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Assembly Properties of Bolaamphiphiles from Dimeric Acids.

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' J = 4 . X H r . 1 H).3.26(s.YH).2.81 (s.3H);IR(KBr) FIcm '1 = 1835(C=O);MS
(FAB): n y : : 144 [Mi]: correct C.H . N analysis for C,H,-NO,S.
Received: May 19. 1994 [Z6952 IE]
German vcrsion: Aiigeii-. C h i m 1994. 106. 2202
R. Crossley, T i ~ r r a h ~ ~ d r1992.
o n 4H. 8155 817X.
Chmi. Ei7,q. .Yiws 1992. 70!39), 46-79: ;bid 1993, 71 1 3 9 ~ ~
38 - 6 5 .
Natural L-carnitine has the (R)configuration: T Kaneko. R. Yoshida. BUN.
Chiw. Sor. Jpn. 1962. 3.5. 1183-1155.
I . B. Fritzin C'urwnt i Curnitiiie Re,wurdi (Ed.: A. L. C x t e r ) . CRC
Press 1992. pp. 107 - 119,K. L . Goa. R. N. Brogden, Drug.! 1987.34.1-24; S.
Di Donato, B. Garavaglia. M. Rimoldi. E Carrara in ~-Cur-nitinr
irnd IIY Rok
rii Mctlicriic /ron7 Function I O Thwupv (Eds.: R. Ferrari. S. Di Mauro. G.
Sheruood). Academic Press. 1992. pp. 85-98.
T, C. Vary. J. R. Neely. A i r J. P/ij.siol. 1982. 243. H585- H592, R. Bresslei-. K .
Brendel. .I Eiol. C h m . 1966. 241. 4092-4097.
C.Cavazza (Sigma-Tau). BE-B 877609, 1979 [Chrm.Ahstr. 1980. Y3. I14973 v]
Unpublished results.
S. Shapiro. M . Bernardini, C. Sih (Sigma-Tau). EP-A1 457735. 1991 [Cheni.
.Ab.sri-. 1992. 116. 150142al.
H.C. Kolb. Y. L . Bennani. K. B. Sharpless. Ewuhedron: A ~ v i z n 7 e t r j1993.
133 -341: M . Bols, I. Lundt, C. Pedersen. E~.rruhedrori1992.48.319 324: F.D.
Bellamy. M. Bondoux. P. Dodey, 7i,iruhedrcm Lr,rr. 1990, 31. 7323-7326, H.
Takeda, S.Hosokava. M . Aburatani. K . Achiva. Sj.n/rrr 1991.3. 193- 194: P.
Renaud. D. Seehach. Srnrhem 1986. 3. 424 -426: K. Bock. 1 . Lundt. C.
Pedenen, Actu Chon. Scond. 1983, B37. 341 -344.
0.Mitsunobu. Sjurhctis 1981. I , I 28: S. E Ramer. R. N . Moore. J C
Vederas. Cun. J. Chrwi. 1986, 64. 706.
A. Pommier. J M. Pons. S y r h m O 1993. 5. 441 -459.
a) F. Giannessi. N. Scafettx. I Bernabei. M. 0. Tinti, F. De Angelis. P. De Witt
Scalfaro. D. MiTiti (Sigma-Tau) RM93A00027, 1993. b) An alternative route
to the methanesulfonate derivative 5 could be conversion of (S)-(+)-carnitine
perchlorate into its benzyl ester. followed by mesylation with methanesulfonyl
chloride in pyridine. and final cleavage of the henry1 group by hydrogenation
over Pd;C: F. Giannessi. M. L . Bolognesi. M. 0 Tinti. F. De Angelis. P. De
Witt Scalfaro. D. Misiti (Sigma-Tau ) RM92A000915, 1992. c) Alternativel).
rnethanesulfonyl chloride in pyridine could be used in the mesylation of
isobutyl ester 3.
The structure of lactone 6 was determined on an analytically pure sample (see
€.~peririzentu/F'rcirrdure for isolation, purification, and characterization) by ' H
NMR spectroscopy: the chemical shift of the proton linked to the /I carbon
atom is typical of acylcarnitines (cf., 6 (7) = 5.6 (p-H) in D,O)
Lactone 6 need not be isolated [12a].
[a], (I) = -31 (c = 10 i n H,O): for comparison. the specific rotation of (S)(+)-carnitine obtained by hydrolysis of ( S ) - (+)-carnitinamide (2) is
[XI,= +31 ( 1 = 10 in H,O). We could not detect traces of the enantiomer of
1. the enantiomeric purity ( > 9 9 % ee) was established by treating the final
product with ( +)-1-(9-fluorenyI)ethylchloroformate [( + )-FLEC] and examining the resulting ester by HPLC [16].
P. De Witt Scalfaro, R. DeJas, S. Muck, B. Galletti, D. Meloni. P. Celletti. A.
Marzo. J. Chrc~mEfoiized. Appl., 1994. 6J7. 67 73.
Assembly Properties of Bolaamphiphiles from
Dimeric Acids**
Pilar Bosch,* Jose L. Parra, and Alfonso de la Maza
Self-organization is an important feature of many biologically relevant molecules.['I One of the most interesting questions
which arises is whether it is possible to develop new materials
that simulate natural supramolecular systems whose function
is determined by their three-dimensional self-assembly.[2J
Newkome et al. have described the synthesis of some com[*IDr. P.
Bosch. Prof. Dr. J. L. Parra. Dr. A. de la Maza
Departamento de Tensioactivos. CID-CSIC
C,Jorge Girona Salgddo 18- 26, E-08034 Barcelona (Spain)
Telefax: Int. code f ( 3 ) 204-5904
This work was supported by the Generalitat Catalunya (Cirit postdoctoral
fellowship grant EE92;1-111) for research at the Freie Universitlt Berlin (Prof.
Dr. J. H. Fuhrhop). We thank J. Blavia and A. del Giorgio for the TEM
measurements and image analysis, respectively. and G. von Knorring for his
expert technical assistance.
VCH Verlu~s~esi~llschaft
mhH, 0-69451 Wemheim, 1994
pounds called arborols or dendrimers which form automorphogenic suprastructures possessing helical or ribbonlike morp h o l o g i e ~ . ~We
~ ] sought to demonstrate that the concept of
supramolecular self-assembly can be extended to other organic
compounds having a cyclohexane structure substituted with different ionic side groups and counterions.
Several bolaamphiphiles were prepared from an inexpensive
mixture of a,w-dicarboxylic acids (dimeric acid, versadyme),r41
which were obtained by thermal Diels-Alder cyclization of
methyl-( 1OE,1?E)-linoleate (from tall oil). Tetrasubstituted cyclohexane derivatives were obtained. The dianionic bolaamphiphile DAS 1 was synthesized by reduction of the dimeric
acids with LiAIH, followed by reaction with chlorosulfonic acid
and addition of Na,CO,. The resulting disulfate was obtained
with an overall yield of 65%. Activation of the acid groups of
the dimeric acids with thionyl chloride and reaction with N , N dimethylethylenediamine followed by quaternization yielded
DAC-I 2 (81 YO).Ion exchange on Dowex resin gave the cationic
acid amides, DAC-CI 3 and DAC-CO, 4 with yields of 88 and
86 YO,respectively. All the bolaamphiphiles gave satisfactory
spectra (IR, 'H N M R . FAB-MS) and elemental a n a l y ~ i s . ' ~ ]
DAC-I 2, X=l, DAC-CI 3, X=CI ; DAC-COB 4, X=HCO3
m + n + p + q = 26
p, q = 3-6
The aggregation behavior was studied directly by transmission electron microscopy (TEM) and image analysis.l6] A buffer
solution containing the bolaamphiphiles 0.5 YO(weight per volume) was sonicated for I S min at 55 "C. When the internal volume of the sonicated samples was measured by dye encapsulation (carboxyfluorescein and pyranine) no closed vesicles
formed. Sonicated samples were stained (1 YOuranyl acetate) for
TEM imaging and then digitalized for image analysis. Depending on the TEM magnification, 1 pixel corresponds to 0.123,
0.246, 0.328, and 0.579 nm (DAC-CI, DAS, DAC-CO,, and
DAC-I, respectively; Fig. 1 ) .
Some rodlike structures with internal organization may be
recognized for the anionic species DAS 1 in Figure 1 . Cationic
species form multilamellar arrangements whose specific features
depend on the counterion. Thus, with the bicarbonate counterion (DAC-CO,) a complex multilayer structure resembling a
fingerprint is seen. In the case of chloride counterion the arrangement is less well defined. The presence of iodide counterion leads to the formation of more complex multilamellar aggregates (Fig. 1).
It seems that both the ionic character of the synthesized bolaamphiphiles and the counterions of the cationic compounds
rule out the three-dimensional arrangement of such molecules.
However, as described by Okahata et aI.l6] the aggregate morphology of ionic dialkyl amphiphiles is relatively insensitive to
the chemical structure. and vesicles and lamellae are the most
common morphologies. In sharp contrast, the morphology of
the aggregates formed by polyoxyethylene glyceryl a,%'-diethers
S 10 00+ .25:0
Aiigeiv. Chem. In/. Ed.
Engl. 1994. 33, No. 20
Fig. 1 TEM microphotographs of 1 4. The white arrows point t o the beginning of
the three-dimensional opcn multilamellar structure.
(2Cn-gl-xG) varies remarkably with their chemical structures."'
To obtain further information on some characteristics of selfassembly we determined the periods or the average distance of
the pattern ordering in each lamellar structure by analysis of the
TEM images. Two approaches were used: a) Fourier transformation (FT) and b) profile of direct measurements from digitalized TEM pictures (Fig. 2). The good correlation of the results
obtained by the two methods is shown in Table 1 . The largest
period was found for DAC-I.
From physico-chemical studies we know that critical micelle
concentrations (CMC) for DAS, DAC-I, DAC-Cl, and DACCO, are 1420, 20, 2600, and 300 ppm, respectively.[51The areas
for these bolaamphiphiles measured with a Langmuir film balance are 100, l 16, 62, and 78 A', re~pectively.[~I
The most striking results are the lowest CMC value (20 ppm) and the highest
area per molecule (1 16 A) obtained for DAC-I. The peculiar
three-dimensional arrangement of 2 and its lamellar period of
10 nm, the largest in the series, cannot be explained by the small
difference between the van der Waals diameters of chloride
(4.2 A) and iodide (4.6 A). An alternative explanation could be
that a macrocycle of approximately 18 atoms is formed by hydrogen bonding between the two amide groups of both chains
containing ionic head groups (Fig. 3). Thus, the chaotropic
characterr8]of the iodide anion closely bound to the trimethylammonium head group may prevent the formation of such a
macrocycle. As a consequence, a more extended arrangement of
the molecule with a greater surface area at the liquid-air interface would result. In addition, a more hydrophobic bolaamphiphile would have a lower CMC value. With the other counterions not having chaotropic characteristics the macrocyclic
molecular arrangement could be maintained, and consequently
a smaller surface area would be occupied by the bolaamphiphile
A I ~ M Cliiw.
J I I I . Ed. Engl. 1994. 33, No. 20
Fig. 2. Color pictures: Fourier transformations of TEM microphotographs for the
bolaarnphiphiles. Plots: Profiles of the digitalized T E M picture\ I = intcnsity,
n = points. Ten points correspond to 1 pixel.
Table 1. Lamellar periods [nm] for 1 - 4 obtained experimentally by two methods.
0.63 1.25
molecule. Moreover, the macrocycle formation could account
for the periods measured for the lainellae of the bolaamphiphiles (Table 1).
t:) VCH Verlugsgesellschufi mhH, 0-69451 Weinhrim,1994
0570-0833/94/2020-2079 $ 10.00+ .2.W
Fig. 3. Energy-minimized structure shows the formation of a macrocycle from the
cationic bolaamphiphiles 2-4 through hydrogen bonds between the carbonyi 0
atom and the amide N H group. When X = I, the counterion disturbs the binding
interaction by increasing the N - - 0 distance.
cussed recently.['] The excited state properties of this compound
and the nature of the reaction products generated upon irradiation in solution have been studied in detail.I3] Other researchers
have shown that a wide variety of organic compounds can be
deposited from solution as two-dimensional (2D) crystals on the
basal plane of highly oriented pyrolytic graphite (HOPG) and
imaged in situ by scanning tunneling microscopy (STM) at the
solid -fluid interface.L41Until now photochemically unreactive
organic molecules have been studied by STM; light-induced
transformations in a thin liquid film have previously not been
examined by this high-resolution technique. We report here
on the first such STM study of the phototransformation
of 10-diazo-2-hexadecylanthrone ( I ) to 2-hexadecyl-9,lO-anthraquinone (2) [Eq. (a)]
It is noteworthy that bolaamphiphiles form multilamellar aggregates at low concentrations. The morphology of these stable
aggregates depends on the bolaamphiphile's ionic groups and
nature of the counterion.
Received: March 8, 1994
Revised version: April 23. 1994 [Z 6738 IE]
German version: A n g a . Chem. 1994, 106. 2157
[ I ] J. H . Fendler. Mwihrune Mfmrric Cheinirru~.,Wile?. Nen York. 1982.
[Z] J.-M. Lehn. Aii,q(m. C/wi?i.1990. 102. 1347; A I I ~ P I !Chcwi. I n / . Ed. E j i ~ /1990,
29. 1304.
[ 3 ] G. R Ncwkoine. C N.Moorefield, G. R. Baker. R. K . Behera. G. H. Escamillia. M . J. Saunders. A n p i c . Cliem. 1992. 104, 901 : Angeri-. Chem. h i / . Ed. Engl.
1992. 31. 917
[4] J. H. Fuhrhop, W. Kaufmann. F. Schambil, Lungmuir 1985, 1, 387.
[S] P. Bosch. F. J. SBncheL-Bacra. J. L. Parra, Curi. J. C I I P ~1993,
71. 2095.
161 Y. Okahata. S. Tanamachi. M. Nag& T. Kunitdke. J Col/(~rrlInfru/uce
Sci. 1981.
x2. 401
171 J. Khninp. C. Boeltvher. H Winkler. E. Zeitler, Y Talmon. J. H. Fuhrh0p.J An1
C%riii. S01,. 1993. 115. 693.
181 T. Pigor. R. Lawaczck. Z . Nutur/orx/i. C 1983. 83. 307
Photodecomposition of 10-Diazo-2-hexadecylanthrone on Graphite Studied by Scanning
Tunneling Microscopy
Roland Heinz, Andreas Stabel, Jurgen P. Rabe,"
Gerhard Wegner, Frans C. De Schryver,*
D a v i d Corens, Wim Dehaen, and Carsten Suling
Diazoanthrone has long been used in photoresists,[" and the
structure and spectroscopic properties of some p-benzoquinonediazides including 10-diazoanthrone have been dis['I
Prof. Dr. J. P. Rabe.'+' DipLChem. R. Heinz. DiplLCheni. A. Stahel.
Prof. Dr. G. Wcgner
Max-Planck-Institut fur Polymerforschung
Postfdch 3148. D-55021 Mainz (FRG)
Telefu: Inc. code + (6131)379-100
Nelr. addreas: lnatitul fur Physikalische Chemie
der UniversitHt Mainz
Jakob-Welder-Weg 11. D-55099 Mainz (FRG)
Telcfax: Int. code (6131)39-3768
Prof. Or. E C . De Schryver. D. Corens. Dr. W. Dehaen. Dr. C. Suling
K U Leuven, Department of Chemistry
Celestijnenlaan 20OF- B-3001 Heverlee (Belgiuin)
The Belgian authors thank the Ministry of Wetenschapsbeleid for support
(IUAP-11-16 and IUAP-111.040). The German authors acknowledge support
through ESPRIT Basic Research Projects 7282 (TOPFIT) and 8523 (PRONANO). R.H. and A.S. thank the Fonds der Chemischen Industrie for KekulC
scholarships F. C . De Schryker thanks the Alexander-\~oii-Humboldt-Stiftung
for support during his stay in Mainz.
An oxygen-saturated 0.05 M solution (3 mL) of diazoanthrone 1 in 1,2,4-trichlorobenzene (Aldrich 99.9 %) was irradiated for 24 h in a 1 cm quartz tube with a cold light source
(Schott, KL 1500, light power 1.3 W). Since the solvent chosen
has no easily abstractable hydrogen atoms, undesirable side
reactions such as insertion into a C-H bond should be eliminated. The solution was saturated with oxygen to optimize the
conversion of 1 into 2. UV spectra were recorded before and
after irradiation to confirm the transformation of 1 (starting
material, I.,, = 418 nm) to anthraquinone 2 (photoproduct,
i,,, = 340 nm). Compound 2 was also synthesized independently and characterized by UV spectroscopy.
Two-dimensional crystals precipitated from the above-mentioned solutions of 1 and of 2 and were analyzed with a scanning
tunneling microscope constructed in our institute which allows
imaging in situ at solid-liquid interface^.^^] A droplet of a solution of 1 or 2 in 1,2,4-trichlorobenzene was applied to a vertically oriented piece of HOPG to form a thin liquid film (Fig. 1
top). The thickness of the liquid film in the vicinity of the STM
tip is less than 20 pm (Fig. 1 bottom). The photoreaction was
then studied in situ at the graphite-solution interface. An optical multimode PMMA fiber (diameter 1 mm) was used for irradiation (Fig. 1 top). The light intensity was approximately
5 mWcrn-' at the graphite surface. The temperature of the
graphite was measured in situ with a Pt 100 thermoresistor fixed
at one side (Fig. 1 top). The temperature was simultaneously
measured at the surface and at the side of the piece of graphite
in a control experiment to exclude a nonnegligible temperature
gradient. In another control experiment photochemically unreactive monolayers were imaged with and without illumination,
and no difference was observed.
The STM images were obtained in constant height mode under ambient conditions (scan rate 0.3 Hz per image, positive tip
bias). They were recorded on a videotape in real time and digitized later. Data as recorded without digital image processing
are displayed in the figures. The tunneling tips were electrochemically etched (2 N KOH + 6 N NaCN) from a 0.25 mm Pt/
Ir (80:20) wire. Every tip was then calibrated in situ by imaging
the hexagonal graphite lattice (a = 246 pni) .
Physisorption of diazoanthrone 1 and of anthraquinone 2
from 1,2,4-trichlorobenzene on HOPG leads to well-ordered 2D
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acid, properties, assembly, dimeric, bolaamphiphiles
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