Fluorophobic effect induces the self-assembly of semifluorinated tapered monodendrons containing crown ethers into supramolecular columnar dendrimers which exhibit a homeotropic hexagonal columnar liquid crystalline phase

Article abstract of DOI:10.1021/ja9615738

The rational design, synthesis, and characterization of the building blocks obtained by the esterification of the first generation of tapered monodendrons 3,4,5-tris(p-dodecan-1-yloxy)benzoic acid (12-AG) and 3,4,5-tris[p-(n-dodecan-1-yloxy)benzyloxy]benz

Full text of DOI:10.1021/ja9615738

J. Am. Chem. Soc. 1996, 118, 9855-9866
9855
Fluorophobic Effect Induces the Self-Assembly of
Semifluorinated Tapered Monodendrons Containing Crown
Ethers into Supramolecular Columnar Dendrimers Which
Exhibit a Homeotropic Hexagonal Columnar Liquid Crystalline
Phase
Virgil Percec,*,† Gary Johansson,† Goran Ungar,‡ and Jianping Zhou‡
Contribution from The W. M. Keck Laboratories for Organic Synthesis,
Department of Macromolecular Science, Case Western ReserVe UniVersity,
CleVeland, Ohio 44106-7202, and Department of Engineering Materials and Centre for
Molecular Materials, UniVersity of Sheffield, Sheffield S1 4DU, UK
ReceiVed May 10, 1996X
Abstract: The rational design, synthesis, and characterization of the building blocks obtained by the esterification of
the first generation of tapered monodendrons 3,4,5-tris(p-dodecan-1-yloxy)benzoic acid (12-AG) and 3,4,5-tris[p-
(n-dodecan-1-yloxy)benzyloxy]benzoic acid (12-ABG) containing semifluorinated dodecyl groups [i.e., 12Fn-AG-
15C5 (n ) 0, 4, 6, 8), 12Fn-AG-B15C5, 12Fn-ABG-15C5, and 12Fn-ABG-B15C5 (n ) 0 and 8) where n following
the letter F represents the number of outer perfluorinated methylenic units of the dodecyl group] with 4′-hydroxymethyl-
(benzo-15-crown-5) (B15C5) and 1-hydroxymethyl(15-crown-5) (15C5) are described. All building blocks self-
assemble into supramolecular cylindrical or rod-like dendrimers Via ion-mediated complexation processes. These
rod-like supermolecules form a thermotropic hexagonal columnar (Φh) liquid crystalline (LC) phase. The fluorination
of the dodecyl groups of these tapered building blocks enhances dramatically their self-assembly ability. The building
blocks based on n ) 6 and 8 self-assemble into supramolecular columns solely Via the fluorophobic effect. Direct
structural characterization of the supramolecular columns obtained Via these two molecular recognition processes by
a combination of techniques consisting of differential scanning calorimetry, X-ray diffraction, and thermal optical
polarized microscopy, and of the columns obtained solely Via the fluorophobic effect allowed the construction of
molecular models for the supramolecular columns obtained Via these two organizing forces. An increase in the
column diameter with increasing n and with the complexation of metal salts (i.e., alkali metal trifluoromethane-
sulfonates) accounts for a structural model in which the uncomplexed and complexed crown ethers are placed side-
by-side in the center of the column with the melted tapered side groups radiating toward its periphery. The
perfluorinated segments of the building blocks are microsegregated from the perhydrogenated and aromatic segments
of the column. The supramolecular columns obtained from building blocks with n ) 8 align homeotropically in the
Φh LC phase on untreated glass slides, i.e., form single crystal liquid crystals in which the long axes of their columns
are perpendicular to the glass surface. Both the self-assembly of supramolecular columns induced solely by the
fluorophobic effect and the homeotropic alignment of these columns in their Φh LC phase open extremely interesting
new synthetic and technologic opportunities in the area of self-assembly of well-defined supramolecular architectures
obtained from monodendrons and other building blocks.
Introduction
shapes and functions by using specifically designed monoden-
drons and dendrimers and/or combinations of dendrimers and
other macromolecular topologies as building blocks.2 The
One of the most fascinating subjects of research which
evolved from the field of dendrimers1 is concerned with the
construction of novel complex molecular, macromolecular, and
supramolecular nanoscopic architectures with well defined
(2) For a few recent examples on the design of new complex architectures
and shapes from dendrimers, see: (dendrimer box) (a) Jansen, J. F. G. A.;
de Brabander-van den Berg, E. M. M.; Meijer, E. W. Science 1994, 266,
1226. (b) Jansen, J. F. G. A.; Janssen, R. A. J.; de Brabander-van den Berg,
E. M. M.; Meijer, E. W. AdV. Mater. 1995, 7, 561. (c) Jansen, J. F. G. A.;
Meijer, E. W.; de Brabander-van den Berg, E. M. M. J. Am. Chem. Soc.
1995, 117, 4417. (molecular ball bearings) (d) Hawker, C. J.; Farrington,
P. J.; MacKay, M. E.; Wooley, K. L.; Fre´chet, J. M. J. J. Am. Chem. Soc.
1995, 117, 4409. (sugar balls) (e) Aoi, K.; Itoh, K.; Okada, M. Macromol-
ecules 1995, 28, 5391. (chiral dendritic surfaces) (f) Jansen, J. F. G. A.;
Peerlings, H. W. I.; de Brabander-van den Berg, E. M. M.; Meijer, E. W.
Angew. Chem., Int. Ed. Engl. 1995, 34, 1206 and references cited therein.
(well-defined micellar aggregates from dendrimers containing block
copolymers and amphiphilic surfaces) (g) Hawker, C. J.; Fre´chet, J. M. J.
J. Am. Chem. Soc. 1992, 114, 8405. (h) Newkome, G. R.; Moorefield, C.
N.; Keith, J. M.; Baker, G. R.; Escamilla, G. H. Angew. Chem., Int. Ed.
Engl. 1994, 33, 666. (i) Fre´chet, J. M. J.; Gitsov, I. Macromol. Symp. 1995,
98, 441. (j) Gitsov, I.; Fre´chet, J. M. J. J. Am. Chem. Soc. 1996, 118, 3785.
(k) van Hest, J. C. M.; Delnoye, D. A. P.; Baars, M. W. P. L.; van Genderen,
M. H. P.; Meijer, E. W. Science 1995, 268, 1592. (l) Chapman, T. M.;
Hillyer, G. L.; Mahan, E. J.; Shaffer, K. A. J. Am. Chem. Soc. 1994, 116,
11195. (m) Hawker, C. J.; Wooley, K. L.; Fre´chet, J. M. J. J. Chem. Soc.,
Perkin Trans. 1 1993, 1287.
† Case Western Reserve University. Phone: 216-368-4242. Fax: 216-
368-4202. e-mail: vxp5@po.cwru.edu.
‡ University of Sheffield.
X Abstract published in AdVance ACS Abstracts, October 1, 1996.
(1) For recent reviews and highlights on dendrimers, see: (a) Tomalia,
D. A. Macromol. Symp. 1996, 101, 243. (b) Bell, T. W. Science 1996, 271,
1077. (c) Bradley, D. Science 1995, 270, 1924. (d) Service, R. F. Science
1995, 267, 458. (e) Tomalia, D. A. Sci. Amer. 1995, May, 62. (f) Newkome,
G. R.; Moorefield, C. N. In Mesomolecules: From Molecules to Materials;
Mendenhall, G. D., Greenberg, A., Liebman, J. F., Eds.; Chapman & Hall:
New York, 1995; p 27. (g) Ardoin, N.; Astruc, D. Bull. Soc. Chim. Fr.
1995, 875. (h) Young, J. K.; Moore, J. S. In Modern Acetylene Chemistry;
Stang, P. J., Diederich, F., Eds.; VCH: Weinheim, 1995; p 415. (i) Fre´chet,
J. M. J. Science 1994, 263, 1710. (j) Vo¨gtle, F.; Issberner, J.; Moors, R.
Angew. Chem., Int. Ed. Engl. 1994, 33, 2413. (k) AdVances in Dendritic
Macromolecules; Newkome, G. R., Ed.; JAI Press, Inc.: Greenwich, 1994;
Vol. 1. (l) Tomalia, D. A. AdV. Mater. 1994, 6, 529. (m) Escamilla, G. H.;
Newkome, G. R. Angew. Chem., Int. Ed. Engl. 1994, 33, 1937. (n) Tomalia,
D. A.; Durst, H. D. Top. Curr. Chem. 1993, 165, 193. (o) Dvornic, P. R.;
Tomalia, D. A. Chem. Brit. 1994, 641.
S0002-7863(96)01573-9 CCC: $12.00 © 1996 American Chemical Society

9856 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
synthetic capabilities of this field increased dramatically after
the convergent approach to dendrimers was developed.3 Nev-
ertheless, the expansion of this field relies on the availability
of accelerated synthetic methods for the preparation of both
monodendrons and dendrimers.4 Consequently, the use of
supramolecular chemistry to self-assemble monodendrons into
supramolecular dendrimers may generate synthetic strategies5
which are at least complementary to those based on covalent
chemistry. The molecular recognition process which was the
most exploited both in the construction of monodendrons and
of dendrimers is based on various metal binding strategies.6
Although molecular recognition strategies based on hydrogen
bonding were employed in the self-assembly of various mac-
romolecular systems,7a it was only very recently that they
were applied to the functionalization7b and self-assembly of
dendrimers7c in solution. A particular self-assembly event can
be dominated by a single molecular recognition process based
on either hydrogen bonding, van der Waals interactions,
electrostatic interactions, and the hydrophobic effect.8 However,
all these processes are cooperative, and their contribution could
be equally important not only in the aggregation process but
also especially in the stabilization of a unique architecture. While
most molecular recognition processes are based on attractive
exoenthalpic forces, the hydrophobic effect provides a unique
organizing force based on repulsion by the solvent or by other
dissimilar parts of the same molecule.8
cylindrical shape was suggested without any experimental
evidence for a poly(p-phenylene) containing Fre´chet type
monodendrons as side groups.12 Rod-like dendrimers were
reported by Tomalia13 by attaching poly(amidoamine) mono-
dendrons to a linear polyethyleneimine, and supramolecular disc-
like hexameric dendrimers were recently self-assembled Via an
elegant exact H-bonding.1b,7c All this indirect experimental
evidence for spherical6f,14a-c and rod-like14d shapes obtained
from dendrimers is strongly supported by their direct visualiza-
tion Via transmission electron and atomic force microscopy
which, however, cannot easily discriminate between individual
and aggregated dendrimers.
Direct determination of the shape and of the internal structure
of the dendrimer within this shape can be obtained only from
X-ray diffraction experiments. Several years ago we initiated
a research program to design monodendrons which produce
macromolecular and supramolecular dendrimers that generate
well-defined shapes in solid and melt states. Two different
synthetic approaches are investigated toward this goal. One is
based on the use of AB2 rod-like conformationally flexible
building blocks which produce monodendrons and macromo-
lecular dendrimers which display thermotropic calamitic nematic
and smectic liquid crystalline (LC) phases in addition to a
crystalline phase.15 Characterization of LC and crystalline
phases of these monodendrons and dendrimers by a combination
of various techniques including X-ray diffraction demonstrated,
as expected, an elongated rather than a globular shape. The
other approach is based on the design of various generations of
monodendrons which exhibit a tapered shape.16-19 These
tapered monodendrons are functionalized with suitable endo-
receptors such as crown ethers, polypodands or with a poly-
merizable group. Ion-mediated electrostatic and H-bonding
recognition processes16 and/or polymerization reactions17 self-
assemble these building blocks in solution, melt phase and in
solid state into a cylindrical or rod-like supramolecular archi-
tecture which is responsible for the formation of a thermotropic
hexagonal columnar (Φh) LC phase. This LC phase warrants
a thermodynamically controlled self-assembly process and its
characterization by X-ray diffraction provides direct information
on the shape and size of the cylindrical supramolecular
dendrimer as well as on the arrangement of the monodendrons
within the column.16-19
Little is presently known about the design of dendrimers
which exhibit a well-defined shape in solution, in melt phase,
or solid state, and even less is understood about the change of
their shape at the transition from solution to melt and to solid
state.1e,i,n For example, in solution a transition from an extended
to a globular shape was theoretically predicted1in,9 and experi-
mentally supported by a plot of intrinsic viscosity Versus
molecular weight10 and by other indirect methods.1i However,
in solid state the same dendrimers are amorphous.1i,2d,11
A
(3) For the convergent synthetic approach to dendrimers, see: (a) Hawker,
C. J.; Fre´chet, J. M. J. J. Chem. Soc., Chem. Commun. 1990, 1010. (b)
Hawker, C. J.; Fre´chet, J. M. J. J. Am. Chem. Soc. 1990, 112, 7638. (c)
Miller, T. M.; Neenan, T. X. Chem. Mater. 1990, 2, 346.
(4) For new accelerated synthetic methods to monodendrons and den-
drimers, see: (a) Spindler, R.; Fre´chet, J. M. J. J. Chem. Soc., Perkin Trans.
1 1993, 913. (b) Wooley, K. L.; Hawker, C. J.; Fre´chet, J. M. J. J. Am.
Chem. Soc. 1991, 113, 4252. (c) Twyman, L. J.; Beezer, A. E.; Mitchell, J.
C. J. Chem. Soc., Perkin Trans. 1 1994, 407. (d) Fre´chet, J. M. J.; Henmi,
M.; Gitsov, I.; Aoshima, S.; Leduc, M. R.; Grubbs, R. B. Science 1995,
269, 1080. (e) Hawker, C. J.; Fre´chet, J. M. J.; Grubbs, R. B.; Dao, J. J.
Am. Chem. Soc. 1995, 117, 10763.
(5) Lehn, J. M. Supramolecular Chemistry; VCH: Weinheim, 1995.
(6) For selected examples of recent publications on various metal-binding
strategies used in the construction of dendrimers, see: (a) Serroni, S.; Denti,
G.; Campagna, S.; Ciano, M.; Balzani, V. J. Am. Chem. Soc. 1992, 114,
2944. (b) Constable, E. C.; Harverson, P. Chem. Commun. 1996, 33. (c)
Newkome, G. R.; Gu¨ther, R.; Cardullo, F. Macromol. Symp. 1995, 98, 467.
(d) Campagna, S.; Giannetto, A.; Serroni, S.; Denti, G.; Trusso, S.;
Mallamace, F.; Micali, N. J. Am. Chem. Soc. 1995, 117, 1754. (e) Liao,
Y.-H.; Moss, J. R. Organometallics 1995, 14, 2130. (f) Huck, W. T. S.;
van Veggel, F. C. J. M.; Kropman, B. L.; Blank, D. M. A.; Keim, E. G.;
Smithers, M. M. A.; Reinhoudt, D. N. J. Am. Chem. Soc. 1995, 117, 8293
and references cited therein.
(7) (a) Lehn, J.-M. Makromol. Chem., Macromol. Symp. 1993, 69,1. (b)
Newkome, G. R.; Moorefield, C. N.; Gu¨ther, R.; Baker, G. R. Am. Chem.
Soc. DiV. Polym. Chem., Polym. Prepr. 1995, 36(1), 609. (c) Zimmerman,
S. C.; Zeng, F.; Reichert, D. E. C.; Kolotuchin, S. V. Science 1996, 271,
1095.
(11) Wooley, K. L.; Hawker, C. J.; Pochan, J. M.; Fre´chet, J. M. J.
Macromolecules 1993, 26, 154.
(12) (a) Frendenberger, R.; Claussen, W.; Schlueter, A.-D.; Wallmeier,
H. Polymer 1994, 35, 4496. (b) Claussen, W.; Schulte, N.; Schlueter, A.-
D. Macromol. Rapid Commun. 1995, 16, 89. (c) Schlueter, A.-D.; Claussen,
W.; Frendenberger, R. Macromol. Symp. 1995, 98, 475.
(13) See: Tomalia, D. A. in ref 1n, p 229 and private communication.
(14) (a) Tomalia, D. A.; Baker, H.; Dewald, J.; Hall, M.; Kallos, G.;
Martin, S.; Roeck, J.; Ryder, J.; Smith, P. Polym. J. (Japan) 1985, 17, 117.
(b) Tomalia, D. A.; Baker, H.; Dewald, J.; Hall, M.; Kallos, G.; Martin, S.;
Ryder, J.; Smith, P. Macromolecules 1986, 19, 2466. (c) Newkome, G. R.;
Yao, Z.; Baker, G. R.; Gupta, V. K.; Russo, P. S.; Saunders, M. J. J. Am.
Chem. Soc. 1986, 108, 849. (d) Newkome, G. R.; Moorefield, C. N.; Baker,
G. R.; Behera, R. K.; Escamilla, G. H.; Saunders, M. J. Angew. Chem., Int.
Ed. Engl. 1992, 31, 917.
(15) Percec, V.; Chu, P.; Ungar, G.; Zhou, J. J. Am. Chem. Soc. 1995,
117, 11441.
(16) For experiments which concluded that tapered monodendrons
containing crown ethers and polypodands self-assemble Via ion-mediated
and H-bonding processes into supramolecular rod-like shapes, see: (a)
Percec, V.; Heck, J. Am. Chem. Soc. DiV. Polym. Chem., Polym. Prepr.
1992, 33(1), 217. (b) Percec, V.; Johansson, G.; Heck, J.; Ungar, G.; Batty,
S. V. J. Chem. Soc., Perkin Trans. 1 1993, 1411. (c) Percec, V.; Heck, J.;
Tomazos, D.; Falkenberg, F.; Blackwell, H.; Ungar, G. J. Chem. Soc., Perkin
Trans. 1 1993, 2799. (d) Percec, V.; Heck, J. A.; Tomazos, D.; Ungar, G.
J. Chem. Soc., Perkin Trans. 2 1993, 2381. (e) Johansson, G.; Percec, V.;
Ungar, G.; Abramic, D. J. Chem. Soc., Perkin Trans. 1 1994, 447. (f) Percec,
V.; Tomazos, D.; Heck, J.; Blackwell, H.; Ungar, G. J. Chem. Soc., Perkin
Trans. 2 1994, 31. (g) Tomazos, D.; Out, G.; Heck, J. A.; Johansson, G.;
Percec, V.; Mo¨ller, M. Liq. Cryst. 1994, 16, 509. (h) Ungar, G.; Batty, S.
V.; Percec, V.; Heck, J.; Johansson, G. AdV. Mat. Opt. Electr. 1994, 4,
303.
(8) (a) Schneider, H.-J. Angew. Chem., Int. Ed. Engl. 1991, 30, 1417.
(b) Tanford, C. Science 1978, 200, 1012. (c) Buckingham, A. D. In
Principles of Molecular Recognition; Buckingham, A. D., Legon, A. C.,
Roberts, S. M., Eds.; Chapman & Hall: London, 1993; p 1. (d) Ciferri, A.
Progr. Polym. Sci. 1995, 20, 1081.
(9) (a) de Gennes, P. G.; Hervet, H. J. Phys. Lett. (Paris) 1983, 44, 35.
(b) Naylor, A. M.; Goddard, III, W. A.; Keifer, G.; Tomalia, D. A. J. Am.
Chem. Soc. 1989, 111, 2339. (c) Lescanec, R. L.; Muthukumar, M.
Macromolecules 1990, 23, 2280.
(10) Mourey, T. H.; Turner, S. R.; Rubinstein, M.; Fre´chet, J. M. J.;
Hawker, C. J.; Wooley, K. L. Macromolecules 1992, 25, 2401.

Self-Assembly of Semifluorinated Monodendrons
J. Am. Chem. Soc., Vol. 118, No. 41, 1996 9857
It is well established that perfluorinated alkanes are more rigid
and linear and due to their extremely low surface energy less
miscible than the corresponding perhydrogenated alkanes (fluo-
rophobic effect).20 Consequently, the replacement of a perhy-
drogenated alkane with a perfluorinated one in the tail of a rigid
rod-like molecular LC enhances the thermal stability of calamitic
LC phases.21 At the same time, the combination of a suitable
length and ratio of perfluorinated and perhydrogenated alkane
segments within the same molecule produces a microsegregation
at the molecular level, and this process has been shown to be
alone responsible for the formation of highly ordered lamellar
thermotropic22,23 and lyotropic mesophases.24 Recently, we
discovered a dramatic stabilization of the Φh LC phase generated
from supramolecular and macromolecular columns Via semif-
luorination of the alkyl groups of their tapered building blocks.25
A dramatic enhancement of the ability of semifluorinated tapered
building blocks to self-assemble into supramolecular columns
which produce Φh phases via H-bonding processes was also
demonstrated.26 Finally, the stabilization of the Φh phase
generated from fluoroalkylated discotic molecules was reported
by Ringsdorf et al.27 This extremely broad range of capabilities
of the fluorophobic effect, which represents an amplification
of the hydrophobic effect, to stabilize LC phases prompted us
to investigate its potential in the design of tapered monodendrons
which self-assemble solely Via the fluorophobic effect.
The goal of this paper is to report the rational design,
synthesis, and characterization of the simplest tapered mono-
dendrons containing crown ethers which self-assemble into
cylindrical or rod-like supramolecular dendrimers which display
a thermotropic Φh LC phase solely Via the fluorophobic effect.
The structure of these supramolecular rod-like dendrimers
determined by X-ray diffraction experiments was compared with
that of the corresponding assemblies generated Via a combina-
tion of fluorophobic and ion-mediated interactions. These
experiments provide the first structural comparison of the two
supramolecular systems assembled either by ion-mediated
processes or by the fluorophobic effect and demonstrate the
extraordinary potential of the fluorophobic effect in supramo-
lecular chemistry.
(17) For experiments which demonstrate that polymers containing tapered
monodendrons which conceptually were derived from hemiphasmidic
mesogens produce macromolecular rod-like architectures, see: (a) Percec,
V.; Heck, J. Am. Chem. Soc. DiV. Polym. Chem., Polym. Prepr. 1989, 30-
(2), 450. (b) Heck, J.; Percec, V. Am. Chem. Soc. DiV. Polym. Chem., Polym.
Prepr. 1991, 32(1), 263. (c) Percec, V.; Heck, J. Am. Chem. Soc. DiV. Polym.
Chem., Polym. Prepr. 1991, 32(3), 698. (d) Percec, V.; Heck, J. J. Polym.
Sci.: Part A: Polym. Chem. 1991, 29, 591. (e) Percec, V.; Heck, J. Polym.
Bull. 1990, 24, 255. (f) Percec, V.; Heck, J. Polym. Bull. 1991, 25, 55 and
431. (g) Percec, V.; Heck, J.; Ungar, G. Macromolecules 1991, 24, 4957.
(h) Percec, V.; Heck, J.; Ungar, G. Am. Chem. Soc. DiV. Polym. Chem.,
Polym. Prepr. 1992, 33(1), 152. (i) Percec, V.; Lee, M.; Heck, J.; Blackwell,
H.; Ungar, G. Alvarez-Castillo, A. J. Mater. Chem. 1992, 2, 931. (j) Percec,
V.; Heck, J.; Lee, M.; Ungar, G.; Alvarez-Castillo, A. J. Mater. Chem.
1992, 2, 1033. (k) References 16c,d,f. (l) Percec, V.; Schlueter, D.; Ronda,
J. C.; Johansson, G.; Ungar, G.: Zhou, J. P. Macromolecules 1996, 29,
1464.
(18) For X-ray characterization of a more ordered hexagonal phase
obtained from macromolecular and supramolecular dendrimers which
provides a structural arrangement of the monodendrons in the column, see:
(a) Kwon, Y. K.; Chvalun, S.; Schneider, A.-I.; Blackwell, J.; Percec, V.;
Heck, J. A. Macromolecules 1994, 27, 6129. (b) Kwon, Y. K.; Danko, C.;
Chvalun, S.; Blackwell, J.; Heck, J. A.; Percec, V. Macromol. Symp. 1994,
87, 103. (c) Kwon, Y. K.; Chvalun, S. N.; Blackwell, J.; Percec, V.; Heck,
J. A. Macromolecules 1995, 28, 1552.
(19) For some brief reviews on the design of macromolecular and
supramolecular rod-like architectures obtained from tapered and confor-
mationally flexible rod-like building blocks, see: (a) Percec, V.; Heck, J.;
Johansson, G.; Tomazos, D.; Ungar, G. Macromol. Symp. 1994, 77, 237.
(b) Percec, V.; Heck, J.; Johansson, G.; Tomazos, D.; Kawasumi, M.; Ungar,
G. J. Macromol. Sci.:-Pure Appl. Chem. 1994, A31, 1031. (c) Percec, V.;
Heck, J.; Johansson, G.; Tomazos, D.; Kawasumi, M.; Chu, P.; Ungar, G.
Mol. Cryst. Liq. Cryst. 1994, 254, 137. (d) Percec, V.; Heck, J.; Johansson,
G.; Tomazos, D.; Kawasumi, M.; Chu, P.; Ungar, G. J. Macromol. Sci.:-
Pure Appl. Chem. 1994, A31, 1719. (e) Percec, V.; Johansson, G. Macromol.
Symp. 1995, 96, 173. (f) Percec, V. Pure Appl. Chem. 1995, 67, 2031. (g)
Percec, V.; Johansson, G.; Schlueter, D.; Ronda, J. C.; Ungar, G. Macromol.
Symp. 1996, 101, 43.
(20) For a few fundamental publications on fluorinated materials, see:
(a) Smart, B. E. In Organofluorine Chemistry: Principles and Commercial
Applications; Banks, R. E., Smart, B. E., Tatlow, J. C., Eds.; Plenum: New
York, 1994; p 57. (b) Feiring, A. E. J. Macromol. Sci.:-Pure Appl. Chem.
1994, A31, 1657. (c) Eaton, D. F.; Smart, B. E. J. Am. Chem. Soc. 1990,
112, 2821. (d) Bunn, C. W.; Howells, E. R. Nature 1954, 174, 549.
(21) For examples on the stabilization of thermotropic LC phases by
replacing perhydrogenated with perfluorinated segments: (a) Tournilhac,
F.; Bosio, L.; Nicoud, J. F.; Simon, J. Chem. Phys. Lett. 1988, 145, 452.
(b) Koden, M.; Nakagawa, K.; Ishii, Y.; Funada, S.; Matsuura, M.; Awani,
K. Mol. Cryst. Liq. Cryst. Lett. 1989, 6, 285. (c) Nguyen, H. T.; Sigaud,
G.; Achard, M. F.; Hardouin, F.; Tweig, R. J.; Betterton, K. Liq. Cryst.
1991, 10, 389. (d) Chiang, Y. H.; Ames, A. E.; Gaudiana, R. H.; Adams,
T. G. Mol. Cryst. Liq. Cryst. 1991, 208, 85. (e) Takenaka, S. J. Chem.
Soc., Chem. Commun. 1992, 1748. (f) Pugh, C.; Arehart, S.; Liu, H.;
Warayanan, R. J. Macromol. Sci.-Pure Appl. Chem. 1994, A31, 1591. (g)
Johansson, G.; Percec, V.; Ungar, G.; Smith, K. Chem. Mater., in press.
(22) For representative publications on thermotropic liquid crystal phases
from semifluorinated alkanes, see: (a) Mahler, W.; Guillon, D.; Skoulios,
A. Mol. Cryst. Liq. Cryst. Lett. 1985, 2, 111. (b) Viney, C.; Twieg, R. J.;
Gordon, B. R.; Rabolt, J. F. Mol. Cryst. Liq. Cryst. 1991, 198, 285. (c)
Ho¨pken, J.; Pugh, C.; Richtering, W.; Mo¨ller, M. Makromol. Chem. 1988,
189, 911. (d) Ho¨pken, J.; Faulstich, S.; Mo¨ller, M. Mol. Cryst. Liq. Cryst.
1992, 210, 59.
Results and Discussion
Rationale, Molecular Design, and Synthesis. Scheme 1
outlines the self-assembly of the building blocks obtained by
the esterification of first generation 3,4,5-tris(p-dodecyloxy-
benzyloxy)benzoic acid (12-ABG) and 3,4,5-tris(p-dodecyloxy)-
benzoic acid (12-AG) monodendrons with 4′-hydroxymethyl-
(benzo-15-crown-5) (B15C5) and 1-hydroxymethyl(15-crown-
5) (15C5) (i.e., 12-ABG-B15C5, 12-ABG-15C5, 12-AG-
B15C5, 12-AG-15C5) mediated by the complexation of their
crown ether with Li, Na, and K trifluoromethanesulfonates
(MOTf).16b,e,19a,e,f The tapered group of these building blocks
(brick) is responsible for the cylindrical or rod-like shape of
the self-assembled architecture. Simultaneously, the crown ether
overcomes Via its interaction with MOTf (mortar) the entropy
loss during the self-assembly process and determines the stability
of the resulted supramolecular column. These columns are
stable in solution, melt phase, and solid state. X-ray investiga-
tions performed in the Φh phase indicated a column structure
in which the crown ethers are placed side-by-side in the center
of the column with their tapered side groups radiating toward
its periphery. In the absence of ion complexation these building
blocks form lamellar crystals. Since the formation of liquid
crystalline phases are thermodynamically controlled processes,28
this guarantees a thermodynamically controlled self-assembly
(23) For selected examples of thermotropic mesophases formed from
semifluorinated polymers, see: (a) Wilson, L. M.; Griffin, A. C. Macro-
molecules 1993, 26, 6212. (b) Davidson, T.; Griffin, A. C.; Wilson, L. M.;
Windl, A. H. Macromolecules 1995, 28, 354. (c) Jariwala, C. P.; Mathias,
L. J. Macromolecules 1993, 26, 5129. (d) Hoyle, C. E.; Kang, D.; Jariwala,
C.; Griffin, A. C. Polymer 1993, 34, 3070. (e) Wilson, L. M. Liq. Cryst.
1994, 17, 277. (f) Wilson, L. M.; Griffin, A. C. Macromolecules 1994, 27,
1921. (g) Wilson, L. M.; Griffin, A. C. Macromolecules 1994, 27, 4611.
(h) Wilson, L. M. Macromolecules 1995, 28, 347. (i) Wilson, L. M. Liq.
Cryst. 1995, 18, 347. (j) Ref 21f.
(24) For selected publications on lyotropic systems from semifluorinated
compounds, see: (a) Elbert, R.; Folda, T.; Ringsdorf, H. J. Am. Chem. Soc.
1984, 106, 7687. (b) Turberg, M. P.; Brady, J. E. J. Am. Chem. Soc. 1988,
110, 7797. (c) Kawahara, H.; Hamada, M.; Ishikawa, Y.; Kunitake, T. J.
Am. Chem. Soc. 1993, 115, 3002. (d) Ishikawa, Y.; Kuwahara, H.; Kunitake,
T. J. J. Am. Chem. Soc. 1989, 111, 8530. (e) Giulieri, F.; Krafft, M. P.;
Riess, J. G. Angew. Chem., Int. Ed. Engl. 1994, 33, 1514.
(25) (a) Johansson, G.; Schlueter, D.; Percec, V. Abstracts of the 35th
IUPAC International Symposium on Macromolecules 1994, 354. (b) Percec,
V.; Schlueter, D.; Kwon, Y. K.; Blackwell, J.; Mo¨ller, M.; Slangen, P. J.
Macromolecules 1995, 28, 8807.
(26) Johansson, G.; Percec, V.; Ungar, G.; Zhou, J. P. Macromolecules
1996, 29, 646.
(27) Dahn, U.; Erdelen, C.; Ringsdorf, H.; Festag, R.; Wendorff, J. H.;
Heiney, P. A.; Maliszewskyj, N. C. Liq. Cryst. 1995, 19, 759.

9858 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
Scheme 1. Schematic Representation of the Self-Assembly of Tapered Building Blocks into a Supramolecular Columnar
Architecture
Scheme 2. Synthesis of 12Fn-AG-15C5 (4-m/n) and 12F8-AG-B15C5 (5-4/8)
Scheme 3. Synthesis of 12F8-ABG-15C5 (14-4/8) and 12F8-ABG-B15C5 (15-4/8)
process. The evolution of this self-assembling process is
estimated and analyzed by comparing the thermodynamic
parameters of the Φh phase generated from supramolecular
columns as a function of MOTf used in the complexation
process with established theoretical and experimental depend-
encies of various parameters of thermodynamically controlled
phase transitions Versus degree of polymerization (i.e., first order
transition temperatures, their corresponding enthalpy and entropy
changes, and glass transition temperatures).29-31 These experi-
(28) (a) deGennes, P. G.; Prost, J. The Physics of Liqud Crystals; Oxford
University Press: Oxford, 1993. (b) Chandrasekhar, S. Liquid Crystals, 2nd
ed.; Cambridge University Press: 1992.

Self-Assembly of Semifluorinated Monodendrons
J. Am. Chem. Soc., Vol. 118, No. 41, 1996 9859
ments have demonstrated a similar behavior for the supramo-
lecular polymer “backbone” generated Via ion-mediated inter-
actions with that of covalent polymer backbones.19a,e,f When
the crown ether of these building blocks was replaced with
oligooxyethylenic segments containing a terminal -OH group
which induces H-bonding interactions, the resulting 12-ABG-
nEO-OH self-assemble in the absence of ion complexation. In
the absence of the H-bonding -OH group, the self-assembly
process requires ion-complexation. Alternatively, the -OH
group can be replaced with a polymer backbone to facilitate
the self-assembly process.16c,d,19a,e,f 12-AG-nEO-OH self-
assemble only Via an ion mediated recognition process or by
replacing the -OH groups with a suitable polymer backbone.16f,19a,f
Recently we discovered that semifluorination of the alkyl groups
of 12-AG-nEO-OH and of their corresponding polymers
produces a dramatic stabilization of their Φh phase.25 Subse-
quently, we discovered that a suitable length of the semifluori-
nated alkyl tail of 12-AG-nEO-OH induces their self-assembly
in the absence of ion complexation,26 i.e., by a combination of
the fluorophobic effect and H-bonding interactions. This last
result prompted us to advance the hypothesis that a suitable
semifluorination of the alkyl groups of 12-ABG-B15C5, 12-
ABG-15C5, 12-AG-B15C5, and 12-AG-15C5 may induce their
self-assembly Via the fluorophobic effect, and, therefore, this
would have to occur in the absence of metal ion complexation
or H-bonding processes.
a
b
Scheme 2 outlines the synthesis of 12Fn-AG-15C5 and 12F8-
AG-B15C5 (where n and respectively 8 following the letter F
indicates the number of fluorinated methylenic groups out of a
total of 12). The synthesis of 12Fn-AG with n ) 8, 6, and 4
was reported previously.26 The esterification of 12Fn-AG with
1-hydroxymethyl(15-crown-5) (2)16e and 4′-hydroxymethyl-
benzo(15-crown-5) (3)16b was performed with DCC catalyzed
by 4-dimethylaminopyridinium p-toluenesulfonate (DPTS),16b
in CH2Cl2 when n ) 4, 6 and in a mixture of CH2Cl2/Freon
113 (1:1 ratio) when n ) 8. The yield of the esterification
decreases with the increase of n due to the decreased solubility
of the acylurea intermediate formed by the addition of 12Fn-
AG to DCC. The resulted building blocks were purified by
flash column chromatography (SiO2, CHCl3/MeOH gradient)
to more than 99% purities (HPLC, single spot TLC).
Figure 1. (a) The dependence of the transition temperatures of the
complexes of 12F8-AG-15C5 with NaOTf on the NaOTf/12F8-AG-
15C5 molar ratio (a) from the second heating scan: ) Tk -k ; 4 Tk -Φ ;
1
2
2
h
0 Ti; (b) from the cooling scan: 9 Ti-Φ ; 2 TΦ -k. (b) The dependence
h
h
of the i-Φh transition temperatures of the complexes of 12Fn-AG-15C5
with NaOTf on the NaOTf/12Fn-AG-15C5 molar ratio: b F0; [ F4;
2 F6; 9 F8.
Scheme 3 describes the synthesis of 12F8-ABG-15C5 and
12F8-ABG-B15C5. 4-Hydroxymethylbenzoate (7) was alky-
lated (DMF/K2CO3) with n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,-
12,12-heptadecafluorododecyl bromide (6-4/8) which was syn-
thesized as reported previously26 at 65 °C to produce 8-4/8 in
82% yield after 20 h. Reduction of 8-4/8 with LiAlH4 in Et2O
(room temperature, 1.5 h) yielded 9-4/8 (75% yield) which was
chlorinated with SOCl2 (CH2Cl2, DMF catalyst, room temper-
ature) to produce 10-4/8 in 94% yield. Alkylation of methyl
gallate with 10-4/8 by using standard conditions (DMF/K2CO3,
60 °C, 10 h) produced 12-4/8 (88% yield) (i.e., 12F8-ABG-
CH3) which upon hydrolysis with KOH in EtOH (reflux, 2 h),
neutralization with 10% HCl in THF and recrystallization from
acetone produced 13-4/8 (12F8-ABG) in 88% yield. Esterifi-
cation of 12F8-ABG with 2 and respectively 3 [DCC/DPTS in
CH2Cl2/Freon 113 (1:1)] produced 12F8-ABG-15C5 (80%
yield) and respectively 12F8-ABG-B15C5 (81% yield). 12F8-
ABG-15C5 was purified by flash column chromatography
(SiO2, CHCl3/MeOH gradient), and 12F8-ABG-B15C5 was
recrystallized from acetone to give products of more than 99%
purities (HPLC, TLC).
Thermal Characterization. The self-assembling process of
these semifluorinated building blocks was investigated by a
combination of techniques consisting of differential scanning
calorimetry (DSC), thermal optical polarized microscopy, and
X-ray diffraction experiments. When the building blocks self-
assemble in the melt phase, they generate a columnar structure
which produces the Φh LC phase which can be recognized and
characterized by this combination of techniques. Figure 1 of
Supporting Information shows selected heating and cooling DSC
traces of various building blocks which self-assemble into
supramolecular columns. The transition temperatures and the
corresponding enthalpy changes of all compounds are sum-
marized in Table 1. As we can observe from Figure 1a of
Supporting Information, 12F8-AG-15C5 exhibits a crystalline
(29) For general reviews on main chain and side chain LC polymers
which show different trends of phase transition temperatures-molecular
weight dependence, see: (a) Percec, V.; Pugh, C. In Side Chain Liquid
Crystalline Polymers; McArdle, C. B., Ed.; Chapman and Hall: New York,
1989; p 30. (b) Percec, V.; Tomazos, D. In ComprehensiVe Polymer Science,
First. Suppl.; Allen, G., Ed.; Pergamon: Oxford, 1992; p 209. (c) Percec,
V.; Tomazos, D. AdV. Mater. 1992, 4, 548. (d) Percec, V. In Handbook of
Liquid Crystal Research; Collings, P. J., Patel, J. S., Eds.; Oxford University
Press: Oxford, in press.
(30) For thermodynamic schemes which explain the dependence of liquid
crystalline and crystalline transitions on molecular weight, see: (a) Percec,
V.; Keller, A. Macromolecules 1990, 23, 4347. (b) Keller, A.; Ungar, G.;
Percec, V. In AdVances in Liquid Crystalline Polymers; Weiss, R. A., Ober,
C. K., Eds.; ACS Symposium Series 435; American Chemical Society:
Washington, DC, 1990; p 308.
(31) For the dependence of thermodynamic parameters of phase transi-
tions on molecular weight in liquid crystal polymers, see: (side chain) (a)
Percec, V.; Tomazos, D.; Pugh, C. Macromolecules 1989, 22, 3259. (main
chain) (b) Percec, V.; Nava, H.; Jonsson, H. J. Polym. Sci., Polym. Chem.
Ed. 1987, 25, 1943. (c) Percec, V.; Kawasumi, M. Macromolecules 1993,
26, 3663.

9860 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
Table 1. Thermal Characterization of Semifluorinated Building
Blocks and Selected Intermediary Compounds
phase transitions (°C) and corresponding
enthalpy changes (kcal/mol)a
compd
heating
k 32 (24.5) i
k 7 (12.8) -k 16 (5.66)
k 32 (6.81) i
cooling
12-AG-15C516e
i -8 (13.3) k
12F4-AG-15C5
12F6-AG-15C5
12F8-AG-15C5
k -35 (0.90) i
i -41 (1.45) k
i -14 (2.32) k
k -35 (1.36) i
k -5 (2.35) i
k -5 (2.66) i
k 46 (13.0) k 67 (1.83) i
i 25 (0.29) Φh
12 (4.46) k
k 21 (4.58) Φh 31 (0.30) i
12-AG-B15C519e
12F8-AG-B15C5
k 30 (0.90) k 88 (21.2) i
i 55 (19.8)
k 15 (2.08) k
k 85 (20.1) i
k 37 (1.75) -k 49 (0.85)
k 68 (5.26) Φh 78 (0.31) i
g 14 Φh 78 (0.26) i
k 67 (13.8) ib
i 74 (0.25) Φh 0 g
16b
12-ABG-CH3
i 37 (15.7) k
12F8-ABG-CH3
k 104 (11.4) Φh 144 (3.37) i i 140 (3.02) Φh 81 k
Figure 2. The dependence of the transition temperatures of the
complexes of 12Fn-AG-15C5 with 1.0 equiv NaOTf on the number
of fluorinated methylenes in the alkyl tails (n). Data from the cooling
scan: 9 Ti-Φ ; 2 TΦ -k; b Tg. Data from the second heating scan: )
k 104 (10.1) Φh 144 (3.01) i
12-ABG16c
k 71 (6.92) Φh 143 (3.1) ic
i 137 (3.0)
Φh 51 (6.9) k
12F8-ABG
k 87 (6.56) Φh 203d
k 60 (18.3) i
h
h
12-ABG-15C516e
i 12 (15.4) k
T
k-k; O Tg; 4 Tk-Φ ; 0 TΦ -i.
h h
k 45 (16.0) i
12F8-ABG-15C5
k 56 (6.19) Φh 135 (0.82) i
i 132 (0.83)
pization simultaneous with decomposition at 203 °C. The Φh
phase of 12-ABG is stable only up to 143 °C.16c,32 We should
mention that 12-ABG and 12F8-ABG form columnar structures
by the dimerization of their carboxylic acid Via H-bonding.
Therefore, a direct comparison of these two Φh phases permits
the determination of the contribution of the fluorophobic effect
to the stabilization of this column which is of about 60 °C.
Simultaneously, if we compare the stability of the Φh phase of
12F8-ABG (Ti ) 203 °C) with that of 12F8-ABG-CH3 (Ti )
144 °C) we find out that the contribution of two H-bonds to
the stabilization of this column is 59 °C, i.e., almost identical
to that of the fluorophobic effect. Extremely interesting is that
12F8-ABG-15C5 shows a Φh phase up to 135 °C, while 12F8-
ABG-B15C5 is only crystalline on heating and exhibits a cubic
phase on cooling. This trend is the reverse of that observed
for the homologous 12F8-AG compounds. The formation of a
cubic phase is associated with a change in the shape of the
building block from tapered to conic, and this will be discussed
in a different publication.
Characterization by Optical Polarized Microscopy. On
the optical polarized microscope, the Φh phase generated from
supramolecular columns displays identical textures as the similar
columnar LC phases obtained from discotic liquid crystals.28b,33
Figure 2a (Supporting Information) presents the texture exhibited
by the Φh phase of 12F8-AG-15C5. The sample was sand-
wiched between untreated glass slides and cooled at 0.1
°C‚min-1 from the isotropic melt. The texture is characterized
by several large fans surrounded by large homeotropic domains.
However on shearing, the texture becomes highly birefringent.
In the homeotropic alignment, the supramolecular columns are
oriented with their cylindrical axes perpendicular to the substrate.
Such a facile alignment in the absence of an externally applied
magnetic or electric field is remarkable. A similar texture is
observed for the Φh phase of 12F8-ABG-CH3 (Figure 2b,
Φh 30 (4.27) k
k 36 (1.06) k 69 (3.08) Φh
135 (0.86) i
12-ABG-B15C516b k 96 (19.3) i
i 34 (12.5) k
k 50 -k 66-80 (3.47)
k 94 (15.9) i
12F8-ABG-B15C5 k 63 (2.12) -k 85 (7.36)
k 125 (15.2) i
i 112 (0.32)
Cu 108 (0.05) 20 g
g 27 -k 76 (12.1)
k 125 (15.0) i
a Data on the first line under cooling and heating are from the first
scans. Data on the second line under heating are determined during
the second heating scan. b Obtained during the second heating scan,
lit.32 mp, 65.5 °C. c Obtained during the second heating scan. d Sample
decomposed during the first heating scan.
phase which melts and recrystallizes into a second crystalline
phase, followed by isotropization at 67 °C. On subsequent
cooling and heating scans this compound exhibits a narrow Φh
phase (from 21 °C to 31 °C on heating and from 25 °C to 12
°C on cooling). The replacement of 15C5 with B15C5 yields
compound 12F8-AG-B15C5 which exhibits a melting into a
Φh phase followed by isotropization in the first heating scan.
The following cooling and heating scans show a very broad
enantiotropic Φh phase from 74 °C to Tg ) 0 °C on cooling
and from Tg ) 14 °C to Ti ) 78 °C on heating. These two
results are extremely rewarding considering that 12-AG-15C5,16e
12-AG-B15C5,19e 12F4-AG-15C5, and 12F6-AG-15C5 are
only crystalline compounds (Table 1). The thermodynamic
control of this self-assembling process can be assessed by
observing the extremely low degree of supercooling (4 °C) and
the almost identical enthalpy change (0.26 kcal/mol on heating
Vs 0.25 kcal/mol on cooling) associated with the isotropization
temperature of the Φh phase (Table 1) of 12F8-AG-B15C5.
The transition from building blocks based on 12F8-AG to
building blocks based on 12F8-ABG demonstrates an expected
increase in the stability of the Φh phase obtained by the self-
assembly Via the fluorophobic effect. 12F8-ABG-CH3 (Figure
1a, Supporting Information) exhibits an enantiotropic Φh phase
which is stable over a broad range of temperature (Table 1),
while the corresponding 12-ABG-CH3 is crystalline (mp ) 67
°C). Very instructive is to compare the stability of the Φh phase
generated from 12F8-ABG Versus that of 12-ABG. On the first
DSC scan, 12F8-ABG shows a melting at 87 °C into a Φh phase
(Figure 1b, Supporting Information) which undergoes isotro-
(32) Maltheˆte, J.; Collet, A.; Levelut, A.-M. Liq. Cryst. 1989, 5, 123.
(33) For specific textures exhibited by columnar mesophases of discotic
liquid crystals, see: (a) Percec, V.; Cho, C. G.; Pugh, C. J. Mater. Chem.
1991, 1, 217. (b) Percec, V.; Cho, C. G.; Pugh, C.; Tomazos, D.
Macromolecules 1992, 25, 1164. (c) Serrette, A.; Lai, C. K.; Swager, T.
M. Chem. Mater. 1994, 6, 2252. (d) Chandrasekhar, S.; Rangarath, G. S.
Rep. Prog. Phys. 1990, 53, 57. (e) Destrade, C.; Foucher, P.; Gasparoux,
H.; Tinh, N. H.; Levelut, A. M.; Maltheˆte, J. Mol. Cryst. Liq. Cryst. 1984,
106, 121.

Self-Assembly of Semifluorinated Monodendrons
J. Am. Chem. Soc., Vol. 118, No. 41, 1996 9861
Table 2. Thermal Characterization of the 1:1 Complexes of
12Fn-A(B)G-(B)15C5 with NaOTf
phase transitions (°C) and corresponding
enthalpy changes (kcal/mol)a
compd
heating
cooling
12-AG-15C5‚1.016e
k 33 (0.32) k 69 (18.7) i
i 27 (0.06)
Φh 5 (7.51) k
k 29 (7.79) -k 39 (12.6)
k 62 (13.0) i
12F4-AG-15C5‚1.0
12F6-AG-15C5‚1.0
g -22 Φh 50 (0.06) i
i 43 (0.02) Φh -30 g
g -22 Φh 49 (0.04) i
k 11 (0.89) Φh 77 (0.06) i i 70 (0.06)
Φh 1 (1.01) k
k 10 (1.15) Φh 77 (0.06) i
k 46 (4.69) Φh 110 (0.23) i i 105 (0.11)
12F8-AG-15C5‚1.0
Φh 24 (1.84) k
k 31 (1.25) Φh 110 (0.11) i
12-AG-B15C5‚1.019e k 45 (-) Φh 62 (12.1)b i
g 13 Φh 66 (0.05) i
i 54 (0.04) Φh -4 g
12-ABG-15C5‚1.016e k 46 (14.3) Φh 94 (0.39) i i 84 (0.18) Φh 10 g
g 19 Φh 94 (0.17) i
12-ABG-B15C5‚1.016b g 38 Φh 107 (0.51) i
g 41 Φh 106 (0.24) i
i 98 (0.24) Φh 31 g
Figure 3. Comparison of the column diameter of the supramolecular
columns (at the temperature indicated) obtained by the self-assembly
of selected fluorinated and non-fluorinated compounds.
a Data on the first line under cooling and heating are from the first
scans. Data on the second line under heating are determined during
the second heating scan. b Sum of overlapped transition enthalpies.
Supporting Information) and of other semifluorinated supramo-
lecular columns. The Φh phase of 12F8-ABG-15C5 is homeo-
tropically aligned over its entire temperature range. On shearing,
faint birefringence is observed.
weight until they reach a plateau. However, since the slope of
the Ti-Mn is higher than that of Tk-Mn,30,31 the thermal stability
of the LC phase broadens Via polymerization. In the case of
LC polymers this trend is known as the “polymer effect”.29,30
By analogy with this nomenclature, we suggest the name
“supramolecular polymer effect” for the case of the self-
assembly of polymer-like structures Via a supramolecular
polymer backbone.
Mechanism of Fluorophobic-Mediated Self-Assembly with
the Aid of Ion-Mediated Self-Assembly. The comparative
investigation of self-assembly via ion-mediated, fluorophobic-
mediated and by a combination of both allows the elucidation
of the mechanism of self-assembly solely via fluorophobic
effect. Ion-mediated self-assembly experiments were carried
out for the series 12Fn-AG-15C5/NaOTf. An example of DSC
traces and a complete phase diagram are provided for the system
12F8-AG-15C5/NaOTf in Figures 3 (Supporting Information)
and 1a. An increase of the stability of the Φh phase is observed
upon complexation with a very small amount of NaOTf. For
example 0.2 mol of NaOTf per 12F8-AG-15C5 increases the
stability of the Φh phase with 45 °C (Figure 3, Supporting
Information). A continuous increase of the stability of this phase
is observed with the increase in NaOTf until the limit of the
complexation ability of 12F8-AG-15C5 is reached. Above this
value, a plateau of the temperature transition is observed.
Simultaneous with this trend, the melting temperature is
increasing much less, and the rate of crystallization decreases.
A plot of the experimental data collected from Figure 3
(Supporting Information) is presented in Figure 1a. This plot
can be inspected in two different ways. First it can be
considered as a solid state titration experiment. The plateau of
T Vs 12F8-AG-15C5/NaOTf (mol/mol) ratio provides the
maximum amount of complexed NaOTf, which unexpectedly
is larger than 1.0 mol of NaOTf per 15C5. We should
remember that the crown ether groups are packed side-by-side
in the center of the column, and in the Φh phase they are melted.
This means that the NaOTf is complexed both in the cavity of
the crown ether with a very small amount being placed in
between the melted crown ethers. The second way we should
inspect this phase diagram is as a first order temperature
transition dependence on molecular weight of a polymer. An
increased amount of NaOTf complexed by the crown ether
creates a “supramolecular” polymer with a higher molecular
weight. Therefore, the ratio 12F8-AG-15C5/NaOTf from
Figure 1a can be envisioned as molecular weight or degree of
polymerization. An inspection of Figure 1a from this point of
view demonstrates a textbook like dependence of the isotro-
pization and melting transition temperatures as a function of
molecular weight.29-31 Both the isotropization and the melting
temperature should increase with the increase of molecular
Figure 1b plots the dependence of the isotropic-Φh temper-
ature transition on 12Fn-AG-15C5/NaOTf (mol/mol) ratio for
n ) 0, 4, 6, and 8. The DSC figures, plots, and tables with
complete experimental data are available as supporting informa-
tion. A similar trend is observed for the entire set of semiflu-
orinated tapered groups. The increase in the extent of fluori-
nation shifts this dependence to higher temperatures. The entire
set of transition temperatures (i.e., Φh-isotropic (i); i-Φh, melting,
crystallization, and Tg) of 12Fn-AG-15C5/NaOTf ) 1/1
collected from these diagrams is summarized in Table 2 and
plotted in Figure 2 as a function of n. This “phase diagram”
shows a eutectic composition for melting and crystallization and
a continuous dependence of the Φh-i temperature on n. These
two dissimilar trends explain the fluorophobic effect in this self-
assembly process. From n ) 0-4, there is a small increase in
the stability of the Φh and a dramatic destabilization of the
crystalline phase. As a consequence, even such a very small
amount of semifluorination increases dramatically the ability
of these building blocks toward self-assembly. From n ) 4 to
8 both Φh-i and melting transition temperatures increase with a
slightly higher slope for the former. As a consequence, at n )
8 the melting temperature does not recover up to the parent
value of n ) 0, while the Φh-i transition temperature increases
with another 60 °C. At this point, ion mediated self-assembly
can be replaced completely by the fluorophobic effect.
The bar graph in Figure 10 (Supporting Information) provides
a direct comparison of the thermal stability of the various phases
displayed by the most representative building blocks and of
some of their 1:1 complexes with NaOTf as reported in Tables
1 and 2. The following remarkable conclusion is obtained from
these data. 12F8-AG-15C5 shows a broader temperature range
for its Φh phase than 12-AG-15C5‚1.0. The suffix 1.0 refers
to the amount of NaOTf in the corresponding complex.
However, the thermal stability of the Φh phase of the latter is
lower than of its semifluorinated partner. In both 12-AG-

9862 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
Table 3. Characterization of 12Fn-AG-15C5, 12Fn-AG-B15C5, 12Fn-ABG, 12F8-ABG-CH3, 12Fn-ABG-15C5, and 12Fn-ABG-B15C5 by
Small-Angle X-ray Scattering
a
NaOTf
(equiv)
T
(°C)
d100
(Å)
d110
(Å)
d200
(Å)
d210
(Å)
d300
(Å)
d100
(Å)
ab
(Å)
Rc
(Å)
Sd
(Å)
Fe
(g/cc)
entry
µ f
12-AG-15C5
1.6
1.0
1.0
1.0
1.0
1.0
0
1.0
1.0
0
0
0
0
1.6
0
59
29
42.1
41.8
42.1
20.6
21.0
41.7
41.9
42.1
43.1
43.6
42.9
39.7
46.1
44.9
39.6
45.2
48.1
48.4
48.6
49.8
50.3
49.5
45.8
53.2
51.8
45.7
52.2
42.9h
41.1
61.7
45.6
56.9
24.1
24.2
24.3
24.9
25.2
24.8
22.9
26.6
25.9
22.9
26.1
21.5
20.6
30.9
22.8
28.5
27.8
27.9
28.1
28.7
29.0
28.6
26.5
30.7
29.9
26.4
30.1
24.8
23.7
35.6
26.3
32.9
1.12
1.25
4.36
3.70
12F4-AG-15C5
12F4-AG-15C5
12F4-AG-15C5
12F6-AG-15C5
12F6-AG-15C5
12F8-AG-15C5
12F8-AG-15C5
12F8-AG-15C5
12F8-AG-B15C5
12F8-ABG-CH3
12-ABG
24.1
24.5
15.9
15.8
39
59g
28
43.0
42.7
39.5
46.1
44.7
39.7
45.0
25.3
24.7
21.9
21.6
23.0
23.0
22.5
19.8
22.5
16.6
1.41
3.96
59
30
59
80
70
120
1.55
1.54
1.54
1.63
1.63
3.54
4.32
4.10
3.61
4.40
14.9
17.2
14.9
13.2
12F8-ABG
122
70
100
66
35.7
52.9
40.3
49.0
20.5
31.8
18.0
26.2
19.7
25.1
13.3
14.7
35.6
53.5
39.5
49.3
cubic
1.63
1.15
1.62
1.09
1.57
2.85
5.71
3.11
5.09
12-ABG-15C5
12F8-ABG-15C5
12-ABG-B15C5
12F8-ABG-B15C5
0.6
0
28.1
110
a
d100 ) (d100 + x3‚d110 + x4‚d200 + x7‚d210 + x9‚d300)/5. b a ) 2 d100 /x3. c R ) d100 /x3. d S ) 2R/x3. e Densities were measured at 20
°C. f Values of µ are based on a layer thickness, t, of 3.74 Å. g Extrapolated value. h From ref 32.
B15C5‚1.0/12F8-AG-B15C5 and 12-ABG-15C5‚1.0/12F8-
ABG-15C5 pairs the range of the stability of the Φh phase and
its isotropization temperature are higher for the fluorinated
compound.
local energy minima corresponding to two gauche and one trans
conformer of decafluorobutane exist in a ratio of trans/gauche
conformers of 95/5 due to the increased van der Waals radius
of the fluorine atom.21b Therefore, fluorination increases both
the linearity and the rigidity of the perfluoroalkane segments.
This may be the major contributing factor to the increase in the
column diameter with increasing n.
Characterization by X-ray Diffraction Demonstrates the
Control of Column Diameter Wia Ion-Complexation and
Flourination. Table 3 summarizes the results of small angle
X-ray diffraction experiments on the series of semifluorinated
building blocks. Analysis was carried out on unoriented samples
in glass capillaries mounted in a temperature controlled cell.
The effect of ion complexation on the column diameter is
exemplified by comparing 12F8-AG-15C5 and 12F8-AG-
15C5‚1.0 (Figure 3). Complexation of 12F8-AG-15C5 with
1.0 mol NaOTf results in an increase in the column diameter
from 45.8 to 51.8 Å. An even more striking example is provided
by the comparison of 12-ABG-15C5‚1.6 (1.6 mol NaOTf/15C5)
with 12F8-ABG-15C5. The former has a column diameter of
61.7 Å Versus 45.6 Å for 12F8-ABG-15C5. Therefore, the
resulting complex must accommodate both the cation and the
bulky triflate counteranion within the columnar structure result-
ing in this expansion of the column diameter. Similar results
have been obtained from ABG-based complexes of nonfluori-
nated tapered building blocks containing an oligooxyethylenic
ligand with LiOTf.16c The noncomplexed ABG-based tapered
groups are self-assembled Via H-bonding. The largest diameters
are observed, as expected, for the complexes of 12-ABG-B15C5
and 12-ABG-15C5 which contain the combination of metal
complexes in the column center and benzyl ether moieties in
the alkyl tails.
Short exposures were obtained after slow cooling (<1 °C min-1
)
from the isotropic melt to the temperature of interest within
the Φh phase. Most of the compounds displayed at least three
or more reflections characteristic of the Φh LC phase with Bragg
spacings in the ratio of d100:d110:d200:d210:d300 ) 1:(1/x3):(1/
x4): (1/x7):(1/x9).16b The intensities were of the order of
d100 > d110 > d210 for the nonfluorinated compounds and d100
> d210 > d110 for the semifluorinated compounds. This
inversion is due to the higher electron density present in the
semifluorinated alkyl tails.25,26 The hexagonal lattice parameter
(a ) 2 d100 /x3) is equal to the diameter of the self-assembled
column which is responsible for the generation of the Φh phase
as shown in Scheme 1. Values for the radius (R ) a/2) and
the hexagonal side length (S ) 2R/x3) are also reported in Table
3.
The bar graph in Figure 3 provides a comparison of the
diameter of the supramolecular columns formed from various
nonfluorinated and semifluorinated building blocks. Strict
comparisons of column diameters of supramolecular columns
formed from various tapered building blocks are difficult to
obtain due to the nonlinear contraction of the columnar lattice
parameter with increasing temperature.18 For the series, 12Fn-
AG-15C5‚1.0, the diameter of the columns was found to
increase with increasing the value of n. These values range
from 48.1 Å for n ) 0 (12-AG-15C5‚1.6) to 53.2 Å for n ) 8
(12F8-AG-15C5‚1.0). One factor that can account for the
overall increase is the larger -CF2CF2- bond length (1.58 Å)
compared to -CH2CH2- (1.54 Å). A similar analysis for
compounds where oligooxyethylenic units were used in place
of the crown ether moieties showed that based on molecular
models, the marginal increase (+0.7 Å) in the alkyl tail length
could not accommodate the large increase in the column
diameter with increasing n.26 Therefore, we consider that other
factors such as the increased rigidity and volume of the
perfluoroalkane segments may contribute as well. The three
To better understand the packing arrangement of the tapered
building blocks within the supramolecular column, density
measurements were obtained and the number, µ, of tapered
groups per column layer was calculated from µ ) 3x3FNAS2t/
2M,16b where F is the density (g/Å3), NA is Avogadro’s number
(6.022045 × 1023 mol-1), S is the distance from the column
center to the hexagonal vertex (Å), t is the layer thickness (Å),
and M is the molar mass of the tapered building block.
Experimentally determined values for F and S are reported in
Table 3. Since all of our X-ray experiments have been
conducted on unoriented samples in the Φh phase, we do not
have any information about the repeat unit along the column.
Therefore, the layer thickness, t, is taken as the average distance
between adjacent benzene rings in the direction of the column
axis (3.74 Å) as reported in the literature.34 We have used this
value consistently in reporting molecular arrangements within
the layers of analogous supramolecular columns and retain it
(34) Safinya, C. R.; Liang, K. S.; Varady, W. A.; Clark, N. A.; Anderson,
G. Phys. ReV. Lett. 1984, 53, 1172.

Self-Assembly of Semifluorinated Monodendrons
J. Am. Chem. Soc., Vol. 118, No. 41, 1996 9863
here for purposes of comparison. The calculated values for µ
are reported in Table 3. Based on these values, the number of
tapered building blocks per column stratum ranges from 3 to 6.
Arrangements of the alkali metal complexes of the nonfluori-
nated entries, 12-AG-15C5, 12-ABG-15C5, and 12-ABG-
B15C5 have been dicussed in detail,16b,e and their values of µ
range from 4.4 to 5.7. Semifluorinated tapered building blocks
self-assemble into columnar structures containing 3.1 to 4.4
structural units per stratum according to the data in Table 3.
Notable exceptions are 12-ABG and 12F8-ABG. The former,
as previously mentioned, exists as a H-bonded dimer in the
column layer. It is therefore expected that 12F8-ABG should
have a similar packing arrangement. However, the calculated
value of µ for 12F8-ABG is 3.1. In order to obtain a model
based on the H-bonded dimer, a layer thickness, t, of 5.82 Å
would have to be assumed. The cross-sectional area occupied
by hexagonally packed perfluoroalkanes (28.3 Å2) has been
reported in the literature.35 Based on this value, a layer
thickness, t, which is determined by the thickness of the
perfluorinated segments of the alkyl tails can be calculated as
6.02 Å which is in good agreement with the dimer model.
Therefore, the values of µ calculated for the semifluorinated
tapered building blocks of Table 3 are most probably underes-
timated by ∼35%. If the range of values is adjusted for the
semifluorinated tapered building blocks, we find that 4.2 to 5.9
molecules pack within the column layer. This is in good
agreement with the values reported for the complexes of 12-
AG-15C5, 12-ABG-15C5, and 12-ABG-B15C5 with NaOTf
in Table 3.
Molecular Model of the Supramolecular Column. Mo-
lecular models of the self-assembled supramolecular columns
can be constructed based on the data discussed in the preceding
sections. Figure 4a shows a space-filled molecular model of
the top view of the self-assembled supramolecular column of
the complex of 12F8-AG-15C5 with NaOTf. Five molecules
of 12F8-AG-15C5 are arranged within a column stratum with
the crown ethers arranged side-by-side in the center and the
melted alkyl tails radiating toward the periphery of the column.
The taper shaped structural units are situated in a close packed
arrangement with disordered alkyl tails representative of the melt
phase. Sodium cations are colored blue and are complexed
within the cavity of the crown ether. Triflate counteranions
are sandwiched between the layers and have been arbitrarily
positioned in close proximity to the complexed metal atoms.
The interlayer distance is 6 Å, and the column diameter is 50
Å. This view shows the microphase segregation of the
perfluorinated and perhydrogenated/aromatic portions of the
semifluorinated tapered building blocks in the Φh phase. A
cross-section of the side-view for the same structure is shown
in Figure 4b. The complexed metal cations are readily visible
in the column center arrayed along the column axis. Since the
column is packed in a liquid crystalline phase and three-
dimensional order in this phase is absent both within the column
and in between columns, we purposely show it in Figure 4 with
some structural irregularities.
Figure 4. Space filled molecular model of the self-assembled
supramolecular columnar structure of the complex of 12F8-AG-15C5
with NaOTf. (a) Top view and (b) cross-section of side view: F, yellow;
O, red; S, yellow; H, white; C, gray.
the immediate application of this concept to self-assembly and/
or stabilization of other related supramolecular systems.36-39
These supramolecular semifluorinated columns assemble into
a Φh liquid crystalline phase which aligns homeotropically, i.e.,
on untreated glass slides forms single crystal liquid crystals with
the columns oriented with their long axes perpendicular to the
glass surface. This is an extremely important result with
implications in many technological applications such as, for
example, in the design of one-dimensional membranes,40
ionic16bh,41,42 and electronic43 conductors, photoconductors,44 etc.
In conclusion, the results summarized in this paper have
demonstrated the self-assembly of tapered monodendrons
containing crown ethers into cylindrical or rod-like supramo-
lecular dendrimers solely Via the fluorophobic effect. Previ-
ously, similar cylindrical dendrimers were assembled Via ion-
mediated and H-bonding processes and by a combination of
both or Via the attachment of these building blocks to a suitable
polymer backbone. This demonstration enlarges the already rich
arsenal of molecular recognition processes used in self-assembly
with the new and very powerful fluorophobic effect. We foresee
(36) (a) van Nunen, J. L. M.; Stevens, R. S. A.; Picken, S. J.; Nolte, R.
J. M. J. Am. Chem. Soc. 1994, 116, 8826. (b) van Nunen, J. L. M.;
Schenning, A. P. H. J.; Hafkamp, R. J. H.; van Nostrum, C. F.; Feiters, M.
C.; Nolte, R. J. M. Macromol. Symp. 1995, 98, 483.
(37) (a) Fu, D. K.; Xu, B.; Swager, T. M. J. Org. Chem. 1996, 61, 802.
(b) Xu, B.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 5011. (c) Zheng,
H.; Swager, T. M. J. Am. Chem. Soc. 1994, 116, 761. (d) Serrette, A.-G.;
Swager, T. M. Angew. Chem., Int. Ed. Engl. 1994, 33, 2342. (e) Serrette,
A. G.; Swager, T. M. J. Am. Chem. Soc. 1993, 115, 8879. (f) Lai, C. K.;
Serrette, A. G.; Swager, T. M. J. Am. Chem. Soc. 1992, 114, 7948.
(38) van Velzen, E. U. T.; Engbersen, J. F. J.; Reinhoudt, D. N. J. Am.
Chem. Soc. 1994, 116, 3597.
(35) (a) Ho¨pken, J.; Mo¨ller, M. Macromolecules 1992, 25, 2482. (b)
Dorset, D. L. Chem. Phys. Lipids 1977, 20, 13.
(39) Kato, T.; Fre´chet, J. M. J. Macromol. Symp. 1995, 98, 311.

9864 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
otherwise noted. First order transition temperatures were reported as
the maxima and minima of their endothermic and exothermic peaks.
Glass transition temperatures (Tg) were read at the middle of the change
in heat capacity. Zn and In were used as calibration standards. An
Olympus BX-40 optical polarized microscope (100× magnification)
equipped with a Mettler FP 82 hot stage and a Mettler FP 80 central
processor was used to verify thermal transitions and characterize
anisotropic textures.
X-ray diffraction experiments on liquid crystal phases were per-
formed using an Image Plate area detector (MAR Research) with a
graphite-monochromatized pinhole-collimated beam and a helium tent.
The samples, in glass capillaries, were held at constant temperature
((0.1 °C) in a temperature-controlled cell.
The formation of single crystal liquid crystals from Φh meso-
phases is a very difficult process which so far was manipulated
most efficiently by using a very high magnetic field45a or
LC elastomers obtained from mesogens forming columnar
mesophases.45b The LC phase of fluorinated systems show
sharper phase transitions and lower viscosity.
Preliminary experiments have demonstrated that the crown
ethers of these semifluorinated tapered groups can be replaced
with a large number of other functionalities which become part
of the core of these supramolecular columns (i.e., donors,
acceptors, donor-acceptor complexes, nonlinear optical com-
pounds, etc.). Last but not least, this self-assembly Via
fluorophobic effect, which is an amplified version of the
hydrophobic effect, suggests that the hydrophobic effect alone
should be able to generate a similar organizing force which is
based on repulsive rather than attractive forces at the site of
organization. The absence of strong attractive forces provides
nonrigid self-assembled structures which are known to be
uniquely suited for the first critical steps in the organization of
living matter whose deformability is not only a virtue but very
likely a necessity.8b Since the liquid crystalline state is a
preorganized state of the crystalline phase,46 this soft order47
which is not generated Via directed polar bonds should be as
important in the assembly of synthetic systems as in the
biological ones.
Macromodel 5.0 from Columbia Innovation Corp. was used on a
Silicon Graphics Indy workstation to model the self-assembled su-
pramolecular columnar structures.
Synthesis. The syntheses of 4-dimethylaminopyridinium p-tolu-
enesulfonate (DPTS),16b 3,4,5-tris(n-dodecan-1-yloxy)benzoic acid (1-
12/0),16b 3,4,5-tris(n-9,9,10,10,11,11,12,12,12-nonafluorododecan-1-
yloxy)benzoic acid (1-8/4),26 3,4,5-tris(n-7,7,8,8,9,9,10,10,11,11,12,12,12-
tridecafluorododecan-1-yloxy)benzoic acid (1-6/6),26 3,4,5-tris(n-
5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan-1-
yloxy)benzoic acid (1-4/8),26 1-hydroxymethyl 15-crown-5 (2),16e 4′-
hydroxymethylbenzo-15-crown-5 (3),16b methyl 15-crown-5 3,4,5-tris(n-
dodecan-1-yloxy)benzoate (4-12/0, 12-AG-15C5),16e 4′-methylbenzo-
15-crown-5 3,4,5-tris(n-dodecan-1-yloxy)benzoate (5-12/0, 12-AG-
B15C5),19e n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluoro-
dodecyl bromide (6-4/8),26 methyl 3,4,5 tris[p-(n-dodecan-1-yloxy)-
benzyloxy]benzoate (12-ABG-CH3),16b 3,4,5 tris[p-(n-dodecan-1-yloxy-
)benzyloxy]benzoic acid (13-12/0, 12-ABG),16c methyl 15-crown-5
3,4,5-tris[p-(n-dodecan-1-yloxy)benzyloxy]benzoate (14-12/0, 12-ABG-
15C5),16e 4′-methylbenzo-15-crown-5 3,4,5 tris[p-(n-dodecan-1-yloxy)-
benzyloxy]benzoate (15-12/0, 12-ABG-B15C5),16b and NaOTf16b have
been reported previously.
Methyl 15-Crown-5 3,4,5-Tris(n-9,9,10,10,11,11,12,12,12-non-
afluorododecan-1-yloxy)benzoate (4-8/4, 12F8-AG-15C5). Com-
pound 4-8/4 was synthesized by the esterification of 1-8/4 and
1-hydroxymethyl-15-crown-5 (2) with DCC and catalyzed by DPTS.
Compound 1-8/4 (1.20 g, 1.03 mmol), 2 (0.309 g, 1.24 mmol), and
DPTS (64 mg, 20 mol %) were dissolved in 10 mL of CH2Cl2. DCC
(0.283 g, 1.37 mmol) was added, and the mixture was heated to reflux.
After 12 h, CH2Cl2 was evaporated on a rotary evaporator. The product
was dissolved in hexanes and separated from the insoluble reaction
byproducts by filtration. After purification by flash column chroma-
tography [SiO2; CH2Cl2-CH2Cl2:MeOH (20:1) gradient], 1.10 g
(76.7%) of a clear oil was obtained. Purity (HPLC), 99%; TLC (9:1
CHCl3:MeOH), Rf ) 0.2. Thermal transitions and corresponding
enthalpy changes are summarized in Table 1. 1H NMR (CDCl3, TMS,
δ, ppm): 1.37-1.48 (overlapped peaks, 30H, CF2CH2(CH2)5), 1.78 (m,
6H, CH2CH2OAr), 2.05 (m, 6H, CF2CH2), 3.68-3.76 (overlapped
peaks, 19H, CO2CH2C(H)CH2(OCH2CH2)4), 4.01 (overlapped t, 6H,
CH2OAr, J ) 6.2 Hz), 4.41 (m, 2H, CO2CH2), 7.26 (s, 2H, ortho to
CO2); 19F NMR (CDCl3, δ, ppm): -81.7 (m, 9F, CF3), -115.3 (m,
6F, CF2CH2), -125.1 (m, 6F, CF2CF2CH2), -126.7 (m, 6F, CF3CF2);
13C NMR (CDCl3, δ, ppm): 20.0 (CF2CH2CH2), 25.9 (CH2CH2CH2-
OAr), 29.0-29.2 (CF2CH2CH2CH2(CH2)2), 30.2 (CH2CH2OAr), 30.7
(CF2CH2CH2CH2), 31.1 (t, CF2CH2, J ) 22.5 Hz), 64.9 (CO2CH2),
69.0 (CH2OAr, 3,5-position), 70.4, 70.5, 70.7, 70.9, 71.1 (C(H)CH2-
(OCH2CH2)3OCH2, CH2C(H)OCH2), 73.3 (CH2OAr, 4-position), 77.7
(CH2C(H)CH2), 108.1 (ortho to CO2), 124.8 (ipso to CO2), 142.2
(para to CO2), 152.7 (meta to CO2), 166.1 (ArCO2). Anal. Calcd for
C54H71F27O10: C, 46.56; H, 5.14. Found: C, 46.71; H, 5.27.
Experimental Section
Materials. DCC (99%), DMAP (99%), methyl p-hydroxybenzoate
(7) (99%), LiAlH4 (95+%), SOCl2 (99+%), and methyl 3,4,5-
trihydroxybenzoate (11) (98%) (all from Aldrich) were used as received.
p-TsOH and 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113) (all from
Fisher Scientific) were used as received. THF (A.C.S. reagent, Fisher
Scientific) was refluxed over sodium ketyl and distilled freshly before
use. CH2Cl2 (Fisher) was dried by refluxing over CaH2 and freshly
distilled before use. DMF (Fisher, A.C.S. reagent) was used as
received.
General Methods. 1H NMR (200 MHz), 19F NMR (188 MHz),
and 13C NMR (50 MHz) spectra were recorded on a Varian Gemini
200 spectrometer. The purity of products was determined by a
combination of TLC (single spot) on silica gel plates (Kodak) with
fluorescent indicator and HPLC using a Perkin-Elmer Series 10 HPLC
equipped with an LC-100 column oven, Nelson Analytical 900 Series
integrator data station, and two Perkin-Elmer PL gel columns of 5 ×
102 and 1 × 104 Å after the structure was confirmed by NMR and
elemental analyses. Elemental analyses were carried out by Galbraith
Laboratories. THF was used as solvent at the oven temperature of 40
°C unless otherwise noted. Detection was by UV absorbance at 254
nm. In some instances, purity was determined by GC using a Hewlett
Packard 5890A gas chromatograph equipped with a Hewlett Packard
3392A integrator. A packed column consisting of 10% SP2100 on
80/100 Supelcoport stationary phase was used with a head pressure of
40-60 psi. The carrier gas was N2.
Thermal transitions were measured on a Perkin Elmer DSC-7. In
all cases, the heating and cooling rates were 10 °C min-1 unless
(40) Gankema, H.; Hempenius, M. A.; Mo¨ller, M.; Johansson, G.; Percec,
V. Macromol. Symp., in press.
(41) (a) Simon, J.; Sirlin, C. Pure Appl. Chem. 1989, 61, 1625. (b)
Toupance, T.; Ahsen, V.; Simon, J. J. Chem. Soc., Chem. Commun. 1994,
75.
(42) Sielcken, O. E.; van de Kuil, L. A.; Drenth, W.; Schoonman, J.;
Nolte, R. J. M. J. Am. Chem. Soc. 1990, 112, 3086.
(43) (a) Boden, N.; Borner, R. C.; Bushby, R. J.; Clements, J. J. Am.
Chem. Soc. 1994, 116, 10807. (b) Boden, N.; Bushby, R. J.; Clements, J.
J. Chem. Phys. 1993, 98, 5920.
(44) Adam, D.; Schuhmacher, P.; Simmerer, J.; Ha¨nssling, L.; Siemens-
meyer, K.; Etzbach, K. H.; Ringsdorf, H.; Haarer, D. Nature 1994, 371,
141.
(45) (a) Spiess, H. W. Ber. Bunsenges. Phys. Chem. 1993, 97, 1294. (b)
Bengs, H.; Finkelmann, H.; Ku¨pfer, J.; Ringsdorf, H.; Schuhmacher, P.
Makromol. Chem., Rapid Commun. 1993, 14, 445.
(46) Keller, A. Macromol. Symp. 1995, 98, 1.
Methyl 15-Crown-5 3,4,5-Tris(n-7,7,8,8,9,9,10,10,11,11,12,12,12-
tridecafluorododecan-1-yloxy)benzoate (4-6/6, 12F6-AG-15C5). From
1-6/6 (1.0 g, 0.73 mmol), 2 (0.19 g, 0.77 mmol), DPTS (42 mg, 0.15
mmol), and DCC (0.20 g, 0.97 mmol) in 5 mL of CH2Cl2 was obtained
0.70 g (60%) of a clear oil after purification by flash column
chromatography (neutral Al2O3, 2:1 hexanes:ethyl acetate). Purity
(HPLC), 99+%; TLC (2:1 hexanes:ethyl acetate), Rf ) 0.1. Thermal
transitions and corresponding enthalpy changes are summarized in Table
1. 1H NMR (CDCl3, TMS, δ, ppm): 1.50 (m, 18H, CF2CH2(CH2)3),
1.84 (m, 6H, CH2CH2OAr), 2.07 (m, 6H, CF2CH2), 3.68-3.80
(overlapped peaks, 19H, CO2CH2C(H)CH2(OCH2CH2)4), 4.02 (t, 6H,
(47) de Gennes, P.-G. Angew. Chem., Int. Ed. Engl. 1992, 31, 842.

Self-Assembly of Semifluorinated Monodendrons
J. Am. Chem. Soc., Vol. 118, No. 41, 1996 9865
CH2OAr, J ) 6.2 Hz), 4.41 (m, 2H, CO2CH2), 7.26 (s, 2H, ortho to
CO2); 19F NMR (CDCl3, δ, ppm): -81.4 (m, 9F, CF3, J ) 9.6 Hz),
-115.1 (m, 6F, CF2CH2), -122.6 (m, 6F, CF2CF2CH2), -123.6 (s,
6F, CF3CF2CF2CF2), -124.2 (s, 6F, CF3CF2CF2), -126.8 (m, 6F,
CF3CF2); 13C NMR (CDCl3, δ, ppm): 20.0 (CF2CH2CH2), 25.8 (CH2-
CH2CH2OAr), 28.8 (CH2CH2OAr, 3,5-position), 28.9 (CH2CH2OAr,
4-position), 29.0 (CF2CH2CH2CH2, 3,5-position), 30.0 (CF2CH2-
CH2CH2, 4-position), 30.7 (t, CF2CH2, J ) 22.6 Hz), 64.9 (ArCO2CH2),
68.8 (CH2OAr, 3,5-position), 70.4, 70.5, 70.7, 70.9, 71.1, 71.2
(CH2C(H)CH2(OCH2CH2)3OCH2, CH2C(H)CH2), 73.1 (CH2OAr, 4-po-
sition), 77.7 (CH2C(H)CH2), 108.1 (ortho to CO2), 124.9 (ipso to CO2),
142.2 (para to CO2), 152.7 (meta to CO2), 166.1 (ArCO2). Anal. Calcd
for C54H59F39O10: C, 40.33; H, 3.70. Found: C, 40.44, H, 3.71.
at 0 °C yielded 12.0 g (81.9%) of white, sheet-like crystals. Purity,
(HPLC): 99+%; TLC (2:1 hexanes:ethyl acetate), Rf ) 0.7. The
following thermal transitions (°C) and their enthalpies of transition (kcal
mol-1) were observed by DSC (10 °C min-1): k 70 (7.83) sA 81 (1.44)
i, on the first heating scan; i 75 (1.48) sA 52 (5.71) k, on the cooling
1
scan; and k 69 (6.35) sA 81 (1.45) i, on the second heating scan; H
NMR (CDCl3, TMS, δ, ppm): 1.88 (m, 4H, CF2CH2(CH2)2), 2.17 (m,
2H, CF2CH2), 3.89 (s, 3H, CH3), 4.06 (t, 3H, CH2OAr, J ) 5.5 Hz),
6.89 (d, 2H, ortho to O, J ) 8.0 Hz), 7.97 (d, 2H, ortho to CO2, J )
8.0 Hz); 19F NMR (CDCl3, δ, ppm): -81.3 (t, 3F, CF3, J ) 10.0 Hz),
-115.0 (m, 2F, CF2CH2), -122.4 (m, 6F, (CF2)3CF2CH2), -123.3 (m,
2F, CF3CF2CF2CF2), -124.1 (m, 6F, CF3CF2CF2), -126.7 (m, 6F,
CF3CF2); 13C NMR (CDCl3, δ, ppm): 17.2 (CF2CH2CH2), 28.6 (CH2-
CH2OAr), 30.6 (t, CF2CH2, J ) 22.0 Hz), 51.8 (CH3), 67.3 (CH2OAr),
114.0 (ortho to O), 122.7 (ipso to CO2), 162.6 (ipso to O), 166.8 (CO2).
Anal. Calcd for C20H15F17O3: C, 38.36; H, 2.41. Found: C, 38.46;
H, 2.40.
Methyl 15-Crown-5 3,4,5-Tris(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,-
12,12,12-heptadecafluorododecan-1-yloxy)benzoate (4-4/8, 12F8-
AG-15C5). From 1-4/8 (0.70 g, 0.44 mmol), 2 (0.22 g, 0.88 mmol),
DPTS (30 mg, 0.090 mmol), and DCC (0.12 g, 0.58 mmol) in a 50
mL mixture of refluxing CH2Cl2 and Freon 113 (1:1 ratio) was obtained
0.37 g (46%) of a white, waxy solid after purification by flash column
chromatography (SiO2; CHCl3/MeOH gradient, 20:1 CHCl3:MeOH
minimum ratio). Purity (GPC), 99+%; TLC (20:1 CHCl3:MeOH), Rf
) 0.2. Thermal transitions and corresponding enthalpy changes are
summarized in Table 1. 1H NMR (CDCl3, TMS, δ, ppm): 1.89
(overlapped peaks, 12H, CF2CH2(CH2)2), 2.14 (m, 6H, CF2CH2), 3.62-
3.82 (overlapped peaks, 19H, CO2CH2C(H)CH2(OCH2CH2)4), 4.07
(overlapped t, 6H, CH2OAr), 4.42 (m, 2H, ArCO2CH2), 7.28 (s, 2H,
ortho to CO2); 19F NMR (CDCl3, δ, ppm): -81.4 (m, 9F, CF3, J )
10.0 Hz), -115.1 (m, 6F, CF2CH2), -122.6 (m, 18F, (CF2)3CF2CH2),
-123.4 (s, 6F, CF3CF2CF2CF2), -124.1 (s, 6F, CF3CF2CF2), -126.8
(m, 6F, CF3CF2); 13C NMR (CDCl3, δ, ppm): 17.1 (CF2CH2CH2, 3,5-
position), 17.3 (CF2CH2CH2, 4-position), 28.7 (CH2CH2OAr, 3,5-
position), 29.7 (CH2CH2OAr, 4-position), 31.0 (t, CF2CH2, J ) 22.3
Hz), 65.0 (CO2CH2), 68.4 (CH2OAr, 3,5-position), 70.5, 70.7, 70.9,
71.1, 71.2 (CH2C(H)CH2(OCH2CH2)3OCH2, CH2C(H)OCH2), 72.6
(CH2OAr, 4-position), 77.7 (CH2C(H)CH2), 108.2 (ortho to CO2), 125.3
(ipso to CO2), 141.9 (para to CO2), 152.5 (meta to CO2), 166.0 (CO2).
Anal. Calcd for C54H47F51O10: C, 35.54; H, 2.60. Found: C, 36.08;
H, 2.64.
4-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-Heptadecafluorodode-
can-1-yloxy)benzyl Alcohol (9-4/8). Compound 9-4/8 was prepared
by reduction of 8-4/8 with LiAlH4. 8-4/8 (8.0 g, 12 mmol) dissolved
in 100 mL of anhydrous Et2O was added dropwise to a stirred
suspension of LiAlH4 (0.52 g, 13 mmol) in 10 mL of anhydrous Et2O.
After complete addition, the reaction mixture was stirred for an
additional 1.5 h. The reaction was quenched by successive addition
of 0.5 mL of H2O, 0.5 mL of 15% NaOH (aqueous), and 1.5 mL of
H2O. The granular solids were filtered and rinsed with Et2O. After
distillation of Et2O on a rotary evaporator and recrystallization from
acetone at 0 °C, 4.42 g (60.1%) of a white solid was obtained. An
additional 1.10 g (15.0%) of pure product was obtained by concentration
of the mother liquor and subsequent recrystallization from hexanes:
ethyl acetate (1:1). Purity, (HPLC): 99+%. The following thermal
transitions (°C) and their enthalpies of transition (kcal mol-1) were
observed by DSC (10 °C min-1): k 92 (6.80) i, on the first heating
scan; i 88 (0.20) sA 81 (6.18) k, on the cooling scan; and k 89, 91
(6.70) i, on the second heating scan; 1H NMR (CDCl3, TMS, δ, ppm):
1.86 (m, 4H, CF2CH2(CH2)2), 2.17 (m, 2H, CF2CH2), 4.01 (t, 2H, CH2-
OAr, J ) 5.4 Hz), 4.63 (s, 2H, ArCH2OH), 6.91 (d, 2H, ortho to O, J
) 6.6 Hz), 7.28 (d, 2H, ortho to CH2, J ) 6.6 Hz); 19F NMR (CDCl3,
δ, ppm): -81.2 (t, 3F, CF3, J ) 9.9 Hz), -114.9 (m, 2F, CF2CH2),
-122.4 (m, 6F, (CF2)3CF2CH2), -123.3 (m, 2F, CF3CF2CF2CF2),
-124.1 (m, 6F, CF3CF2CF2), -126.6 (m, 6F, CF3CF2); 13C NMR
(CDCl3, δ, ppm): 17.4 (CF2CH2CH2), 28.9 (CH2CH2OAr), 30.8 (t,
CF2CH2, J ) 22.0 Hz), 64.9 (CH2OH), 67.3 (CH2OAr), 114.6 (ortho
to O), 128.8 (ortho to CH2), 133.6 (ipso to CH2), 158.6 (ipso to O).
Anal. Calcd for C19H15F17O2: C, 38.14; H, 2.53. Found: C, 38.16;
H, 2.46.
4’-Methylbenzo-15-crown-5 3,4,5-Tris(n-5,5,6,6,7,7,8,8,9,9,10,10,-
11,11,12,12,12-heptadecafluorododecan-1-yloxy)benzoate (5-4/8, 12F8-
AG-B15C5). From 1-12/0 (1.00 g, 0.628 mmol), 3 (0.206 g, 0.691
mmol), DPTS (0.040g, 0.125 mmol), and DCC (0.174 g, 0.835 mmol)
in a 50 mL mixture of CH2Cl2 and Freon 113 (1:1) was obtained 0.80
g (68%) of a white, waxy solid. Purity, (HPLC): 99+%; TLC (20:1
CHCl3:MeOH), Rf ) 0.3. Thermal transitions and corresponding
enthalpy changes are recorded in Table 1. 1H NMR (CDCl3, TMS, δ,
ppm): 1.88 (overlapped peaks, 12H, CF2CH2(CH2)2), 2.18 (m, 6H,
CF2CH2), 3.76 (bs, 8H, (OCH2CH2)2), 3.94 (m, 4H, ArOCH2CH2O),
4.05 (overlapped t, 6H, CH2OAr), 4.15 (m, 4H, ArOCH2CH2O), 5.25
(s, 2H, CO2CH2), 6.88 (d, 1H, meta to CH2, J ) 8.0 Hz), 6.96
(overlapped peaks, 2H, ortho to CH2); 19F NMR (CDCl3, δ, ppm):
-81.4 (m, 9F, CF3, J ) 10.0 Hz), -115.1 (m, 6F, CF2CH2), -122.6
(s, 18F, (CF2)3CF2CH2), -123.4 (s, 6F, CF3CF2CF2CF2), -124.1 (s,
6F, CF3CF2CF2), -126.8 (m, 6F, CF3CF2); 13C NMR (CDCl3, δ,
ppm): 16.9 (CF2CH2CH2, 4-position), 17.1 (CF2CH2CH2, 3,5-position),
28.5 (CH2CH2OAr, 3,5-position), 29.5 (CH2CH2OAr, 4-position), 30.4
(t, CF2CH2, J ) 22.1 Hz), 66.8 (CO2CH2), 68.3 (CH2OAr, 3,5-position),
68.3, 68.8, 68.9, 69.3, 70.3, 70.8 (crown ether), 72.5 (CH2OAr,
4-position), 107.9 (ortho to CO2), 113.5 (ortho to CH2 and O on crown
ether), 114.5 (meta to CH2 on crown ether), 121.8 (ortho to CH2 on
crown ether), 125.2 (ipso to CO2), 128.8 (ipso to CH2 on crown ether),
141.4 (para to CO2), 148.8 (ipso to O on crown ether), 152.4 (meta to
CO2), 165.9 (CO2). Anal. Calcd for C58H47F51O10: C, 37.20; H, 2.53.
Found: C, 37.38; H, 2.49.
4-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-Heptadecafluorodode-
can-1-yloxy)benzyl Chloride (10-4/8). Compound 10-4/8 was pre-
pared by the chlorination of 9-4/8 with SOCl2. SOCl2 (1.44 g, 12.1
mmol) was added dropwise to a stirring solution of 9-4/8 (5.18 g, 8.67
mmol) in 50 mL of CH2Cl2 containing a catalytic amount of DMF.
After 10 min, the solvent was removed by vacuum distillation. The
product was dissolved in Et2O, washed with saturated NaHCO3 and
once with water, dried over MgSO4 and filtered. The solvent was
removed on a rotary evaporator to yield 5.0 g (94 %) of a white powder
which was used in the next step without further purification, mp, 61-
62 °C. Purity, (HPLC): 99+%; TLC (4:1 hexanes:ethyl acetate), Rf
) 0.8. 1H NMR (CDCl3, TMS, δ, ppm): 1.86 (m, 4H, CF2CH2(CH2)2),
2.17 (m, 2H, CF2CH2), 4.00 (t, 2H, CH2OAr, J ) 5.6 Hz), 4.57 (s, 2H,
ArCH2Cl), 6.89 (d, 2H, ortho to O, J ) 8.7 Hz), 7.29 (d, 2H, ortho to
CH2, J ) 8.7 Hz); 19F NMR (CDCl3, δ, ppm): -81.3 (t, 3F, CF3, J )
9.8 Hz), -115.1 (m, 2F, CF2CH2), -122.4 (m, 6F, (CF2)3CF2CH2),
-123.3 (m, 2F, CF3CF2CF2CF2), -124.1 (m, 6F, CF3CF2CF2), -126.7
(m, 6F, CF3CF2); 13C NMR (CDCl3, δ, ppm): 17.3 (CF2CH2CH2), 28.7
(CH2CH2OAr), 30.7 (t, CF2CH2, J ) 22.6 Hz), 46.2 (CH2Cl), 67.3 (CH2-
OAr), 114.6 (ortho to O), 130.1 (ortho to CH2), 129.9 (ipso to CH2),
159.0 (ipso to O).
Methyl 4-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-Heptadecaf-
luorododecan-1-yloxy)benzoate (8-4/8). Compound 8-4/8 was syn-
thesized by the etherification of 7 with 6-4/8. Compound 7 (3.56 g,
23.4 mmol) and K2CO3 (9.69 g, 0.070 mmol) were combined in 130
mL of DMF under a N2 atmosphere. 6-4/8 (13.0 g, 23.4 mmol) was
added, and the mixture was heated to 65 °C. After 20 h, the reaction
mixture was cooled to room temperature and poured into 1000 mL of
ice water. After acidification with dilute HCl, the product was collected
by vacuum filtration and dried in air. Recystallization from acetone
Methyl 3,4,5-Tris[p-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-hep-
tadecafluorododecan-1-yloxy)benzyloxy]benzoate (12-4/8, 12F8-
ABG-CH3). Compound 12-4/8 was synthesized according to the same
general procedure described for the synthesis of 8-4/8. From 11 (0.48
g, 2.6 mmol), K2CO3 (9.7 g, 70 mmol), and 10-4/8 (4.8 g, 7.8 mmol)
in 50 mL of DMF was obtained 4.37 g (87.6%) of a white solid after

9866 J. Am. Chem. Soc., Vol. 118, No. 41, 1996
Percec et al.
recystallization from acetone at 0 °C. Purity, (HPLC): 99+%; TLC
(4:1 hexanes:ethyl acetate), Rf ) 0.5. Thermal transitions and corre-
sponding enthalpy changes are summarized in Table 1. 1H NMR
(CDCl3, TMS, δ, ppm): 1.87 (overlapped peaks, 12H, CF2CH2(CH2)2),
2.18 (m, 6H, CF2CH2), 3.89 (s, 3H, CH3), 4.01 (overlapped t, 6H, CH2-
OAr), 5.00 (s, 2H, ArCH2OAr, 4-position), 5.05 (s, 4H, ArCH2OAr,
3,5-position), 6.76 (d, 2H, ortho to O on 4-position, J ) 8.7 Hz), 6.91
(d, 4H, ortho to O on 3,5-position, J ) 8.7 Hz), 7.27 (d, 2H, ortho to
CH2 on 4-position, J ) 8.6 Hz), 7.36 (d, 4H, ortho to CH2 on 3,5-
position, J ) 8.7 Hz), 7.37 (s, 2H, ortho to CO2); 19F NMR (CDCl3, δ,
ppm): -81.4 (m, 9F, CF3, J ) 9.0 Hz), -115.0 (m, 6F, CF2CH2),
-122.5 (s, 18F, (CF2)3CF2CH2), -123.4 (s, 6F, CF3CF2CF2CF2),
-124.1 (s, 6F, CF3CF2CF2), -126.7 (m, 6F, CF3CF2); 13C NMR
(CDCl3, δ, ppm): 17.3 (CF2CH2CH2), 28.7 (CH2CH2OAr), 30.7 (t,
CF2CH2, J ) 12.5 Hz), 52.1 (CO2CH3), 67.2 (CH2OAr, 3,5-position),
71.0 (ArCH2OAr), 74.7 (CH2OAr, 4-position), 109.2 (ortho to CO2),
114.1 (ortho to O, 4-position), 114.4 (ortho to O, 3,5-position), 124.9
(ipso to CO2), 129.0 (ortho to CH2, 4-position), 129.3 (ortho to CH2,
3,5-position), 129.9 (ipso to CH2, 4-position), 130.3 (ipso to CH2, 3,5-
position), 142.1 (para to CO2), 152.7 (meta to CO2CH3), 158.8 (para
to CH2OAr), 166.5 (CO2). Anal. Calcd for C65H47F51O8: C, 40.56;
H, 2.46. Found: C, 40.53; H, 2.41.
3,4,5-Tris[p-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadeca-
dodecan-1-yloxy)benzyloxy]benzoic Acid (13-4/8, 12F8-ABG). Com-
pound 13-4/8 was synthesized by the basic hydrolysis of 12-4/8.
Compound 12-4/8 (4.17 g, 2.17 mmol) was dissolved in a refluxing
mixture of 50 mL of absolute EtOH and 25 mL of THF. To this
solution was added 5 mL of 10 N KOH. After 2 h, the mixture was
cooled to room temperature. The mixture was concentrated on a rotary
evaporator and redissolved in 500 mL of THF. After acidification with
100 mL of 10% HCl, the mixture was once again concentrated and
precipitated into 2 L of ice water. After filtration and recrystallization
from acetone, 3.62 g (87.9%) of a white powder was obtained. Purity,
(HPLC): 99+%. Thermal transitions and corresponding enthalpy
changes are summarized in Table 1. 1H NMR (CDCl3/Freon 113, TMS,
δ, ppm): 1.89 (overlapped peaks, 12H, CF2CH2(CH2)2), 2.17 (m, 6H,
CF2CH2), 4.03 (overlapped t, 6H, CH2OAr), 5.06 (s, 2H, ArCH2OAr,
4-position), 5.09 (s, 4H, ArCH2OAr, 3,5-position), 6.79 (d, 2H, ortho
to O on 4-position, J ) 8.6 Hz), 6.93 (d, 4H, ortho to O on 3,5-position,
J ) 8.7 Hz), 7.26 (d, 2H, ortho to CH2 on 4-position, J ) 8.7 Hz),
7.38 (d, 4H, ortho to CH2 on 3,5-position, J ) 8.7 Hz), 7.44 (s, 2H,
ortho to CO2). The 19F NMR spectrum was not recorded due to the
necessity of Freon 113 as a cosolvent. The 13C NMR spectrum was
not recorded due to the low solubility of 13-4/8 in CDCl3/Freon 113
mixtures. Anal. Calcd for C64H45F51O8: C, 40.23; H, 2.37. Found:
C, 39.56; H, 2.31.
Methyl 15-Crown-5 3,4,5-Tris[p-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,-
11,12,12,12-heptadecafluorododecan-1-yloxy)benzyloxy]benzoate (14-
4/8, 12F8-ABG-15C5). Compound 14-4/8 was synthesized according
to the same general procedure described for the synthesis of 4-4/8. From
13-4/8 (1.0 g, 0.53 mmol), 2 (0.15 g, 0.58 mmol), DPTS (0.033 g, 20
mol %), and DCC (0.15 g, 0.71 mmol) in 20 mL of a refluxing mixture
of CH2Cl2:Freon 113 (1:1) was obtained 0.90 g (80%) of a white powder
after purification by flash column chromatography [SiO2; CHCl3-
CHCl3:MeOH (20:1) gradient). Purity, (HPLC): 99+%; TLC (20:1
CHCl3:MeOH), Rf ) 0.3. Thermal transitions and corresponding
enthalpy changes are summarized in Table 1. 1H NMR (CDCl3, TMS,
δ, ppm): 1.86 (overlapped peaks, 12H, CF2CH2(CH2)2), 2.17 (m, 6H,
CF2CH2), 3.67-3.84 (m, 19H, CHCH2(OCH2CH2)4), 4.00 (overlapped
t, 6H, CH2OAr), 5.00 (s, 2H, ArCH2OAr, 4-position), 5.04 (s, 4H,
ArCH2OAr, 3,5-position), 6.76 (d, 2H, ortho to O on 4-position, J )
8.5 Hz), 6.90 (d, 4H, ortho to O on 3,5-position, J ) 8.6 Hz), 7.27 (d,
2H, ortho to CH2 on 4-position, J ) 8.5 Hz), 7.36 (d, 4H, ortho to
CH2 on 3,5-position, J ) 8.7 Hz), 7.37 (s, 2H, ortho to CO2); 19F NMR
(CDCl3, δ, ppm): -81.4 (m, 9F, CF3, J ) 9.0 Hz), -115.0 (m, 6F,
CF2CH2), -122.5 (s, 18F, (CF2)3CF2CH2), -123.4 (s, 6F, CF3CF2-
CF2CF2), -124.1 (s, 6F, CF3CF2CF2), -126.7 (m, 6F, CF3CF2); 13C
NMR (CDCl3, δ, ppm): 17.3 (CF2CH2CH2), 28.7 (CH2CH2OAr), 30.7
(t, CF2CH2, J ) 12.5 Hz), 65.0 (CO2CH2), 67.2 (CH2OAr, 3,5-position),
70.5, 70.6, 70.8, 70.9, 71.0 (crown ether), 71.2 (ArCH2OAr), 74.7 (CH2-
OAr, 4-position), 109.4 (ortho to CO2), 114.1 (ortho to O, 4-position),
114.5 (ortho to O, 3,5-position), 125.1 (ipso to CO2), 128.3 (ortho to
CH2, 4-position), 129.3 (ortho to CH2, 3,5-position), 129.9 (ipso to
CH2, 4-position), 130.3 (ipso to CH2, 3,5-position), 142.7 (para to CO2),
152.6 (meta to CO2CH3), 158.7 (para to CH2OAr), 165.7 (CO2). Anal.
Calcd for C75H65F51O13: C, 42.03; H, 3.06. Found: C, 42.15; H, 3.03.
4’-Methylbenzo-15-crown-5 3,4,5-Tris[p-(n-5,5,6,6,7,7,8,8,9,9,10,-
10,11,11,12,12,12-heptadecafluorododecan-1-yloxy)benzyloxy]ben-
zoate (15-4/8, 12F8-ABG-B15C5). From 13-4/8 (1.0 g, 0.53 mmol),
3 (0.17 g, 0.58 mmol), DPTS (0.033 g, 20 mol %), and DCC (0.15 g,
0.71 mmol) in 20 mL of a refluxing mixture of CH2Cl2:Freon 113 (1:
1) was obtained 0.94 g (81%) of a white powder after recrystallization
from acetone. Purity, (HPLC): 99+%; TLC (20:1 CHCl3:MeOH), Rf
) 0.2. Thermal transitions and corresponding enthalpy changes are
summarized in Table 1. 1H NMR (CDCl3, TMS, δ, ppm): 1.84
(overlapped peaks, 12H, CF2CH2(CH2)2), 2.17 (m, 6H, CF2CH2), 3.75
(bs, 8H, (OCH2CH2)2), 3.89-4.03 (overlapped peaks, 10H, CH2OAr
and ArOCH2CH2O), 4.14 (m, 4H, ArOCH2CH2O), 4.99 (s, 2H, ArCH2-
OAr, 4-position), 5.03 (s, 4H, ArCH2OAr, 3,5-position), 5.24 (s, 2H,
CO2CH2), 6.76 (d, 2H, ortho to O on 4-position, J ) 8.7 Hz), 6.90
(overlapped peaks, 5H, ortho to O on 3,5-position and ortho to CH2
on crown ether), 7.26 (d, 2H, ortho to CH2 on 4-position, J ) 8.7 Hz),
7.30 (d, 4H, ortho to CH2 on 3,5-position, J ) 8.4 Hz), 7.37 (s, 2H,
ortho to CO2); 19F NMR (CDCl3, δ, ppm): -81.3 (m, 9F, CF3), -115.1
(m, 6F, CF2CH2), -122.5 (s, 18F, (CF2)3CF2CH2), -123.3 (s, 6F, CF3-
CF2CF2CF2), -124.1 (s, 6F, CF3CF2CF2), -126.7 (m, 6F, CF3CF2);
13C NMR (CDCl3, δ, ppm): 17.3 (CF2CH2CH2), 28.7 (CH2CH2OAr),
30.6 (t, CF2CH2, J ) 12.5 Hz), 66.8 (CO2CH2), 67.1 (CH2OAr, 3,5-
position), 69.0, 69.1, 69.5, 70.4 (crown ether), 71.0 (ArCH2OAr), 74.7
(CH2OAr, 4-position), 109.3 (ortho to CO2), 113.8 (ortho to CH2 and
O on crown ether), 114.1 (ortho to O, 4-position), 114.4 (ortho to O,
3,5-position), 114.7 (meta to CH2 on crown ether), 121.9 (ortho to CH2
on crown ether), 125.1 (ipso to CO2), 128.9 (ipso to CH2 on crown
ether), 129.1 (ortho to CH2, 4-position), 129.5 (ortho to CH2, 3,5-
position), 129.9 (ipso to CH2, 4-position), 130.2 (ipso to CH2, 3,5-
position), 142.6 (para to CO2), 152.6 (meta to CO2CH3), 158.7 (para
to CH2OAr), 166.1 (CO2). Anal. Calcd for C79H65F51O13: C, 43.30;
H, 2.99. Found: C, 43.44; H, 2.92.
Preparation of Complexes of 4-m/n with NaOTf. Complexes of
4-m/n with NaOTf were prepared by mixing solutions of 4-m/n (ca.
50 mg/mL) in anhydrous THF with an appropriate volume of a 0.05
M stock solution of NaOTf in THF. The solvent was evaporated under
a gentle N2 stream, and the resulting complexes were further dried in
a vacuum desiccator over SiO2 under high vacuum for 12-20 h at
room temperature.
Acknowledgment. Financial support by the National Science
Foundation (DMR 92-06781), the Engineering and Physical
Research Council, UK and NATO (traveling grant) is gratefully
acknowledged. The authors thank Professor S. Z. D. Cheng,
University of Akron, for density measurements.
Supporting Information Available: DSC traces of semi-
fluorinated blocks or intermediary compounds and of their
complexes with NaOTf. Tables of phase transition temperatures
and their corresponding enthalpies of transition for all of the
complexes of 12Fn-AG-15C5 with NaOTf. Phase diagrams
illustrating the dependence of phase transition temperature on
the NaOTf/crown ether molar ratio for 12Fn-AG-15C5. Optical
micrographs and bar graphs of building blocks (14 pages). See
any current masthead page for ordering and Internet access
instructions.
JA9615738