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Facile Synthesis and Solid-State Structure of a Benzylic Amide [2]Catenane.

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full agreement with the insensitivity of its rotation with respect
to changes in the molecular environment. The constant [XI,
value does not imply that the camphor sulfonamide and camphanic amide shells are not densely packed nor that they do not
possess frozen-in conformations. However, in these densely
packed surfaces the frozen-in conformations all have the same
optical activity and no internal compensation effects are operative here. Also the number and strength of the hydrogen bonds
in these cases will be lower than in the case of the amino acid
derived dendrimers. Further research to elucidate the reasons
for the observations presented here are in progress. It is foreseen
that research on chiral dendrimers with highly packed shells will
yield important information for this type of curved structures;
structures that are so prominently present in nature.
Received: November 8. 1994
Revised version: January 26, 1995 [Z74591E]
German version: Angen.. Chem. 1995, 107, 1321 - 1324
Keywords: chirality . chiroptical studies . circular dichroism
dendrimers stereochemistry
M. M. Green, 8. A . Garetz, Terruhedron Lert. 1984, 25. 2831
0. Wallach. Jusrus Liebies Ann. Chem. 1895. 286. 90-143
C.
1 P. Brock, W. B. Schweizer, J. Dunitz, J. Am. Chem. Soc. 1991, 113, 98119820
I. Weissbuch, F. Frolow, L. Addadi, M. Lahav. L. Leiserowitz, J Am. Chem.
Soc. 1990. 112, 7718-7724.
In order to discriminate between disorder and pseudo-ceiitrosymmetry, we
performed experiments using scalemic mixtures of D-Phe and L-Tyr in the
formation of the fifth-generation box. In sharp contrast to the [.IDvalues of 0
for the pure o-Phe or L-Tyr, we found [.ID = + 16 (c = 1 , DMSO) for the 50: 50
scalemic mixture of D-Phe and L-Tyr, and optical rotations between + 16 and
0 for the other mixtures studied. The trend observed is indicative for some kind
of pseudo-centrosymmetric ordering in the shell. in which in the case of the
S O : 50 scalemic mixture both units can adopt their preferred conformation and
still the most dense packing is formed.
This conclusion seems at first glance to be in contrast with "la coupe du roi"
in which both chiral halves are of the same handedness, however a chiral
dendritic surface possesses molecular chirality while "la coupe du roi" has only
macroscopic chirality, see K. Mislow, Bull. Sur. Chim. Fr. 1994, 131, 534-538.
.
[l] a) F. Ciardclli. Encylopediu qf'Poljmer Science und Enginering. Vol10. Wiley,
New York, 1987. p 463; h) J. M. Lehn, Angew. Chem. 1988, 100, 91-116:
AnReii. Chrm. In[. Ed. EngI. 1988. 27, 89-112; c) M. Kitamura, S. Okada, S.
Suga, R. Noyori. J Am. Chem. Soc. 1989, 111.4028-4036; d) M. Kitamura,
R. Noyori. Angcw. Chem. 1991. 103. 34 - 5 5 ; Angen.. Chem. In[. Ed. Engl. 1991,
30.49.- 76; e) T. Katsuki. K. B. Sharpless. J. A m . Chem. SOC.1980,102,59745976: f ) D. K. Mitchell. J.-P. Sauvage, Angew Chem. 1988, 100, 985-987:
A n p r . C%rm.fnr. Ed. h g l . 1988.27. 930-933; g) H. Ringsdorf, B. Schlarh,
J. Venzmer. dnd. 1988, 100. 117-162 and 1988, 27, 113-158: h) D. Seebach,
ihd. 1990. 102. 1363-1409 and 1990.29, 1320-1366.
(21 a ) L. Addadi, 2. Berkovitch-Yellin. I. Weisshuch. M. Lahav, L. Leiserowitz, in
Top. Srrrwchem. 1986, 16, 1: h) T. Kunitake, N. Nakashima. S. Hayashida. K.
Yonemori. Chem. Lrrl. 1979. 1413; c) T. Kunitake, N. Nakashima. M. Shimomurlt. Y Okahata. K. Kano. T. Ogawa. J. Am. Chon. SOC.1980, 1/12, 6642;
d ) N. Nakashima. R. Ando. T. Muramtsu, T. Kunitake, Lungmuir 1994. 10,
232
[3] a ) D. A Tomdlia. A. Naylor, W. A. Goddard, Ange". Chem. 1990. 102, 119157. Angeiv. ('hem. f n t . Ed. EngI. 1990,29,138-175; h ) G . R.Newkome, C. N.
Moorfield. G. R. Baker, A. L. Johnson. R. K. Behera, J. Org. Chem. 1992.57.
358 362: c) Z. Xu. J. S . Moore, Angew. Chrm. 1993,105.1394-1396: Angew.
('hrtn. I n / . 6 1 . Engl. 1993, 32, 1354-1357; d ) C. Worner. R. Mulhaupt. ibid.
367-1370and 1993.32.1306-1308e)K. L. Woo1ey.C. J. Hawker.
chet, J. Am. Chem. Soc. 1991, 113, 4252-4261: f) K. L. Wooley,
C . J. Hawker. J. M. J. Frechet, Angew. Chem. 1994. 106, 123-126; Angekv.
Chcn?. fn!. E d Enx/. 1994. 33. 82-85; g) T. M. Miller, T. X. Neenan. E. W.
Kwock, S . M . Stein. J. Am. Cheni. Soc. 1993. 115. 356-357: h) J. Issherner, R.
Moors, E Vogtle, Angew. Chem. 1994, 106,2507-2514; Angew. Chem. fnr. Ed.
Engl. 1994, 33. 2413-2420.
(41 G . R. Newkome. X. Lin, C. D . Weis, Tetruhrdron Asynimerry 1991, 2, 957960
[S] a ) D. Seehach. J.-M. Lapierre, K. Skohridis. G. Greiveldrnger, Angew. Chem.
1994. 106, 457- 458; Angew. Chem. f n r . Ed. Engl. 1994. 33, 440-442; Helv.
Chini. AcIu 1994, 77. 1673-1688.
[6] a) H:F. Chow, L. E Fok, C. C. Mak. E'trahedron Lett. 1994,3S, 3547--3550:
h) H:F. ('how, C. C. Mak. J. Chrm. SOC.Perkin Trans. f1994, 2223.
(71 R. H . E. Hudson, M. J. Damha. 1 Am. Chem. Soc. 1993. 115, 2119-2124.
[XI L. W. Twyman, A. E. BceLer. J. C. Mitchell, Tetrahedron Lerr. 1994, 35. 4423.
[9] a) R. G. Denkewalter. J. F. Kolc, W. J. Lukasavage. US-A 4410688, 1983
[('hrm. Ahsrr. 1984. 100. 103907p]; h) R. G . Denkewalter, J. F. Kolc. W. J.
Lukasavage. US-A 4289872, 1981 [Chem. Abstr. 1985, 102,79324q1.
[lo] E. M . M. den Brabander-van den Berg. E. W. Meijer, Angen. Chem. 1993,105.
1 3 7 0 ~1372; Angew. Chem. In!. Ed. Engl. 1993. 32, 1308-1311.
[11] J. F. G. A. Jansen, E. M. M. den Brabander-van den Berg, E. W. Meijer, Sciewe. 1994, 266, 1226-1229.
[12] The 1x1, values of the dendrimers of all generations are comparable to the
Fpecitic optical rotation per chiral group. In the class of chiral dendrimers with
a chiral core and achiral branches it i s obvious that the optical rotation decreases with generation (51.
[13] D. 0. McDonnald. W. C. Still, J Am. Chem. SOC.1994, 116, 11550-11553:
b) S H. Gellman, G. P. Dado. G.-B. Liang. B. R. Adams, J. Am. Chem. SOC.
1991. 113. 1164.
[14] A similar decrease in optical activity, although not as pronounced, is found for
the amidc ahsorption in trifluoroethanol. In this solvent. however, neither the
aromatic nor the carhamate absorption could he detected with CD.
Anjirii.. C'bvm. lnt. Ed. E n d 1995, 34, No. 11
[15]
[16]
~ 7
Facile Synthesis and Solid-state Structure
of a Benzylic Amide [2]Catenane**
Andrew G. Johnston, David A. Leigh,* Robin J.
Pritchard, and Michael D. Deegan
The synthesis of interlocked molecular rings, catenanes, is one
of the greatest challenges in preparative chemistry." - 31 Large
macromolecular catenane structures (10' D) are found in DNA,
where they appear to act as intermediates during the replication,
transcription, and recombination p;oce~ses,[~~
and are probably formed in small quantities in some polymerization reactions
by the chance threading of growing molecular chains through
large rings.c61Recently the structural characteristics of smaller
catenanes (lo3 D) have earmarked them, together with their
relatives the rotaxanes, as key elements in the development of
components for nanoscale electronic devices and molecular machines such as molecular shuttles, switches, and information
storage systems.[3* Here we report the serendipitous formation
of a new amide-based [2]catenane (1) prepared in one step from
two commercially available starting materials (see Scheme 2).
The catenane is obtained in 20 % yield (remarkable for an eightmolecule condensation) following a chromatography-free purification procedure simple enough to be performed in a wellequipped high school or undergraduate laboratory. The
structure of 1 has been confirmed by N M R spectroscopy, mass
spectrometry, and, in particular, by X-ray crystallography,
which reveals a beautiful self-assembled system held together by
networks of inter- and intramolecular hydrogen bonds and perfectly tessellating n-stacking interactions between four aromatic
rings. Each catenane consists of two identical, interlocked, 26membered rings with an internal cavity of 4 x 6 A, making 1 the
smallest interlocked ring system yet isolated.
[*I Dr. I).A. Leigh, A. G. Johnston, Dr. R. J. Pritchard
Department of Chemistry
University of Manchester Institute of Science and Technology
Sackville St., Manchester M60 1QD (UK)
Telefax: Int. code (161)200-4539
M. D. Deegan
Gas Research Centre, British Gas PLC
Loughhorough (UK)
[**I We thank Dr. J. P. Smart for useful discussions and advice, and S. Davey, M.
Bolgar. and Prof. S . Gaskell for mass spectral data. This work was carried out
through the support of a British Gas Scholarship award (to A. G. J).
8 VCH firiugsgesellschafr nibH, 0-69451 Weinheim, 1995
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0570-0833l95llIl/-l2093 10.00 .25/0
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As part of a program to prepare chemical sensors for small
gas molecules we identified the simple amide macrocycle 2 as a
potential molecular receptor for carbon dioxide. Molecular
modeling indicated a favorable mode and enthalpy of interaction of 2 with CO, (Scheme 1)J8] and the synthesis was attemptC
I
e
,
8.50 8.00 7.50
,
f
----r----r------r--
7.00 6.50 6.00 5.50
5.00
4.50 4.00
-6
2 + co2
b)
Scheme 1. Structure of an amide macrocycle designed to bind to CO,
ed by means of a direct [2 + 21 condensation (Scheme 2). Upon
addition of equimolar quantities of isophthaloyl dichloride (3)
and para-xylylenediamine (4) to a solution of triethylamine in
chloroform, a precipitate began to form almost immediately.
After 24 h the precipitate was removed by filtration, and the
filtrate was washed with acid, base, and water, and concentrated
to dryness to give a white solid which proved to be a single
compound. 'H and 13C NMR spectra in [D,]dimethylsulfoxide
(Figs. l a and lb) and the low molecular weight mass spectrum
(< 1000 Da, Fig. Ic) were consistent with the anticipated
macrocyclic structure. However, in complexation experiments
the material showed no signs of binding CO,.
__-_
-
-
-, . _ _ _
-,--190 180 170 160 150 140 130 120 110 100 90 80- 70-z'<5-&-30
_ 7
~
-20
-6
0
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c)
CI
+
100
2
CI
2?3
+
J
308
60
533
I
I'
I
4?0
20
0
200
loo--,I
400
300
600
500
1
Scheme 2. One step, eight-molecule condensation to give the [2]catenane 1.
1) Et,N, anhydrous CHCI,.
Single crystals were obtained (by slow diffusion of acetone
vapor into a methanolic solution of the material) which proved
suitable for structural investigation by X-ray crystallography
(Figs. 2-4). The crystal study revealed why CO, binding did
not occur; the [2 + 21 macrocycle formed was not in fact a
discrete molecule but rather the [2]catenane 1 with a second
macrocycle threaded tightly through the cavity of the first!
Octaamide [2]catenanes derived from a hindered aniline have
been independently reported by Hunter et ahc9-I and Vogtle
et al.,[''l and characterized by extremely elegant NMR experi1210
0 VCH
Verla~sgesellschuftmhH, 0-69451 Weinheim. 1995
1
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600
700
' ! ' "
800
" " "
" " " '
900
"
"
1000
Fig. 1. Selected spectroscopic data for 1: a) 'H NMR and b) "C NMR spectra in
[DJDMSO at room temperature (298K). The second macrocycle is represented by
the heavy ring. The simple NMR spectra indicate that the macrocyclic rings of 1
rotate rapidly on the NMR timescale at room temperature in DMSO, but the signals
for protons e andfare still broad. c) Fast atom bombardment mass spectrum using
meta-nitrobenzyl alcohol as matrix.
ments and mass spectrometry. However, 1 is the first amidebased catenane for which the structure has been determined by
X-ray crystallography. The solid-state ensemble is dominated
by inter- and intramolecular hydrogen bonding interactions together with n-stacks composed of four aromatic rings.
0570-0833195jllll-1210 $ 10.00f ,2510
Angekv. Chem. Int. Ed. Engl. 1995, 34, N o . 11
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Fig. 2. Solid-state structure of [2]catenane 1 as determined by X-ray crystallography (for clarity, carbon atoms of one
macrocyclic ring of a catenane are shown in blue and those of the other in yellow; oxygen atoms are red, nitrogen atoms
purple. and hydrogen atoms white). a ) A single macrocyclic ring (the minimum repeating unit in the crystal structure),
maximum internal diameter 4 x 6 A. Selected bond lengths [A]:01-C9 1.261,02-C13 1.226,03-C20 1.241,04-C24 1.224,
N5-CY 1 321, " 3 0
1.466, N6-Cl3 1.353, N6-Cl4 1.472, N7-Cl9 1.453, N7-C20 1.336, N8-C24 1.339, N8-C25 1.449.
Selected bond angles ['I: 01-CY-C10 119.218,01-C9-N5 122.150.02-Cl3-Cl2 119.349,02-C13-N6 122.677.03-C20-C21
119.916,03-C20-N7 120.218.04-C24-C23 121.674.04-C24-N8 121.191, N5-C9-C10 118.630, N5-C30-C29 115.287. N6C13-CI2 117.560, N6-Cl4-Cl5 116.266, N7-C20-C21 119.855, N7-Cl9-Cl8 113.918, N8-C24-C23 117.091, N8-C25-C26
113.913. Selecteddihedralangles["]:Cll-C10-C9-N5 -27.081,Cll-C10-C9-01 152.343, C10-C9-NS-C30 173.748, C9-N5C30-C29 109.880. N5-C30-C29-C28 63.120, C1 l-C12-C13-N6 -150.140. Cll-Cl2-C13-02 22.751, C12-C13-N6-C14
179.816. C13-Nb-Cl4-Cl5 -77.409, N6-C14-C15-C34 -85.918, C22-C21-C20-N7 - 18.619, C22-C21-C20-03 160.175,
C21-C2o-N7-C19 178.022. C20-N7-CiY-C18 139.509, N7-Cl9-CiX-Cl7 -30.022, C22-C23-C24-NX 25.692, C22-C23C24-04 - 151.932. C23-C24-NX-C25 178.325, C24-NX-C25-C26 - 152.766. N8-C25-C26-C39 91.121. b) Representation
of 1 with 100'% van der Waals radii.
ring contains one cndo- and three
exo-carbonyl groups). The two
isophthaloyl rings of each macrocycle are parallel to each other
and form roughly an 80" angle
with the mutually parallel xylylene units of the same macrocycle (Figs. 2a and b).
The two macrocyclic rings of
each catenane are held in a
fixed orientation in the solid state
by a total of six hydrogen bonds,
including two sets of bifurcated
hydrogen bonds between the
amide hydrogens of the cisoid
isophthaloyldiamide unit of each
macrocycle and the rxo-carbonyl
group of the transoid isophthaloyldiamide unit of the other
macrocycle (i.e. N7 ' ' ' 01'' ' ' N8
and N7' ' ' ' 0 1 ' . ' N8', Fig. 3).
The fixed orientation of the
The macrocyclic rings of each catenane are structurally and,
in the solid state, conformationally identical (Fig. 2a), bearing
close resemblance to the conformation determined for the
Hunter catenane in CDCI,/CD,OD solution.191Each macrocycle adopts a chairlike conformation with a single carbonyl
group pointing into the macrocyclic cavity (i.e. each macrocyclic
macrocyclic rings within a
Ilane confers
upon the
individual catenanes (adjacent
n,o[ecules in the crystal structure
form enantiomeric pairs' Fig' 3)'
The crystal lattice has a fascinating layered structure. In both
directions within each layer the
catenanes assemble to maximize
both inter- and intramolecular rcstacking interactions. Each stack
consists of four units in three different catenanes in an ABCD
sequence (Fig. 4). The four aromatic rings in each stack are
close to parallel and offset from each other in the classic manner
which maximizes favorable electrostatic interactions within the
Every aromatic ring in every catenane is involved in
one of these rc-stacks, which pack perfectly to form a single layer.
Fig. 3. Interlayet- packing in the crystal structure of 1 in which all three modes of
hydrogen bonding (two intra- and one intermolecular) are clearly shown. The layers
are held together by an exquisite hydrogen bonding array in which four intramolecular hydrogen bonds per catenane hold the macrocyclic rings of an individual
molecule in a fixed orientation and two intermolecular hydrogen bonds per
catenane pair hold adjacent layers in place. Note that only the protons of the
"inverted" nmide groups are available for intermolecular hydrogen bonding Distances for these intracatrnane hydrogen bonds [A]: 01-N7' ( = 01'-N7) 3.264,
01-N8' ( = Ol'-NX) 3.119. 02-N5' ( = 0 2 - N 5 ) 3.052; distance for the hydrogen
bond between the catenanes: 04A-N6 ( = N 6 A - 0 4 ) 2.913.
Fig. 4. Intralayer packing in the crystal structure showing tessellation of the TCstacks of four aromatic units to form discrete layers within the crystal. A is a
xylylene group bearing one exo- and one endo-carbonyl group: B is a xylylene group
bonded to two rxo-carbonyl groups ofa second, adjacent catenane: Cis the transoid
isophthaloyldiamide unit of the other macrocycle of the second catenane; and D is
the cisoid isophthaloyldiamide unit of a third catenane, adjacent to the second and
one-removed from the first. Distances between the centroids of the rings forming a
a-stack [A]: A ' . B 3.874, B"'C4.033, C " ' D 4 2 3 9 .
Angelc. ('hrm. l n l . Ed Enxl 1995, 34, No. 11
c) VCH Verlug.sgesellschu/fimhH, D-69451 Wrmhritn, I995
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The catenane layers, in turn, are held together by van der
Waals interactions and two intermolecular hydrogen bonds between each catenane and its nearest neighbors in the layers
above and below (Fig. 3). The interlayer hydrogen bonds are
formed between the amide hydrogen atoms of the inverted
amide groups and the carbonyl groups of the cisoid isophthaloyldiamide units. The remaining amide hydrogen atoms and
carbonyl groups (NS' and 0 2 ; N5 and 02') appear, by the positioning of the heavy atoms, to be connected through an unusual
hydrogen bonding architecture in which the amide proton either
binds to the n-cloud of the O=C bond or binds in a nonlinear
arrangement to the oxygen atom. Since the H atoms are not
resolved in the structure, these two possibilities cannot currently
be distinguished.
The X-ray crystal structure supports the proposal that the
driving force for catenane formation is hydrogen bonding between the newly formed 1,3-diamide units and carbonyl groups
on the acid chloride or other intermediates. The stacking of the
electron-rich xylylene and electron-poor isophthaloyl rings may
also play a supporting role. In the mannerfirst introduced with
the Stoddart catenanes, the formation of new functionalgroups in
this reaction controls the self-assembly of a topologicully complex
product.[31
The following communication["] shows that 1 is not an isolated example of a [2]catenane, but rather the simplest of a
diverse family of catenanes derived in one step from aromatic
1,3-dicarbonyl compounds and benzylic diamines. Self-assembly processes currently provide the only viable route to these
kinds of topologically complex molecules which exhibit, in both
solution and the solid state, a range of structural and dynamic
properties not available to topologically trivial molecules.
Experimental Procedure[' '1
To a stirred solution of triethylamine (1.19 g, 18.9 mmol) in anhydrous chloroform
(130mL, stabilized with amylenes not ethanol) [19] under argon were added 3
(0.87 g, 4.3 mmol) in anhydrous chloroform (130 mL) and 4 (0.58 g, 4.3 mmol) in
anhydrous chloroform (130 mL) simultaneously, over 30 min by means of motordriven syringe pumps. The mixture was allowed to stir for about 12 h and then
filtered. The filtrate was washed with 1 M aqueous hydrochloric acid (3 x 200 mL).
then 5 % aqueous sodium hydroxide (3 x 200 mL), and finally water (3 x 200 mL).
The organic layer WAS then dried over anhydrous magnesium sulfate and concentrated under reduced pressure to afford 0.23 g (20.1 %)of [2]catenane 1. M.p. 31 5 "C
(decomp); ' H N M R (300 MHz. [DJDMSO): 6 = 4.01 (br. s, 16H, CH,), 6.75 (br.
s, 16H, p-xylyl H), 7.50 (t, J,. = Js, = 8 Hz, 4H, isophthaloyl 5-H), 7.88 (dd,
J4. = 8 Hz, J2.4= 1 Hz, 8H, isophthaloyl 4-H and 6-H), 8.05 (d, J2.&= 1 Hz. 4H,
isophthaloyl 2-H), 8.62 (s, 8H, CONH); "C NMR (75 MHz, [DJDMSO):
6 = 46.98, 130.03, 130.81, 132.40, 133.78, 138.40, 141.35, 168.94; FAB-MS (mNBA
matrix): m/z 1065 [ ( M + H ) + ] ,533 [(M/2 + H)+]. The precipitate from the reaction contains polymers, larger macrocycles, and catenanes (as indicated by FAB-MS
and NMR analysis) which have not yet been completely characterized.
Received: January 9, 1995 [Z7610IE]
German version: Angew. Chem. 1995, 107, 1324-1327
Keywords: catenanes . macrocycles . structure elucidation
[I] G. Schill, Catenones. Rofoxanes and Knots, Academic Press, New York, 1971.
[2] For a representative paper from the Strasbourg group see J.-F. Nierengarten,
C. 0 . Dietrich-Buchecker, J.-P. Sauvage, J. Am. Chem. Soc. 1994, 116,
375-376.
[3] For a representative paper from the Birmingham group see D. B. Amabilino,
P. R. Ashton, C. L. Brown, E. Cordova, L. A. Godinez, T. T. Goodnow, A. E.
Kaifer, S. P. Newton, M. Pietraszkiewicz, D. Philp, E M. Raymo, A. S. Reder,
M. T Rutland, A. M. 2. Slawin, N. Spencer, J. E Stoddart, D. J. Williams, J.
Am. Chem. Soc. 1995, 117, 1271-1293.
[4] M. A. Gellert, Annu. Rev. Biochem. 1981, 50, 879-910.
[S] J. C. Wang, J. Biol. Chem. 1991, 266, 6659-6662.
[6] J. E. Mark, New J. Chem. 1993, 17, 703-709.
[7] R. A. Bissell. E. Cordova, A. E. Kaifer, J. F, Stoddart, Nature (London) 1994,
369, 133-137.
1212
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Verlagsgesellschaft mbH, 0-6945f Weinheim, 1995
[8] Molecular modeling calculations (carried out on a CAChe Tektronix workstation with an MM2 forcefield) and semiempirical quantum mechanical calculations (MOPAC 6.0; AM1 parameterization) indicate favorable enthalpies for
the interaction of 2 and CO,. The complexation properties of a derivative of
2 with CO, will be reported elsewhere.
[9] C. A. Hunter, J. Am. Chem. Soc. 1992, 114, 5303-5311.
[lo] C. A. Hunter, D. H. Purvis, Angew. Chem. 1992,104,779-782; Angew. Chem.
Int. Ed. Engl. 1992, 31, 792-795.
[ l l ] F. J. Carver, C. A. Hunter, R. J. J. Shannon, J. Chem. Soc. Chem. Commun.
1994, 1277-1280.
[12] F. Vogtle, S. Meier, R. Hoss, Angew,. Chem. 1992, 104, 1628-1631; Angew.
Chem. I n t . Ed. Engl. 1992, 31. 1619-1622.
[13] C. A. Hunter, J. K. M. Sanders, J. Am. Chem. SOC.1990,112. 5525-5534.
M =1065.2, orthorhombic, space group
1141 Crystal data for 1: C,,H,,O,N,,
Pbcn (No. 60), a = 17.510(4), b = 12.632(4), c = 23.834(8) A, V = 5272(5) A',
pCalcd
= 1.342 g cm-3, Z = 8; 4171 reflections measured, 765 with I > 2u(1).
Diffractometer Rigaku AFC6S. 26,,, = 50", Mo, radiation, I = 0.73069 A,
T = 296. The structure WAS solved by direct methods (SHELLXS-86 [15]) and
subjected to least-squares refinement (TEXSAN 1361) to yield final residuals of
R = 0.062 and R, = 0.063 for 161 parameters. All hydrogen atoms were placed
in chemically reasonable positions. Further details of the crystal structure
investigation may be obtained from the Director of the Cambridge Crystallographic Data Centre, 12 Union Road, GB-Cambridge CB2 1EZ (UK), on
quoting the full journal citation.
[15] G. Sheldrick, SHELLXS-86, Crystallographic Computing 3 175, OUP. 0 x ford, 1985.
[16] Molecular Structure Corporation, TEXSAN, Texray Structure Analysis Package, 1985, MSC 3200A Research Forest Drive, The Woodlands, TX 77381,
USA.
1171 A. G. Johnston, D. A. Leigh, L. Nezhat, J. P. Smart, M. D. Deegan, Angew.
Chem. 1995. 107. 1327-1331; Angew. Chem. I n t . Ed. Engl. 1995, 34, 12121216.
[18] Few examples of self-assembly processes are straightforward enough to be
introduced into undergraduate laboratories. The synthesis of 1 is an exception
and has been successfully incorporated into the first-year organic chemistry
course at the University of Manchester Institute of Science and Technology.
[19] The use of chloroform that has not been rigorously dried or contains ethanol
gives lower yields of the [2]catenane and, more problematically, produces
byproducts arising from the partial hydrolysis of the starting acid chloride.
These are not removed in the above workup procedure. However, in this case
the [2]catenanecan be obtained pure by carefully washing the end product with
cold chloroform.
Structurally Diverse and Dynamically Versatile
Benzylic Amide [2]Catenanes Assembled Directly
from Commercially Available Precursors**
Andrew G. Johnston, David A. Leigh,* Lida Nezhat,
John P. Smart, and Michael D. Deegan
The unique architectures and structural characteristics of
catenanes and rotaxanes have identified them as attractive
targets in the search for nanoscale devices and molecular electronic applications.['] Accordingly, following the pioneering
work of Stoddart et a1.f2]and Sauvage et al.,13] there is great
interest in the development of new catenane systems that can be
obtained in high yieldk4- "1 and especially syntheses that are
tolerant towards structural variations which can be used to control the dynamic properties of the catenanes. In 1992 Hunter
'1
and Vogtle et al. reported the first amide-based catenane~,[~.
[*] Dr. D. A. Leigh, A. G . Johnston, Dr. L. Nezhat, Dr. J. P. Smart
Department of Chemistry
University of Manchester Institute of Science and Technology
Sackville St.. Manchester M60 1QD (UK)
Telefax: Int. code + (161)200-4539
M. D. Deegan
Gas Research Centre, British Gas PLC
Loughborough (UK)
[*"I This work was carried out through the support of a British Gas Scholarship
award (to A. G. J) and the EPSRC IPS initiative (GR/J/88579).
0570-0833/95j1111-1212$ 10.00+.25/0
Angew. Chem. Int. Ed. Engl. 1995, 34, No. f 1
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catenane, structure, synthesis, solis, benzylic, amid, state, faciles
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