Rotaxane or pseudorotaxane? Effects of small structural variations on the deslipping kinetics of rotaxanes with stopper groups of intermediate size

Article abstract of DOI:10.1002/1099-0690(200108)2001:15<2877::AID-EJOC2877>3.0.CO;2-R

Three series of rotaxanes have been synthesized variously by slipping synthesis, in which axis and wheel are melted in admixture, by recognition of amide groups inside the macrocyclic wheel, or by an anionic template method, in which the stoppering phenol

Full text of DOI:10.1002/1099-0690(200108)2001:15<2877::AID-EJOC2877>3.0.CO;2-R

FULL PAPER
Rotaxane or Pseudorotaxane? Effects of Small Structural Variations on the
Deslipping Kinetics of Rotaxanes with Stopper Groups of Intermediate Size
Ansgar Affeld,[a] Gosia M. Hübner,[a] Christian Seel,[a] and Christoph A. Schalley*[a]
Keywords: Arrhenius kinetics / Eyring theory / Rotaxanes / Slipping synthesis / Supramolecular chemistry / Template
synthesis
Three series of rotaxanes have been synthesized variously by
slipping synthesis, in which axis and wheel are melted in
ing theory. Small structural variations give rise to surprising
effects on the activation parameters. Firstly, in some ex-
admixture, by recognition of amide groups inside the macro- amples, the axle length affects the deslipping barrier, al-
cyclic wheel, or by an anionic template method, in which the
stoppering phenolates are hydrogen bonded to the wheel
and then joined by reaction with a semi-axle. The 3,5-di-tert-
though the size complementarity of stopper and wheel re-
main unchanged. Secondly, stopper flexibility has an import-
ant influence on the deslipping rate. Thirdly, exchange of a
butylphenyl stopper used for most of these rotaxanes is large carbonamide for a sulfonamide in the wheel significantly re-
enough to permit their isolation, but still allows the wheel to
duces the entropic costs of the deslipping, resulting in a pro-
deslip from the axle under appropriate conditions. The de- nounced deslipping rate enhancement. Fourthly, intramolec-
slipping activation parameters for all rotaxanes are derived
ular hydrogen bonding within the wheel decelerates deslip-
from 1H NMR kinetic measurements and have been evalu- ping by a factor of more than 104.
ated from the Arrhenius equation as well as according to Eyr-
Introduction
covalent bond. This process has several aspects which are
of interest. Firstly, the height of the activation barrier is
determined by the relative sizes of the inner diameter of the
wheel and the outer boundary of the stoppers.[15] Kinetic
measurements of the deslipping of a series of rotaxanes
with, for example, the same wheel and different axles can
thus be used to measure the effective size requirements for
different stoppers. A similar approach making use of half-
life time measurements has recently been applied to rotax-
anes with dendritic stoppers.[16] Secondly, depending on
conditions such as temperature and solvent, there exists a
region of intermediate stability[17] between rotaxanes and
pseudorotaxanes.[18] While the former are stable entities,
due to the presence of bulky end groups attached to the
axle, the latter do not form inclusion complexes in the ab-
sence of attractive forces, due to the entropic preference for
the free species. Between these two extremes, rotaxanes with
stoppers of medium size exist as metastable species, the
stability of which strongly depends on the environment. De-
slipping experiments provide insights into the requirements
necessary to render a rotaxane metastable. Thirdly, deslip-
ping is the retro reaction corresponding to the slipping syn-
thesis.[19] Study of it consequently yields more detailed in-
formation about the slipping synthesis and might be useful
for its further refinement. Finally, how does a wheel move
along the axle? This question has been addressed with re-
spect to molecular shuttles,[20] rotaxanes that bear two ‘‘sta-
tions’’ in the axle, as well as to the related process of cir-
cumrotation in catenanes.[21] A kinetic analysis of the de-
slipping represents another approach to this question, since
the entropy of activation should be affected by the nature
of the shuttling process.
During the last decade, the chemistry of mechanically
linked molecules[1] Ϫ rotaxanes, catenanes, and knots[2]
Ϫ
has received fresh impetus from the development of effici-
ent template methods for the synthesis of these com-
pounds.[3] It is not, however, only their synthetic availabil-
ity that has promoted increasing interest in these species.
The discovery of naturally occurring, catenated DNA
rings,[1b,4] knotted proteins,[5] and the rotaxane-like ATP
synthase[6] and flagellum motors in bacteria[7] have also
shed new light on their artificial analogs and their proper-
ties. Topological chirality[8] and the development of mo-
lecular machines based on rotaxanes and catenanes[9] are
two of the most intriguing aspects of these species. Many
other functional properties such as electron transfer or
energy transfer from one stopper to the other,[10] the
quenching of luminescence in self-assembled pseudorot-
axanes,[11] photoswitchability of the catenanes’ ring geo-
metry,[12] electric conductance through polyrotaxanes,[13]
and the implementation of logic functions at the molecu-
lar level[14] have been studied intensely.
Here, we present results from deslipping experiments that
give insight into those features of the rotaxanes that relate
to molecular mobility. In the deslipping reaction
(Scheme 1), one of the stoppers slides through the wheel,
abolishing the mechanical bond between axle and wheel and
liberating the free components, but without cleaving any
[a]
´
Kekule-Institut für Organische Chemie und Biochemie der
Universität,
Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
E-mail: c.schalley@uni-bonn.de
Eur. J. Org. Chem. 2001, 2877Ϫ2890
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ193X/01/0815Ϫ2877 $ 17.50ϩ.50/0
2877

A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
Another approach to the kinetic parameters of the deslip-
ping reaction is the determination of ∆G‡, ∆H‡, and ∆S‡
according to the Eyring theory [Equations (3) and (4), kB is
the Boltzmann constant, h the Planck quantum]. The two
methods of evaluation differ somewhat, each having its own
advantages and disadvantages. For comparative purposes,
both were used to evaluate the data summarized in Table 1.
Although the two approaches do not produce identical re-
sults in an absolute sense, the trends follow the same pat-
terns and it seems reasonable to discuss the data jointly.
Before discussion of several structural variations and
their effects on deslipping kinetics, let us consider one rep-
resentative example of a kinetics experiment. Figure 1
Scheme 1. Schematic representation of the deslipping process and
illustration of the working hypothesis
Results and Discussion
The Working Hypothesis and its Implications
As a starting point for our investigation, we will use the
following model. An idealized rotaxane in its simplest rep-
resentation (Scheme 1) is a structure built out of three dif-
ferent subunits: a cyclic wheel, a straight and slender axle,
and a spherical, bulky stopper at each of the two ends of
the axle. The bond between axle and wheel is purely mech-
anical; dethreading is hampered only by the stoppers, and
not by additional forces between axle and wheel. In this
view, movement of the wheel along the axle can be regarded
as a unidimensional diffusion process, which may result in
successful deslippage upon collision of the wheel with one
of the stoppers. This process is a unimolecular reaction, and
accordingly follows first order kinetics.
1
shows the H NMR spectra of Rot1@2 after several time
intervals at 384 K. It can clearly be seen that the signals of
the rotaxane are becoming smaller and those of the free
components appearing. In particular, the signals for Hc and
Hd in the axle’s central part can easily be followed, because
they are significantly shifted to higher field in the rotaxane
(δ ϭ 6.69 and 6.95) than in the free axle (δ ϭ 7.38 and
7.63), due to the anisotropy of the aromatic rings incorpor-
ated in the wheel. On the basis of these measurements at
four different temperatures, it is possible to determine the
rate constants k (Figure 2, a) and evaluate the kinetic para-
meters in Arrhenius (Figure 2, b) and Eyring (Figure 2, c)
plots.
(1)
(2)
Different Axle Central Units
With respect to our simple model, let us first consider the
effects of different axle central units on the deslipping kinet-
ics of rotaxanes with the same 3,5-di-tert-butylphenyl stop-
pers and the same tetralactam wheel 2. Scheme 2 summar-
izes the data obtained for Rot1@2ϪRot4@2, together with
the structures of their wheel and axles. In all of these rotax-
anes, the central units differ not in length but in flexibility.
While Rot1@2 has some additional degrees of freedom due
to the axle’s single bonds, rotation of these bonds is cer-
tainly reduced with the introduction of the amide bond,
with its partial double bond character, and of the double
bond in the other two rotaxanes. Furthermore, Rot3@2 is
capable of hydrogen bonding to the wheel with at least two,
and more probably three hydrogen bonds Ϫ as implied by
studies of the much better binding abilities[22] of secondary
amides versus tertiary ones and the presence of three hydro-
gen bonds in X-ray structures of similar rotaxanes.[23] How-
ever, the kinetic data do not show large differences in this
series of rotaxanes. There seems to be a trend in the en-
tropic terms (kϰ and ∆S‡), with lower axle flexibility re-
sulting in a lower activation entropy, but the effects are so
small that we may consider Rot1@2ϪRot4@2 to be more
or less the same in terms of their kinetic deslippage para-
meters.
This model has some implications for the activation para-
meters kϱ and EA, as derived from the Arrhenius equation
[Equations (1) and (2)]. The energy of activation, EA, rep-
resents the barrier of the rate-determining step of a reac-
tion. For the deslipping process, it may reasonably be ex-
pected that this value is determined by the passage of the
bulkiest part of the stopper. In contrast, the slender central
part of the axle should not be associated with high barriers
of any kind and so would not be expected to affect EA.
Accordingly, different rotaxanes with the same stoppers and
wheels, but with different central axle moieties should be
subject to the same barrier EA. The frequency factor kϱ
instead encompasses the entropic effects of the deslipping
reaction. In particular, for closely related rotaxanes with
different axle lengths, one would expect to find frequency
factors decreasing with increasing axle length, since a
longer axle results in an increased time needed by the wheel
to shuttle from one end of the axle to the other. Thus, a
lower number of collisions of the wheel with the two stop-
pers should result for longer axles, also reducing the pre-
exponential factor.
This picture changes, however, when axles of different
lengths are considered (Scheme 3), in that a longer axle in-
deed results in a decreased value of kϰ, as predicted by our
simple model. Not very pronounced in the first series
(Rot4@2ϪRot6@2), which was studied in [D7]DMF, the ef-
fect becomes obvious for the structurally related rotaxanes
(3)
(4)
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Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
1
Table 1. Kinetic parameters derived from evaluation of H NMR kinetic experiments according to the Arrhenius and Eyring theories,
together with half-lifes at 333 K and axle lengths obtained from molecular modeling of the most extended conformations, using the Sybyl
force field as implemented in the Spartan program[33]
EA
kϱ
[MHz]
∆G‡ (298 K)
∆H‡
∆S‡
t1/2 (333 K)
[h]
l
[kJ molϪ1
]
[kJ molϪ1
]
[kJ molϪ1
]
[J KϪ1 molϪ1
]
[A]
˚
[a]
[a]
[a]
[b]
[a]
[a]
[c]
[c]
[c]
[d]
Rot1@2
Rot3@2
Rot4@2
Rot4@2
Rot5@2
Rot6@2
Rot7@2
Rot8@2
Rot9@2
Rot9@2
84
81
77
63
83
77
104
98
88
85
77
79
75
82
134
26
16
4
0.1
42
2
94
93
92
88
92
93
96
93
88
82
80
85
76
75
142
81
78
68
60
81
74
101
95
85
87
74
76
68
75
Ϫ45
Ϫ49
Ϫ80
Ϫ93
Ϫ39
Ϫ64
18
111
61
58
23
48
115
82
38
8
5
Ͻ 1
4
Ͻ 0.5
Ͻ 0.5
Ͼ106
14.5
14.5
14.6
14.6
10.6
16.9
10.0
14.1
16.0
16.0
10.0
16.0
14.6
10.6
14.5
48300
12050
1530
848
470
130
920
4940
50
7
Ϫ10
Ϫ15
Ϫ19
Ϫ30
Ϫ26
0
[c]
[c]
Rot10@2Ј
Rot11@2Ј
Rot4@12
Rot5@12
Rot3@13
Rot3@14
[a]
[a]
[a]
[a]
130
Ϫ40
No deslipping observed
[b]
[a] Solvent: [D7]dimethylformamide. Ϫ Solvent: [D8]tetrahydrofuran. Ϫ [c] Solvent: [D2]tetrachloroethane. Ϫ [d] Solvent: [D]chloroform.
Figure 1. 1H NMR kinetics experiment with Rot1@2 at a temperature of 384 K (increasing time intervals from bottom to top). The
arrows indicate the decreasing signals of the rotaxane and the growing signals of the free components. The signal assignment is given in
the formulae, together with the definition of axle length used in the text and Table 1
Eur. J. Org. Chem. 2001, 2877Ϫ2890
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A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
with ether axles Rot7@2ϪRot9@2, for which deslippage
was followed in [D2]tetrachloroethane. Unfortunately, we
have not been able to study a rotaxane with three or even
more benzene units in the axle central unit, due to insolubil-
ity in the solvents used here. Thus, we rely on the ethano
bridge in axles 6 and 9, which of course induces an element
of flexibility not present in the shorter analogs. Neverthe-
less, the overall qualitative result of decreasing kϰ can
clearly be seen and is also found for the Rot10@2Ј and
Rot11@2Ј pair of rotaxanes (see below).
Figure 2. From top to bottom: (a) Determination of rate constants
for Rot1@2 at four different temperatures, (b) Arrhenius plot for
the evaluation of EA and kϱ. (c) Eyring plot for the determination
of ∆G‡, ∆H‡, and ∆S‡
Scheme 3. Kinetic parameters of rotaxanes with axles of different
lengths. Note that solubility required that the series
Rot4@2ϪRot6@2 was studied in [D7]DMF, while the data for
Rot7@2ϪRot11@2Ј were collected in [D2]tetrachloroethane. Direct
comparison between these two series is thus not possible
More strikingly, however, the series Rot7@2ϪRot9@2
shows a decrease in EA (104, 98, and 88 kJ/mol, respect-
ively) and ∆H‡ (101, 95, and 85 kJ/mol) with increasing axle
length. Although this effect is still not large, it is clearly
beyond the experimental error limits in this series. It is also
reflected in the half lives of these rotaxanes (Table 1), which
decrease by a factor of 10, from 82 h for Rot7@2 to 8 hours
for Rot9@2. This effect is not predicted by our model and
Scheme 2. Kinetic parameters of rotaxanes with axles of the same
length, but different flexibilities. Note that Rot3@2 is capable of
hydrogen bonding between axle and wheel, while the other two
rotaxanes are not. For readability, part of the data in Table 1 is
given
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Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
Ϫ although we do not have a conclusive interpretation of
it Ϫ clearly demonstrates that the model may serve as no
more than a first approximation to a description of a rotax-
ane and its behavior.
Consequently, two different, but structurally closely re-
lated series of rotaxanes were found to display very different
deslipping kinetics, probably due to the different solvents
that had to be used in these studies, due to solubility prob-
lems. One effect might be caused by π-π interactions be-
tween axle and wheel, which should be quite different in
magnitude in polar and in nonpolar solvents.
Solvent Effects
Because of solubility problems, some of the rotaxanes
were examined in [D7]DMF, others in [D2]tetrachloro-
ethane. The solvent was, however, kept the same within each
series. All trends discussed here are derived from series of
rotaxanes treated under the same conditions, and direct
comparison of rotaxanes studied in different solvents has
carefully been avoided. It nevertheless appeared relevant to
try to establish whether there are significant solvent effects.
Two rotaxanes were studied: Rot4@2 was examined in
[D7]DMF and [D8]THF, while the deslipping kinetics of
Rot9@2 were followed in [D2]tetrachloroethane and
[D]chloroform. In both cases, the effects were rather small.
For Rot9@2, all parameters were the same within experi-
mental error, independent of the solvent. In contrast,
Rot4@2 exhibited lower EA and ∆H‡ values in [D8]THF
than in [D7]DMF, which might be attributable to (i) hyd-
rogen bonding between the wheel’s amide protons and the
solvent, which would be less pronounced in THF, and (ii) s-
tronger π-π interactions between the two components in the
more polar DMF. Nevertheless, this effect does not have
any dominating effect on deslippage, although the differ-
ence between DMF and tetrachloroethane may, of course,
result in much larger effects.
Scheme 4. Kinetic parameters of rotaxanes with stoppers of differ-
ent sizes and shapes
Of course, the stoppers need not necessarily deslip with
both substituents passing through the wheel at the same
time; they might also follow a stepwise deslippage mechan-
ism. Hence, one of the tert-butyl or phenyl groups would
pass through the macrocycle first, followed by the other in
the next reaction step. In this case, deslipping would involve
two barriers, one of which would have to correlate to the
rate-determining step. If that scenario does hold true, the
total span is probably not important. Instead, a smaller ef-
fective size becomes relevant, amounting (Figure 3, a, b) to
˚
ca. 9.3 A for the diphenyl-phenyl stopper and again being
˚
ca. 2 A shorter for the di-tert-butylphenyl stopper. Con-
sequently, the conclusion would not change. The stopper
span alone thus cannot explain the results obtained from
deslipping experiments.
Stopper Shape and Flexibility
When comparing two stoppers of different sizes, we enco-
There are, however, two effects that can probably account
untered a second surprising effect (Scheme 4). The 3,5-di- for the increase in deslipping rate for Rot10@2Ј and
phenylphenyl stopper in Rot10@2Ј and Rot11@2Ј[24] has a Rot11@2Ј. In terms of stopper shape, the tert-butyl groups
˚
span of ca. 11.8 A, while the 3,5-di-tert-butylphenyl stopper represent a more spherical substituent, extending vertically
˚
˚
is more than 2 A narrower (Figure 3). In a simplified view, from the aromatic plane by ca. 4.4 A (Figure 3, c, d) as
˚
one would thus expect Rot10@2Ј and Rot11@2Ј to deslip compared to the 3.4 A of the phenyl substituents in axles
more slowly than their counterparts Rot7@2 and Rot9@2, 10 and 11. Thus, deslippage of Rot7@2 requires a more
respectively. Instead, the half life of Rot10@2Ј at 333 K (less pronounced expansion of the wheel upon deslippage, while
than 1 hour) is more than 80 times shorter than that of the rather flat diphenyl-phenyl stopper may slip through
Rot7@2 (82 hours) and a similar, although less pronounced, more easily. Of course, the terphenyl system in these stop-
decrease was found for the other pair.
pers is not perfectly planar. As in any biphenyl system, the
Eur. J. Org. Chem. 2001, 2877Ϫ2890
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A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
(kϰ and ∆S‡) contributions to the deslipping barrier for
Rot10@2Ј. Indeed, the data in Scheme 4 and Table 1 are in
agreement with this interpretation. The second pair,
Rot9@2/Rot 11@2Ј, for which the same effects are found,
shows that our findings are not a singular case valid only
for Rot10@2Ј and thus provides additional evidence.
Tetralactam Wheel versus Sulfonamide Macrocycle
Rather than a tetralactam wheel, the rotaxanes may also
feature a sulfonamide wheel, in which only one of the
amides is replaced by a sulfonamide (Scheme 5), and thus
only one carbonyl group is exchanged for a sulfonyl group.
Practical experience has been that the sulfonamide rotax-
anes deslip more quickly than those with the tetralactam
macrocycle, and the assumption of a larger wheel diameter
due to the longer SϪC and SϪN bonds has been invoked
as an explanation.[16d] In our experiments, the sulfonamide
rotaxanes Rot4@12 and Rot5@12 did indeed turn out to
deslip much more rapidly than their tetralactam analogs
Rot4@2 and Rot5@2. The half life decreased by a factor of
more than 100, from ca. 50 hours for Rot4@2 and Rot5@2
to less than 0.5 hours for Rot4@12 and Rot5@12 at 333 K.
To our surprise, however, it was not the enthalpic contribu-
tion to the barrier that made the difference. That would
have been to be expected, were increased bond lengths in
the wheel to affect the stopper/wheel size complementarity.
However, the changes in EA and ∆H‡ are within experi-
mental error. Much larger differences were observed in the
entropic contributions. The pre-exponential factor kϰ in-
creases by a factor of more than 100, and ∆S‡ is much less
negative for both sulfonamide rotaxanes as compared to
their tetralactam analogs. Again, the same observation was
Figure 3. Top (a, b) and side (c, d) views of space-filling models of
the 3,5-di-tert-butylphenyl and 3,5-diphenylphenyl stoppers gener-
ated with the Sybyl force field. The dimensions given for each stop-
per are those measured between the centers of the corresponding made for two examples, confirming that it is indeed a real
hydrogen atoms
effect.
What chemical reason, if not the lengths of the SϪC and
two phenyl rings will be tilted somewhat out of the plane SϪN bonds, can provide the basis for an explanation of
of the central ring. Nevertheless, this stopper can adapt this drastic change in activation entropy? Sulfonamides dif-
more easily to size requirements and steric stress, because fer from carbonamides in several respects. Firstly, if it has
rotation of the two phenyl substituents can result in further any effect on the deslipping kinetics at all, the presence of
flattening of the stopper without a large energetic demand. an additional oxygen atom should result in increased steric
Rotation of the tert-butyl groups, on the other hand, does hindrance and thus a deceleration of the deslippage reac-
not produce any significant change in size and shape. This tion. This is not observed and thus, most probably, the oxy-
leads directly on to the second effect. Stopper flexibility gen atom is not the cause of the faster decomposition of
might also contribute to the different kinetic behavior of the sulfonamide rotaxanes. Secondly, the sulfur in Rot4@12
Rot7@2 and Rot 10@2Ј. If a bending motion of the phenyl and Rot5@12 is more or less tetrahedral, while the carbonyl
rings in Rot10@2Ј were to result in a favorable geometry carbon in Rot4@2 and Rot5@2 is sp2-hybridized and thus
suitable for deslipping, the enthalpy of deslippage could should form the center of a CCN angle rather larger than
even be lower than that of the more bulky, not very easily the CSN angle in 12. Consequently, the inner diameter of
deformable, 3,5-tert-butyl-phenyl stopper. In other words, if the wheel might be expected to be somewhat smaller in
the bending potential energy surface is fairly flat for a Rot4@12 and Rot5@12, again resulting in slower deslip-
phenyl substituent, but steeper for a tert-butyl group, then page. Since this prediction is once more not in line with our
the transition structure for deslippage of Rot10@2Ј might findings, we can also rule out changes in bond angles as a
be energetically more favorable than that of Rot7@2. On reason for accelerated deslippage. Thirdly, the amide hydro-
the other hand, one might expect a tighter transition struc- gens are more acidic and so may produce stronger hydrogen
ture for Rot10@2Ј, resulting in higher entropic costs, since bonding. However, our axles do not have any hydrogen
a more peculiar spatial arrangement would be required for bond acceptors (except for the π-systems of the aromatic
productive deslippage. Consequently, expectation would rings, which are unlikely to play a dominant role). Thus,
predict lower enthalpic (EA and ∆H‡) and higher entropic hydrogen bonding between axle and wheel is not possible.
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Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
case, in which entropic disadvantages are compensated for
by a beneficial enthalpic situation. Seemingly, this is not
feasible in the case of Rot4@12 and Rot5@12, and a favor-
able entropic situation is found, with an almost unchanged
enthalpic contribution to the barrier.
Intracycle Hydrogen Bonding and its Effect on the
Deslipping Rate
The largest effect, however, is observed for rotaxanes that
again differ in only a minor structural variation. The wheel
in Rot3@2 bears two isophthalic amide building blocks,
while in Rot3@13 one of these is exchanged for a 2,6-pyridi-
nedicarboxylic acid diamide subunit (Scheme 7). Thus,
these two wheels differ only in the replacement of a CϪH
group for an isoelectronic nitrogen atom. Despite this small
structural change, the half lives of the two compounds dif-
fer by more than a factor of 104. The half life of ca. 60
hours at 333 K for Rot3@2 increases to a calculated value
of more than 1 million hours for Rot3@13, which reflects
the fact that it is possible to follow the deslipping kinetics
of Rot3@2 in a temperature range of around 300 to 380 K,
while Rot3@13 requires temperatures between 390 and
450 K for a reasonable, but still much longer, timeframe.
This huge difference is due to a much higher barrier EA,
which is of the order of 130 kJ/mol for Rot3@13 while
amounting to only ca. 80 kJ/mol for Rot3@2. In contrast,
the difference in entropy is rather small. The same trends
can be seen in the Eyring parameters. For rotaxane
Rot3@14, with two 2,6-pyridinedicarboxylic acid diamide
blocks, the changes are even more pronounced; no deslip-
page was observed at all, although the sample of Rot3@14
was kept at 423 K for a prolonged period.
Scheme 5. Kinetic parameters of rotaxanes with tetralactam wheels
in comparison with those with sulfonamide wheels
Furthermore, comparison of Rot3@2 and Rot4@2, studied
under the same conditions, led us to the conclusion that
hydrogen bonding does not play a significant role. Fourthly,
rotational barriers (Scheme 6) in carbonamides have been
studied intensely both experimentally[25] and theoretic-
ally[26] and are of the order of 80 kJ/mol, while those of
sulfonamides have been calculated to amount to ca. 40 kJ/
1
mol.[27] This difference is in line with the H NMR spectra
of, for example, dimethyl acetamide and dimethyl methane-
sulfonamide. While the former shows slow exchange of the
amide methyl groups, resulting in two separate signals for
both, the latter gives only one signal, due to an exchange
that is fast on the NMR timescale.
Scheme 6. Origin of the higher flexibility of the sulfonamide wheel
A lower rotational barrier for Rot4@12 and Rot5@12 re-
sults in an increased flexibility of the sulfonamide wheel
and thus may well affect entropy. However, it affects not
only the entropy of the transition structure, but also that of
the rotaxane in its energetic minimum. It is thus not clear
a priori that increased flexibility should necessarily result in
an increased entropy of activation. Indeed, the examples of
Scheme 7. Kinetic parameters of rotaxanes with isophthalic amide
and pyridinedicarboxylic acid diamide building blocks in the
wheels. Note that wheel 14 has one additional methyl group at-
tached to each of the cyclohexyl rings. Without these methyl groups
different stoppers discussed above represent the opposite the macrocycle is insoluble and does not permit rotaxane synthesis
Eur. J. Org. Chem. 2001, 2877Ϫ2890 2883

A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
through a wheel and capped by two bulky end groups is
too simplified a view for detailed analysis of the deslipping
kinetics. Not unexpectedly, rotaxanes, as rather complex
systems, display complicated behavior. This result has some
conceptual implications for analysis of the size
complementarity of stoppers and wheels as used previously
to determine the ranking of dendritic stoppers by Vögtle et
al.[16a] The authors cautiously speak of the ‘‘effective size’’
of the stoppering dendrons. As corroborated by our finding
that seemingly larger stoppers can deslip more quickly due
to their shape and flexibility, similar effects might occur
with dendritic stopper groups. A large dendron might still
allow faster deslippage, if it is flexible enough to slip
through the wheel by means of a multi-step process, one
branch after the other. Thus, careful analysis of the kinetic
parameters is suggested in deslipping experiments, if con-
clusions are drawn with respect to the size complementarity.
This highlights the major argument, of why the simplified
view of a rotaxane presented at the start is only a first order
approximation. Even if structural changes do not change
the static properties such as ring size much, they may pro-
foundly alter the dynamic behavior of the rotaxane. Indeed,
with the sulfonamide wheels, the terphenyl stoppers, and
the hydrogen bonding within the pyridinedicarboxylic acid
diamide building blocks, effects that are dynamic in nature
have been observed. Clearly, a purely static model for de-
slipping cannot provide a satisfying explanation if dynamics
play such an important role.
Another interesting observation is the magnitude of some
of the effects observed. In particular, the introduction of a
2,6-pyridinedicarboxylic acid diamide building block into
the wheel produces enormous effects. This in turn implies
that deslipping Ϫ when completely understood and care-
fully interpreted Ϫ may be developed into a sensitive tool
for the examination of steric parameters.
Our study identifies several features that have an import-
ant influence on rotaxane deslipping kinetics, all of which
need more in-depth investigation in order to provide more
profound understanding of the intramolecular mobility and
the dynamic processes associated with the deslipping reac-
tion. These are: (i) the size complementarity of stoppers and
wheel, (ii) the shape and flexibility of the rotaxanes’ com-
ponents, (iii) the effect of weak intramolecular forces such
as hydrogen bonds that, for example, stabilize certain con-
formations, and (iv) potentially the solvent and the effects
caused by its reorganization. As an initial survey, the know-
ledge gained about these parameters is a great help in defin-
ing the next steps in this project, which will be reported in
due course.
Scheme 8. Conformational preferences and hydrogen bonding pat-
terns found for the pyridino wheel, compared with those of the
tetralactam macrocycle with isophthalic amide subunits
The explanation for this large effect certainly does not
involve the hydrogen atom missing in the pyridine case. A
hydrogen atom occupies more space inside the wheel than
the nitrogen lone pair does, and so deslippage should be
faster with the pyridine building block. However, a search
for an explanation uncovers several literature reports on the
extraordinary properties of the 2,6-pyridinedicarboxylic
acid diamide building block. From X-ray structures of
benzylamide catenanes,[28] furano catenanes,[29] and open
chain analogs,[31a] it is known to form hydrogen bonds be-
tween the amide protons and the central pyridine nitrogen
or furane oxygen (Scheme 8). This hydrogen bonding pat-
tern has been reported to cause slower circumrotation in
benzylamide catenanes[30] and to change the angle α
(Scheme 8) from 120° to an αЈ of ca. 90Ϫ100° in open chain
analogs.[31] This difference in α is probably smaller in our
macrocyclic wheels, because of the rather rigid structure of
the macrocycle. Nevertheless, it may well alter the deslip-
ping rate significantly, thanks to a smaller wheel diameter
and the corresponding increase in the deslipping barrier.
A second effect might also contribute. The hydrogen
bonding pattern of the 2,6-pyridinedicarboxylic acid di-
amide subunit also shifts the conformational equilibrium of
the two amides towards the in/in conformation, with the
two amide protons pointing towards the center of the mac-
rocycle as shown in Scheme 8.[32] As seen in X-ray struc-
tures of rotaxanes and catenanes of the amide type,[23]
isophthalic amides such as in 2 often adopt an in/out con-
formation, which is further disfavored in 13 and 14 by re-
pulsion between the lone pairs situated at the carbonyl oxy-
gens and the pyridine nitrogen atom. With a more or less
fixed conformation with both amide protons inside the
wheel, the space available for the passage of the stopper
through the wheel becomes even smaller. We believe that
these two effects explain the large difference in deslipping
rates.
Experimental Section
Kinetic Studies: For each of the rotaxanes, the rate constants of the
Conclusions
deslipping reaction were measured at several different temperatures
1
in H NMR experiments. In preliminary experiments, the temper-
This study shows that our simplified starting hypothesis
is only valid as a first and rather rough approximation. To
ature range was chosen so that deslipping occurred with a half life
of between one and ca. 400 hours. The NMR samples were kept
regard a rotaxane merely as a slender stick threaded in an oil bath at constant temperature. When the half life was found
2884 Eur. J. Org. Chem. 2001, 2877Ϫ2890

Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
to be sufficiently short at temperatures accessible with the NMR
instrument’s heater, the samples were transferred to the NMR spec- accomplished by DEPT and CH-COSY measurements. All NMR
trometer. In each experiment, deslipping was followed until at least experiments were performed on 250, 400, and 500 MHz Bruker
75% of the rotaxane had been consumed. For evaluation of the instruments; the solvent signal was used for internal calibration.
on 1H and 13C NMR experiments, for which signal assignment was
data, integrals of several signals were averaged wherever possible, in
order to reduce experimental error. However, some of the rotaxanes
produced NMR spectra in which decreasing and increasing signals
NMR spectra of those rotaxanes that dethread quickly of course
also contain small signals from the free components. In the meas-
urements of deslipping over time, the data were corrected for these
overlapped to such an extent that only one or two of the signals initial contributions of the free components. Furthermore, all rot-
could be evaluated safely. The estimated experimental error range axanes gave clean FAB (Kratos Concept 1 H) or MALDI (Micro-
is Ϯ4 kJ/mol for EA and ∆H‡. Because of the logarithmic nature mass MALDI-TofSpec-E) mass spectra that Ϫ apart from signals
of the plots, the errors in kϱ and ∆S‡ are somewhat larger and we
estimate them to be Ϯ30% for kϱ and ∆S‡. The Arrhenius activa-
originating from the matrices (m-nitrobenzyl alcohol and dihy-
droxybenzoic acid, respectively) Ϫ contained only prominent peaks
tion parameters were derived from a plot of ln k against 1/T, while for the rotaxane, free axle, and free wheel, a pattern that is typical
ln (k/T) was plotted against 1/T in order to determine ∆G‡, ∆H‡,
and ∆S‡ by the Eyring equation. Close inspection of those signals
increasing over time confirmed that they corresponded to the intact
free components and thus ruled out decomposition of the axle or
wheel rather than deslipping as the reason for rotaxane degrada-
tion. Unfortunately, solubility problems forced us to measure some
of the rotaxanes in [D7]DMF and the series of ether rotaxanes in
[D2]tetrachloroethane. These two series thus cannot be compared
directly, but trends emerging within each of them can of course be
analyzed. Finally, for correlation with the activation parameters,
the axle lengths and the stopper size were determined by molecular
modeling with the Sybyl force field as implemented in the Spartan
program package[33] according to the definition given in Figures 1
and 3.
for these rotaxanes. Under the same conditions, mixtures of the free
components do not give signals at the m/z ratio of the rotaxanes,
indicating that these signals, when indeed observed, are due to the
intact rotaxane rather than any proton-bridged complex without a
mechanical bond. The isotope patterns agree well with those calcu-
lated on the basis of natural abundances.
General Procedure for the Melting Synthesis: Equimolar amounts
of the corresponding macrocycle and axle were thoroughly mixed
under argon and the mixture was melted with a heat gun at about
350 °C. After the reaction mixture had been chilled in cold water,
the residue was dissolved in CH2Cl2/MeOH 5:1 and subjected to
column chromatography on silica gel with dichloromethane/ethyl
acetate (CH2Cl2/EtOAc) mixtures.
Axle 3: N,NЈ-Bis(3,5-di-tert-butylphenyl)-4,4Ј-biphenyldicarboxylic
Acid Diamide:[19i] Yield: 53%; m.p. Ͼ 300 °C. Ϫ 1H NMR
(250 MHz, [D7]DMF) δ (ppm) ϭ 1.34 [s, 36 H, C(CH3)3], 7.27 (s,
Synthesis of Rotaxanes: In terms of their syntheses, the rotaxanes
selected for this study fall into three different groups.
(i) The first series bears axles that are purely hydrocarbon in nature
(Rot1@2, Rot4@2ϪRot6@2, Rot4@12, Rot5@12). This type of
axle reduces the possible complications arising from noncovalent
forces between axle and wheel. As the axles were deliberately se-
lected to be rigid, the aromatic ring systems could not be avoided.
Synthesis was achieved by melting mixtures of axle and wheel at
350 °C for a short time interval and separating the rotaxane from
the remaining reactants.[19] The precursors, 3,5-diphenylphenol,[34]
axles[35] 1, 4, 5, and 6, and wheels 2,[36] 12,[37] 13,[32] and 14,[32]
were prepared according to well established literature procedures.
Macrocycle 14 has a methyl group attached to each of the cyclo-
hexyl rings to improve solubility. Attempted rotaxane synthesis us-
ing the same wheel but without these methyl groups was not suc-
cessful.[38]
3
2 H, Ar-H), 7.88 (s, 4 H, Ar-H), 7.98 (AAЈBBЈ, J ϭ 8.3 Hz, 4 H,
Ar-H), 8.23 (AAЈBBЈ, 3J ϭ 8.3 Hz, 4 H, Ar-H), 10.30 (s, 2 H, NH).
Ϫ
13C NMR (62.9 MHz, CDCl3/CD3OD) δ (ppm) ϭ 31.65 (CH3),
35.39 (Cq), 115.50, 118.25, 127.75, 129.00 (CH), 135.63, 143.15,
151.70 (Cq), 165.80 (CO). Ϫ FAB-MS: m/z ϭ 617.4 [M ϩ Hϩ].
Axle
6:
E,E-4,4Ј-Bis(3,5-di(tert-butyl)phenylethenyl]-1,1Ј-bi-
benzyl:[35] Yield: 52%; m.p. 177Ϫ180 °C. Ϫ 1H NMR (250 MHz,
CDCl3) δ (ppm) ϭ 1.37 [s, 36 H, C(CH3)3], 2.95 (s, 4 H, CH2), 7.07
(AB, 3J ϭ 16.6 Hz, 2 H, vinyl-H), 7.17 (AB, 3J ϭ 16.6 Hz, 2 H,
vinyl-H), 7.18 (d, 3J ϭ 8 Hz, 4 H, Ar-H), 7.37 (m, 6 H, Ar-H), 7.47
(d, 3J ϭ 8 Hz, 4 H, Ar-H). Ϫ 13C NMR (100.6 MHz, CDCl3) δ
(ppm) ϭ 31.56 (CH3), 34.95 (CH2), 37.70 (Cq), 120.86, 122.04,
126.52, 127.94, 128.88, 129.16 (CH), 135.50, 136.73, 141.12, 151.07
(Cq). Ϫ FAB-MS: m/z ϭ 610.3 [Mϩ·].
(ii) Rot7@2ϪRot11@2Ј are rotaxanes with ether groups in the
axles. Synthesis could easily be accomplished using a recently pub-
lished anion template effect.[39] With a few exceptions (see below),
the synthetic precursors for the series of ether rotaxanes were com-
mercially available and were used without further purification.
Rot1@2:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethyl]-1,1Ј-bi-
phenyl}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.55 (CH2Cl2/EtOAc ϭ 20:1); yield: 3%; m.p. 136Ϫ140 °C. Ϫ
1H NMR (500 MHz, [D8]THF) δ (ppm) ϭ 1.29 [s, 36 H, C(CH3)3],
1.36 [s, 9 H, C(CH3)3], 1.56 (br. s, 4 H, CH2), 1.71 (br. s, 8 H, CH2),
1.96 (s, 12 H, Ar-CH3), 1.97 (s, 12 H, Ar-CH3), 2.43 (br. s, 8 H,
CH2), 2.67 (br. s, 8 H, CH2), 6.71 (s, 8 H, Ar-H), 7.02 (d,4J ϭ
1.7 Hz, 4 H, Ar-H), 7.14 (s, 4 H, Ar-H), 7.16 (s, 4 H, Ar-H) 7.25
(iii) The third series (Rot3@2, Rot3@13, Rot3@14) features amide
groups in the axle that are capable of forming three hydrogen bonds
with the wheel. Rot3@2 was prepared by melting synthesis as de-
scribed above; the other two were synthesized by a template syn-
thesis, in which the semi-axle was fitted with the second stopper
while held within the wheel by hydrogen bonds.[40]
Characterization of the rotaxanes was sometimes obstructed by de-
slipping being quite fast even at room temperature, with a propor- (t, 4J ϭ 1.7 Hz, 2 H, Ar-H), 7.51 (t, 3J ϭ 7.7 Hz, 1 H, Ar-H), 7.63
tion of the rotaxane degrading during column chromatography.
Elemental analyses are consequently not always within the usually
(t, 4J ϭ 1.6 Hz, 1 H, Ar-H), 7.66 (s, 2 H, CONH), 7.82 (s, 2 H,
4
CONH), 7.84 (t, 4J ϭ 1.6 Hz, 1 H, Ar-H), 7.93 (dd, 3J ϭ 7.7, J ϭ
accepted range and are further complicated by varying amounts of 1.6 Hz, 2 H, Ar-H), 8.05 (d, 4J ϭ 1.6 Hz, 2 H, Ar-H). Ϫ 13C NMR
solvents that could not entirely be removed from the samples. We (125 MHz, [D8]THF) δ (ppm) ϭ 19.6, 19.7, 31.8, 32.2 (CH3), 24.3,
therefore base the characterization of the target compounds mainly 27.8, 36.9, 38.9, 39.6 (CH2), 120.9, 123.5, 125.3, 127.3, 127.4, 127.5,
Eur. J. Org. Chem. 2001, 2877Ϫ2890
2885

A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
3
128.2, 128.5, 129.7, 130.0, 131.3 (CH), 35.7, 46.4, 134.0, 134.1, (br. s, 8 H, CH2), 6.64 (s, 4 H, Ar-H), 6.75 (d, J ϭ 16.3 Hz, 2 H,
135.5, 135.8, 136.8, 137.1, 138.6, 142.0, 142.2, 148.6, 148.7, 151.6, vinyl-H), 6.91 (d, 3J ϭ 16.3 Hz, 2 H, vinyl-H), 7.09 (s, 4 H, Ar-H),
153.6 (Cq), 166.0, 166.1 (CO). Ϫ FAB-MS: m/z (%) ϭ 1574.9 (50) 7.10 (s, 4 H, Ar-H), 7.29 (d, 4J ϭ 1.7 Hz, 4 H, Ar-H), 7.30 (t, 4J ϭ
3
4
[M ϩ Hϩ].
1.7 Hz, 2 H, Ar-H), 7.52 (t, J ϭ 7.7 Hz, 1 H, Ar-H), 7.85 (t, J ϭ
1.5 Hz, 1 H, Ar-H), 7.90 (s, 2 H, CONH), 7.96 (dd, 3J ϭ 7.7, J ϭ
4
1.6 Hz, 2 H, Ar-H), 8.01 (s, 2 H, CONH), 8.06 (d, 4J ϭ 1.5 Hz, 2 H,
Rot3@2: [2]{N,NЈ-Bis[3,5-di(tert-butyl)phenyl]-1,1Ј-biphenyl-4,4Ј-di-
carboxamide}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octa-
methyldispiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazahepta-
cyclo[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.45 (CH2Cl2/EtOAc ϭ 30:1); yield: 7%; m.p. Ͼ 300 °C. Ϫ
1H NMR (500 MHz, [D7]DMF) δ (ppm) ϭ 1.29 [s, 36 H, C(CH3)3],
1.39 [s, 9 H, C(CH3)3], 1.50 (br. s, 4 H, CH2), 1.60 (br. s, 8 H, CH2),
2.01 (s, 24 H, CH3), 2.45 (br. s, 8 H, CH2), 7.09 (d, J ϭ 7.5 Hz, 4
H, Ar-H), 7.25 (s, 8 H, Ar-H), 7.27 (s, 2 H, Ar-H), 7.55 (d, J ϭ
7.5 Hz, 4 H, Ar-H), 7.67 (s, 4 H, Ar-H), 7.69 (t, J ϭ 7.4 Hz, 1 H,
Ar-H), 8.08 (d, J ϭ 7.4 Hz, 2 H, Ar-H), 8.14 (s, 2 H, Ar-H), 8.30
(s, 1 H, Ar-H), 8.45 (s, 1 H, Ar-H), 9.00 (s, 2 H, CONH), 9.02 (s,
2 H, CONH), 9.72 (s, 2 H, CONH). Ϫ 13C NMR (125 MHz,
[D7]DMF) δ (ppm) ϭ 19.02, 31.38, 31.61, 23.62, 26.89, 25.09,
35.39, 35.50, 35.72, 45.73, 115.44, 118.70, 126.35, 126.85, 124.82,
127.20, 128.06, 128.63, 128.82, 129.81, 131.18, 133.50, 133.56,
134.87, 135.53, 135.56, 135.76, 135.91, 139.46, 142.72, 147.94,
151.67, 153.01, 166.01, 166.25, 166.67. Ϫ FAB-MS: m/z (%) ϭ
1578.1 (70) [M ϩ Hϩ]. Ϫ C106H124N6O6·2H2O (1614.21): calcd. C
78.87, H 7.99, N 5.21; found C 78.96, H 8.59, N 5.18.
Ar-H), 8.07 (d, J ϭ 1.6 Hz, 1 H, Ar-H). Ϫ 13C NMR (125 MHz,
4
[D8]THF) δ (ppm) ϭ 19.0, 19.1, 23.9, 27.3, 31.4, 31.6, 35.3, 35.6,
36.7, 46.2, 121.6, 122.3, 124.9, 127.1, 127.2, 127.6, 127.8, 128.4,
129.4, 129.7, 130.4, 133.5, 133.6, 135.8, 136.5, 136.7, 137.0, 137.7,
148.4, 151.4, 153.0, 165.6, 165.8. Ϫ FAB-MS: m/z (%) ϭ 1467.7
(78) [M ϩ Hϩ].
Rot6@2:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethenyl]-1,1Ј-bi
benzyl}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј, 38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.60 (CH2Cl2/EtOAc ϭ 20:1); yield: 8%; m.p. 187Ϫ190 °C. Ϫ
1H NMR (500 MHz, [D8]THF) δ (ppm) ϭ 1.31 [s, 36 H, C(CH3)3],
1.37 [s, 9 H, C(CH3)3], 1.57 (br. s, 4 H, CH2), 1.71 (br. s, 8 H, CH2),
1.97 (s, 12 H, Ar-CH3), 1.99 (s, 12 H, Ar-CH3), 2.42 (br. s, 8 H,
CH2), 2.63 (s, 4 H, CH2), 6.78 (d, 3J ϭ 16.3 Hz, 2 H, vinyl-H), 6.79
(d, 3J ϭ 8.1 Hz, 4 H, Ar-H), 6.91 (d, 3J ϭ 8.1 Hz, 4 H, Ar-H), 7.03
3
3
3
3
3
(d, J ϭ 16.3 Hz, 2 H, vinyl-H), 7.09 (s, 4 H, Ar-H), 7.10 (s, 4 H,
3
Ar-H), 7.31 (s, 2 H, Aryl-H), 7.33 (s, 4 H, Aryl-H), 7.50 (t, J ϭ
4
7.7 Hz, 1 H, Ar-H), 7.88 (t, J ϭ 1.4 Hz, 1 H, Ar-H), 7.93 (s, 2 H,
4
CONH), 7.96 (dd, 3J ϭ 7.7, J ϭ 1.4 Hz, 2 H, Ar-H), 8.05 (s, 2 H,
Rot4@2:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethenyl]-1,1Ј-bi-
CONH), 8.09 (s, 2 H, Ar-H), 8.10 (s, 1 H, Ar-H). Ϫ 13C NMR
(125 MHz, [D8]THF) δ (ppm) ϭ 19.5, 19.6, 24.4, 27.8, 31.9, 32.2,
35.8, 37.0, 38.5, 46.6, 122.0, 122.6, 125.5, 127.5, 128.3, 128.5, 128.9,
129.7, 129.9, 131.1, 134.0, 134.1, 136.1, 136.5, 136.8, 137.1, 138.3,
141.9, 148.7, 151.9, 153.5, 166.1, 166.2. Ϫ MALDI-TOF-MS: m/z
(%) ϭ 1572.40 (95) [M ϩ Hϩ].
phenyl}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
1
Rf ϭ 0.40 (CH2Cl2/EtOAc ϭ 30:1); yield: 3%; m.p. 208 °C. Ϫ H
NMR (400 MHz, [D8]THF) δ (ppm) ϭ 1.33 [s, 36 H, C(CH3)3],
1.37 [s, 9 H, C(CH3)3], 1.51 (br. s, 4 H, CH2), 1.71(br. s, 8 H, CH2),
1.97 (s, 12 H, CH3), 1.99 (s, 12 H, CH3), 2.47 (br. s, 8 H, CH2),
6.90 (d, 3J ϭ 16.3 Hz, 2 H, vinyl-H), 6.97 (d, 3J ϭ 8.5 Hz, 4 H,
Rot4@12:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethenyl]-
1,1Ј-biphenyl}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octa-
methyldispiro[cyclohexane-1,2Ј-26-thia-7Ј,15Ј,25Ј,33Ј-tetraazahepta-
cyclo[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,32Ј-trione-26Ј,26Ј-dioxide}
rotaxane: Rf ϭ 0.77 (CH2Cl2/EtOAc ϭ 20:1); yield: 4% (contains
3
3
Ar-H), 7.04 (d, J ϭ 8.5 Hz, 4 H, Ar-H), 7.05 (d, J ϭ 16.3 Hz, 2
4
H, vinyl-H), 7.15 (s, 8 H, Ar-H), 7.35 (t, J ϭ 1.7 Hz, 2 H, Ar-H),
7.37 (d, 4J ϭ 1.7 Hz, 4 H, Ar-H), 7.51 (t, 3J ϭ 7.6, 1 H, Ar-H),
7.75 (t, 4J ϭ 1.6 Hz, 1 H, Ar-H), 7.85 (s, 2 H, CONH), 7.93 (d,
1
ca. 30% deslipping products). Ϫ H NMR (500 MHz, [D8]THF) δ
3
4J ϭ 1.6 Hz, 2 H, Ar-H), 7.95 (d, J ϭ 7.6, 2 H, Ar-H), 8.04 (d,
(ppm) ϭ 1.37 [s, 36 H, C(CH3)3], 1.40 [s, 9 H, C(CH3)3], 1.50Ϫ1.55
(br. s, 8 H, CH2), 1.66 (br. s, 4 H, CH2), 1.99 (s, 6 H, Ar-CH3),
2.02 (s, 6 H, Ar-CH3), 2.06 (s, 6 H, Ar-CH3), 2.07 (s, 6 H, Ar-CH3),
4J ϭ 1.6 Hz, 1 H, Ar-H), 2NH covered by signal at 7.95. Ϫ 13C
NMR (125 MHz, [D8]THF) δ (ppm) ϭ 16.62, 16.81, 16.85, 29.13,
29.42, 34.30, 21.66, 22.89, 25.09, 33.07, 43.93, 119.36, 120.17,
122.66, 124.76, 124.82, 125.25, 125.53, 125.75, 127.16, 127.78,
128.36, 131.34, 131.41, 133.43, 134.12, 134.38, 134.97, 135.36,
136.96, 145.99, 149.22, 150.75, 163.38, 163.38, 163.53. Ϫ FAB-MS:
m/z (%) ϭ 1544.0 (52) [M ϩ Hϩ]. Ϫ C108H126N4O4·2H2O
(1579.71): calcd. C 82.09, H 8.29, N 3.55; found C 82.19, H 8.49,
N 2.90.
3
2.37 (br. s, 8 H, CH2), 6.89 (d, J ϭ 16.7 Hz, 2 H, vinyl-H), 7.01
(d, 3J ϭ 8.3 Hz, 4 H, Ar-H), 7.08 (s, 2 H, Ar-H), 7.09 (d, 3J ϭ
3
8.4 Hz, 4 H, Ar-H), 7.13 (s, 2 H, Ar-H), 7.19 (d, J ϭ 16.7 Hz, 2
H, Ar-H), 7.20 (s, 1 H, Ar-H), 7.31 (s, 2 H, Ar-H), 7.40 (t, 4J ϭ
1.8 Hz, 2 H, Ar-H), 7.48 (d, 4J ϭ 1.8 Hz, 2 H, Ar-H), 7.85 (t, 3J ϭ
7.9 Hz, 1 H, Ar-H), 8.07 (s, 1 H, Ar-H), 8.09 (s, 1 H, Ar-H), 8.20
3
(s, 1 H, Ar-H), 8.24 (s, 1 H, Ar-H), 8.32 (d, J ϭ 7.9 Hz, 2 H, Ar-
H), 8.69 (s, 1 H, CONH), 8.94 (s, 1 H, CONH), 9.04 (s, 1 H,
CONH), 9.12 (s, 1 H, SO2NH); due to rapid deslipping (half-life
time at room temperature: Ͻ 2 hours), no 13C NMR was recorded.
Ϫ FAB-MS: m/z (%) ϭ 1579.9 (30) [M ϩ Hϩ].
Rot5@2:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethenyl]ben-
zene}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј- Rot5@12:
[2]{(E,E)-4,4Ј-Bis[3,5-di(tert-butyl)phenylethenyl]ben-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane: zene}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
Rf ϭ 0.56 (CH2Cl2/EtOAc ϭ 20:1); yield: 13%; m.p. 215Ϫ218 °C. spiro[cyclohexane-1,2Ј-26-thia-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
Ϫ
1H NMR (500 MHz, [D8]THF) δ (ppm) ϭ 1.29 [s, 36 H, [32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-
C(CH3)3], 1.37 [s, 9 H, C(CH3)3], 1.58 (br. s, 4 H, CH2), 1.72 (br. 3Ј,5Ј,9Ј,11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,
s, 8 H, CH2), 1.97 (s, 12 H, Ar-CH3), 1.99 (s, 12 H, Ar-CH3), 2.41 42Ј,45Јoctadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,32Ј-trione-26Ј,26Ј-
2886
Eur. J. Org. Chem. 2001, 2877Ϫ2890

Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
dioxide}rotaxane: Rf ϭ 0.50 (CH2Cl2/EtOAc ϭ 20:1); yield: 5%
149.2, 164.3, 165.6. Ϫ MALDI-TOF-MS: m/z (%) ϭ 1576.2 (95)
(contains ca. 20% deslipping products), 1H NMR (500 MHz, [M ϩ Naϩ].
[D8]THF) δ (ppm) ϭ 1.35 [s, 36 H, C(CH3)3], 1.36 [s, 9 H,
Rot9@2:
[2]{4,4Ј-Bis(3,5-di-tert-butylphenyloxymethyl)-1,1Ј-bi-
C(CH3)3], 1.46Ϫ1.59 (br. s, 8 H, CH2), 1.61Ϫ1.70 (br. s, 4 H, CH2),
benzyl}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.89 (CH2Cl2/MeOH ϭ 20:1); yield: 57%; m.p. 206Ϫ208 °C.
1.90 (s, 6 H, Ar-CH3), 2.07 (s, 6 H, Ar-CH3), 2.09 (s, 6 H, Ar-
CH3), 2.11 (s, 6 H, Ar-CH3), 2.37Ϫ2.46 (br. s, 8 H, CH2), 6.51 (s,
4 H, Ar-H), 6.53 (d, 3J ϭ 17.5 Hz, 2 H, vinyl-H), 7.04 (d, 3J ϭ
17.5 Hz, 2 H, vinyl-H), 7.08 (s, 2 H, Ar-H), 7.22 (s, 2 H, Ar-H),
4
7.27 (s, 2 H, Ar-H), 7.30 (s, 2 H, Ar-H), 7.37 (t, J ϭ 1.7 Hz, 2 H,
Ar-H), 7.42 (d, 4J ϭ 1.7 Hz, 4 H, Ar-H), 7.81 (t, 3J ϭ 7.8 Hz, 1 H,
Ϫ
1H NMR (250 MHz, C2D2Cl4) δ (ppm) ϭ 1.24 [s, 36 H,
4
Ar-H), 8.09 (t, 4J ϭ 1.7 Hz, 2 H, Ar-H), 8.14 (t, J ϭ 1.7 Hz, 1 H,
C(CH3)3], 1.41 [s, 9 H, C(CH3)3], 1.60 (br, 8 H, CH2), 1.74 (br. s,
8 H, CH2), 1.95 (s, 12 H, Ar-CH3), 1.96 (s, 12 H, Ar-CH3), 2.42
3
3
Ar-H), 8.33 (d, J ϭ 7.8 Hz, 1 H, Ar-H), 8.42 (d, J ϭ 7.8 Hz, 1
H, Ar-H), 8.43 (s, 1 H, Ar-H), 8.74 (s, 1 H, CONH), 8.99 (s, 1 H,
CONH), 9.19 (s, 1 H, CONH), 9.28 (s, 1 H, SO2NH); due to rapid
deslipping (half-life at room temperature: Ͻ 2 hours), no 13C NMR
was recorded. Ϫ FAB-MS: m/z (%) ϭ 1503.7 (30) [M ϩ Hϩ].
3
(br. s, 8 H, CH2), 4.56 (s, 4 H, OCH2), 6.47 (d, J ϭ 7.7 Hz, 4 H,
3
Ar-H), 6.61 (d, J ϭ 7.7 Hz, 4 H, Ar-H), 6.64 (s, 4 H, Ar-H), 7.02
(s, 2 H, Ar-H), 7.04 (s, 4 H, NH), 7.11 (s, 8 H, Ar-H), 7.55 (s, 1 H,
3
Ar-H), 7.70 (s, 1 H, Ar-H), 7.72 (t, J ϭ 7.6 Hz, 1 H, Ar-H), 8.16
(d, 3J ϭ 7.6 Hz, 2 H, Ar-H), 8.18 (s, 2 H, Ar-H). Ϫ 13C NMR
(62.5 MHz, CDCl3) δ (ppm) ϭ 18.8, 23.0, 26.3, 31.1, 31.3, 34.9,
35.3, 35.7, 37.6, 45.3, 70.0, 108.8, 115.7, 121.5, 124.2, 126.2, 126.8,
127.9, 128.6, 129.4, 130.3, 131.0, 131.1, 132.1, 134.4, 134.5, 134.7,
134.8, 140.8, 148.6, 148.7, 152.6, 154.2, 157.9, 165.0, 165.4. Ϫ FAB-
MS: m/z (%) ϭ 1580.6 (55) [M ϩ Hϩ].
General Procedure for the Synthesis of Ether Rotaxanes: The wheel
was stirred in dichloromethane, together with 1 equiv. of the axle’s
dibromide central unit, 2. equiv. of the stoppers, 0.25 equiv. of di-
benzo-18-crown-6, and an excess of K2CO3 for six days (depending
on the deslipping rate, it was in some cases beneficial to terminate
the reaction somewhat earlier). After removal of the solvent, the
rotaxane was purified by column chromatography with CH2Cl2/
ethyl acetate mixtures on silica gel.
Rot10@2Ј:
[2]{1,4-Bis(3,5-diphenylphenyloxymethyl)benzene}-
{11Ј, 29Ј-di-tert-b utyl-5Ј, 17Ј, 23Ј, 35Ј, 38Ј, 40Ј, 43Ј, 45Ј-
o ct am e th y l d i sp i ro [ cycl o h ex a n e- 1 , 2Ј -7 Ј, 1 5 Ј, 2 5 Ј, 3 3 Ј-
tetraazaheptacyclo[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetra-
conta-3Ј,5Ј,9Ј,11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,
37Ј,40Ј,42Ј,45Ј-octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-
tetrone}rotaxane: Rf ϭ 0.20 (CH2Cl2/MeOH ϭ 100:1); yield: 17%.
Ϫ 1H NMR (500 MHz, CDCl3) δ (ppm) ϭ 1.27 [s, 18 H, C(CH3)3],
1.56 (br, 4 H, CH2), 1.70 (br. s, 8 H, CH2), 1.94 (s, 24 H, Ar-CH3),
Rot7@2:
[2]{1,4-Bis(3,5-di-tert-butylphenyloxymethyl)benzene}-
{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldispiro[cyclo-
h e x a n e - 1 , 2 Ј - 7 Ј , 1 5 Ј , 2 5 Ј , 3 3 Ј - t e t r a a z a h e p t a c y c l o -
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.20 (CH2Cl2/MeOH ϭ 30:1); yield: 37%. Ϫ 1H NMR
(250 MHz, CDCl3) δ (ppm) ϭ 1.35 [s, 36 H, C(CH3)3], 1.38 [s, 9
H, C(CH3)3], 1.55 (br. s, 4 H, CH2), 1.68 (br. s, 8 H, CH2), 1.85 (s,
12 H, Ar-CH3), 1.88 (s, 12 H, Ar-CH3), 2.32 (br. s, 8 H, CH2), 4.33
(s, 4 H, OCH2), 5.81 (s, 4 H, Ar-H), 7.01 (s, 4 H, Ar-H), 7.02 (s, 4
H, Ar-H), 7.05 (s, 2 H, Ar-H), 7.45 (s, 2 H, NH), 7.50 (s, 2 H,
3
2.34 (br. s, 8 H, CH2), 4.56 (s, 4 H, OCH2), 6.45 (d, J ϭ 8.2 Hz,
2 H, Ar-H), 6.78 (d, 3J ϭ 8.2 Hz, 2 H, Ar-H), 7.00 (s, 8 H, Ar-H),
7.05 (s, 4 H, Ar-H), 7.10 (br. s, 2 H, Aryl-H), 7.28 (s, 4 H, Aryl-
H), 7.39 (m, br, 16 H, Ar-H), 7.44 (m, br, 16 H, Ar-H), 7.64 (s, 2
H, Ar-H), 8.19 (s, 4 H, Ar-H). Ϫ 13C NMR (125 MHz, CDCl3) δ
(ppm) ϭ 19.1, 23.4, 26.7, 31.4, 32.8, 35.1, 45.7, 70.3, 113.4, 127.3,
127.4, 127.6, 127.8, 128.0, 128.4, 129.1, 129.3, 131.5, 134.5, 135.1,
136.7, 141.2, 143.6, 143.7, 156.7, 159.2, 166.2. Ϫ MALDI-TOF-
MS: m/z (%) ϭ 1650.7 (55) [M ϩ Kϩ].
3
NH), 7.65 (t, J ϭ 8.6 Hz, 1 H, Ar-H), 7.75 (s, 1 H, Ar-H), 7.92
3
(s, 1 H, Ar-H), 8.20 (d, J ϭ 8.6 Hz, 2 H, Ar-H), 8.22 (s, 2 H, Ar-
H). Ϫ 13C NMR (62.5 MHz, CDCl3) δ (ppm) ϭ 18.5, 18.6, 23.0,
26.3, 31.2, 31.3, 34.8, 35.2, 35.7, 45.2, 71.3, 108.8, 116.6, 122.1,
124.7, 126.8, 126.9, 127.8, 129.6, 130.4, 131.1, 131.2, 132.4, 134.2,
134.4, 135.1, 135.9, 149.0, 153.1, 154.0, 157.7, 165.3, 165.7. Ϫ
MALDI-TOF-MS: m/z (%) ϭ 1498.3 (100) [M ϩ Naϩ].
Rot11@2Ј:
[2]{4,4Ј-Bis(3,5-diphenylphenyloxymethyl)-1,1Ј-bi-
benzyl}-{11Ј,29Ј-di-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octa-
methyldispiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazahepta-
cyclo[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.23 (CH2Cl2/MeOH ϭ 100:1); yield: 19%. Ϫ 1H NMR
(500 MHz, CDCl3) δ (ppm) ϭ 1.43 [s, 18 H, C(CH3)3], 1.59 (br. s,
4 H, CH2), 1.72 (br. s, 8 H, CH2), 2.07 (s, 24 H, Ar-CH3), 2.38 (br.
s, 8 H, CH2), 2.44 (s, 4 H, C2H4), 4.81 (s, 4 H, OCH2), 6.44 (d,
Rot8@2: [2]{4,4Ј-Bis(3,5-di-tert-butylphenyloxymethyl)biphenyl}-
{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј-tetraazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
Rf ϭ 0.22 (CH2Cl2/MeOH ϭ 30:1); yield: 42%. Ϫ 1H NMR
(250 MHz, C2D2Cl4) δ (ppm) ϭ 1.25 [s, 36 H, C(CH3)3], 1.35 [s, 9
H, C(CH3)3], 1.57 (br. s, 4 H, CH2), 1.71 (br. s, 8 H, CH2), 1.96 (s,
24 H, Ar-CH3), 2.36 (br. s, 8 H, CH2), 4.79 (s, 4 H, OCH2), 6.45
(d, 3J ϭ 7.9 Hz, 4 H, Ar-H), 6.65 (s, 4 H, Ar-H), 6.69 (d, 3J ϭ
7.9 Hz, 4 H, Ar-H), 6.94 (s, 2 H, Ar-H), 6.99 (s, 2 H, NH), 7.06 (s,
2 H, NH), 7.10 (s, 8 H, Ar-H), 7.35 (s, 1 H, Ar-H), 7.49 (s, 1 H,
Ar-H), 7.61 (t, 3J ϭ 7.7 Hz, 1 H, Ar-H), 8.15 (d, 3J ϭ 7.7 Hz, 2 H,
Ar-H), 8.20 (s, 2 H, Ar-H). Ϫ 13C NMR (62.5 MHz, CDCl3) δ
(ppm) ϭ 23.1, 26.3, 29.2, 29.5, 29.6, 31.4, 31.9, 34.9, 36.2, 45.4,
3
3J ϭ 8.0 Hz, 4 H, Ar-H), 6.71 (d, J ϭ 8.0 Hz, 4 H, Ar-H), 7.04
(s, 8 H, Ar-H), 7.09 (s, 4 H, Ar-H), 7.28 (s, 4 H, NϪH), 7.40 (m,
br, 16 H, Ar-H), 7.46 (m, br, 16 H, Ar-H), 7.56 (s, 2 H, Ar-H), 7.57
(s, 4 H, Ar-H), 8.20 (s, 4 H, Ar-H). Ϫ 13C NMR (125 MHz, CDCl3)
δ (ppm) ϭ 19.3, 22.7, 26.7, 31.5, 34.5, 36.1, 38.1, 45.7, 70.9, 112.7,
127.3, 127.5, 127.6, 127.9, 128.2, 128.5, 129.1, 129.2, 129.3, 129.8,
131.5, 134.6, 134.8, 135.1, 141.0, 143.8, 145.2, 154.6, 159.5, 165.9.
Ϫ MALDI-TOF-MS: m/z (%) ϭ 1737.7 (90) [M ϩ Naϩ].
General Procedure for the Synthesis of Amide Rotaxanes: Equimo-
70.1, 108.8, 115.9, 121.6, 124.1, 124.7, 127.2, 127.3, 128.5, 129.6, lar amounts of the macrocycle and 4,4Ј-biphenyldicarboxylic acid
129.7, 130.3, 131.1, 131.4, 132.3, 134.1, 134.6, 134.9, 135.9, 137.8, dichloride were treated with the stopper amine and 2 equiv. triethyl-
Eur. J. Org. Chem. 2001, 2877Ϫ2890
2887

A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
amine in dichloromethane. The stopper was added by perfusor
over 8 hours. After complete addition, the mixture was stirred at
room temperature for 36 hours, the solvent was then removed, and
the residue was purified by column chromatography on silica gel
with CH2Cl2/ethyl acetate mixtures.
H, Ar-H), 6.99 (s, 4 H, ArH), 7.47Ϫ7.54 (m, 6 H, Ar-H), 7.73 (d,
3J ϭ 8.2 Hz, 4 H, ArH), 7.98 (d, 3J ϭ 8.2 Hz, 4 H, ArH), 8.10Ϫ8.17
(m, 2 H, Ar-H), 8.36Ϫ8.54 (m, 4 H, Ar-H), 8.89 (s, 1 H, NH), 8.92
(s, 1 H, NH), 9.64 (s, 1 H, NH), 9.74 (s, 1 H, NH). Ϫ 13C NMR
(125.8 MHz, CDCl3) δ (ppm) ϭ 18.4, 19.0, 19.6, 23.4, 31.8 (CH3),
23.1, 23.3, 29.7, 30.0, 30.1, 35.4, 45.3, 45.4 (CH2), 28.9, 29.0, 114.5,
115.2, 119.4, 125.7, 125.8, 126.3, 126.4, 126.9, 127.5, 127.9, 128.1,
128.8, 139.8, 140.0, 140.1 (CH), 29.7, 46.1, 46.3, 131.9, 135.4, 136.0,
136.3, 137.6, 147.6, 149.1, 152.2, 152.3, 152.4 (Cq), 161.1, 161.3,
161.8, 162.0 (CO). Ϫ MALDI-MS: m/z (%) ϭ 1578.8 (100) [M
ϩ Naϩ].
Macrocycle 14: 3,3ЈЈ,5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-decamethyldispiro-
[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј,39Ј,44Ј-hexaazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј, 32Ј-tetrone:
The macrocycle was a mixture of syn/anti isomers with respect to
the two methyl groups at the cyclohexyl rings. Some of the NMR
signals therefore appear as a double set. Ϫ Rf ϭ 0.43 (CH2Cl2/
Acknowledgments
1
EtOAc ϭ 8:1); yield: 29%; m.p. Ͼ 300 °C. Ϫ H NMR (400 MHz,
CDCl3) δ (ppm) ϭ 0.91Ϫ0.99 (br. s, 6 H, CH3), 1.41Ϫ1.50 (m, 2
H, CH2), 1.55Ϫ1.75 (m, 10 H, CH2), 2.15Ϫ2.22 (m, 24 H, CH3),
2.57Ϫ2.75 (m, 4 H, CH2), 6.91 (s, 2 H, Ar-H), 6.93 (s, 2 H, Ar-H),
6.98 (s, 4 H, Ar-H), 8.12Ϫ8.17 (m, 2 H, Ar-H), 8.44Ϫ8.50 (m, 4
H, ArH), 8.96 (s, 1 H, NH), 9.02 (s, 1 H, NH), 9.05 (s, 1 H, NH),
9.09 (s, 1 H, NH). Ϫ 13C NMR (100.6 MHz, CDCl3) δ (ppm) ϭ
18.9, 19.0, 23.0 (CH3), 22.7, 22.8, 35.0, 35.1, 35.6, 44.8 (CH2), 28.4,
28.5, 125.2, 125.3, 125.4, 125.8, 125.9, 127.4, 127.5, 127.8, 139.7,
139.8 (CH), 45.6, 45.7, 130.3, 130.4, 130.5, 134.3, 134.4, 134.9,
135.0, 146.2, 148.2, 148.5, 148.6, 150.9 151.0 (Cq), 160.9, 161.0,
161.1, 161.2 (CO). Ϫ MALDI-MS: m/z (%) ϭ 958.3 (100) [M ϩ
Naϩ]. Ϫ C60H66N6O4·H2O (935.20): calcd. C 75.60, H 7.19 N 8.81,
found C 75.75 H 7.00 N 8.62.
We warmly thank Prof. Fritz Vögtle for valuable advice, Dr. Jens
Windscheidt, and Dr. Annette Hünten for their help in the syn-
thesis of the rotaxanes, and Dr. Heinz-Rudolf Hartmann and Ul-
rike Weynand for recording the 2D NMR spectra and the generous
supply of instrument time for the NMR kinetics experiments.
C.A.S. thanks the Fonds der Chemischen Industrie for a Liebig
fellowship. This work was funded in part by the Deutsche For-
schungsgemeinschaft.
[1]
[1a] G. Schill, Catenanes, Rotaxanes and Knots, Academic Press,
[1b]
New York, 1971. Ϫ
Molecular Catenanes, Rotaxanes, and
Knots (Eds.: J. P. Sauvage, C. Dietrich-Buchecker), Wiley-VCH,
Weinheim, 1999.
[2]
[3]
For a recent example of a knot synthesis based on nonionic
template effects, see: O. Safarowsky, M. Nieger, R. Fröhlich, F.
Vögtle, Angew. Chem. 2000, 112, 1699Ϫ1701; Angew. Chem.
Rot3@13:
[2]{N,NЈ-Bis[3,5-di(tert-butyl)phenyl]-1,1Ј-biphenyl-
4,4Јdicarboxamide}-{11Ј-tert-butyl-5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-octa-
methyldispiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј,39Ј-pentaazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane.
Rf ϭ 0.87 (CH2Cl2/EtOAc ϭ 10:1); yield: 3%; m.p. Ͼ 300 °C. Ϫ
1H NMR (500 MHz, [D7]DMF) δ (ppm) ϭ 1.30 [s, 36 H, C(CH3)3],
1.37 [s, 9 H, C(CH3)3], 1.47Ϫ1.57 (br. s, 4 H, CH2), 1.58Ϫ1.69 (br.
s, 8 H, CH2), 1.96 (s, 12 H, CH3), 2.06 (s, 12, CH3), 2.32Ϫ2.58 (br.
s, 8 H, CH2), 7.24Ϫ7.27 (m, 6 H, Ar-H), 7.28 (s, 8 H, Ar-H), 7.35
(br, 4 H, ArϪH, NH), 7.65 (s, 3 H, Ar-H), 8.02 (s, 6 H, Ar-H),
8.15 (br. s, 1 H, NH), 8.33Ϫ8.40 (m, 3 H, Ar-H), 8.76 (s, 1 H, NH),
9.22 (br. s, 1 H, NH), 10.22 (br. s, 1 H, NH). Ϫ 13C NMR
(100.6 MHz, CD2Cl2/CD3OD) δ (ppm) ϭ 18.2, 18.4, 30.9 (CH3),
23.1, 26.3, 36.1 (CH2), 114.7, 119.4, 123.6, 125.7, 126.7, 126.9,
127.5, 128.5 (CH), 34.9, 45.4, 118.4, 126.9, 130.5, 131.6, 134.5,
134.8, 135.3, 136.1, 137.2, 140.2, 142.2, 148.4, 148.6, 149.8, 152.1
154.1 (Cq), 161.6, 166.4, 166.7 (CO). Ϫ MALDI-MS: m/z (%) ϭ
1602.9 (100) [M ϩ Naϩ].
Int. Ed. 2000, 39, 1616Ϫ1618.
[3a]
For reviews, see:
C. O. Dietrich-Buchecker, J.-P. Sauvage,
Chem. Rev. 1987, 87, 795Ϫ810. Ϫ [3b] J.-P. Sauvage, Acc. Chem.
Res. 1990, 23, 319Ϫ327. Ϫ
J. K. M. Sanders, Acc. Chem. Res. 1993, 26, 469Ϫ475. Ϫ
R. Hoss, F. Vögtle, Angew. Chem. 1994, 106, 389Ϫ398; Angew.
Chem. Int. Ed. Engl. 1994, 33, 375Ϫ384. Ϫ [3e] J.-C. Chambron,
C. O. Dietrich-Buchecker, V. Heitz, J.-F. Nierengarten, J.-P.
[3c]
S. Anderson, H. L. Anderson,
[3d]
Sauvage, C. Pascard, J. Guilhem, Pure Appl. Chem. 1995, 67,
[3f]
233Ϫ240. Ϫ
R. Jäger, F. Vögtle, Angew. Chem. 1997, 109,
966Ϫ980; Angew. Chem. Int. Ed. Engl. 1997, 36, 930Ϫ944. Ϫ
[3g]
S. A. Nepogodiev, J. F. Stoddart, Chem. Rev. 1998, 98,
[3h]
1959Ϫ1976. Ϫ
F. M. Raymo, J. F. Stoddart, Chem. Rev.
1999, 99, 1043Ϫ1063.
[4] [4a]
D. E. Adams, E. M. Shekhtman, E. L. Zechiedrich, M. B.
[4b]
Schmid, N. R. Cozzarelli, Cell 1992, 71, 277Ϫ288. Ϫ
Chen, C. A. Rauch, J. H. White, P. T. Englund, N. R. Cozzar-
J.
[4c]
elli, Cell 1995, 80, 61Ϫ69. Ϫ For a review, see:
N. C. See-
man, Angew. Chem. 1998, 110, 3408Ϫ3428; Angew. Chem. Int.
Ed. 1998, 37, 3220Ϫ3238.
[5] [5a]
C. Liang, K. Mislow, J. Am. Chem. Soc. 1994, 116,
11189Ϫ11190. Ϫ [5b] F. Takusagawa, S. Kamitori, J. Am. Chem.
Soc. 1996, 118, 8945Ϫ8946.
Rot3@14:
[2]{N,NЈ-Bis[3,5-di(tert-butyl)phenyl]-1,1Ј-biphenyl-
4,4Јdicarboxamide}-{3,3ЈЈ,5Ј,17Ј,23Ј,35Ј,38Ј,40Ј,43Ј,45Ј-decamethyldi-
spiro[cyclohexane-1,2Ј-7Ј,15Ј,25Ј,33Ј,39Ј,44Ј-hexaazaheptacyclo-
[32.2.2.23Ј.6Ј.216Ј.19Ј.221Ј.24Ј.19Ј.13Ј.127Ј.31Ј]hexatetraconta-3Ј,5Ј,9Ј,
11Ј,13Ј(44Ј),16Ј,18Ј,21Ј,23Ј,27Ј,29Ј,31Ј(39Ј),34Ј,36Ј,37Ј,40Ј,42Ј,45Ј-
octadecaene-20Ј,1ЈЈ-cyclohexane]-8Ј,14Ј,26Ј,32Ј-tetrone}rotaxane:
The rotaxane was a mixture of syn/anti isomers with respect to the
two methyl groups at the cyclohexyl rings. Some of the NMR sig-
nals therefore appear as a double set. Ϫ Rf ϭ 0.31 (CH2Cl2/
[6] [6a]
P. D. B oye r, Angew. Chem. 1998, 110, 2424Ϫ2436; Angew.
Chem. Int. Ed. 1998, 37, 2296Ϫ2307. Ϫ [6b] J. E. Walker, Angew.
Chem. 1998, 110, 2438Ϫ2450; Angew. Chem. Int. Ed. 1998,
37, 2308Ϫ2319.
[7]
R. M. Macnab, S.-I. Aizawa, Annu. Rev. Biophys. Bioeng. 1984,
13, 51Ϫ83.
[8] [8a]
D. K. Mitchell, J.-P. Sauvage, Angew. Chem. 1988, 100,
985Ϫ987; Angew. Chem. Int. Ed. Engl. 1988, 27, 930Ϫ932. Ϫ
[8b] Y. Kaida, Y. Okamoto, J.-C. Chambron, D. K. Mitchell, J.-
P. Sauvage, Tetrahedron Lett. 1993, 34, 1019Ϫ1023. Ϫ [8c] P. R.
Ashton A. S. Reder, N. Spencer, J. F. Stoddart, J. Am. Chem.
Soc. 1993, 115, 5286Ϫ5287. Ϫ [8d] C. Yamamoto, Y. Okamoto,
1
EtOAc ϭ 20:1); yield: 2%; m.p. Ͼ 300 °C. Ϫ H NMR (500 MHz,
CDCl3) δ (ppm) ϭ 0.88Ϫ0.98 (br. s, 6 H, CH3), 1.30 [s, 36 H,
C(CH3)3], 1.33Ϫ1.36 (m, 6 H, CH3), 1.37Ϫ1.41 (m, 3 H, CH3),
1.54Ϫ1.59 (m, 6 H, CH3), 1.62Ϫ1.78 (m, 10 H, CH2), 1.79Ϫ1.91
(m, 6 H, CH3), 2.21Ϫ2.34 (m, 3 H, CH3), 2.54Ϫ2.71 (m, 4 H, CH2),
6.64Ϫ6.71 (m, 4 H, Ar-H), 6.72 (s, 4 H, Ar-H), 6.78Ϫ6.88 (m, 4
T. Schmidt, R. Jäger, F. Vögtle, J. Am. Chem. Soc. 1997, 119,
[8e]
10547Ϫ10548. Ϫ
P. R. Ashton, J. A. Bravo, F. M. Raymo,
2888
Eur. J. Org. Chem. 2001, 2877Ϫ2890

Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes
FULL PAPER
[19] [19a]
J. F. Stoddart, A. J. P. White, D. J. Williams, Eur. J. Org. Chem.
I. T. Harrison, J. Chem. Soc., Chem. Commun. 1972,
[8f]
1999, 899Ϫ908. Ϫ
R. Schmieder, G. Hübner, C. Seel, F.
231Ϫ232. Ϫ [19b] I. T. Harrison, J. Chem. Soc., Perkin Trans. 1
Vögtle, Angew. Chem. 1999, 111, 3741Ϫ3743; Angew. Chem.
1974, 301Ϫ304. Ϫ [19c] G. Agam, D. Graiver, A. Zilkha, J. Am.
[8g]
[19d]
Int. Ed. 1999, 38, 3528Ϫ3530. Ϫ
C. Reuter, A. Mohry, A.
Chem. Soc. 1976, 98, 5206Ϫ5214. Ϫ
J. Am. Chem. Soc. 1976, 98, 5214Ϫ5216. Ϫ
Beckmann, N. Schweickert, H. Fritz, Chem. Ber. 1986, 119,
G. Agam, A. Zilkha,
[19e]
Sobanski, F. Vögtle, Chem. Eur. J. in press. Ϫ For a review,
G. Schill, W.
[8h]
see:
J.-C. Chambron, C. O. Dietrich-Buchecker, J. P. Sauv-
[19f]
´
P. R. Ashton, M. Belohradsky, D. Philp, J.
age, Top. Curr. Chem. 1993, 165, 131Ϫ162.
2647Ϫ2655. Ϫ
F. Stoddart, J. Chem. Soc., Chem. Commun. 1993, 1269Ϫ1274.
[9a] K. E. Drexler, Annu. Rev. Biophys. Biomol. Struct. 1994, 23,
[9]
[19g]
[9b]
´
Ϫ
P. R. Ashton, M. Belohradsky, D. Philp, N. Spencer, J.
´ ´
V. Balzani, M. Gomez-Lopez, J. F. Stoddart,
377Ϫ405. Ϫ
[9c]
F. Stoddart, J. Chem. Soc., Chem. Commun. 1993, 1274Ϫ1277.
Acc. Chem. Res. 1998, 31, 405Ϫ413. Ϫ
J.-P. Sauvage, Acc.
[19h]
Chem. Res. 1998, 31, 611Ϫ619. Ϫ [9d] J.-P. Collin, P. Gavina, V.
Ϫ
D. H. Macartney, J. Chem. Soc., Perkin Trans. 2 1996,
˜
2775Ϫ2778. Ϫ [19i] M. Händel, M. Plevoets, S. Gestermann, F.
[9e]
Heitz, J.-P. Sauvage, Eur. J. Inorg. Chem. 1998, 1Ϫ14. Ϫ
Z.
Vögtle, Angew. Chem. 1997, 109, 1248Ϫ1250; Angew. Chem.
Int. Ed. Engl. 1997, 36, 1199Ϫ1201. Ϫ
M. Raymo, J. F. Stoddart, in: Stimulating Concepts in Chem-
istry (Eds.: J. F. Stoddart, F. Vögtle), Wiley-VCH, Weinheim,
Asfari, J. Vicens, J. Incl. Phenom. Macrocyc. Chem. 2000, 36,
[19j]
[9f]
M. C. T. Fyfe, F.
103Ϫ118. Ϫ
V. Balzani, A. Credi, F. M. Raymo, J. F. Stod-
dart, Angew. Chem. 2000, 112, 3484Ϫ3530; Angew. Chem. Int.
[9g]
Ed. 2000, 39, 3348Ϫ3391. Ϫ
C. A. Schalley, K. Beizai, F.
2000, p. 211.
For a few examples, see:
Vögtle, Acc. Chem. Res. submitted.
[20]
[21]
[22]
[20a]
[10] [10a]
P. L. Anelli, N. Spencer, J. F.
´
D. J. Cardenas, P. Gavin˜as, J.-P. Sauvage, Chem. Commun.
[20b]
[10b]
Stoddart, J. Am. Chem. Soc. 1991, 113, 5131Ϫ5133. Ϫ
R.
1996, 1915Ϫ1916. Ϫ
D. B. Amabilino, C. O. Dietrich-Bu-
´
A. Bissell, E. Cordova, A. E. Kaifer, Nature 1994, 369,
checker, J.-P. Sauvage, J. Am. Chem. Soc. 1996, 118,
[20c]
[10c]
133Ϫ137. Ϫ
D. B. Amabilino, P.-L. Anelli, P. R. Ashton,
´
D. J. Cardenas, P. Gavin˜as, J.-P. Sauvage, J.
3285Ϫ3286. Ϫ
´
´
G. R. Brown, E. Cordova, L. A. Godınez, W. Hayes, A. E.
Kaifer, D. Philp, A. M. Z. Slawin, N. Spencer, J. F. Stoddart,
M. S. Tolley, D. J. Williams, J. Am. Chem. Soc. 1995, 117,
11142Ϫ11170. Ϫ
Am. Chem. Soc. 1997, 119, 2656Ϫ2664. Ϫ For a review, see:
[10d]
J.-C. Chambron, S. Chardon-Noblat, A. Harriman, V.
Heitz, J.-P. Sauvage, Pure Appl. Chem. 1993, 65, 2343Ϫ2349.
[20d]
A. C. Benniston, A. Harriman, V. M.
[11]
[12]
´
´
F. Diederich, L. Echegoyen, M. Gomez-Lopez, R. Kessinger,
[20e]
Lynch, J. Am. Chem. Soc. 1995, 117, 5275Ϫ5291. Ϫ
A. S.
J. F. Stoddart, J. Chem. Soc., Perkin Trans. 2 1999, 1577Ϫ1586.
Lane, D. A. Leigh, A. Murphy, J. Am. Chem. Soc. 1997, 119,
F. Vögtle, W. M. Müller, U. Müller, M. Bauer, K. Rissanen,
Angew. Chem. 1993, 105, 1356Ϫ1358; Angew. Chem. Int. Ed.
Engl. 1993, 32, 1295Ϫ1297.
11092Ϫ11093. Ϫ [20f] J.-P. Collin, P. Gavina, J.-P. Sauvage, New
˜
J. Chem. 1997, 21, 525Ϫ528. Ϫ [20g] H. Murakami, A. Kawabu-
chi, K. Kotoo, M. Kunitake, M. Nakashima, J. Am. Chem.
Soc. 1997, 119, 7605Ϫ7606. Ϫ
Zerbetto, Angew. Chem. 2000, 112, 358Ϫ361; Angew. Chem.
Int. Ed. 2000, 39, 350Ϫ353.
For a small selection of references, see:
Dietrich-Buchecker, J.-P. Sauvage, J. Am. Chem. Soc. 1994, 116,
9399Ϫ9400. Ϫ
[13]
[20h]
S. S. Zhu, P. J. Carroll, T. M. Swager, J. Am. Chem. Soc. 1996,
118, 8713Ϫ8714.
D. A. Leigh, A. Troisi, F.
[14] [14a]
A. Credi, V. Balzani, S. J. Langford, J. F. Stoddart, J. Am.
[14b]
[21a]
Chem. Soc. 1997, 119, 2679Ϫ2681. Ϫ
M. Asakawa, P. R.
A. Livoreil, C. O.
Ashton, V. Balzani, A. Credi, G. Mattersteig, O. A. Matthews,
M. Montalti, N. Spencer, J. F. Stoddart, M. Venturi, Chem.
Eur. J. 1997, 3, 1992Ϫ1996.
[21b]
A. G. Johnston, D. A. Leigh, R. J. Pritch-
ard, M. D. Deegan, Angew. Chem. 1995, 107, 1324Ϫ1327; An-
[21c]
[15]
gew. Chem. Int. Ed. Engl. 1995, 34, 1209Ϫ1212. Ϫ
D. A.
For a computational study of the size requirements of the de-
slipping process, see: F. M. Raymo, K. N. Houk, J. F. Stoddart,
J. Am. Chem. Soc. 1998, 120, 9318Ϫ9322.
Leigh, K. Moody, J. P. Smart, K. J. Watson, A. M. Z. Slawin,
Angew. Chem. 1996, 108, 326Ϫ331; Angew. Chem. Int. Ed.
Engl. 1996, 35, 306Ϫ310. Ϫ
Schmidt, Acc. Chem. Res. 1996, 29, 451Ϫ460. Ϫ
eil, J.-P. Sauvage, N. Armaroli, V. Balzani, L. Flamigni, B. Ven-
tura, J. Am. Chem. Soc. 1997, 119, 12114Ϫ12124. Ϫ [21f] M. C.
T. Fyfe, P. T. Glink, S. Menzer, J. F. Stoddart, A. J. P. White,
[21d]
[16] [16a]
F. Vögtle, T. Dünnwald, T.
G. Hübner, G. Nachtsheim, Q.-Y. Li, C. Seel, F. Vögtle,
Angew. Chem. 2000, 112, 1315Ϫ1318; Angew. Chem. Int. Ed.
[21e]
A. Livor-
[16b]
2000, 39, 1269Ϫ1272. Ϫ Also, see:
H. W. Gibson, S. Liu,
P. Lecavalier, C. Wu, Y. X. Shen, J. Am. Chem. Soc. 1995, 117,
[16c]
852Ϫ874. Ϫ
C. Heim, Ph. D. Thesis, Universität Bonn,
D. J. Williams, Angew. Chem. 1997, 109, 2158Ϫ2160; Angew.
1998. Ϫ [16d]C. Heim, A. Affeld, M. Nieger, F. Vögtle, Helv.
Chim. Acta 1999, 82, 746Ϫ759.
[21g]
Chem. Int. Ed. Engl. 1997, 36, 2068Ϫ2070. Ϫ
M. S. De-
leuze, D. A. Leigh, F. Zerbetto, J. Am. Chem. Soc. 1999, 121,
[17] [17a]
´
P. R. Ashton, R. Ballardini, V. Balzani, M. Blohradsky,
2364Ϫ2379.
M. T. Gandolfi, D. Philp, L. Prodi, F. M. Raymo, M. V.
C. Seel, A. H. Parham, O. Safarowsky, G. M. Hübner, F.
Vögtle, J. Org. Chem. 1999, 64, 7236Ϫ7242.
Reddington, N. Spencer, J. F. Stoddart, M. Venturi, D. J. Willi-
[17b]
ams, J. Am. Chem. Soc. 1996, 118, 4931Ϫ4951. Ϫ
M.
ˇ
[23] [23a]
C. Reuter, C. Seel, M. Nieger, F. Vögtle, Helv. Chim. Acta
Asakawa, P. R. Ashton, R. Ballardini, V. Balzani, M. Be-
lohradsky, M. T. Gandolfi, O. Kocian, L. Prodi, F. M. Raymo,
2000, 83, 630Ϫ640. Ϫ [23b] A. Mohry, F. Vögtle, M. Nieger, H.
Hupfer, Chirality 2000, 12, 76Ϫ83.
Rot10@2Ј and Rot11@2Ј both bear an additional tert-butyl
group at the periphery of the wheel. We believe that it does not
significantly alter the deslipping kinetics. If so, one would ex-
pect some additional steric hindrance, which, however, is not
in line with the results in Table 1.
´
J. F. Stoddart, M. Venturi, J. Am. Chem. Soc. 1997, 119,
[24]
[17c]
302Ϫ310. Ϫ
P.R. Ashton, I. Baxter, M. C. T. Fyfe, F. M.
Raymo, N. Spencer, J. F. Stoddart, A. J. P. White, D. J. Willi-
ams, J. Am. Chem. Soc. 1998, 120, 2297Ϫ2307.
[18]
For a study of binding constants of the pseudorotaxane axles
[18a]
in the corresponding wheels, see:
P. R. Ashton, D. Philp,
[25]
B. Sunners, L. H. Piette, W. G. Schneider, Can. J. Chem. 1960,
38, 681Ϫ688.
M. V. Reddington, A. M. Z. Slawin, N. Spencer, J. F. Stoddart,
D. J. Williams, J. Chem. Soc., Chem. Commun. 1991,
[26] [26a]
K. B. Wiberg, K. E. Laidig, J. Am. Chem. Soc. 1987, 109,
1680Ϫ1682. Ϫ For some recent publications on pseudorotax-
[26b]
[18b]
5935Ϫ5943. Ϫ
For a review, see: K. B. Wiberg, C.M.
´
P. R. Ashton, M. C. T. Fyfe, M.-V. Martınez-
anes, see:
Hadad, C. M. Breneman, K. E. Laidig, M. A. Murcko, T. J.
LePage, Science 1991, 252, 1266Ϫ1272.
´
Dıaz, S. Menzer, C. Schiavo, J. F. Stoddart, A. J. P. White, D.
J. Williams, Chem. Eur. J. 1998, 4, 1523Ϫ1534. Ϫ [18c] C. Gong,
[27]
[28]
C. M. Breneman, L. W. Weber, Can. J. Chem. 1996, 74,
1271Ϫ1282.
H. W. Gibson, Angew. Chem. 1998, 110, 323Ϫ327; Angew.
[18d]
Chem. Int. Ed. 1998, 37, 310Ϫ314. Ϫ
P. R. Ashton, I. W.
Parsons, F. M. Raymo, J. F. Stoddart, A. J. P. White, D. J.
Williams, R. Wolf, Angew. Chem. 1998, 110, 2016Ϫ2019; An-
gew. Chem. Int. Ed. 1998, 37, 1913Ϫ1916.
D. A. Leigh, A. Murphy, J. P. Smart, A. M. Z. Slawin, Angew.
Chem. 1997, 109, 752Ϫ756; Angew. Chem. Int. Ed. Engl. 1997,
36, 728Ϫ732.
Eur. J. Org. Chem. 2001, 2877Ϫ2890
2889

A. Affeld, G. M. Hübner, C. Seel, C. A. Schalley
FULL PAPER
[29]
[36] [36a]
S. OttensϪHildebrandt, M. Nieger, K. Rissanen, J. Rouvinen,
C. A. Hunter, J. Chem. Soc., Chem. Commun. 1991,
[36b]
S. Meier, G. Harder, F. Vögtle, J. Chem. Soc., Chem. Commun.
1995, 777Ϫ778.
A. G. Johnston, D. A. Leigh, L. Nehzat, J. P. Smart, M. D.
749Ϫ751. Ϫ
C. A. Hunter, J. Am. Chem. Soc. 1992, 114,
5303Ϫ5311. Ϫ [36c] F. Vögtle, S. Meier, R. Hoss, Angew. Chem.
1992, 104, 1628Ϫ1631; Angew. Chem. Int. Ed. Engl. 1992, 31,
1619Ϫ1622.
[30]
Deegan, Angew. Chem. 1995, 107, 1327Ϫ1331; Angew. Chem.
[37] [37a]
S. Ottens-Hildebrandt, T. Schmidt, J. Harren, F. Vögtle,
Int. Ed. Engl. 1995, 34, 1202Ϫ1216.
Liebigs Ann. 1995, 1855Ϫ1860. Ϫ [37b] R. Jäger, M. Händel, K.
[31] [31a]
Y. Hamuro, S. J. Geib, A. D. Hamilton, Angew. Chem.
[37c]
Rissanen, F. Vögtle, Liebigs Ann. 1996, 1201Ϫ1207. Ϫ
F.
1994, 106, 465Ϫ467; Angew. Chem. Int. Ed. Engl. 1994, 33,
[31b]
Vögtle, R. Jäger, M. Händel, S. Ottens-Hildebrandt, W.
446Ϫ448. Ϫ
C. A. Hunter, L. D. Sarson, Angew. Chem.
Schmidt, Synthesis 1996, 353.
A. Affeld, Ph. D. Thesis, Universität Bonn, 2000. Ϫ
A. Hünten, Ph. D. Thesis, Universität Bonn, 2001.
1994, 106, 2424Ϫ2426; Angew. Chem. Int. Ed. Engl. 1994, 33,
[38] [38a]
[38b]
2313Ϫ2316.
[32] [32a]
C. A. Hunter, D. H. Purvis, Angew. Chem. 1992, 104,
779Ϫ782; Angew. Chem. Int. Ed. Engl. 1992, 31, 792Ϫ795. Ϫ
[39] [39a]
G. M. Hübner, J. Gläser, C. Seel, F. Vögtle, Angew. Chem.
1999, 111, 395Ϫ398; Angew. Chem. Int. Ed. 1999, 38, 383Ϫ386.
[32b]
V. Berl, I. Huc, R. G. Khoury, M. J. Krische, J.-M. Lehn,
[39b]
Ϫ
C. Reuter, W. Wienand, G. M. Hübner, C. Seel, F.
[32c]
Nature 2000, 407, 720Ϫ723. Ϫ
Huc, J.-M. Lehn, M. Schmutz, Chem. Eur. J. 2000, 6,
V. Berl, M. J. Krische, I.
[39c]
Vögtle, Chem. Eur. J. 1999, 5, 2692Ϫ2697. Ϫ
C. Reuter, F.
[39d]
Vögtle, Org. Lett. 2000, 2, 593Ϫ595. Ϫ
C. Seel, F. Vögtle,
1938Ϫ1946.
Chem. Eur. J. 2000, 6, 21Ϫ24.
[33]
Sybyl force field, Spartan, Wavefunction Inc., 18401 Von
Karman Ave., Irvine, CA 92612, USA.
[40] [40a]
S. Ottens-Hildebrandt, S. Meier, W. Schmidt, F. Vögtle,
Angew. Chem. 1994, 106, 1818Ϫ1821; Angew. Chem. Int. Ed.
[34] [34a]
[40b]
M. Miyaura, T. Yanagi, A. Suzuki, Synth. Commun. 1981,
Engl. 1994, 33, 1767Ϫ1770. Ϫ
F. Vögtle, M. Händel, S.
[34b]
7, 513Ϫ519. Ϫ
A. R. Katritzky, S. A. Belyakov, S. A.
Meier, S. Ottens-Hildebrandt, F. Ott, T. Schmidt, Liebigs Ann.
[40c]
Henderson, P. J. Steel, J. Org. Chem. 1997, 62, 8215Ϫ8217.
1995, 739Ϫ743. Ϫ
R. Jäger, T. Schmidt, D. Karbach, F.
[35] [35a]
[40d]
J. Heinze, J. Mortensen, K. Müllen, R. Schenk, J. Chem.
Vögtle, Synlett 1996, 723. Ϫ
R. Jäger, S. Baumann, M.
[35b]
Soc., Chem. Commun. 1987, 701Ϫ703. Ϫ
R. Schenk, J.
Fischer, O. Safarowsky, M. Nieger, F. Vögtle, Liebigs Ann./Rec-
ueil 1997, 2269Ϫ2273. Ϫ [40e] R. Jäger, F. Vögtle, Angew. Chem.
1997, 109, 966Ϫ980; Angew. Chem. Int. Ed. Engl. 1997, 36,
930Ϫ944.
Hucker, H. Hopf, H. J. Raeder, K. Müllen, Angew. Chem. 1989,
101, 942Ϫ944; Angew. Chem. Int. Ed. Engl. 1989, 28, 904Ϫ906.
Ϫ
[35c] K. Sandros, M. Sundahl, O. Wennerström, U. Norinder,
J. Am. Chem. Soc. 1992, 112, 3082Ϫ3086.
Received February 7, 2001
[O01061]
2890
Eur. J. Org. Chem. 2001, 2877Ϫ2890