rise to orientational order, which leads to the formation of
nematic phases (orientational ordering only), and smectic or
columnar LC phases if there is additional positional order.2,8
New and more complex mesophase morphologies can arise if
these driving forces are combined in a competitive way, or if
there are other forces which compete with these fundamental
organizations. Chirality, for example, favors a helical organiza-
tion of molecules, which is in competition with a layered
organization, leading to quite complex superstructures (TGB
phases, blue phases, and other complex 3D ordered structures).9
In bent-core mesogens, as another example, a polar order results
from the directed organization of the molecules in layers, which
is in competition with a layerlike organization, leading to
frustrated phase structures and supramolecular chirality.10
From the field of multiblock copolymers, it is known that
increasing the number of incompatible units fixed to one another
is an alternative way to amazingly complex morphologies.11,12
However, this concept is less explored in low-molecular mass
LC materials. There are some reports about rodlike,13,14 taper-
shaped, and dendritic polyphilic molecules,15,16 where different
incompatible units were connected in a linear fashion. However,
this molecular topology inherently favors the organization
provided by the molecular shape, leading predominately to the
formation of triple-layer structures for calamitic molecules and
formation of onion-like columns or spheroids for taper-shaped
molecules. Another approach aims at the competitiVe combina-
tion of the organization provided by rigid segments with a
polyphilic molecular structure.3a,b,17-20
with complex morphologies. These compounds can be regarded
as block molecules consisting of three incompatible units: a
rigid rodlike aromatic unit, two hydrophilic terminal groups,
and a liphophilic lateral alkyl chain. All three structural units
are incompatible with respect to one another, and therefore, they
are forced to organize within different subspaces. Furthermore,
a strong competition arises between the parallel alignment of
the rodlike biphenyl units and the steric interaction caused by
the lateral alkyl chains. The space requirement of the lateral
(13) Examples of polyphilic calamitic mesogens: (a) Ostrovskii, B. I. In
Structure and Bonding 94, Liquid Crystals I; Mingos, D. M. P., Eds.;
Springer: Berlin, 1999, 200-240. (b) Kain, J.; Diele, S.; Pelzl, G.; Lischka,
C.; Weissflog, W. Liq. Cryst. 2000, 27, 11-16. (c) Bruce, D. W. Acc.
Chem. Res. 2000, 33, 831-840. (d) Tournilhac, F.; Blinow, L. M.; Simon,
J.; Yablonsky, S. V. Nature 1992, 359, 621-623 (e) Creed, D.; Gross, J.
R. D.; Sullivan, S. L.; Griffin, A. C.; Hoyle, C. E. Mol. Cryst. Liq. Cryst.
1987, 149, 185-193. (f) Robinson, W. K.; Carboni, C.; Kloess, P.; Perkins,
S. P.; Coles, H. J. Liq. Cryst. 1998, 25, 301-307. (g) Nishikawa, E.;
Samulski, E. T. Liq. Cryst. 2000, 27, 1457-1462. (h) Lee, M.; Lee D.-W.;
Cho, B.-K.; Yoon, J.-Y.; Zin, W. C. J. Am. Chem. Soc. 1998, 120, 13258-
13259. (i) Ohtake, T.; Ogasawara, M.; Ito-Akita, K.; Nishina, N.; Ujiie,
S.; Ohno, H.; Kato, T. Chem. Mater. 2000, 12, 782-789. (j) Neumann,
B.; Sauer, C.; Diele S.; Tschierske, C. J. Mater. Chem. 1996, 6, 1087-
1098. (k) Lindner, N.; Ko¨lbel, M.; Sauer, C.; Diele, S.; Jokiranta J.;
Tschierske, C. J. Phys. Chem. B 1998, 102, 5261-5273. (l) Ewing, D. F.;
Glew, M.; Goodby, J. W.; Haley, J. A.; Kelly, S. M.; Komanschek, B. U.;
Letellier, P.; Mackenzie, G.; Mehl, G. H. J. Mater. Chem. 1998, 8, 871-
880. (m) Ujiie, S.; Yano, Y. Chem. Commun. 2000, 79-80. (n) Ibn-Elhaj,
M.; Mo¨hwald, H.; Cherkaoui, M. Z.; Zniber, R. Langmuir 1998, 14, 504-
516. (o) Sebastiao, P.; Mery, S.; Sieffert, M.; Nicoud, J. F.; Galerne, Y.;
Guillon, D. Ferroelectrics 1998, 212, 133-141. (p) Lose, D.; Diele, S.;
Pelzl, G.; Dietzmann, E.; Weissflog, W. Liq. Cryst. 1998, 24, 707-717.
(q) Guillon, D.; Osipov, M. A.; Me´ry, S.; Siffert, M.; Nicoud, J.-F.;
Bourgogne, C.; Sebastiao, P. J. Mater. Chem. 2001, 11, 2700-2708.
(14) Selected examples of calamitic LC with perfluorinated segments: (a)
Nguyen, H. T.; Sigaud, G.; Achard, M. F.; Hardouin, F.; Twieg, R. J.;
Betterton, K. Liq. Cryst. 1991, 10, 389-396. (b) Doi, T.; Sakurai, Y.;
Tamatani, A.; Takenaka, S.; Kusabayashi, S.; Nishihata, Y.; Terauchi, H.
J. Mater. Chem. 1991, 1, 169-173. (c) Pensec, S.; Tournilhac, F.-G.;
Bassoul, P. J. Phys. II 1996, 6, 1597-1605. (d) Pensec, S.; Tournilhac,
F.-G.; Bassoul, P.; Durliat, C. J. Phys. Chem. B 1998, 102, 52-60. (e)
Johansson, G.; Percec, V.; Ungar. G.; Smith, K. Chem. Mater. 1997, 9,
164-175. (f) Diele, S.; Lose, D.; Kruth, H.; Pelzl, G.; Guittard, F.; Cambon,
A. Liq. Cryst. 1996, 21, 603-608. (g) Guittard, F.; Taffin de Givenchy,
E.; Geribaldi, S.; Cambon, A. J. Fluorine Chem. 1999, 100, 85-96. (h)
Guillevic, M.-A.; Bruce, D. W. Liq. Cryst. 2000, 27, 153-156.
(15) Examples of taper-shaped molecules: (a) Percec, V.; Cho, W.-D.; Ungar,
G. J. Am. Chem. Soc. 2000, 122, 10273-10281. (b) Percec, V.; Cho, W.-
D.; Ungar, G.; Yeardley, D. J. P. J. Am. Chem. Soc. 2001, 123, 1302-
1315. (c) Percec, V.; Cho, W.-D.; Ungar, G.; Yeardley, D. J. P. Chem.
Eur. J. 2002, 8, 2011-2025. (d) Percec, V.; Holerca, M. N.; Uchida, S.;
Cho, W.-D.; Ungar, G.; Lee, Y.; Yeardley, D. J. P. Chem. Eur. J. 2002, 8,
1106-1117.
(16) Examples of taper-shaped LC with perfluorinated chains: (a) Johanssson,
G. J.; Percec, V.; Ungar, G.; Zhau, J. P. Macromolecules 1996, 29, 646-
660. (b) Percec, V.; Johansson, G.; Ungar, G.; Zhou, J. J. Am. Chem. Soc.
1996, 118, 9855-9866. (c) Percec, V.; Glodde, M.; Bera, T. K.; Miura,
Y.; Shiyanovskaya, I.; Singer, K. D.; Balagurusamy, V. S. K.; Heiney, P.
A. Schnell, I.; Rapp, A.; Spiess, H.-W.; Hudson, S. D.; Duan, H. Nature
2002, 419, 384-387. (d) Cheng, X.; Das, M. K.; Diele, S.; Tschierske, C.
Langmuir 2002, 18, 6521-6529.
(17) Different columnar phases were reported for thermotropic and lyotropic
mesophases of calamitic p-terphenyl derivatives with lateral polar groups:
(a) Hildebrandt, F.; Schro¨ter, J. A.; Tschierske, C.; Festag, R.; Kleppinger,
R.; Wendorff, J. H. Angew. Chem., Int. Ed. Engl. 1995, 34, 1631-1633.
(b) Hildebrandt, F.; Schro¨ter, J. A.; Tschierske, C.; Festag, R.; Wittenberg,
M.; Wendorff, J. H. AdV. Mater. 1997, 9, 564-567. (c) Schro¨ter, J. A.;
Tschierske, C.; Wittenberg, M.; Wendorff, J. H. J. Am. Chem. Soc. 1998,
120, 10669-10675. (d) Plehnert, R.; Schro¨ter, J. A.; Tschierske, C. J. Mater.
Chem. 1998, 8, 2611-2626.
(18) Examples for oligomesogens and dendrimers with laterally attached
mesogenic units: (a) Saez, I. M.; Goodby, J. W.; Richardson, R. M. Chem.
Eur. J. 2001, 7, 2758-2764. (b) Barbera´, J.; Gime´nez, R.; Marcos, M.;
Serrano, J. L. Liq. Cryst. 2002, 29, 309-314.
Rigid bolaamphiphiles with flexible lateral alkyl chains 1/n21
represent one class of compounds in which this approach was
very successfully used to obtain novel liquid crystalline phases
(7) Stebani, U.; Lattermann, G.; Festag, R.; Wittenberg, M.; Wendorff, J. H.
J. Mater. Chem. 1995, 5, 2247-2251. (b) Pegenau, A.; Cheng, X. H.;
Tschierske, C.; Go¨ring P.; Diele, S. Angew. Chem., Int. Ed. 2000, 39, 592-
595.
(8) Tschierske, C. Curr. Opin. Colloid Interface Sci. 2002, 7, 69-80.
(9) (a) Kitzerow, H.-S.; Bahr, C. Chirality in Liquid Crystals; Springer: New
York, 2001. (b) Pansu, B. Mod. Phys. Lett. B 1999, 13, 769-782.
(10) (a) Niori, T.; Sekine, T.; Watanabe, J.; Furukawa T.; Takezoe, H. J. Mater.
Chem. 1996, 6, 1231-1233. (b) Gorecka, E.; Pociecha, D.; Araoka, F.;
Link, D. R.; Nakata, M.; Thisayukta, J.; Takanishi, Y.; Ischikawa, K.;
Watanabe J.; Takezoe, H. Phys. ReV. E 2000, 62, R4524-R4527. (c)
Nakata, M.; Link, D. R.; Thisayukta, J.; Takanishi, Y.; Ishikawa, K.;
Watanabe J.; Takezoe, H. J. Mater Chem. 2001, 11, 2694-2699. (d) Walba,
D. M.; Ko¨rblova, E.; Shao, R.; Maclennan, J. E.; Link, D. R.; Glaser M.
A.; Clark, N. A. Science 2000, 288, 2181-2184. (e) Nadasi, H.; Weissflog,
W.; Eremin, A.; Pelzl, G.; Diele, S.; Das, B.; Grande, S. J. Mater. Chem.
2002, 12, 1316-1324. (f) Shen, D.; Pegenau, A.; Diele, S.; Wirth I.;
Tschierske, C. J. Am. Chem. Soc. 2000, 122, 1593-1601. (g) Dantlgraber,
G.; Eremin, A.; Diele, S.; Hauser, A.; Kresse, H.; Pelzl G.; Tschierske, C.
Angew. Chem., Int. Ed. 2002, 41, 2408-2412. (h) Bedel, J. P.; Rouillon,
J. C.; Marcerou, J. P.; Laguerre, M.; Nguyen H. T.; Achard, M. F. J. Mater.
Chem. 2002, 12, 2214-2220. (i) Amaranatha, R.; Reddy, R. A.; Sadashiva,
B. K. J. Mater. Chem. 2002, 12, 2627-2642.
(11) Selected examples of complex morphologies in linear ABC triblock
copolymers: (a) Mogi, Y.; Nomura, M.; Kotsuji, H.; Ohnishi, K.;
Matsushita Y.; Noda, I. Macromolecules 1994, 27, 6755-6760. (b)
Matsushita, Y.; Tamura, M.; Noda, I. Macromolecules 1994, 27, 3680-
3682. (c) Krappe, U.; Stadler, R.; Voigt-Martin, I. Macromolecules 1995,
28, 4558-4561. (d) Breiner, U.; Krappe, U.; Abetz, V.; Stadler, R.
Macromol. Chem. Phys. 1997, 198, 1051-1083. (e) Breiner, U.; Krappe
U.; Stadler, R. Macromol. Rapid. Commun. 1996, 17, 567-575. (f) Breiner,
U.; Krappe, U.; Jakob, T.; Abetz V.; Stadler, R. Polymer Bull. 1998, 40,
219-226. (g) Auschra, C.; Stadler, R. Maromolecules, 1993, 26, 2171-
2174. (h) Abetz, V.; Goldacker, T. Macromol. Rapid Commun. 2000, 21,
16-34. (i) Cochran, E. W.; Morse, D. C.; Bates, F. S. Macromolecules
2000, 36, 782-792. (j) Bailey, T. S.; Hardy, C. M.; Epps, T. H.; Bates, F.
S. Macromolecules 2002, 36, 7007-7017.
(19) SmA and SmC phases were reported for calamitic molecules with terminal
semiperfluorinated chains and lateral aliphatic substituents: (a) Arehart,
S. V.; Pugh, C. J. Am. Chem. Soc. 1997, 119, 3027-3037. (b) Small, A.
C.; Hunt, D. K.; Pugh, C. Liq. Cryst. 1999, 26, 849-857. (c) Pugh, C.;
Bae, J.-Y.; Dharia, J.; Ge, J. J.; Cheng, S. Z. D. Macromolecules 1998, 31,
5188-5200. (d) Pugh, C.; Small, A. C.; Helfer, C. A.; Mattice, W. L. Liq.
Cryst. 2001, 28, 991-1001.
(20) Zniber, R.; Achour, R.; Cherkaoui, M. Z.; Donnio, B.; Gehringer, L.;
Guillon, D. J. Mater. Chem. 2002, 12, 2208-2213.
(21) (a) Ko¨lbel, M.; Beyersdorff, T.; Sletvold, I.; Tschierske, C.; Kain, J.; Diele,
S. Angew. Chem. 1999, 111, 1146-1149. (b) Ko¨lbel, M.; Beyersdorff, T.;
Cheng, X. H.; Tschierske, C.; Kain, J.; Diele, S. J. Am. Chem. Soc. 2001,
123, 6809-6818.
(12) Examples of complex morphologies in ABC heteroarm star terpolymers:
(a) Sioula, S.; Hadjichristidis, N.; Thomas, E. L. Macromolecules 1998,
31, 8429-8432. (b) Hu¨cksta¨dt, H.; Go¨pfert A.; Abetz, V. Macromol. Chem.
Phys. 2000, 201, 296-307.
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