Pseudorotaxanes and rotaxanes incorporating diarylcycloheptatriene stations

Article abstract of DOI:10.1002/ejoc.200400607

The nature of the interaction between the tetracationic cyclophane cyclobis(paraquat-4,4′-biphenylene) and molecular threads incorporating arylcycloheptatriene units as stations was studied through the differences between the proton resonances observed in

Full text of DOI:10.1002/ejoc.200400607

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Pseudorotaxanes and Rotaxanes Incorporating Diarylcycloheptatriene Stations
Werner Abraham,*[a] Lutz Grubert,[a] Sebastian Schmidt-Schäffer,[a] and Karin Buck[a]
Keywords: Cycloheptatriene / Rotaxanes / Supramolecular chemistry / Tropylium ion
The nature of the interaction between the tetracationic cyclo-
for pseudorotaxanes and rotaxanes. The main contribution to
phane cyclobis(paraquat-4,4Ј-biphenylene) and molecular the driving forces behind the complexation of pseudorotax-
threads incorporating arylcycloheptatriene units as stations
was studied through the differences between the proton res-
onances observed in the NMR spectra of free molecular thre-
anes and the co-conformation of rotaxanes was deduced from
the CIS values of distinct parts of the molecular threads. The
unusual signal dispersion of the cyclophane proton reson-
ads and in those of corresponding pseudorotaxanes and rot- ances is attributed to the asymmetry caused by the molecular
axanes (CIS values). Molecular threads of different lengths thread incorporating the asymmetric cycloheptatriene ring.
possessing one or two recognition stations and incorporating (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
two different isomeric arylcycloheptatriene units were used
Germany, 2005)
In contrast with other molecular threads previously used
for rotaxanes and catenanes, the cycloheptatriene ring as
Introduction
The electron-deficient tetracationic cyclophane cyclobis- donor station has two interesting properties: firstly, it is a
(paraquat-p-phenylene) (1) has been widely used by the nonplanar, boat-shaped ring, and secondly, two aryl sub-
Stoddart group[1] and others[2] as a fundamental building stituents can be arranged in various positions along the π-
block of rotaxanes and catenanes. Rotaxanes of host 1 are system of the seven-membered ring, as shown in Scheme 1.
designed with molecular threads incorporating electron-rich
aromatic subunits: stations on which the cyclophane should
reside due to non-covalent interaction. The driving forces
involved in thread-binding include electrostatic interaction,
hydrogen bonding, and solvation effects, rather than
charge-transfer interaction.[3Ϫ5] With pseudorotaxanes it
has been found that both oxygen functionalities along the
chain between donor stations and an aromatic core are
necessary in order to position the guest in the cavity of 1.
On the other hand, there is no strong correlation between
the binding constants measured for pseudorotaxanes based
on 1 with various threads containing aromatic donors and
the co-conformation of rotaxanes or catenanes,[4,5] and so
a trial and error approach to the rotaxane design is often
necessary. The oxidation potential of the electron donor
station of the molecular thread may serve as a first ap-
Scheme 1
proach towards the design of such subunits that would be
In this paper we report the co-conformation of pseudoro-
expected to interact with 1.
taxanes and rotaxanes incorporating the substructures I
We have recently reported on rotaxanes containing two
and II (see Scheme 1).
equivalent diarylcycloheptatriene stations[6] and on a pho-
Structure I is characterized by two aryl substituents, not
toswitchable rotaxane with one diarylcycloheptatriene
conjugated to each other. Therefore, two separated subun-
station together with a second electron donor station,[7] and
its, namely the 3-aryl-cycloheptatriene and aniline, might
the question arises as to which forces govern the co-confor-
interact separately with the tetracationic ring. Furthermore,
mation of the rotaxanes formed with the cyclophane 1.
this structure exists as two enantiomers. Structure II is
available from I through the thermal hydrogen shift reaction
[a]
Humboldt-University, Institute of Chemistry,
and corresponds to an entire interaction unit. While the
recognition units of the investigated molecular threads were
varied, the length of the chain attached to the recognition
stations was kept constant, so that differences observed in
Brook-Taylor-Str. 2, 12489 Berlin
Fax: (internat.) ϩ 49-30-20937266
E-mail: abraham@chemie.hu-berlin.de
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
374
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DOI: 10.1002/ejoc.200400607
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Rotaxanes Incorporating Diarylcycloheptatriene Stations
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the complexation of the molecular threads with the host 1 thesis of the molecular threads 10Ϫ13 was reported re-
could be attributed to the properties of these subunits.
cently.[6,7]
Pseudorotaxanes and Rotaxanes
Results and Discussion
The molecular threads studied can be divided into three
types:
Ϫ those containing only the diarylcycloheptatriene
Synthesis of Molecular Threads
Compound 3 was obtained as outlined in Scheme 2, by station with varying extents of π-conjugation (compounds
alkylation of 7-(4-hydroxyphenyl)-1,3,5-cycloheptatriene 6 and 8),
and subsequent acylation. The aniline substituent was in-
Ϫ those incorporating two competing donor stations
troduced by nucleophilic attack of aniline on the tropylium (compounds 9 and 10),
salt to afford the two isomers 6 and 7, which could be sepa-
Ϫ compounds with shortened threads, used for compari-
rated by column chromatography. Only isomer 6 was used son (compounds 11Ϫ13 are included here).
for further studies. The isomeric molecular thread 8 of the
structure type II was easily obtained through a thermal hy-
The interaction of different parts of the molecular
drogen shift. Compounds 6 and 8 were used to study threads with the cyclophane 1 was not studied by means of
pseudorotaxanes and rotaxanes incorporating only one the association constants,[4] but rather by use of the chemi-
station for the interaction with the cyclophane 1. The syn- cally induced shifts (CISs), determined by the differences
Scheme 2
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between the proton resonances of uncomplexed 1 and the ent protons of the subunits seems to be adequate for detec-
threads and the related proton resonances within the tion of the region of the strongest interaction for such re-
pseudorotaxane formed by 1:1 mixtures (0.01 m) of the two lated molecular threads.
components (δuncomplexed Ϫ δcomplexed). It was checked that
the CIS values do not vary significantly in the concen-
tration range used, because these values are similar to the
maximal observable difference between the chemical shifts
One-Station Pseudorotaxanes and Rotaxanes
The molecular threads 6 and 8 serve as standards for the
of uncomplexed and complexed components. The associ- structures I and II (Scheme 1) to explore the interaction of
ation constants can only supply information about the over- these two different diarylcycloheptatriene stations with 1.
all interaction of the components, but we were interested in The CIS values of the pseudorotaxanes 14 and 16, together
the interaction of specific regions of the thread with the with those of the related rotaxanes 15 and 17, are given in
ring. Each cycloheptatriene station consists of three interac- Scheme 4 and Scheme 5. The assignment of different reson-
tion units: the CHT ring and the two donor substituents B ances of the aromatic protons to the rings A and B is pos-
and C (see Scheme 3). Use of of the CIS values of the differ- sible with the help of NOEs (ROESY spectra).
Scheme 3
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Scheme 4. Proton CIS values (δfree component Ϫ δpseudorotaxane/rotaxane) of the components of 14 and 15
With regard to the CIS values of the type I and II broadening is therefore unlikely to be due to the exchange
pseudorotaxanes (see Scheme 1), two findings are remark- process between the complexed and non-complexed compo-
able.
nents. We consider the restricted internal rotation of the
Firstly, the strongest interaction in both types of pseudo- aryl group B due to interaction with 1 to be responsible for
rotaxane is found between 1 and the aniline part A of the this effect. The proton resonances of the glycol chain are
diarylcycloheptatriene station. The observed upfield shift of not shifted upon complexation.
the proton resonances indicates the sandwich-like arrange-
The CT absorption band of the two pseudorotaxanes at
ment of the aromatic substituents A and B between the bi- 400Ϫ680 nm is centered at 450 nm and corresponds to the
pyridinium units of the cyclophane 1. In contrast, the up- alkoxyarylcycloheptatriene part; the CT absorption caused
field shift of the proton resonances of the CHT unit playing by the interaction between the aniline substituent and 1 is
the role of a link between A and B is very small.
expected to appear at 570 nm, and is hidden under the long-
Secondly, it is obvious that the cycloheptatriene ring in wavelength tail of the first CT band (see Supporting Infor-
structure II, enabling a conjugative connection between the mation).
aromatic substituents, is more strongly involved than in
The formation of pseudorotaxanes is attested to the typi-
structure I; the strongest interaction of the cyclophane 1 cal CIS values observed for the protons of the cyclophane
occurs with the stronger electron donor A of the CHT 1.[8] In particular, the upfield shift of the β-protons of the
station. The link between the two aryl groups represented bipyridinium rings and the downfield shift of the protons
by the CHT subunit is mostly affected at the positions ad- of the benzylic spacer units are characteristic for such types
jacent to the aryl substituents. Because A is rather far from of host-guest complexes.
the ethyleneoxy units of the chain, it can be concluded that
Rotaxanes were obtained by alkylation of the amino
it is not the interaction of 1 with the chain that plays the groups of the molecular threads with the voluminous tris-
dominant role, but rather electrostatic and charge transfer iPr-benzyl group in the presence of 1 (see Scheme 6).
interactions.
The alkylated molecular threads that were obtained in
The aryl protons of the substituent A appear as fairly addition to the rotaxanes were used to determine the CIS
sharp doublets in the pseudorotaxane 14. In contrast, the values of the related rotaxanes. The compounds 15 and 17
proton resonances of B are broad (see Supporting Infor- represent the prototypes of rotaxanes incorporating the di-
mation). The dynamic process giving rise to the signal arylcycloheptatriene recognition station with different ar-
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Scheme 5. Proton CIS values (δfree component Ϫ δpseudorotaxane/rotaxane) of the components of 16 and 17
rangements of the π-system of the seven-membered ring
Note that there is a large twisting angle between the main
with respect to the aryl groups. Because only one station plane of CHT and the aniline ring A.
exists, the observed CIS values given in Scheme 4 and
The change of residence of the cyclophane 1 within the
Scheme 5 represent the maximal shift of the protons that rotaxane compared with the pseudorotaxane is obviously
can be expected if the cyclophane 1 resides exclusively on due to the steric hindrance of the bulky benzylic triisoprop-
the diarylcycloheptatriene station. There are remarkable ylphenyl group, which does not allow the occupation of A.
differences between the pseudorotaxanes and the related ro-
taxanes.
Secondly, the protons of the cyclophane are anisochron-
ous, resulting in signal broadening or even splitting (see
The co-conformation of the rotaxane 15 differs from that Supporting Information). This effect is especially pro-
of 14 in two ways. nounced in the rotaxanes, including the structure element I,
Firstly, the cyclophane 1 resides exclusively on the CHT and it can be attributed to the asymmetry caused by the
and B subunits, resulting in strong upfield shifts of these entire thread, especially by the seven-membered ring (see
protons (see Scheme 5). The parts of the CHT subunit ad- Figure 1).
jacent to B are deeply involved. Both the aniline substituent
Therefore, two different bipyridinium units exist, pro-
and the adjacent parts of CHT lie outside the cyclophane vided that the internal rotation of these subunits is restric-
cavity in the plane of the bipyridinium units, resulting in a ted. The splitting into several singlets is especially pro-
downfield shift of the proton resonances.
nounced for the benzylic protons (b in Figure 1). These pro-
378
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Rotaxanes Incorporating Diarylcycloheptatriene Stations
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Scheme 6
tons cannot exchange places by internal rotation, and fast
The CT absorption band of the rotaxane 15 resembles
exchange by rotation of the entire ring 1 around the molec- that of the pseudorotaxane and is centered at 430 nm.
ular thread is obviously prevented. Signal splitting of the The conjugative arrangement of A and B across the
resonances of the benzylic protons is also observed in the seven-membered ring in the rotaxane 17 results in delocaliz-
rotaxane 17. However, the α- and β-proton resonances are ation of the cyclophane over the entire CHT station, while
only broadened (see Supporting Information).
the greater shielding of the aryl group B indicates that it
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W. Abraham, L. Grubert, S. Schmidt-Schäffer, K. Buck
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mation is changed on going from the pseudorotaxane 16
to the rotaxane 17. It is worth noting that the absorption
maximum of the CHT station in the rotaxane 17 is ba-
thochromically shifted by 18 nm (1250 cmϪ1) from the ab-
sorption maximum of the non-complexed molecular thread
19. This strong shift can be attributed to the polar environ-
ment formed around the CHT station by the cyclophane.[7]
Because of the long-wavelength absorption edge of the
molecular thread at 440 nm, no CT band could been de-
tected in this region, only a CT band at 575 nm being vis-
ible. This long-wavelength absorption band is consistent
with the co-conformation derived from the CIS values with
the cyclophane also residing on the aniline substituent A.
Unlike the rotaxane 15, compound 17 can be quantitat-
ively transformed into the tropylium rotaxane 20 by electro-
chemical oxidation. In this rotaxane, the former donor
station is now an acceptor station, and it is interesting to
explore how the tetracationic ring 1 behaves. Compound
21, obtained by electrochemical oxidation of the thread 19,
was used in order to calculate the CIS values from which
Figure 1. Structure of the rotaxane 15
spends more time on this subunit. The greater upfield shift the co-conformation is determined. According to the pro-
of B observed in the rotaxane 15 in relation to that in com- ton resonances of 21 (see Scheme 7), the electron-deficient
pound 17 indicates that the delocalization of the cyclophane natures not only of the tropylium ring but also of rings A
over the CHT station in the rotaxane 17 gives rise to a di- and ring B can be inferred. However, the cyclophane sur-
minished shielding of the entire station. Unlike in com- prisingly remains on the tropylium station above B, which
pound 15, the steric hindrance does not fully prevent the can be confirmed from the very large upfield shift of the
interaction of 1 with the A ring, because this interaction is proton resonances of the substituent B (see Scheme 7).
stronger than in the situation found in rotaxane 15. How- NOEs show the contacts between the cyclophane 1 (β-pro-
ever, it can also be inferred in this case that the co-confor- tons) and B. The signal pattern of the proton resonances of
Scheme 7. Proton CIS values (δfree
thread 21
Ϫ δrotaxane) of the components of 20 and proton resonances (in ppm) of the molecular
component
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the cyclophane 1 is preserved on going from the cyclohepta-
The molecular threads 11, 12, and 13 were involved in
trienyl rotaxane 17 to the rotaxane with the tropylium unit; our studies of the complexation behavior in order to explore
broad signals of the α- and β-protons and the split reson- the ‘‘monoarylcycloheptatriene’’ interaction unit, as well as
ance of the benzylic protons indicate the different sites of the influence of the bulky end-group on the interaction be-
the thread seen by the cyclophane.
tween the thread and the cyclophane 1. Furthermore, com-
pounds 11Ϫ13 have cycloheptatriene stations without
conjugation between B and CHT, and the question arises
as to whether this has consequences for the interaction
strength.
In general, the assignment of proton resonances to the
two alkoxyaryl groups B and C suffers from the broadening
of the signals in the complexes 25 and 26, preventing cross-
peaks in the ROESY spectra. In contrast, all other proton
resonances of the thread, and also of the host 1, appear as
sharp signals. We have learned from the other pseudorotax-
anes and rotaxanes that the extent of the upfield shifts of
the aromatic subunits of the thread is continued in the ad-
jacent parts, such as the seven-membered ring or the ali-
phatic chain on the ester side of station C, and if this is
taken into account, an assignment is possible according to
this criterion (see Scheme 9).
It is obvious that the interaction of B and C with 1 is
comparable in the complex 25. In contrast, there is a clear
difference between B and C in the pseudorotaxane 26. Un-
like compound 12, the thread 11 is accessible from two
ends, giving rise to a shared interaction of the host 1 be-
tween B and C during threading and dethreading move-
ments. Accordingly, station C is clearly much less involved
in the interaction with the cyclophane 1 in the pseudorotax-
ane 26 (see Scheme 9). Furthermore, the diminished interac-
tion of the two CHT stations, which can be inferred from
the observed CIS values for the complex 27 (see Scheme 9),
is explainable by the statistical distribution of the interac-
tion possibilities on two equal recognition stations during
the complexation and decomplexation processes.
Two-Station Pseudorotaxanes and Rotaxanes
The pseudorotaxane 22 formed from thread 9 is an iso-
mer of the pseudorotaxane formed with the molecular
thread 10, described recently.[7] The most important result
for the pseudorotaxane 10/1 was the finding that the cyclo-
phane resides exclusively on the cycloheptatriene station
and that the strongest interaction occurs between ring A
and 1.
The situation is drastically changed for 22: both station
C and the diarylcycloheptatriene station interact with the
cyclophane 1 (see Scheme 8). Unfortunately, the resonances
of B and C in the pseudorotaxane 22 cannot be assigned
because of the very broad signals of these aromatic protons
(see Supporting Information). Nevertheless, it is clear that
the signals for the ring protons of both B and of C are
shifted upfield comparably in the pseudorotaxane 22, be-
cause only strongly upfield-shifted resonances of aromatic
protons are observed.
The interruption of the conjugated π-system in the mo-
lecular threads 11 and 12 does not result in a decreased
interaction of the aryl-CHT unit with the cyclophane. Obvi-
ously, the aromatic ring B, together with the adjacent ethyl-
eneoxy bridge, is the decisive structure element.
Despite the rather large differences in the CIS values ob-
served with the molecular threads of the pseudorotaxanes
25Ϫ27, the CIS values of the cyclophane 1 are very similar
in all pseudorotaxanes. This supports the assumption that
the differences are products of the interaction mode and
not of different stability constants of the complexes.
The influence of the conjugative connection of A and B
through the CHT-ring in the thread 10 can be inferred by
comparison of the different CIS values caused by the inter-
action of compounds 9 (Scheme 8) and 10[7] with 1: the in-
creased donor strength of the CHT structure II causes pref-
erential residence of the cyclophane on this station.
Like those of the one-station pseudorotaxanes, the CT
absorption of 22 is centered at 450 nm and differs from the
CT band of the rotaxane (see below). Consistently with the
increased interaction of the conjugated CHT station in
Scheme 8. Proton CIS values (δfree component Ϫ δpseudorotaxane/rotaxane
)
of the components of 22 and 23
The relatively sharp signals of aromatic protons are attri- compound 10, the CT absorption band of 10/1 now appears
buted to the substituent A.
at 580 nm.
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Scheme 9. Proton CIS values (δfree component Ϫ δpseudorotaxane/rotaxane) of the components of 25Ϫ27
The rotaxane 23, which is related to the pseudorotaxane changes of the co-conformation on going from the pseudo-
22, was synthesized similarly to rotaxanes 15 and 17 (see rotaxane 22 to the rotaxane 23.
Scheme 10).
Again, the introduction of the bulky group at the amino
end of the molecular thread prevents residence of 1 on the
substituent A of the CHT station. Instead, the interaction
of 1 with the aryl group B and the CHT ring itself is in-
creased in relation to 22. The CIS values of the proton res-
onances of the parts B and CHT are comparable with those
observed with the one-station rotaxane 15.
Furthermore, the interaction with the station C is in-
creased. We interpret this finding in terms of a folded con-
formation of the thread resulting in contacts between
station C and the cyclophane 1. This assumption is sup-
ported by different CIS values of the protons of the ethyl-
eneoxy chain. Unlike the protons adjacent to the aryl
groups B and C, the central part is shifted downfield. At
Scheme 10
In contrast with the pseudorotaxane, only the proton res- the same time, NOEs between these protons and α- and β-
onances of A can be observed at room temperature in the protons of 1 (relative to the N atom in the bipyridinium
rotaxane 23. However, at 343 K the doublets of the protons units) confirm the contacts. This behavior resembles that of
at B and C appear (see Supporting Information) and can the isomeric rotaxane with conjugation between the sub-
be assigned through NOEs (ROESY spectra at 343 K). Ac- stituents A and B.[7] Whereas the CIS values observed for
cording to the CIS values shown in Scheme 8, there are compound 23 and the related isomeric rotaxane are com-
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dichloromethane as solvent, the organic phases were washed with
a saturated aqueous solution of NaCl and dried (Na2SO4), and the
solvents were evaporated. The ester 4 (4.64 g, 91%) was purified by
CC (silica gel, cyclohexane/acetone 4:1), yielding an oil (3.7 g,
70%). 1H NMR (300 MHz, CD3CN, TMS): δ ϭ 1.69, 1.86, 1.93
(br. m, 15 H, adamantane), 2.62 (t, JH,H ϭ 6 Hz, 1 H; CHT, 7-H),
3.61 (m, 6 H; 3-H, 4-H, 5-H), 3.78 (m, 2 H; 1-H), 4.11 (m, 4 H; 2-
H, 6-H), 5.36 (m, 2 H; CHT, 1-H, 6-H), 6.24 (m, 2 H, CHT, 2-H,
5-H), 6.75 (m, 2 H; CHT, 3-H, 4-H), 6.93 (d, JH,H ϭ 9 Hz, 2 H;
phenyl), 7.29 ppm (d, JH,H ϭ 9 Hz, 2 H; phenyl). C30H38O5
(478.6197): calcd. (%): calcd. C 75.28, H 8.00; found (%) C 74.97,
H 8.11.
parable, the yield of the synthesis of 23 is only half of that
of the isomeric rotaxane.[7]
The observation of two CT absorption bands at 430 and
570 nm corresponds to the interaction of the cyclophane 1
both with BϪCHT and A.
Conclusions
The degrees of occupation of the different stations in
both pseudorotaxanes and rotaxanes by the tetracationic
ring are determined mainly by the strength of the electro-
static and charge-transfer interactions. The oxidation po-
tentials of the stations can be used to estimate the strength
of such interactions, assisting the design of the molecular
thread. As expected, the substitution pattern of the seven-
membered ring strongly influences the interaction between
this recognition station and the cyclophane.
Steric interference between the ring and the end-group of
the thread may hinder the interaction. In the design of the
bulky stopper group to be introduced at the ends of the
molecular thread it has to be taken into account that the
stopper group must not overlap with the recognition
station.
The ester 4 (3.7 g, 7.7.mmol) was oxidized by treatment with trityl
tetrafluoroborate (2.64 g, 7.7 mmol) in dichloromethane (20 mL),
affording the tropylium salt 5 as a red foam (2.97 g, 67%) after
the reaction mixture had been poured into methyl-tert-butyl ether
1
(MTBE) and the resulting oil treated with MTBE and CHCl3. H
NMR (300 MHz, CD3CN, TMS): δ ϭ 1.70, 1.86, 1.94 (br. m, 15
H, adamantane), 3.64 (m, 6 H; 2-H, 3-H, 4-H), 3.86 (m, 2 H; 5-
H), 4.11 (m, 2 H; 1-H), 4.26 (m, 2 H; 6-H), 7.25 (d, JH,H ϭ 9 Hz,
2 H; phenyl), 8.00 (d, JH,H ϭ 9 Hz, 2 H; phenyl), 8.90 (m, 4 H,
tropylium), 9.25 ppm (d, JH,H
ϭ 11 Hz, 2 H; tropylium).
C30H37ClO9 (577.066): calcd. (%): calcd. C 62.44, H 6.64, Cl 6.14;
found (%) C 62.32, H 6.51, Cl 5.83.
The tropylium salt 4 (3.0 g, 5.2 mmol), dissolved in dichlorometh-
ane (20 mL) and acetonitrile (10 mL), was added to aniline (1.94 g,
20.8 mmol) in acetonitrile (1 mL). After having been stirred for 5 h
at room temperature, the solution was washed with a NaHCO3
solution, the organic phase was dried (Na2SO4), and the solvent
was removed under reduced pressure. The excess of aniline was
removed by use of n-hexane. The isomer 6 was separated from 7
by CC (silica gel, toluene/ethyl acetate 10:1) (oil, 593 mg, 20%). 1H
NMR (300 MHz, CD3CN, TMS): δ ϭ 1.67, 1.84, 1.943 (br. m, 15
H, adamantane), 2.68 (t, JH,H ϭ 6 Hz, 1 H; CHT, 7-H), 3.64 (m,
4 H; 3-H, 4-H), 3.77 (m, 2 H; 1-H), 4.06 (br., 1 H, NH), 4.1 (m, 6
H; 2-H, 5-H, 6-H), 5.44 (m, 1 H; CHT, 6-H), 5.51 (m, 1 H; CHT,
1-H), 6.28 (m, 1 H, CHT, 5-H), 6.33 [d, J(H,H ϭ 10 Hz, 1 H; CHT,
2-H), 6.64 (d, JH,H ϭ 9 Hz, 2 H; A), 6.93 (d, JH,H ϭ 9 Hz, 2 H;
B), 7.10 (d, JH,H ϭ 9 Hz, 2 H; A), 7.44 ppm (d, JH,H ϭ 9 Hz, 2 H;
B). C36H43NO5 (569.7303): calcd. (%): calcd. C 75.89, H 7.61, N
2.46; found (%) C 75.92, H 7.66, N 2.74.
Experimental Section
General Methods: MeCN was distilled from over CaH2. Silica gel
60 (0.040Ϫ0.063 mm) (Fluka) was used for column chromatogra-
phy (CC). Melting points (m.p.s) were determined with a Boetius
heating microscope.
NMR spectra were recorded on Bruker DPX 300 (300 MHz),
Bruker Advance 400 (400 MHz) or Bruker AMX 600 (600 MHz)
instruments. UV/Vis spectra were recorded with a Shimadzu UV
2101 PC spectrometer.
Molecular Threads
Compounds 9, 10, and 13 were available from earlier studies.[6,7,9]
Compound 8: A solution of 6 (1 g, 1.7 mmol) in toluene (150 mL)
was heated under reflux for 11 h. After removal of the solvent the
isomer 8 was obtained as an oil, which was purified by CC (silica
gel, toluene/ethyl acetate 10:1) (yellow solid, 0.8 g, 80%), m.p.
82Ϫ84.5. 1H NMR (300 MHz, CD3CN, TMS): δ ϭ 1.70, 1.85, 1.93
(br. m, 15 H, adamantane), 2.76 (d, JH,H ϭ 7 Hz, 2 H; CHT, 7-H),
3.60 (m, 6 H; 3-H, 4-H, 5-H), 3.8 (m, 2 H; 1-H), 4.1 (m, 4 H; 2-H,
6-H), 4.2 (br., 1 H; NH), 5.61 (m, 1 H; CHT, 6-H), 6.40 (d, JH,H ϭ
10 Hz,1 H; CHT, 5-H), 6.53 (d, JH,H ϭ 7 Hz, 1 H; CHT, 2-H), 6.66
(d, JH,H ϭ 9 Hz, 2 H; A), 6.92 (d, JH,H ϭ 9 Hz, 2 H; B), 6.98 (d,
Compound 6: Preparation as indicated in Scheme 3, 7-(4-hydroxy-
phenyl)cyclohepta-1,3,5-triene (2; 3.02 g, 16.4 mmol) and NaOEt
(2.2 g, 32.8 mmol) in MeCN (50 mL) were stirred for 30 min at
room temperature. After that time the solution was heated under
reflux and triethylene glycol monotosylate (5 g, 16.4 mmol) in
MeCN (40 mL) was added dropwise. Heating at reflux was con-
tinued for 4 h. After filtration of a precipitate, the solvent was re-
moved under reduced pressure and the remaining mixture was
worked up by CC (silica gel, cyclohexane/acetone 4:1.5) to provide
1
3 as an oil, 3.4 g (65%). H NMR (300 MHz, CD3CN, TMS): 2.63
JH,H ϭ 7 Hz, 1 H; CHT, 3-H), 7.29 (d, JH,H ϭ 9 Hz, 2 H; A), 7.51
(t, JH,H ϭ 6 Hz, 1 H; CHT, 7-H), 2.79 (t, JH,H ϭ 5 Hz, 1 H; OH),
3.49 (m, 2 H, 1-H), 3.63 (m, 6 H; 2-H, 3-H, 4-H), 3.81 (m, 2 H; 5-
H), 4.11 (m, 2 H; 6-H), 5.40 (m, 2 H; CHT, 1-H, 6-H), 6.28 (m, 2
ppm (d, JH,H ϭ 9 Hz; B). C36H43NO5 (569.73): calcd. (%): calcd.
C 75.89, H 7.61, N 2.46; found (%) C 75.66, H 7.81, N 2.84.
H; CHT, 2-H, 5-H), 6.29 (m, 1 H, CHT, 5-H), 6.77 (m, 2 H; CHT, Compounds 11 and 12: Compound 2 (3.9 g, 21.6 mmol), 3-(4-
3-H, 4-H), 6.96 (d, JH,H ϭ 8 Hz, 2 H; phenyl), 7.32 ppm (d, JH,H ϭ hydroxyphenyl)propanol (3.28 g, 21.6 mmol), and NaOEt (4.4 g,
8 Hz; phenyl). C19H24O4 (316.1675): calcd. (%): calcd. C 72.13, H 64.8 mmol) in MeCN (250 mL) were stirred for 30 min at room
7.65; found (%) C 72.35, H 7.43.
temperature, as in the procedure used for the synthesis of 9.[7] After
Compound 3 (3.17 g, 10.03 mmol) was treated with adamantane-
that period, the solution was heated under reflux, and triethylene
1-carbonyl chloride (2.18 g, 11.03 mmol) in pyridine (25 mL) for glycol bistosylate (9.8 g, 21.8 mmol) in MeCN (50 mL) was added
4 h at 75 °C. The reaction mixture was poured into dilute HCl dropwise to the solution. Heating at reflux was continued for 6 h.
(30 mL). The aqueous solution was extracted several times with The solvent was removed under reduced pressure and the remain-
Eur. J. Org. Chem. 2005, 374Ϫ386
www.eurjoc.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
383

W. Abraham, L. Grubert, S. Schmidt-Schäffer, K. Buck
FULL PAPER
ing mixture was worked up by CC (silica gel, cyclohexane/acetone
cyclophane), 8.0 (br. d, 8 H; cyclophane), 8.84 ppm (br. d, 9 H;
cyclophane).
3:1) thus separating 11 from the symmetric substitution products
1
(oil, 4.45 g, 50%). H NMR (300 MHz, CD3CN, TMS): δ ϭ 1.85
Compound 25: [25.0 mg 1 (0.023 m), 10.3 mg 11 (0.023 m)]. 1H
NMR (400 MHz, CD3CN, 303 K, TMS): 1.60 (m, 2 H; 2-H), 1.9
(m, 2 H; 2-H), 2.6 (m, 3 H; 3-H, CHT, 7-H), 3.66 (t, JH,H ϭ 6 Hz,
2 H; 1-H), 3.76 (s, 4 H; 6-H, 7-H), 3.86 (m, 4 H; 5-H, 8-H), 4.12
(m, 4 H; 4-H, 9-H), 5.40 (m, 2 H; CHT, 1-H, 6-H), 6.25 (m, 2 H,
(1 H; CHT, 7-H), 2.31 (t, JH,H ϭ 7 Hz, 2 H; 3-H), 2.64 (t, JH,H
ϭ
5 Hz, 1 H; OH), 3.51 (m, 2 H; 1-H), 3.78 (m, 4 H; 5-H, 8-H), 3.85
(m, 4 H; 4-H, 9-H), 3.89 (s, 4 H; 6-H, 7-H), 5.1 (br., B or C), 5.13
(m, 2 H; CHT, 1-H, 6-H), 5.5 (br., B or C), 5.7 (br. s, 8 H; cyclo-
phane), 5.8 (br., B or C), 6.2 (br., B or C), 6.36 (m, 2 H; CHT, 2-
H, 5-H), 6.90 (m, 2 H; CHT, 3-H, 4-H), 7.68 (s, 8 H; cyclophane),
7.99 (d, JH,H ϭ 7 Hz, 8 H; cyclophane), 8.86 ppm (d, JH,H ϭ 7 Hz,
8 H; cyclophane).
CHT, 2-H, 5-H), 6.74 (m, 2 H; CHT, 3-H, 4-H), 6.84 (d, JH,H
ϭ
9 Hz, 2 H; C), 6.93 (d, JH,H ϭ 9 Hz, 2 H; B), 7.10 (d, JH,H ϭ 9 Hz;
C), 7.27 ppm (d, JH,H ϭ 9 Hz, B). C28H34O5 (450.57): calcd. (%):
calcd. C 74.64, H 7.61; found (%) C 74.45, H 7.74.
Compound 11 (3.76 g, 8.34 mmol) was treated with adamantane-
1-carbonyl chloride (1.82 g, 9.17 mmol) in pyridine (9 mL) for 4 h
at 75 °C. The reaction mixture was poured into dilute HCl (15 mL).
The aqueous solution was extracted several times with dichloro-
methane as solvent, the organic phases were washed with a satu-
rated aqueous solution of NaCl and dried (Na2SO4), and the sol-
vents were evaporated. The remaining oil was purified by CC (silica
Compound 26: [11 mg 1 (0.01 m), 6.7 mg 12 (0.016 m)]. 1H NMR
(400 MHz, CD3CN, 303 K, TMS): 1.73, 1.88, 1.95 (br. m, 17 H;
adamantane; H-2), 1.9 (1 H; CHT, 7-H), 2.48 (t, JH,H ϭ 7 Hz, 2
H; 3-H), 3.75Ϫ3.85 (m, 12 H, 4-H Ϫ9-H), 3.95 (t, JH,H ϭ 6 Hz, 2
H; 1-H), 5.0 (br., B or C), 5.16 (br., 2 H; CHT, 1-H, 6-H), 5.7 (s,
8 H; cyclophane), 6.1 (br., B or C), 6.2 (br., B or C), 6.4 (m, 2 H;
CHT, 2-H, 5-H), 6.7 (br., B or C), 6.90 (br. s, 2 H; CHT, 3-H, 4-
H), 7 (br., B or C), 7.62 (s, 8 H; cyclophane), 8.06 (d, JH,H ϭ 7 Hz,
8 H; cyclophane), 8.86 ppm (d, JH,H ϭ 7 Hz, 8 H; cyclophane).
1
gel, cyclohexane/acetone 5:2) to afford 12 (2.9 g, 57%). H NMR
(300 MHz, CD3CN, TMS): δ ϭ 1.71, 1.85, 1.98 (m, 17 H; ada-
mantane, 2-H), 2.61 (m, 3 H; 3-H, CHT, 7-H), 3.65 (s, 4 H; 6-H,
7-H), 3.77 (m, 4 H; 5-H, 8-H), 3.97 (t, JH,H ϭ 6 Hz, 2 H; 1-H), 4.1
(m, 4 H; 4-H, 9-H), 5.37 (m, 2 H; CHT, 1-H, 6-H), 6.24 (m, 2 H,
CHT, 2-H, 5-H), 6.75 (m, 2 H; CHT, 3-H, 4-H), 6.83 (d, JH,H
ϭ
1
8 Hz, 2 H; C), 6.93 (d, JH,H ϭ 8 Hz, 2 H; B), 7.10 (d, JH,H ϭ 8 Hz;
C), 7.27 ppm (d, JH,H ϭ 8 Hz, B). C39H48O6 (612.80): calcd. (%):
calcd. C 76.44, H 7.90; found (%) C 76.57, H 7.98.
Compound 27: [22.2 mg 1 (0.02 m), 2.9 mg 13 (0.006 m)]. H NMR
(300 MHz, CD3CN, TMS): δ ϭ 2.46 (t, JH,H ϭ 6 Hz, 2 H; CHT,
7-H), 3.77 (s, 4 H; 4-H, 3-H), 3.8 (m, 4 H; 2-H, 5-H), 4.0 (m, 4 H;
1-H, 6-H), 5.31 (m, 4 H; CHT, 1-H, 6-H), 5.47 (m, 1 H; CHT, 1-
H), 5.56 (d, JH,H ϭ 8 Hz, 2 H; A), 5.70 (s, 8 H; cyclophane), 6.26
(m, 4 H; CHT, 2-H, 5-H), 6.53 (br. s, 4 H; B), 6.77 (m, 4 H; CHT,
3-H, 4-H), 6.9 (br. s, 4 H; B), 7.65 (s, 8 H; cyclophane), 8.01 (br. s,
8 H; cyclophane), 8.85 ppm (br. s, 8 H; cyclophane).
Pseudorotaxanes
The pseudorotaxane NMR spectra were recorded with mixtures of
the cyclophane 1 and the molecular threads in CD3CN (1 mL). The
concentrations of the two components were about 10Ϫ2 m.
Rotaxane 15: Compound 6 (0.15 g, 0.27 mmol), dissolved in MeCN
(1 mL), was added to 1 (0.5 g, 0.45 mmol) in acetonitrile solution
(1 mL). The solution was purged with argon for 0.5 h, and 2,4,6-
tris(isopropyl)benzyl bromide (0.080 g, 0.27 mmol), together with
2,6-di-tert-butyl-4-methylpyridine (0.055 g, 0.27 mmol), dissolved
in acetonitrile (2 mL), was added to the green solution of the
pseudorotaxane. The reaction solution was stirred under an argon
atmosphere for 96 h at room temperature. The precipitate was fil-
tered off, the solution was evaporated, and the residue was ex-
tracted with MTBE (75 mL). The thread 18 was obtained from the
filtrate as an oil and was purified by CC (silica gel, n-hexane/ethyl
acetate 2:1) (0.13 g, 61%). 1H NMR (300 MHz, CD3CN, TMS):
δ ϭ 1.23 (d, JH,H ϭ 7 Hz, 18 H; iPr), 1.68, 1.84, 1.9 (br. m, 15 H;
adamantane), 2.72 (t, JH,H ϭ 6 Hz, 1 H; CHT, 7-H), 2.88 (sept,
JH,H ϭ 7 Hz, 1 H; iPr), 3.21 (sept, JH,H ϭ 7 Hz, 2 H; iPr), 3.6 (m,
6 H; 3-H, 4-H, 5-H), 3.76 (m, 2 H; 1-H), 4.19 (s, 2 H; N-benzyl),
5.47 (m, 1 H; CHT, 6-H), 5.57 (m, 1 H; CHT, 1-H), 6.34 (m, 2 H;
1
Compound 14: [8 mg 1 (0.0073 m), 4.2 mg 6 (0.0073 m)]. H NMR
(400 MHz, CD3CN, TMS): δ ϭ 1.70, 1.85, 1.9 (br. m, 15 H; ada-
mantane), 2.56 (t, JH,H ϭ 6 Hz, 1 H; CHT, 7-H), 3.66 (m, 6 H; 3-
H, 4-H, 5-H), 3.8 (m, 2 H; 2-H), 4.0 (m, 2 H; 1-H), 4.13 (m, 2 H;
6-H), 5.37 (m, 1 H; CHT, 6-H), 5.47 (m, 1 H; CHT, 1-H), 5.56 (d,
H,H ϭ 8 Hz, 2 H; A), 5.75 (br. s, 8 H; cyclophane), 6.31 (d, JH,H ϭ
9 Hz,1 H; CHT, 2-H), 6.39 (m, 1 H; CHT, 5-H), 6.45 (d, JH,H
8 Hz, 2 H; A), 6.5 (br., 2 H, B), 6.97 (d, JH,H ϭ 6 Hz, 1 H; CHT,
4-H), 7.1 (br. s, 2 H; B), 7.62 (s, 8 H; cyclophane), 8.08 (br. s, 8 H;
cyclophane), 8.86 ppm (br. s, 8 H; cyclophane).
J
ϭ
1
Compound 16: [11.1 mg 1 (0.01 m), 6.5 mg 8 (0.0114 m)]. H NMR
(400 MHz, CD3CN, TMS): δ ϭ 1.69, 1.84, 1.9 (br. m, 15 H; ada-
mantane), 2.77 (d, JH,H ϭ 7 Hz, 2 H; CHT, 7-H), 3.6 (m, 6 H; 3-
H, 4-H, 5-H), 3.8 (m, 2 H; 2-H), 3.99 (br. s, 2 H; NH), 4.0 (m, 2
H; 1-H), 4.12 (m, 2 H; 6-H), 5.27 (d, JH,H ϭ 8 Hz, 2 H; A), 5.66
(m, 1 H; CHT, 6-H), 5.7 (br. s, 8 H; cyclophane), 5.84 (d, JH,H
ϭ
CHT, 2-H, 5-H), 6.72 (d, JH,H ϭ 8 Hz, 2 H: A), 6.94 (d, JH,H
ϭ
8 Hz, 2 H; A), 5.93 (d, JH,H ϭ 10 Hz, 1 H; CHT, 5-H), 6.37 (d,
JH,H ϭ 6 Hz,1 H; CHT, 2-H), 6.48 (d, JH,H ϭ 6 Hz,1 H; CHT, 3-
H), 6.53 (d, JH,H ϭ 8 Hz, 2 H; B), 7.15 (d, JH,H ϭ 6 Hz, 2 H; B),
7.66 (s, 8 H; cyclophane), 7.98 (br. s, 8 H; cyclophane), 8.85 ppm
(br. s, 8 H; cyclophane).
9 Hz, 2 H; B), 7.04 (d, JH,H ϭ 6 Hz, 1 H; CHT, 4-H) 7.09 (s, 2 H;
iPr-Ph), 7.19 (d, JH,H ϭ 8 Hz, 2 H; A), 7.46 ppm (d, JH,H ϭ 9 Hz,
2 H; B), C52H67NO5 (786.10): calcd. (%): calcd. C 79.45, H 8.59,
N 1.78; found (%) C 78.99, H 8.44, N 1.84.
The solid, insoluble in MTBE, was purified by column chromatog-
1
Compound 22: [11.8 mg 1 (0.011 m), 8.0 mg 9 (0.013 m)]. H NMR raphy on neutral Al2O3 (Fluka) with a solvent mixture of aceto-
(400 MHz, CD3CN, 303 K, TMS): 1.73, 1.88, 1.95 (br. m, 17 H;
nitrile (400 mL), ethyl acetate (200 mL), and cyclohexane (100 mL)
adamantane; 2-H), 2.51 (t, JH,H ϭ 8 Hz, 2 H; 3-H), 2.67 (d, JH,H ϭ and containing ammonium hexafluorophosphate (7 g). The red
6 Hz, 2 H; CHT, 7-H), 3.8Ϫ3.9 (m, 12 H; 4-H, 9-H), 3.96 (t, JH,H ϭ fraction was concentrated under reduced pressure and the resulting
6 Hz, 2 H; 1-H), 5.46 (m, 1 H; CHT, 6-H), 5.55 (m, 1 H; CHT, 2-
H), 5.7 (br. s, 8 H; cyclophane), 5.9 (br., A, B or C), 6.1 (br. d, 2 as a red solid (mp 202Ϫ206 °C, 0.071 g, 14%). 1H NMR (400 MHz,
H; A, B, or C), 6.23 (d, JH,H ϭ 9 Hz,1 H; CHT, 2-H), 6.38 (m, 1 CD3CN, 333 K, TMS): δ ϭ 1.23 (d, JH,H ϭ 7 Hz, 6 H; iPr), 1.25
H; CHT; 5-H), 6.7 (br.,); A, B or C), 6.8 (d, JH,H ϭ 8 Hz, 2 H; A, (d, JH,H ϭ 7 Hz, 12 H; iPr), 1.67, 1.71, 1.81, 1.9 (br. m, 15 H;
B or C), 6.85 (d, JH,H ϭ 7 Hz, 1 H; CHT, 4-H), 7.66 (s, 8 H; adamantane), 2.87 (sept, JH,H ϭ 7 Hz, 1 H, iPr), 3.06 (t, JH,H
solid was washed with water (350 mL). Compound 15 was obtained
ϭ
384
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2005, 374Ϫ386

Rotaxanes Incorporating Diarylcycloheptatriene Stations
FULL PAPER
6 Hz, 1 H; CHT, 7-H), 3.14 (m, 2 H; iPr), 3.27 (d, JH,H ϭ 9 Hz,2 raphy (silica gel, acetonitrile (400 mL), ethyl acetate (200 mL),
H: B), 3.37 (br. m, 2 H; 6-H), 3.8 (m, 4 H; 2-H, 5-H), 3.9 (s, 4 H; cyclohexane (100 mL) containing ammonium hexafluorophosphate
3-H, 4-H), 4.2 (m, 4 H; H-1; N-benzyl), 4.62 (d, JH,H ϭ 9 Hz, 2 H; (7 g)). Compound 20 (0.05 g, 65%) was obtained as a blue solid,
1
B), 5.69Ϫ5.85 (m, 11 H; CHT, 1-H, 2-H, 6-H; cyclophane), 6.17
m.p. 202Ϫ204 °C. H NMR (600 MHz, CD3CN, TMS): δ ϭ 1.25
(d, JH,H ϭ 6 Hz,1 H; CHT, 4-H), 6.55 (m, 1 H; CHT, 5-H), 6.79 (d, JH,H ϭ 7 Hz, 18 H; iPr), 1.7, 1.9 (br. m, 15 H; adamantane),
(d, JH,H ϭ 8 Hz, 2 H; A), 7.10 (s, 2 H; iPr-Ph), 7.37 (d, JH,H 2.86 (br. m, 2 H; 6-H), 2.93 (sept, JH,H ϭ 7 Hz, 1 H; iPr), 3.00 (d,
8 Hz, 2 H; A), 7.85 (m, 16 H, cyclophane), 8.86Ϫ8.93 ppm (m, 8 JH,H ϭ 9 Hz, 2 H; B), 3.13 (sept, JH,H ϭ 7 Hz, 2 H; iPr), 3.7, 3.8,
ϭ
H; cyclophane). MS (ESI): 1740.6522ϩ (M
[C88H99F18N5O5P3]ϩ), calcd. 1740.656; 797.84732ϩ (M Ϫ 2PF6
Ϫ
PF6
,
,
3.9, 4.2 (br., 10 H; 5-H, 3-H, 4-H, 2-H, 1-H), 4.6 (br. d, 2 H; N-
benzyl), 5.56 (d, JH,H ϭ 9 Hz, B), 5.76, 5.77, 5.78, 5.83, 5.88 (m, 8
Ϫ
Ϫ
[C88H99F12N5O5P2]2ϩ), calcd. 797.8456. C88H99F24N5O5P4 H; cyclophane), 6.27 (br., 1 H; NH), 7.07 (d, JH,H ϭ 8 Hz, 2 H;
(1886.61): calcd. (%): calcd. C 56.02, H 5.29, N 3.71; found (%) C A), 7.17 (s, 2 H; iPr-Ph), 7.79Ϫ7.96 (m, 9 H, cyclophane, tropyl-
56.04, H 5.50, N 3.47.
ium), 7.90 (s, 8 H; cyclophane), 8.2 (m, 3 H; A, tropylium), 8.45
(m, 1 H, tropylium), 8.8 (br., 1 H; tropylium), 8.9 (m, 1 H; tropyl-
Rotaxane 18: Compound 8 (0.114 g, 0.20 mmol), dissolved in
MeCN (1 mL), was added to 1 (0.44 g, 0.40 mmol) in acetonitrile
solution (1 mL). The solution was purged with argon for 0.5 h, and
2,4,6-tris(isopropyl)benzyl bromide (0.060 g, 0.20 mmol), together
with 2,6-di-tert-butyl-4-methylpyridine (0.041 g, 0.20 mmol), dis-
solved in acetonitrile (2 mL) was added to the green solution of
the pseudorotaxane. The reaction solution was stirred under an
argon atmosphere for 96 h at room temperature. The precipitate
was filtered off, the solution was evaporated, and the residue was
extracted with MTBE (75 mL). The thread 19 was obtained from
the filtrate as oil and purified by CC (silica gel, n-hexane/ethyl acet-
ate 2:1) (0.096 g, 61%). 1H NMR (300 MHz, CDCl3, TMS): δ ϭ
1.26 (d, JH,H ϭ 7 Hz, 18 H; iPr), 1.7, 1.9, 2.0 (br. m, 15 H; ada-
mantane), 2.83 (d, JH,H ϭ 7 Hz, 2 H; CHT, 2-H), 2.91 (sept, JH,H ϭ
7 Hz, 1 H; iPr), 3.23 (sept, JH,H ϭ 7 Hz, 2 H; iPr), 3.7 (m, 6 H; 2-
H, 3-H, 4-H), 3.9 (m, 2 H; 5-H), 4.1 (m, 2 H, 6-H), 4.2 (m, 2 H,
1-H), 4.3 (s, 2 H; N-benzyl), 5.61 (m, 1 H; CHT, 5-H), 6.43 (d,
ium) 8.9 ppm (br., 8 H, cyclophane). UV/Vis (acetonitrile): λmax
/
nm (ε) 583 (43800 molϪ1dm3cmϪ1), 350 (10900 molϪ1dm3cmϪ1),
261.5 nm (57500 molϪ1dm3cmϪ1). C88H98F30N5O5P5 (2030.56):
calcd. (%): calcd. C 52.05, H 4.86, N 3.45; found (%) C 51.87, H
5.03, N 3.65.
Molecular Thread 21: Compound 19 (0.096 g, 0.15 mmol) in
Et4NPF6 MeCN solution (0.1 m, 50 mL) was oxidized by controlled
potential electrolysis (EAϭ 0.8Ϫ1.2 V [SCE], HEKA PG285) at a
Pt-electrode in the anode region of a H cell until a charge output
of 2 FmolϪ1 had been consumed. After evaporation and washing
with water, the remaining blue solid was purified by column chro-
matography [silica gel, acetonitrile (400 mL), ethyl acetate
(200 mL), cyclohexane (100 mL) containing ammonium hexa-
fluorophosphate (7 g)] to afford the tropylium thread (0.088 g
78%), the NMR spectrum of which is necessary in order to calcu-
late the CIS values of 20, m.p. 97Ϫ99 °C. 1H NMR (600 MHz,
CD3CN, TMS): δ ϭ 1.23 (d, JH,H ϭ 7 Hz, 18 H, iPr), 1.7 (m, 2 H;
2-H), 1.7, 1.8 (br., 15 H; adamantane), 2.90 (sept, JH,H ϭ 7 Hz, 1
H, iPr), 3.14 (sept, JH,H ϭ 7 Hz, 2 H; iPr), 3.6 (m, 6 H; 2-H, 3-H,
4-H), 3.8 (m, 2 H; 5-H), 4.1 (m, 2 H; 1-H), 4.2 (m, 2 H; 6-H), 4.44
(br., 2 H; N-benzyl), 5.91 (t, JH,H ϭ 4 Hz, 1 H; NH), 6.94 (d,
JH,H ϭ 9 Hz, 2 H; A), 7.12 (s, 2 H; iPr-Ph), 7.15 (d, JH,H ϭ 9 Hz,
2 H; B), 7.80 (d, JH,H ϭ 9 Hz, 2 H; B), 7.95 (d, JH,H ϭ 9 Hz, 2 H;
A), 8.28 (m, 1 H; tropylium), 8.40 (m, 1 H; tropylium), 8.57 (m, 1
H; tropylium), 8.67 (m, 1 H; tropylium), 8.78 ppm (m, 1 H; tropyl-
ium). UV/Vis (acetonitrile): λmax/nm (ε) 575 (41400
molϪ1dm3cmϪ1), 403 (10100 molϪ1dm3cmϪ1), 270.5 nm (22100
molϪ1dm3cmϪ1). C52H66F6NO5P (930.05): calcd. (%): calcd. C
57.15, H 7.15, N 1.51; found (%) C 57.37, H 7.09, N 1.76.
JH,H ϭ 9 Hz, 1 H; CHT, 6-H), 6.52 (d, JH,H ϭ 6 Hz, 1 H: CHT, 2-
H), 6.98 (d, JH,H ϭ 6 Hz, 1 H; CHT, 3-H), 6.69 (d, JH,H ϭ 9 Hz,
2 H; A), 6.91 (d, JH,H ϭ 9 Hz, 2 H; B), 7.07 (s, 2 H; iPr-Ph), 7.44
(d, JH,H ϭ 9 Hz, 2 H; A), 7.45 ppm (d, JH,H ϭ 9 Hz, 2 H; B),
C52H67NO5 (786.09): calcd. (%): calcd. C 79.45, H 8.59, N 1.78;
found (%) C 79.32, H 8.84, N 1.67.
The solid, insoluble in MTBE, was purified by column chromatog-
raphy on neutral Al2O3 (Fluka) with a solvent mixture of aceto-
nitrile (400 mL), ethyl acetate (200 mL), and cyclohexane (100 mL),
and containing ammonium hexafluorophosphate (7 g). The red
fraction was concentrated under reduced pressure and the resulting
solid was washed with water (350 mL). Compound 15 was obtained
as a red solid (mp 202Ϫ206 °C, 0.085 g, 22.5%). 1H NMR
(400 MHz, CD3CN, TMS): δ ϭ 1.25 (d, JH,H ϭ 7 Hz, 6 H; iPr),
1.28 (d, JH,H ϭ 7 Hz, 12 H; iPr), 1.7, 1.8, 1.9 (br. m, 15 H; ada-
mantane), 2.43 (d, JH,H ϭ 8 Hz, 2 H; CHT, 7-H), 2.91 (sept, JH,H ϭ
7 Hz, 1 H; iPr), 3.24 (sept, JH,H ϭ 7 Hz, 2 H; iPr), 3.6 (m, 2 H; 6-
H), 3.7 (m, 2 H; 2-H), 3.8 (m, 6 H, 3-H, 4-H, 5-H), 4.2 (m 4 H, 1-
H, B), 4.3 (s, 2 H; N-benzyl), 4.91 (d, JH,H ϭ 8 Hz, B), 5.20 (d,
JH,H ϭ 7 Hz, 1 H; CHT, 2-H), 5.63Ϫ5.79 (m, 9 H; CHT, 6-H,
cyclophane), 6.23 (d, JH,H ϭ 10 Hz,1 H; CHT, 5-H), 6.71 (d,
Supporting Information (see also the footnote on the first page of
this article): Selected 1H NMR spectra of pseudorotaxanes and rot-
axanes, UV/Vis spectrum of 14.
Acknowledgments
Financial support by the Deutsche Forschungsgemeinschaft is
gratefully acknowledged. We thank S. Jautze for studies regarding
the pseudorotaxane 25.
JH,H ϭ 7 Hz, 1 H; CHT, 3-H), 6.55 (d, JH,H ϭ 8 Hz, 2 H; A), 6.80
(d, JH,H ϭ 8 Hz, 2 H; A), 7.10 (s, 2 H; iPr-Ph), 7.8 (br., 8 H,
cyclophane), 7.89 (s, 8 H; cyclophane), 8.88 ppm (br., 8 H, cyclo-
phane). C52H66F6NO5P (930.05): calcd. (%): calcd. C 67.15, H 7.15,
N 1.51; found (%) C 66.89, H 7.43, N 1.78, MS: found 784.4229
(M Ϫ PF6, [C52H66NO5]ϩ), calcd. 784.4936.
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