Interlocked porphyrin switches

Article abstract of DOI:10.1002/chem.201203983

We describe the synthesis of a series of interlocked structures from porphyrin-glycoluril cage compounds and bis(olefin)-terminated viologens by an olefin-metathesis protocol. The length of the chain connecting the olefin substituents with the viologen ha

Full text of DOI:10.1002/chem.201203983

FULL PAPER
DOI: 10.1002/chem.201203983
Interlocked Porphyrin Switches
Ruud G. E. Coumans, Johannes A. A. W. Elemans,* Alan E. Rowan,* and
Roeland J. M. Nolte*[a]
Abstract: We describe the synthesis of
a series of interlocked structures from
porphyrin–glycoluril cage compounds
give [2]- and [3]catenane structures,
whereas short chains give a mixture of
[3]-, [4]-, and [5]catenanes. For compar-
ison several [2]rotaxane compounds
were prepared. The interlocked cate-
nane and rotaxane structures display
switching behavior, which can be con-
trolled by the addition of acid and
base. The kinetic and thermodynamic
parameters of the switching processes
have been determined by NMR spec-
troscopy.
and bisACHTUNGTRENNUNG(olefin)-terminated viologens by
an olefin-metathesis protocol. The
length of the chain connecting the
olefin substituents with the viologen
has a marked effect on the products of
the ring-closure reaction. Long chains
Keywords: catenanes · interlocked
structures · olefin metathesis · por-
phyrins · rotaxanes · switches
Introduction
The development and study of mechanically interlocked
compounds such as rotaxanes, catenanes, molecular neckla-
ces, and Borromean rings remains a fascinating area of su-
pramolecular chemistry.[1] These interlocked architectures
have shown to be potential candidates for incorporation
into molecular memory devices owing to their tunable
switching (on/off) behavior. The research group of Stoddart
has demonstrated that it is possible to immobilize switchable
[2]catenanes onto a surface, while retaining their switching
behavior, resulting in prototypical molecular memories.[2]
The same group has more recently shown that certain [3]ro-
taxanes, when grafted onto a thin metal surface, are capable
of bending the surface as a result of electrochemically in-
duced mechanical contraction of the rotaxanes.[3] These ex-
amples clearly demonstrate that interlocked molecules are
promising building blocks and have the potential to be ap-
plied as functional elements in nanotechnology.[4] These
studies stimulated us to investigate interlocked structures
that contain one or more functional components, namely,
porphyrins, as part of a project aimed at developing a mo-
lecular device that can perform actions on a polymer tape
according to instructions from a tape head.[5] The blueprint
is shown in Figure 1. As a tape, polymers will be used con-
taining sites that can be chemically transformed, for exam-
ple, alkene double bonds in polybutadiene that can be con-
Figure 1. A molecular device in which information is transferred from a
catenane ring (red oval) to a polymer chain (black line).
verted into epoxide functions.[6] The tape head will be a gly-
coluril double cage compound containing two metal por-
phyrin cages that are held together by a ligand bond (1,4-
diazabicycloACTHNUGTRNEUNG[2.2.2]octane) and by hydrogen-bonding interac-
tions. In a previous paper, we have shown that, in this com-
pound, information can be transferred from one porphyrin
cage to the other by four positive allosteric interactions.[7]
For this concept to be realised, one of the cages will contain
a ring compound, that is, a catenane, that can rotate and
provide the instructions. The other cage will be threaded
onto a polymer chain (see Figure 1).[8] As a first step in the
construction of such a molecular device, we decided to study
the synthesis of a porphyrin–glycoluril rotaxane using olefin
metathesis. We have already demonstrated that olefin meta-
thesis in combination with the selective recognition of violo-
gens by porphyrin–glycoluril host 1 (Scheme 1) is an excel-
lent way to synthesize rotaxanes.[9] This stimulated us to fur-
ther explore this approach and use it for the synthesis of
porphyrin-based catenanes that might function as simple
molecular switches. Here, the synthesis and (photo)physical
[a] Dr. R. G. E. Coumans, Dr. J. A. A. W. Elemans, Prof. A. E. Rowan,
Prof. R. J. M. Nolte
Radboud University Nijmegen
Institute for Molecules and Materials
Heyendaalseweg 135, 6525 AJ Nijmegen (The Netherlands)
Fax : (+31)24-3652929
E-mail: J.Elemans@science.ru.nl
A.Rowan@science.ru.nl
R.Nolte@science.ru.nl
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we will make use of two olefin-
containing viologens, 3 and 4
(see Scheme 2), which differ in
the length of the bipyridine N
substituents.
Synthesis of olefin-containing
viologens: The synthesis of viol-
ogen 3 started with the etherifi-
cation of 1,10-dibromodecane
with 9-decenol using NaH as a
base in THF, affording bromide
derivative 2 in 44% yield after
purification by column chroma-
Scheme 1. Formation of a host–guest complex between the cavity-containing porphyrin 1 and a viologen guest.
properties of a variety of interlocked structures based on
porphyrin host 1 are described.
tography (Scheme 2). This compound was subsequently cou-
pled to 4,4’-bipyridine in hot N,N-dimethylformamide
(DMF), after which ion exchange with NH4PF6 in water
gave 3 in 23% yield, after recrystallization from methanol.
To obtain a viologen with a shorter substituent, 4,4’-bipyri-
dine was reacted with an excess of 8-bromooctene in hot
DMF, followed by ion-exchange with NH4PF6, to give violo-
gen 4 in 61% yield.
Results and Discussion
Design: Our strategy to construct porphyrin-containing cate-
nanes is based on an olefin-metathesis protocol, which was
published previously by our research group.[9] In organic sol-
vents, porphyrin host 1 forms very stable complexes with vi-
Synthesis of catenanes: The mixing of porphyrin clip 1 with
viologen 3 in CHCl3/acetone (1:1, v/v), followed by precipi-
tation of the product in n-hexane, quantitatively furnished
[2]pseudorotaxane 5 (Scheme 3). Indicative for [2]pseudoro-
taxane formation are the large complexation-induced shifts
ologen
(N,N’-dialkyl-4,4’-bipyridinium)
derivatives
(Scheme 1).[10] The strong binding of these guests relies on a
combination of factors, namely, p–p stacking interactions
between the aromatic surfaces of the viologen and 1, elec-
trostatic interactions between the positive charges on the
1
observed in the H NMR spectrum (CDCl3) for the signals
À
guest and the crown ether moieties of 1, and C H···O hy-
of the aromatic viologen protons, Ha (Dd=À2.65 ppm) and
Hb (Dd=À4.07 ppm), shifts that are the result of shielding
by the porphyrin macrocycle and the aromatic side walls of
1. The complex was readily soluble in CH2Cl2, thus setting
the stage for a ring-closing metathesis reaction (RCM) of
the terminal alkene groups of the viologen by using the first
drogen bonding between the a-bipyridinium protons and
the crown ether and carbonyl oxygen atoms of 1. When viol-
ogens that contain terminal olefins as N substituents are
complexed in the cavity of 1, the resulting host–guest com-
plexes can in principle be subjected to olefin-metathesis re-
actions, so that interlocked porphyrin-containing species are
generated. Similar olefin ring-closing and cross metathesis
protocols have proven to be very effective for the high-yield
synthesis of a variety of interlocked molecules.[11] Herein,
generation
Grubbsꢁ
catalyst,
[RuCHPh(Cl)2ACHTUNGTRENNUNG(PCy3)2]
(Scheme 3). To minimize intermolecular crosslinking, the re-
action was performed under high-dilution conditions ([5]
ꢀ0.0005m). At these concentrations, more than 99% of 1 is
Scheme 2. Synthesis of olefin-terminated viologens.
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Interlocked Porphyrin Switches
FULL PAPER
Scheme 3. Synthesis of [2]pseudorotaxane 5, [2]catenane 6, and [3]catenane 7. Cy=cyclohexyl.
complexed by 3 because of the high association constant (Ka
ꢀ107 mÀ1). Subjecting a solution of 5 in CH2Cl2 to 20 mol%
of Grubbsꢁ catalyst for 24 hours at room temperature result-
ed in a mixture of products, of which [2]catenane 6 could be
isolated in 69% yield after column chromatography, as a
mixture of E/Z isomers in a 4:1 ratio. [3]Catenane 7 was
also isolated in 3% yield, as a mixture of E/E, E/Z and Z/Z
isomers (total E/Z ratio=4:1). Both catenanes contain a
very large macrocycle: a 48-membered ring in the case of 6
and a 96-membered one in the case of 7.[12] The MALDI-
TOF spectra of the [2]catenanes (Figure 2) showed peaks
for 6 at m/z 2063.1 and 2208.1, corresponding to [MÀ2PF6]+
and [MÀPF6]+, respectively, and four peaks for 7 at m/z
4125.6, 4271.6, 4416.4, and 4560.7, corresponding to
[MÀnPF6]+ (n=1–4), respectively.
The 2D-NOESY spectrum of 6 revealed nOe contacts be-
tween the pyrrole NH protons of the porphyrin and the aro-
matic protons Ha and Hb (see Scheme 2) of the viologen,
thus indicating that the latter moiety is situated inside the
cavity of 1. The resonances of the trans-alkene protons (Hc,
Scheme 3) are shifted upfield to d=4.87 ppm, (Ddꢀ
À0.5 ppm) compared to other internal alkenes, a character-
Figure 2. MALDI-TOF spectra of [2]catenane 6, [3]catenane 7, [4]cate-
nane 10 and [5]catenane 11.
istic that is attributed to shielding effects by either the por-
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
phyrin macrocycle of 1, the aromatic side walls of 1, or
both. In the H NMR spectrum of [3]catenane 7, the trans-
than performing the reaction at room temperature. The cat-
enanes 10 and 11 could be isolated from the product mix-
ture in 18% and 11% yield, respectively (~95% pure),
using a combination of silica and size-exclusion chromatog-
raphy. Catenane 9, which was only formed in very low yield,
could not be obtained pure. To the best of our knowledge,
these are the first examples of porphyrin-containing [4]- and
[5]catenanes.[14] MALDI-TOF spectra showed six peaks for
catenane 10 at m/z 5088, 5225, 5370, 5516, 5661, and 5805,
corresponding to [MÀnPF6]+ (n=1–6) (Figure 2). For cate-
nane 11, MALDI-TOF spectra showed eight peaks at m/z
6778, 6923, 7068, 7213, 7358, 7503, 7648, 7793, corresponding
to [MÀnPF6]+ (n=1–8) (Figure 2). No formation of a [2]cat-
enane was observed, even when the reaction was performed
at higher dilution (0.0005m), thus indicating that the N sub-
1
alkene protons resonate at d=5.39 ppm, thus indicating that
the alkene parts of the thread are, in this case, situated fur-
ther away from the aromatic surfaces of the host. To investi-
gate the effect of spacer length on the outcome of the meta-
thesis reaction, the same RCM reaction was repeated using
viologen 4, which has shorter N substituents. The desired
[2]pseudorotaxane 8 was readily assembled according to the
aforementioned procedure. Exposing a 0.001m solution of 8
in CH2Cl2 to 20 mol% of Grubbsꢁ catalyst in refluxing
CH2Cl2 for 24 hours gave a mixture of products, containing
[3]catenane 9, [4]catenane 10, [5]catenane 11, and some
higher cyclic oligomers (Scheme 4).[13] It appeared that re-
fluxing the solution resulted in a much better conversion
Scheme 4. Synthesis of [3]catenane 9, [4]catenane 10, and [5]catenane 11.
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Interlocked Porphyrin Switches
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Scheme 5. Synthesis of [2]rotaxanes 18–20.
stituents of 4 are too short to be engaged in an intramolecu-
lar crosslink. Hence, by varying the spacer length it is possi-
ble to control, at least to some extent, the outcome of the
metathesis reaction.
chromatography, the [2]rotaxanes were isolated in yields up
to 60%.
Protonation-induced shuttling: With the novel interlocked
porphyrins at hand, it was decided to investigate if these
molecules could be used as molecular switches. We antici-
pated that protonation of the pyrrole nitrogen atoms of the
porphyrin ring with trifluoroacetic acid (TFA) would result
in an expulsion of the viologen moiety from the porphyrin
cavity owing to Coulombic repulsion, as was observed previ-
ously in a related system reported by Gunter and John-
ston.[15] Indeed, the addition of 5 vol% of TFA to a CDCl3
solution of the simplest [2]catenane, 6, thus providing proto-
nated [2] catenane [6·2H]2+, resulted in dramatic downfield
shifts for viologen resonances Ha (Dd=+2.78 ppm, see
Scheme 2 for proton numbering) and Hb (Dd=+3.77 ppm),
because of expulsion of the viologen from the cavity of 1
(Figure 3). In addition, a significant downfield shift was ob-
served for alkene resonance Hc (Dd=+0.53 ppm). Both ob-
servations indicate a rotation of the viologen-containing ring
with respect to the porphyrin host. Because the resonances
of Ha, Hb, and Hc appear at positions where they are expect-
ed in noncatenated compounds, it can be concluded that the
porphyrin bead in [6·2H]2+ does not reside on the viologen,
whereas in 6, it exclusively resides on this moiety. Detailed
investigations using COSY and 2D-NOESY spectroscopy re-
vealed that the protonated porphyrin in [6·2H]2+ is situated
near one of the ether oxygen atoms of the thread, possibly
because of the presence of NH+···O hydrogen bonds, be-
Synthesis of [2]rotaxanes: It was decided to also synthesize
a series of [2]rotaxanes based on 1, containing threads of
different lengths (Scheme 5), in order to be able to compare
their physical properties with those of the aforementioned
catenane structures. The synthesis of [2]rotaxanes 18–20 was
based on our previously reported protocol.[9] It started with
the synthesis of bulky alkyl bromides 12–14 by reacting the
appropriate dibromides (in the case of 12 and 13) with 3,5-
di-tert-butylphenol under basic conditions in DMF. Com-
pounds 12 and 13 were isolated in 70–80% yield. Bromide
14 was synthesized by first coupling 11-bromoundecan-1-ol
and 3,5-di-tert-butylphenol (yield: 77%), after which the al-
cohol was converted into a bromide by reacting it with PBr3
in CH2Cl2 to give 14 in 62% yield. This procedure was used
because it was difficult to purify the product mixture ob-
tained after reaction of the bulky phenol with 1,11-dibro-
moundecane. The bulky bromides were reacted with an
excess of 4,4’-bipyridine in MeCN to give monoalkylated bi-
pyridium derivatives 15–17 in yields up to 90%, after ion ex-
change using aqueous NH4PF6. It was now possible to syn-
thesize the corresponding rotaxanes 18–20 by simply heating
a mixture of 1, five equivalents of 15–17, respectively, and
40 equivalents of 12–14, respectively, in DMF. After ion ex-
change with aqueous NH4PF6 and purification by column
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
ic changes in the NMR spectrum. Notably, new resonances
appear at high field (0 to À4 ppm), most probably as a
result of shielding effects exerted by the porphyrin ring cur-
rent on protons present inside the cavity. Low-temperature
COSY experiments were used to assign some of these reso-
nances, as is indicated for proton Hf. Not all signals could be
assigned owing to the broadening of the spectra. However,
it is clear from these experiments that protonation induces a
motion in the [2]catenane, involving a switching of the por-
phyrin moiety between two degenerate states (Scheme 6).
Using the coalescence method,[17] the rate and the corre-
Figure 3. Part of the 1H NMR spectra (300 MHz) of (a) unprotonated
[2]catenane 6 and (b) protonated [2]catenane [6·2H]2+. See Scheme 2
and 3 for proton numbering.
cause increasingly larger upfield shifts are observed for the
signals of Hd, He, and Hf (Table 1). The resonance for
proton Hg in [6·2H]2+ could not be identified, as it was
either obscured by other signals or severely broadened. The
symmetry observed in the NMR spectrum of [6·2H]2+ can
Scheme 6. Schematic representation of the proposed dynamic behavior in
[2]catenane [6·2H]2+, demonstrating the possible pathways of movement
of porphyrin host 1 along the thread between two degenerate states.
sponding activation Gibbs energy for this dynamic process
were estimated to be
k
278 =7.0ꢂ103 sÀ1 and DG°
=
278
Table 1. 1H NMR data of [2]catenane
6
and protonated catenane
47 kJmolÀ1, respectively. It is, however, not known if, in this
dynamic behavior, the shuttling between the two degenerate
states takes place via the double bond, via the viologen
moiety, or via both routes (Scheme 6).
[a]
[6·2H]2+
.
Proton
6
G
Shift
ACHTUNGTRNE(NUNG d, ppm)
A
R
a
b
c
d
e
f
6.18
4.80
4.87
1.20
1.50
1.68
8.96
8.57
5.40
0.63
0.20
+2.78
+3.77
+0.53
À0.57
À1.30
À2.28
To obtain a better picture of the dynamic process, it was
decided to investigate in more detail how a viologen can
create a barrier for a shuttling process of the type shown
above. To this end, the dynamic behavior of the series of
[2]rotaxanes 18–20 as result of their protonation with TFA
was investigated. In this type of interlocked molecule, simi-
lar dynamic behavior to that observed for the [2]catenane is
only possible when the porphyrin overcomes the electrostat-
ic barrier posed by the viologen. Protonating [2]rotaxane 18,
to give [18·2H]2+, again led to dramatic changes in the
1H NMR spectra. Most strikingly, the signals of aromatic vi-
ologen protons Ha and Hb shifted downfield (by +1.69 ppm
and +2.71 ppm, respectively). These resonances are,
however, at a higher field (Ha at 7.81 ppm and Hb at
7.67 pm) than expected in a noncomplexed viologen. This is
explained by assuming that the short C5-spacer and the
blocking group prevent the viologen from completely leav-
ing the porphyrin host, whereas the viologen can completely
slide away from the porphyrin moiety in [2]catenane
[6·2H]2+. Also, in the case of [18·2H]2+, a symmetrical NMR
spectrum was observed, indicative of a movement of the
porphyrin clip over the viologen moiety between the two
blocking groups, a movement that is fast on the NMR time
scale at room temperature. This dynamic behavior was con-
firmed by VT-NMR experiments (Figure 5), in which the
temperature dependence of resonances Hg of the side wall
of the porphyrin host and both resonances Hh and Hi of the
blocking group are displayed.
À0.60
[a] 500 MHz, 298 K, CDCl3, ca. 10À3 m. See Scheme 2 and 3 for proton
numbering.
be attributed to the porphyrin bead shuttling between two
degenerate states in which the porphyrin is near the oxygen
atoms in the viologen-containing ring.[16] To investigate this
dynamic behavior further, variable-temperature 1H NMR
(VT-NMR) spectroscopy was carried out on [6·2H]2+. As is
shown in Figure 4, lowering the temperature causes dramat-
Figure 4. Parts of the 1H NMR spectra (500 MHz) of [6·2H]2+ at (a)
298 K and (b) 238 K. See Scheme 3 for proton numbering.
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Interlocked Porphyrin Switches
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Table 2. Thermodynamic and kinetic data for the shuttling process in
protonated [2]rotaxanes [18–20·2H]2+
.
Rotaxane
Probe
proton
Tc
kc
[sÀ1
DG°
c
[b]
[K][a]
G
]
[kJmolÀ1
ACHTUNGTERNNUNG ]
A
i
a
g
258
244
302
970
62
71
48
51
63
E
G
[a] Coalescence temperature. [b] Estimated error 10%. For proton num-
bering see Scheme 2 and 5.
Figure 5. Parts of the VT-NMR spectra (500 MHz) of protonated [2]ro-
taxane [18·2H]2+. See Scheme 5 for proton numbering.
As is shown in Figure 5, the signals Hh and Hi of the
blocking group split up into a downfield- and an upfield-
shifted signal, behavior that is a consequence of shielding ef-
fects of the porphyrin on the protons that are nearest to it.
We propose that the porphyrin also reduces the conforma-
tional freedom of these protons because the upfield signals
are somewhat broadened. Similar to what was observed in
the VT-NMR study of the [2]catenane [6·2H]2+, new reso-
nances appeared below 0 ppm, resonances that are assigned
to the aliphatic spacer protons that are situated inside the
cavity (see below). It is therefore proposed that protonated
[2]rotaxane [18·2H]2+ shuttles between the two degenerate
states that are created owing to the unfavorable electrostatic
interactions between the doubly charged viologen moiety
and the protonated porphyrin (Scheme 7).
Figure 6. (a) Parts of the 1H NMR spectra (500 MHz) of [2]rotaxane
[19·2H]2+ at 298 K and 238 K and (b) [2]rotaxane [20·2H]2+ at 298 K,
showing that at 298 K the shuttling equilibrium is fast on the NMR time-
scale for [19·2H]2+ and slow for [20·2H]2+
.
shuttling between the two degenerate states in [19·2H]2+ is
fast on the NMR timescale, leading to a highly symmetrical
spectrum that shows no resonances in this upfield region. If
the temperature is lowered to 238 K, signals originating
from the aliphatic spacer protons of the thread inside the
cavity become visible between 0 and À4 ppm as a result of
the fact that the exchange between the two degenerate
states has now become slow on the NMR timescale. In
marked contrast, the 1H NMR spectrum of [20·2H]2+ al-
ready shows similar signals in this region at 298 K, indicating
that the Gibbs-energy barrier associated with the dynamic
motion must be higher than that for the shorter-spaced ro-
taxanes. We therefore conclude that the Gibbs energy of ac-
tivation for the shuttling process becomes higher as the
spacer length increases. The thermodynamic parameters for
the shuttling processes involving the [2]rotaxanes, [18–
The dynamic behavior of protonated rotaxanes [19·2H]2+
and [20·2H]2+ was also investigated by VT-NMR experi-
ments. These complexes were found to display a similar dy-
namic motion; however, the increased spacer length be-
tween the viologen moiety and the blocking group had a re-
markable effect on the Gibbs-energy barrier associated with
the shuttling motion when compared to the shorter spaced
rotaxane, [18·2H]2+ (Table 2). This is most clearly exempli-
fied in Figure 6, which shows the 0 to À4 ppm region of the
1H NMR spectra of [19·2H]2+ and [20·2H]2+. At 298 K, the
Scheme 7. Switching between two degenerate states in [2]rotaxanes [18–20·2H]2+, as determined by VT-NMR experiments.
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
20·2H]2+, as determined by the coalescence method, are
summarized in Table 2. Notably, these values are not deter-
mined at the same temperature, so a detailed comparison
between the DG° values is not really allowed. Unfortunate-
c
ly, the activation parameters DH° and DS° could not be de-
termined, as the quality of the spectra was not good enough
for a line-shape analysis. However, we tentatively conclude
that the energy barrier associated with the shuttling process
increases as the spacer length increases. This can be ex-
plained by assuming that, in the case of a longer spacer, the
doubly charged porphyrin host can slide away further from
the doubly charged viologen moiety, thereby lowering the
energies of the two degenerate states associated with the
shuttling process because the electrostatic repulsion is re-
duced. Based on these observations, we propose that the
porphyrin in [2]catenane [6·2H]2+ shuttles between the two
oxygen atoms and moves predominantly over the alkene
part and not over the viologen, owing to unfavorable elec-
trostatic interactions. This behavior is in marked contrast
with the circumrotational movement of a similar [2]cate-
nane, observed by Gunter and Johnston.[15] It is thus possible
to induce a shuttling motion of the porphyrin host across
the circular thread in [2]catenane 6 by simply protonating
the porphyrin pyrrole nitrogen atoms. We also made at-
tempts to investigate the dynamic behavior of the large cate-
nanes, 10 and 11. Unfortunately, complicated NMR spectra
were observed in which the proton signals could not be as-
signed.
Figure 7. UV/Vis (a) and fluorescence (b) spectra of [2]catenanes 6 and
[6·2H]2+
.
In a final series of experiments, we studied the photophys-
ical properties of the interlocked complexes. We first studied
[2]catenane [6·2H]2+ by means of UV/Vis and fluorescence
spectroscopy. Addition of an excess of TFA (5 vol%) to a
CHCl3 solution of [2]catenane 6 ([6]~10À6 m) revealed a red
shift of the Soret band from lmax =421 nm to lmax =437 nm,
accompanied with significant broadening, which is a spectral
change that is generally observed for protonation of simple
porphyrins (Figure 7a). The fluorescence spectrum of 6 in
CHCl3 changed dramatically upon protonation of the por-
phyrin. Whereas in 6, no detectable fluorescence emission
could be observed upon excitation at lmax =421 nm, owing
to efficient fluorescence quenching by the viologen inside
their fluorescence spectra recorded. Figure 8a shows the
UV/Vis spectra of protonated catenane [6·2H]2+ and proto-
nated rotaxanes [18–20·2H]2+. The protonated rotaxanes ex-
hibit a broader Soret band than the one observed for the
protonated catenane. This effect may be related to the dif-
ferent geometries of the two types of structures and the dif-
ferent types of interactions between the porphyrin and viol-
ogen moieties resulting from this. The fluorescence spectra
display some interesting features (Figure 8b). Although [18–
20·2H]2+ display fluorescence emission upon excitation, the
observed fluorescence intensities are much lower than the
emission intensity originating from catenane [6·2H]2+
.
Moreover, a clear spacer-length effect on the fluorescence
intensity is observed: if the length of the rotaxane thread in-
creases, the fluorescence emission also increases. This can
be explained by assuming that when the distance between
the viologen moiety and the porphyrin clip is larger, the vi-
ologen moiety is less efficient in quenching the fluorescence
of the porphyrin.
the cavity, a large fluorescence emission peak at lem
=
643 nm emerged upon addition of TFA and excitation at
lmax =437 nm (Figure 7b).
Because, upon protonation of the porphyrin, the viologen
moiety is expelled from the cavity, it can no longer act as a
quencher, thus resulting in a dramatic increase in porphyrin
fluorescence. The addition of pyridine to the solution result-
ed in deprotonation of [6·2H]2+, regenerating 6, as well as
the previously observed UV/Vis and fluorescence spectra,
indicating the reversible nature of the switching process.
This result clearly demonstrates that [2]catenane 6 can be
switched between a nonfluorescent and a fluorescent state
by using simple acid–base chemistry.[18] The switching be-
tween the two states could be repeated at least 10 times
without signs of fatigue, as was concluded from UV/Vis
measurements. Rotaxanes 18–20 were also protonated and
Conclusion
We have demonstrated that catenanes based on porphyrin 1
and bisACHTNUTRGNE(NUG olefin)-terminated viologens can be easily synthe-
sized in high yields using an olefin-metathesis protocol. The
size of the olefin substituents of the viologens has a marked
effect on the products of the ring-closing reaction. Whereas
a viologen with long substituents (21 atoms) yields a [2]cate-
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Interlocked Porphyrin Switches
FULL PAPER
Following the protocols described in this paper, we are
currently planning the synthesis of functional catenane
structures derived from metal–porphyrin (metal is Zn or
Mn) glycoluril compounds. These will be allowed to form
double-cage compounds with other glycoluril derivatives as
schematically shown in Figure 1. The study of the properties
of these systems as a first step towards a molecular device in
which information can be transferred is envisaged.
Experimental Section
Materials and methods: Tetrahydrofuran was distilled under nitrogen
from sodium and benzophenone. Acetonitrile was distilled under nitro-
gen from calcium hydride. Chloroform was distilled under nitrogen from
calcium chloride. n-Hexane was distilled under nitrogen from sodium. Di-
methylformamide was dried over BaO for one week and then vacuum
distilled. The first 30% of the distillate was discarded. All other solvents
and chemicals were commercially available and used without further pu-
rification. Compounds 12 and 15 were synthesized as described previous-
ly.[9] BioRad Biobeads (SX-1) were used for size-exclusion chromatogra-
phy. Silica 60 (Merck) was used for column chromatography. Fluores-
cence experiments were performed on a Perkin–Elmer LS50B lumines-
cence spectrometer equipped with a thermostatted cuvette holder. UV/
Vis spectra were recorded on a Varian Cary 50 Conc spectrometer.
1H NMR and 13C NMR spectra were recorded on a Bruker DPX-200,
AM-300, or Bruker DRX-500 spectrometers. Chemical shifts are report-
ed in ppm downfield from internal tetramethylsilane (0.00 ppm) in the
case of 1H NMR and 13C NMR spectra in CDCl3 or CDCl3/CD3CN (1:1,
v/v), otherwise the solvent peak was used as a reference (CD3CN:
1.94 ppm). MALDI-TOF spectra were recorded on a Bruker Biflex III
spectrometer using dithranol as a matrix.
Figure 8. UV/Vis (a) and fluorescence (b) spectra of [6·2H]2+ and proto-
nated rotaxanes [18–20·2H]2+
.
nane and a [3]catenane, the viologen with shorter substitu-
ents (8 atoms) gives a mixture of a [3]catenane, a [4]cate-
nane, a [5]catenane, and higher oligomers, from which the
[4]catenane and [5]catenane could be isolated. In addition,
several [2]rotaxanes with threads of different lengths were
successfully synthesized by SN2-type reactions. The inter-
locked [2]catenane and [2]rotaxane structures show interest-
ing switching behavior: a shuttling motion of the porphyrin
in the described catenane and rotaxanes can be turned on
and off using acid and base stimuli. The protonated porphyr-
in host in the [2]catenane shuttles between two oxygen
atoms predominantly by a route via the carbon–carbon
double bond in the aliphatic ring because the cationic violo-
gen moiety poses a severe electrostatic barrier. In the case
of the protonated [2]rotaxanes, the energy barrier associated
with the shuttling is length dependent: when the spacer
length between the viologen moiety and the blocking group
of the thread is increased, the energy barrier also increases.
The induction of motion of the porphyrin moiety in the
[2]catenane and [2]rotaxanes is also accompanied by inter-
esting photophysical changes. Upon protonation of the
[2]catenane, the viologen that quenches the porphyrin fluo-
rescence is expelled from the cavity, resulting in a dramatic
increase in the fluorescence emission. Similar effects were
observed for the [2]rotaxanes, but not as dramatic as in the
case of the [2]catenane, and a clear dependency of the fluo-
rescence properties on the length of the space between the
viologen and the blocking group was observed.
Synthetic procedures and compound data
10-(10-Bromodecyloxy)dec-1-ene (2): Under an argon atmosphere, dec-9-
en-1-ol (1.4 g, 9 mmol) was added to a mixture of NaH (384 mg, 9.6
mmol, 60% dispersion in mineral oil) in argon-purged THF (15 mL).
After the evolution of hydrogen gas had ceased, 1,10-dibromodecane
(16.1 g, 53.6 mmol) was added and the resulting mixture was stirred for 5
days. The solvent was removed by rotary evaporation, after which the re-
sulting crude product was dissolved in Et2O. This solution was washed
with water, dried (MgSO4), filtered, and evaporated to dryness. The resi-
due was purified by column chromatography (silica, n-heptane, Rf =0.65)
to yield
200 MHz) d=5.90–5.70 (m, 1H; H2C=CH), 5.03–4.88 (m, 2H; H2C=CH),
2 as a
clear, colorless oil (1.5 g, 44%). 1H NMR (CDCl3,
3.45–3.33 (m, 6H; CH2OCH2, CH2Br), 2.04 (q, 3J
ACTHNUTRGNE(NUG H,H)=7.0 Hz, 2H;
H2C=CHCH2), 1.69–1.20 ppm (m, 28H; CH2); 13C NMR (CDCl3,
125 MHz) d=139.2, 114.2, 71.1, 37.2, 33.8, 298, 29.5, 28.9, 26.3 ppm.
A
dihexafluoro-
phosphate (3): A mixture of 4,4’-bipyridine (102 mg, 0.65 mmol) and 2
(1.23 g, 3.3 mmol) in DMF (1 mL) was stirred overnight under a N2 at-
mosphere at 1008C. After cooling, Et2O was added and the resulting pre-
cipitate was filtered and washed with Et2O and MeCN. The solid was dis-
solved in MeCN/H2O (1:1, v/v) after which the addition of a saturated
solution of NH4PF6 in H2O resulted in the precipitation of 3. The solid
was recrystallized from hot MeOH and washed with MeOH and Et2O to
give 3 as a white solid (153 mg, 23%). M.p. 2558C (decomposed);
1H NMR (CDCl3/CD3CN (1:1, v/v), 200 MHz) d=8.90 (d, 3J
7.0 Hz, 4H; BipyH,), 8.40 (d, 3J
(H,H)=7.0 Hz, 4H; BipyH), 5.93–5.70
(m, 2H; H2C=CH), 5.05–4.86 (m, 4H; H2C=CH), 4.61 (t, 3J
(H,H)=
6.4 Hz, 4H; BipyCH2), 3.36 (t, 3J(H,H)=6.4 Hz, 8H; CH2O), 2.02 (q, 3J-
(H,H)=7.0 Hz, 4H; H2C=CHCH2), 1.60–1.20 ppm (m, 56H; CH2);
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
13C NMR (CDCl3, 125 MHz) d=147.1, 144.1, 138.7, 126.5, 113.2, 69.9,
32.9, 30.4, 29.0, 28.6, 28.0, 25.3 ppm. IR (KBr) n˜ =2926, 2854,1647, 1508,
1472, 1379, 1182, 1124, 836, 558 cmÀ1; MS (MALDI-TOF): m/z: 746
[MÀ2PF6]+; HRMS (ESI-TOF): m/z calcd for C50H86F6N2O2P: 891.63311
Chem. Eur. J. 2013, 00, 0 – 0
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
5.88 (bs, 8H; H5), 5.44–5.35 (m, 4H; Hu), 4.62 (bs, 8H; Ha), 4.30–4.21
[MÀPF6]+; found: 891.63096; m/z calcd for C50H86N2O2: 746.66674
[MÀ2PF6]+; found: 746.66893.
(m, 8H; H7), 4.16 (d, 2J
ACHTUNGTRENN(UNG H,H)=15.9 Hz, 8H; H4), 3.88–3.75 (m, 8H;
H7), 3.60 (d, 2J
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG(N,N’)-Di-(1-(oct-7-enyl))-4,4’-bipyridinium dihexafluorophosphate (4):
3.40–3.20 (m, 16H; Hc, H6), 2.66–2.55 (m, 8H; H6), 2.10–0.70 (m; CH2),
À2.95 ppm (s, 4H; H14); MS (MALDI-TOF): m/z 4125.6, 4271.6, 4416.4,
4560.7 [MÀnPF6]+ (n=1–4).
A mixture of 4,4’-bipyridine (100 mg, 0.64 mmol) and 8-bromo-octene
(1.2 g, 6.3 mmol) in DMF (1 mL) was stirred overnight under a N2 atmos-
phere at 1008C. After cooling, Et2O was added and the resulting precipi-
tate was filtered and washed with Et2O and MeCN. The solid was dis-
solved in MeCN and a saturated solution of NH4PF6 in H2O was added,
which resulted in the precipitation of 4 as a white solid in a yield of
260 mg (61%). M.p. 2498C (decomposed); 1H NMR (CD3CN, 200 MHz)
[4]Catenane 10 and [5]catenane 11: A solution of 1 (45.6 mg, 0.034
3
3
d=8.91 (d, J
BipyH), 5.95–5.73 (m, 2H; H2C=CH), 5.11–4.89 (m, 4H; H2C=CH), 4.61
(t, 3J
(H,H)=7.4 Hz, 4H; BipyCH2), 2.08 (m, 8H; CH2), 1.39 ppm (bs,
ACHTUNGTRENNUNG(H,H)=6.9 Hz, 4H; BipyH), 8.39 (d, JAHCTUNGTRNEN(UGN H,H)=6.9 Hz, 4H;
ACHTUNGTRENNUNG
12H; CH2); 13C NMR (CDCl3, 125 MHz) d=149.0, 144.7, 137.9, 126.4,
113.4, 61.4, 32.5, 30.1, 27.5, 27.3, 24.6 ppm; IR (KBr) n˜ =3149, 3084, 2933,
2862, 1647, 1565, 1512, 1457, 1230, 1179, 836, 558 cmÀ1; MS (MALDI-
TOF): m/z: 378 [MÀ2PF6]+; HRMS (ESI-TOF): m/z calcd for
C26H38F6N2P: 523.26768 [MÀPF6]+; found: 523.26734.
[2]Catenane 6 and [3]catenane 7: A solution of 1 (40 mg, 0.03 mmol) in
a minimal amount of CHCl3 and a solution of 3 (30.8 mg, 0.03 mmol) in
a minimal amount of acetone were mixed, and the solvent was evaporat-
ed. The resulting solid was dissolved in a minimal amount of CH2Cl2 and
precipitated in n-hexane. After drying in vacuo, the thus obtained
[2]pseudorotaxane 5 was dissolved in CH2Cl2 (60 mL), and the first gen-
eration Grubbsꢁ catalyst (5 mg, 6.1 mmol) was added under an argon at-
mosphere. The resulting mixture was stirred overnight at room tempera-
ture, after which the solvent was removed by rotary evaporation. The
crude mixture was subjected to column chromatography (silica, CH2Cl2/
MeNO2/MeOH, 8:1:1, v/v/v) yielding a mixture of 1, 6, and 7. These com-
pounds were separated by column chromatography (first column: bio-
beads, CH2Cl2; second column: silica, 3% MeOH/CH2Cl2, v/v) to yield 6
(48 mg, 69%, Rf =0.26) and 7 (2 mg, 3%, Rf =0.14) as purple solids.
mmol) in a minimal amount of CHCl3 and a solution of 4 (20.7 mg, 0.031
mmol) in a minimal amount of acetone were mixed, and the solvent was
evaporated. The resulting solid was dissolved in a minimal amount of
CH2Cl2 and precipitated in n-hexane. After drying in vacuo, the thus ob-
tained [2]pseudorotaxane 8 was dissolved in CH2Cl2 (34 mL), 2 mg of
first generation Grubbsꢁ catalyst was added, and the resulting solution
was refluxed under an argon atmosphere. After 30 min., another 2 mg of
Grubbsꢁ catalyst was added and refluxing was continued for 6 hrs after
which a last portion of 0.5 mg Grubbsꢁ catalyst was added (total added
catalyst: 4.5 mg, 5.5 mmol). After an additional hour of refluxing, the sol-
ution was allowed to cool and a drop of ethylvinyl ether was added after
which the solvent was evaporated. The crude mixture was subjected to
column chromatography (silica, CH2Cl2/MeNO2/MeOH, 8:1:1, v/v/v)
yielding a mixture of 1, 9, 10, 11, and higher oligomers. This mixture was
subjected to size-exclusion chromatography (biobeads, CH2Cl2) from
which the [4]catenane 10 and the [5]catenane 11 could be isolated. Both
compounds were subjected to another size-exclusion column to give 10
(12 mg, 18%) and 11 (7 mg, 11%) as purple solids. M.p.>3008C (decom-
posed); the 1H NMR spectra were assigned based on 2D-COSY and 2D-
NOESY spectra, therefore, some values for the integrals and signal
shapes are not given.
Data for 5: 1H NMR (CDCl3, 500 MHz, for proton numbering see figure
below and Scheme 1 and 2): d=9.06 and 8.77 (2 s, 8H; H12–13), 8.09 (d,
3
3J
3J
G
E
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(H,H)=7.0 Hz, 4H; H9), 7.40 (d, 3J
2
Ha), 4.32 (m, 4H; H7), 4.26 (d, J
ACHTUNGTRNE(NUNG H,H)=15.6 Hz, 4H; H4), 4.03 (m, 4H,
H7), 3.72 (d, 2J
ACHTUNGTRENNUNG
H6), 3.33 (m, 4H; Hc), 2.76 (m, 4H; H6), 2.04 (m, 4H; CH2), 1.7–1.55
(m, 8H; CH2), 1.5–1.15 (m, 34H; CH2), 1.08 (m, 8H; CH2), 0.90 (m, 8H;
CH2), À2.83 ppm (s, 2H; H14).
Data for 6: M.p.>3008C (decomposed); 1H NMR (CDCl3, 500 MHz, for
proton numbering see figure below and Scheme 1 and 2): d=9.08 (s, 4H;
Data for 10: 1H NMR (CDCl3, 500 MHz) d=9.07 (m, 12H; H12), 8.72
(m, 12H; H13), 8.06 (m, 12H; H11), 7.82 (m, 12H; H10), 7.44 (m, 24H;
H8, H9), 7.1–6.6 (m, 30H; H1–3), 6.54 (bs; BipyH), 6.42 (bs; BipyH),
6.2–5.8 (m; BipyH), 6.05–5.9 (m; H5), 5.57 (bs; CH=CH, trans), 5.49 (bs;
CH=CH, cis), 4.84 (bs; BipyH), 4.74 (bs; BipyH), 4.60 (bs; BipyH), 4.53
H12), 8.79 (s, 4H; H13), 8.11 (dd, 3J(H,H)=7.3 Hz, 5J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
3
5
4H; H11), 7.84 (dt, J
A
ACHTUNGTRENNUNG(H,H)=8.0 Hz, JACHTNUGTRENNUNG
3J(H,H)=7.5 Hz, 4H; H9), 7.42 (d, 3J
ACHTUNGTRENNUNG
(bs; BipyH), 4.40 (bs; BipyH), 4.29 (bs; H7), 4.19 (d, 2J
ACHTNUTRGNE(NUG H,H)=15.8 Hz;
AHCTUNGTRENNUNG
H4), 4.05–3.8 (m; H7), 3.65–3.05 (m; BipyCH2), 3.45–3.30 (m; H6), 2.80–
2.40 (m; H6), 2.15 (bs; CH2CH=, cis), 2.08 (bs; CH2CH=, trans), 1.60–
0.7 (m; CH2), À2.80–À3.0 ppm (m, 6H; H14); 13C NMR (CDCl3,
125 MHz) d=158.4, 146.0, 142.5, 135.7, 130.6, 130.1, 128.7, 128.0, 120.3,
116.4, 112.4, 85.3, 68.2, 67.2, 64.4, 43.9, 33.9, 30.9, 29.8, 28.8, 25.9,
25.1 ppm. MS (MALDI-TOF): m/z 5088, 5225, 5370, 5516, 5661, 5805
[MÀnPF6]+ (n=1–6).
N
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
(m, 4H; H6), 3.48 (m, 8H; Hl, Hm), 3.44 (m, 4H; Hc), 2.78 (m, 4H;
H6), 1.67 (m, 8H; Hk, Hn), 1.60 (m; Ht, cis), 1.50 (m, 8H; Ho, Hj), 1.46
(m; Ht, trans), 1.30 (m; 8H, He, Hf), 1.20 (m, 8H; Hi, Hp), 1.08 (m, 8H;
Hh, Hq), 0.96 (m, 8H; Hg, Hr), 0.92 (m; Hs, cis), 0.87 (m; Hs, trans),
À2.81 ppm (s, 2H; H14); 13C NMR (CDCl3, 125 MHz) d=158.6, 158.1,
146.2, 142.5, 135.6, 131.2, 130.7, 130.1, 129.8, 129.0, 128.7, 128.1, 123.3,
120.5, 116.7, 116.4, 85.4, 70.9, 68.5, 67.4, 44.0, 32.3, 30.9, 30.5, 29.9, 29.6,
29.4, 29.1, 28.8, 27.0, 26.3, 26.1 ppm. IR (KBr) n˜ =3060, 2928, 2854, 1696,
1653, 1635, 1598, 1581, 1560, 1517, 1465, 1448, 1428, 1384, 1347, 1283,
Data for 11: 1H NMR (CDCl3, 500 MHz, see figure above for proton
numbering) d=9.07 (app. d, 16H; H12), 8.77 (bs, 16H; H13), 8.07 (bs,
16H; H11), 7.83 (bm, 16H; H10), 7.45 (bm, 32H; H8, H9), 7.10–6.65 (m,
40H; H1–3), 6.38 (bs; BipyH), 6.22 (bs; BipyH), 6.19 (bs; BipyH), 6.02
(bs; H5) 6.00 (bs; BipyH), 5.54 (bs; CH=CH, trans), 5.49 (bs; CH=CH,
cis), 4.69 (bs; BipyH), 4.65 (bs; BipyH), 4.57 (bs; BipyH), 4.48 (bs;
BipyH), 4.35 (bs; H7), 4.20 (m; H4), 4.02 (bs; H7), 3.56 (m; H4), 3.50–
3.25 (m; BipyCH2), 3.45 (bs; H6), 2.75 (bs; H6), 2.16 (bs; CH2CH=, cis),
2.09 (bs; CH2CH=, trans), 1.70–0.80 (m; CH2), À2.87 ppm (s, 8H; H14);
13C NMR (CDCl3, 125 MHz) d=158.7, 148.7, 146.2, 142.7, 139.8, 135.6,
132.9, 130.6, 130.1, 128.6, 128.0, 123.3, 120.4, 116.4, 112.4, 85.3, 68.6, 67.5,
64.5, 44.1, 34.4, 33.3, 32.3, 31.9, 30.9, 29.7, 29.6, 29.3, 29.1, 28.6, 25.9,
1251, 1214, 1120, 1064, 967, 956, 841, 805, 752, 720, 696, 668, 557 cmÀ1
;
MS (MALDI-TOF): m/z 2063.1 [MÀ2PF6]+, 2208.1 [MÀPF6]+.
Data for 7: M.p.>3008C (decomposed); 1H NMR (CDCl3, 500 MHz, for
proton numbering see figure below and Scheme 1 and 2): d=9.02 (s, 8H;
H12), 8.65 (s, 8H; H13), 8.02 (dd, 3J
G
ACHTUNGTREN(NUNG H,H)=1.7 Hz,
8H; H11), 7.81 (dt, 3J
N
ACHTUNGTRENNUNG
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Interlocked Porphyrin Switches
FULL PAPER
25.0 ppm; MS (MALDI-TOF): m/z 6778, 6923, 7068, 7213, 7358, 7503,
7648, 7793 [MÀnPF6]+ (n=1–8).
6.6 Hz, 2H; CH2), 1.40 (bs, 8H; CH2), 1.28 ppm (s, 18H; CCH3);
13C NMR (CDCl3, 125 MHz) d=158.6, 154.4, 152.2, 151.4, 144.7, 140.9,
126.0, 121.4, 114.8, 108.8, 67.5, 62.2, 35.0, 31.4, 31.3, 29.4, 29.0, 28.8,
25.9 ppm; IR (KBr) n˜ =3136, 2955, 2870, 1646, 1594, 1550, 1527, 1459,
1-(8-Bromooctyloxy)-3,5-di-tert-butylbenzene (13): A mixture of 3,5-di-
tert-butylphenol (3 g, 14.5 mmol), 1,8-dibromooctane (20 g, 73.5 mmol)
and K2CO3 (10 g, 72.4 mmol) in DMF (30 mL) was stirred overnight
under an argon atmosphere, after which the solvent and the remaining
1,8-dibromooctane was distilled off. The resulting crude product was sub-
jected to column chromatography (silica, n-heptane, Rf =0.08) to yield 13
1430, 1413, 1362, 1324, 1302, 1248, 1222, 1174, 112, 1063, 833, 557 cmÀ1
;
MS (MALDI-TOF): m/z 474 [MÀPF6 +H]+; HRMS (ESI-TOF): m/z
calcd for C32H45N2O: 473.35319 [MÀPF6]+; found: 473.35415.
1-(11-(3,5-Di-tert-butylphenoxy)undecyl)-4,4’-bipyridin-1-ium hexafluoro-
phosphate (17): Compound 14 (85 mg, 0.19 mmol) and 4,4-bipyridine
(300 mg, 1.9 mmol) were dissolved in acetonitrile (10 mL). The mixture
was refluxed overnight under argon. After cooling, the solvent was
evaporated and the residue was dissolved in CHCl3 (5 mL). An aqueous
saturated NH4PF6 solution (5 mL) was added, and the mixture was stir-
red vigorously for 2 h. The organic layer was separated, washed with
water and evaporated to dryness. The crude product was purified by
column chromatography (Silica 60H, 3% MeOH/CHCl3, v/v, Rf =0.02)
to give 17 (112 mg, 88%) as a yellowish oil/wax. 1H NMR (CDCl3,
1
4
as a colorless oil (4.5 g, 78%). H NMR (CDCl3, 200 MHz) d=7.01 (t, J-
(H,H)=1.7 Hz, 1H; para-ArH), 6.75 (d, 4J
(H,H)=1.7 Hz, 2H; ortho-
ArH), 3.96 (t, 3J(H,H)=6.4 Hz, 2H; OCH2), 3.39 (t, 3J
(H,H)=6.9 Hz,
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
2H; CH2Br), 1.95–1.72 (m, 4H; CH2), 1.57–1.23 (m, 8H; CH2), 1.31 ppm
(s, 18H; CCH3); 13C NMR (CDCl3, 125 MHz) d=158.6, 152.1, 114.8,
108.8, 67.6, 35.0, 34.0, 32.8, 31.4, 29.4, 29.2, 28.7, 28.1, 26.0 ppm; IR (KBr)
n˜ =2964, 2861, 1593, 1478, 1465, 1429, 1393, 1362, 1324, 1300, 1247, 1219,
1204, 1122, 1059, 937, 900, 863, 845, 707, 668, 645, 564 cmÀ1; MS (GC-
MS): m/z 396 [M+]; HRMS (EI-TOF): m/z calcd for C22H37BrO:
396.20278 [M+]; found: 396.20190.
300 MHz) d=8.81 (d, 3J
5.1 Hz, 2H; BipyH), 8.13 (d, 3J
(H,H)=4.5 Hz, 2H; BipyH), 6.95 (t, 4J
(d, 4J(H,H)=1.8 Hz, 2H; ArH), 4.55 (t, 3J
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
11-(3,5-Di-tert-butyl-phenoxy)-undecan-1-ol:
3,5-Di-tert-butylphenol
E
ACHTUNGTRENNUNG
(300 mg, 1.46 mmol) and 11-bromoundecanol (350 mg, 1.39 mmol) were
suspended in argon-flushed DMF (10 mL). K2CO3 (750 mg, 5.43 mmol)
was added and the mixture was heated overnight at 1008C under argon.
After cooling, the solvent was evaporated and the residue dissolved in
CH2Cl2. The organic layer was washed first with aqueous 1N HCl and
then with an aqueous saturated NaHCO3 solution. After evaporation of
the solvent, the crude product was purified by column chromatography
(Silica 60H, 5% EtOAc/n-heptane, v/v, Rf =0.05) to give the desired
product as a colorless oil (420 mg, 77%). 1H NMR (CDCl3, 300 MHz)
N
3.91 (t, 2H; ArOCH2), 1.98 (m, 2H; CH2), 1.74 (m, 2H; CH2), 1.6–1.1
(m, 16H; CH2), 1.28 ppm (s, 18H; CH3); 13C NMR (CDCl3, 125 MHz)
d=15.7, 154.4, 152.1, 151.4, 144.7, 140.9, 126.0, 121.4, 114.8, 108.8, 67.7,
62.3, 35.0, 31.4, 26.1, 26.0, 25.9 ppm; IR (KBr) n˜ =2958, 2927, 2856, 1793,
1735, 1648, 1595, 1546, 1526, 1465, 1430, 1412, 1393, 1363, 1334, 1301,
1247, 1220, 1204, 1184, 1122, 1060, 860, 834, 815, 724, 708, 669, 558 cmÀ1
;
MS (MALDI-TOF): m/z 516 [MÀPF6 +H]+; HRMS (ESI-TOF): m/z
calcd for C35H51N2O: 515.40014 [MÀPF6]+; found: 515.40100.
d=6.98 (t, 4J
G
ACHTUNGTREN(NGNU H,H)=1.8 Hz, 2H;
ArH), 3.94 (t, 3J
ACHTUNGTRENNUNG
[2]Rotaxane 18: Porphyrin
1 (10 mg, 7.4 mmol), pyridinium salt 15
1.78 (m, 2H; CH2CH2OH), 1.7–1.1 (m, 17H; CH2 and OH), 1.31 ppm (s,
18H; CH3); 13C NMR (CDCl3, 125 MHz) d=158.7, 152.1, 114.8, 108.8,
67.7, 63.1, 35.0, 32.8, 31.4, 29.6, 26.5, 29.4, 26.1, 25.7 ppm; IR (KBr) n˜ =
3373, 3076, 928, 2856, 1592, 1478, 1465, 1429, 1393, 1362, 1324, 1300,
1247, 1219, 1204, 1122, 1058, 938, 901, 862, 844, 707, 636 cmÀ1; MS
(MALDI-TOF): m/z 377 [M+H]+.
(21 mg, 37 mmol), and bromide 12 (104 mg, 293 mmol) were dissolved in
DMF (1.5 mL). The resulting solution was stirred overnight at 908C
under an argon atmosphere. After cooling, the solvent was evaporated
and the resulting solid was dissolved in MeCN. To this solution a saturat-
ed aqueous solution of NH4PF6 was added. Water and CHCl3 were added
and the organic layer was separated and evaporated to dryness. The
crude mixture was subjected to column chromatography (silica, CH2Cl2
to 0.3% MeOH/CH2Cl2 (v/v) to 0.5% MeOH/CH2Cl2, v/v) to yield 18 as
1-(11-Bromoundecyloxy)-3,5-di-tert-butylbenzene (14): 11-(3,5-Di-tert-bu-
tylphenoxy)-undecan-1-ol (420 mg, 1.12 mmol) was dissolved in freshly
distilled CHCl3 (15 mL) under argon and this solution was cooled to 08C.
PBr3 (0.5 g, 1.85 mmol) was added and the mixture was allowed to warm
to room temperature and stirred overnight. Water was added dropwise to
quench the reaction, and the mixture was extracted with aqueous 0.5N
NaOH. The organic layer was evaporated to dryness, and the residue was
purified by column chromatography (Silica 60H, CHCl3, Rf =0.95) to
a
purple solid (9 mg, 51%). M.p.>3008C (decomposed); 1H NMR
(CDCl3, 500 MHz) d=9.11 (s, 4H; H12), 8.78 (s, 4H; H13), 8.09 (dd, 3J-
A
R
ACHTUNGTREN(NUNG H,H)=8.0 Hz,
5J
ACHTUNGTRENNUNG
3J
ACHTUNGTRENNUNG
5
(thread)), 7.05–6.96 (m, 6H; H1, H2), 6.92–6.88 (m, 4H; H3), 6.83 (d, J-
(H,H)=1.6 Hz, 4H; ortho-ArH (thread)), 6.15 (bd, 3J
(H,H)=5.2 Hz,
4H; BipyH), 6.07 (s, 4H; H5), 4.96 (bs, 4H; BipyH), 4.35 (m, 4H; H7),
1
G
ACHTUNGTRENNUNG
give 14 (305 mg, 62%) as a colorless oil. H NMR (CDCl3, 300 MHz) d=
6.98 (t, 4J(H,H)=1.8 Hz, 1H; ArH), 6.72 (d, 4J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
3
ArH), 3.94 (t, 3J
N
ACHTUNGTRENNUNG
4.23 (d, J
6.0 Hz, 4H; OCH2 (thread)), 3.69 (d, 2J
(m, 4H; H6), 3.32 (bt, 4H; BipyCH2), 2.80 (m, 4H; H6), 1.74 (q, 3J-
(H,H)=7.2 Hz, 4H; CH2 (thread)), 1.36 (s, 36H; CCH3), 1.31 (q, 3J-
(H,H)=6.1 Hz, 4H; CH2 (thread)), 0.99 (bs, 4H; CH2 (thread)),
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
2H; CH2Br), 1.80 (m, 4H; CH2), 1.6–1.2 (m, 16H; CH2), 1.31 ppm (s,
18H; CH3); 13C NMR (CDCl3, 125 MHz) d=158.9, 152.1, 114.8, 108.9,
67.7, 35.0, 34.1, 32.8, 31.5, 29.5, 29.4, 28.8, 28.2, 26.1 ppm; IR (KBr) n˜ =
3076, 2964, 2868, 1593, 1479, 1429, 1393, 1362, 1323, 1300, 1247, 1218,
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
2.82 ppm (s, 2H; H14); 13C NMR (CDCl3, 125 MHz) d=158,7, 158.4,
157.0, 152.3, 146.6, 135.8, 133.6, 129.9, 128.4, 128.1, 119.9, 115.2, 115.1,
111.9, 108.7, 84.8, 67.4, 66.9, 64.5, 51.0, 44.4, 31.4, 28.7, 23.0, 22.4 ppm; IR
(KBr) n˜ =3443, 2952, 2868, 1701, 1653, 1592, 1560, 1517, 1490, 1457,
1448, 1426, 1385, 1363, 1298, 1249, 1215, 1142, 1120, 1062, 967, 843, 802,
752, 708, 557 cmÀ1; MS (MALDI-TOF): m/z 2049.5 [MÀ2PF6]+.
1204, 1122, 1060, 1008, 939, 900, 863, 845, 814, 736, 707, 643, 563 cmÀ1
;
MS (GC-MS): m/z 440 [M+H]+; HRMS (EI-TOF): m/z calcd for
C25H43BrO: 438.24973 [M+]; found: 438.24955.
1-(8-(3,5-Di-tert-butylphenoxy)octyl)-4,4’-bipyridin-1-ium
hexafluoro-
phosphate (16): 4,4’-Bipyridine (4 g, 25.6 mmol) and 13 (1 g, 2.5 mmol)
were dissolved in MeCN (25 mL). The solution was refluxed overnight.
After cooling Et2O was added and the resulting precipitate was filtered
off and washed with Et2O. The resulting gum was dissolved in hot water
and a saturated aqueous solution of NH4PF6 was added resulting in the
formation of an oil which solidified into a white solid upon scratching the
inside of the flask. Filtration gave 16 as a white powder (820 mg, 53%).
M.p. 1168C (decomposed); 1H NMR (CD3CN, 200 MHz) d=8.88 (bs,
[2]Rotaxane 19: Porphyrin
1 (10 mg, 7.4 mmol), pyridinium salt 16
(23 mg, 37 mmol) and bromide 13 (118 mg, 296 mmol) were dissolved in
DMF (1.5 mL). The resulting solution was stirred overnight at 908C
under an argon atmosphere. After cooling, the solvent was evaporated
and the resulting solid was dissolved in MeCN. To this solution a saturat-
ed aqueous solution of NH4PF6 was added. Water and CHCl3 were added
and the organic layer was separated and evaporated to dryness. The
crude mixture was subjected to column chromatography (silica, CH2Cl2
to 0.3% MeOH/CH2Cl2 (v/v) to 0.5% MeOH/CH2Cl2 (v/v)) to yield 19
as a purple solid (11 mg, 61%). M.p.>3008C (decomposed); 1H NMR
(CDCl3, 300 MHz) d=9.08 (s, 4H; H12), 8.77 (s, 4H; H13), 8.10 (dd, 3J-
2H; BipyH), 8.89 (d, 3J
6.6 Hz, 2H; BipyH), 7.93 (d, 3J
(H,H)=1.7 Hz, 1H; para-ArH), 6.72 (t, 4J
ArH), 4.56 (t, 3J(H,H)=7.3 Hz, 2H; BipyCH2), 3.97 (t, 3J
2H; OCH2), 2.01 (q, 3J(H,H)=6.6 Hz, 2H; CH2), 1.74 (q, 3J
ACHTUNGTRENNUNG
G
ACHTUNGTRNE(NUNG H,H)=
AHCTUNGTRENNUNG
R
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
U
Chem. Eur. J. 2013, 00, 0 – 0
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
A
E
G
Lai, Y.-H. Liu, S.-M. Peng, S.-H. Chiu, Angew. Chem. 2012, 124,
10241; Angew. Chem. Int. Ed. 2012, 51, 10094.
5J
E
3J
R
[2] a) C. P. Collier, G. Mattersteig, E. W. Wong, Y. Luo, K. Beverly, J.
Sampaio, F. M. Raymo, J. F. Stoddart, J. R. Heath, Science 2000, 289,
1172; b) Y. Luo, C. P. Collier, J. O. Jeppesen, K. A. Nielsen, E. De-
lonno, G. Ho, J. Perkins, H. R. Tseng, T. Yamamoto, J. F. Stoddart,
J. R. Heath, ChemPhysChem 2002, 3, 519.
(thread)), 7.04–6.97 (m, 6H; H1, H2), 6.94–6.89 (m, 4H; H3), 6.85 (d, J-
(H,H)=1.6 Hz, 4H; ortho-ArH (thread)), 6.13 (d, 3J
(H,H)=6.1 Hz, 4H;
BipyH), 6.07 (s, 4H; H5), 4.90 (d, 3J
(H,H)=6.1 Hz, 4H; BipyH), 4.40–
4.35 (m, 4H; H7), 4.28 (d, 2J
(H,H)=15.9 Hz, 4H; H4), 4.05–3.95 (m,
4H; H7), 4.05 (t, 3J(H,H)=6.0 Hz, 4H; OCH2 (thread)), 3.73 (d, 2J-
(H,H)=15.8 Hz, 4H; H4), 3.56–3.46 (m, 4H; H6), 3.32 (bt, 4H;
BipyCH2), 2.82–2.73 (m, 4H; H6), 1.85 (q, 3J
(H,H)=7.2 Hz, 4H; CH2
R
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
[3] a) T. J. Huang, B. Brough, C. M. Ho, Y. Liu, A. H. Flood, P. A. Bon-
vallet, H. R. Tseng, J. F. Stoddart, M. Baller, S. Magonov, Appl.
Phys. Lett. 2004, 85, 5391; b) Y. Liu, A. H. Flood, P. A. Bonvallett,
S. A. Vignon, B. H. Northrop, H. R. Tseng, J. O. Jeppesen, T. J.
Huang, B. Brough, M. Baller, S. Magonov, S. D. Solares, W. A. God-
dard, C. M. Ho, J. F. Stoddart, J. Am. Chem. Soc. 2005, 127, 9745.
[4] Interlocked molecules are not the only excellent candidates for the
bottom-up approach in nanotechnology, for example, see: a) N. Kou-
mura, R. W. J. Zijlstra, R. A. van Delden, N. Harada, B. L. Feringa,
Nature 1999, 401, 152; b) V. Balzani, A. Credi, F. M. Raymo, J. F.
Stoddart, Angew. Chem. 2000, 112, 3484; Angew. Chem. Int. Ed.
2000, 39, 3348; c) K. Kinbara, T. Aida, Chem. Rev. 2005, 105, 1377;
d) A. Kocer, M. Walko, W. Meijberg, B. L. Feringa, Science 2005,
309, 755. W. R. Browne, B. L. Feringa, Nat. Nanotechnol. 2006, 1,
25; e) K. Miwa, Y. Furusho, E. Yashima, Nat. Chem. 2010, 2, 444.
[5] A. M. Turing, Proc. London Math. Soc. 1937, 42, 230.
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
(thread)), 1.60–1.50 (m, 4H; CH2 (thread)), 1.42–1.20 (m, 8H; CH2
(thread)), 1.35 (s, 36H; CCH3), 1.10 (bs, 4H; CH2 (thread)), 0.94 (bs,
4H; CH2 (thread)), À2.82 ppm (s, 2H; H14); 13C NMR (CDCl3,
125 MHz) d=158.7, 158.5, 158.2, 152.2, 146.2, 145.0, 142.5, 135.6, 132.7,
131.2, 130.6, 130.1, 129.1, 128.8, 128.0, 126.0, 123.2, 121.5, 120.5, 116.5,
114.8, 112.2, 85.4, 68.4, 67.6, 67.3, 64.3, 61.7, 50.8, 44.0, 43.5, 35.0, 31.5,
29.5, 29.1, 28.9, 28.8, 26.1, 26.0 ppm. IR (KBr) n˜ =3455, 2951, 2862, 1701,
1636, 1594, 1521, 1473, 1363, 1301, 1249, 1217, 1121, 1061, 968, 845, 708,
558 cmÀ1; MS (MALDI-TOF): m/z 2280.6 [MÀPF6]+, 2135.6 [MÀ2PF6]+.
[2]Rotaxane 20: Compounds 14 (22 mg, 50 mmol), 17 (22 mg, 33 mmol)
and 1 (8.5 mg, 6.3 mmol) were suspended in argon-flushed DMF (3 mL).
The mixture was heated under argon at 1208C for 5 days. After cooling,
the product was dissolved in CHCl3 (5 mL).
[6] a) P. Thordarson, E. J. A. Bijsterveld, A. E. Rowan, R. J. M. Nolte,
Nature 2003, 424, 915; b) C. Monnereau, P. Hidalgo Ramos, A. B. C.
Deutman, J. A. A. W. Elemans, R. J. M. Nolte, A. E. Rowan, J. Am.
Chem. Soc. 2010, 132, 1529.
[7] P. Thordarson, R. G. E. Coumans, J. A. A. W. Elemans, P. J. Thomas-
sen, J. Visser, A. E. Rowan, R. J. M. Nolte, Angew. Chem. 2004, 116,
4859; Angew. Chem. Int. Ed. 2004, 43, 4755.
[8] a) R. G. E. Coumans, J. A. A. W. Elemans, R. J. M. Nolte, A. E.
Rowan, Proc. Natl. Acad. Sci. USA 2006, 103, 19647; b) P. Hidal-
go Ramos, R. G. E. Coumans, A. B. C. Deutman, R. de Gelder,
J. M. M. Smits, J. A. A. W. Elemans, R. J. M. Nolte, A. E. Rowan, J.
Am. Chem. Soc. 2007, 129, 5699; c) A. B. C. Deutman, C. Monner-
eau, J. A. A. W. Elemans, G. Ercolani, R. J. M. Nolte, A. E. Rowan,
Science 2008, 322, 1668.
[9] R. G. E. Coumans, J. A. A. W. Elemans, P. Thordarson, R. J. M.
Nolte, A. E. Rowan, Angew. Chem. 2003, 115, 674; Angew. Chem.
Int. Ed. 2003, 42, 650.
[10] J. A. A. W. Elemans, M. B. Claase, P. P. M. Aarts, A. E. Rowan,
A. P. H. J. Schenning, R. J. M. Nolte, J. Org. Chem. 1999, 64, 7009.
[11] a) B. Mohr, J.-P. Sauvage, R. H. Grubbs, M. Weck, Angew. Chem.
1997, 109, 1365; Angew. Chem. Int. Ed. Engl. 1997, 36, 1308; b) T. J.
Kidd, D. A. Leigh, A. J. Wilson, J. Am. Chem. Soc. 1999, 121, 1599;
c) P. Mobian, J. M. Kern, J.-P. Sauvage, J. Am. Chem. Soc. 2003, 125,
2016; d) A. F. M. Kilbinger, S. J. Cantrill, A. W. Waltman, M. W.
Day, R. H. Grubbs, Angew. Chem. 2003, 115, 3403; Angew. Chem.
Int. Ed. 2003, 42, 3281; e) G. Kaiser, S. Jarrosson, S. Otto, Y. F. Ng,
A. D. Bond, J. K. M. Sanders, Angew. Chem. 2004, 116, 1993;
NH4PF6 solution (5 mL) was added and the mixture was stirred vigorous-
ly for 2 h. The organic layer was separated, washed with water, and
evaporated to dryness. The crude product was purified by column chro-
matography (first column: Silica 60H, 2% MeOH in CHCl3, v/v; second
column: size exclusion, toluene) to give 20 (6 mg, 38%) as a purple solid.
1
M.p.>3008C (decomposed); H NMR (CDCl3, 300 MHz) d=9.07 (s, 4H;
H12), 8.79 (s, 4H; H13), 8.11 (dd, 3J(H,H)=7.4 Hz, 5J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
3
5
4H; H11), 7.83 (dt, J
3J
(H,H)=7.4 Hz, 4H; H9), 7.42 (d, J
(H,H)=1.5 Hz, 2H; para-ArH (thread)), 7.05–6.99 (m, 6H; H1, H2),
6.95–6.88 (m, 4H; H3), 6.81 (d, 5J
(H,H)=1.6 Hz, 4H; ortho-ArH
(thread)), 6.14 (d, 3J
(H,H)=6.1 Hz, 4H; BipyH), 6.08 (s, 4H; H5), 4.89
(bs, 4H; BipyH), 4.39–4.30 (m, 4H; H7), 4.28 (d, 2J
(H,H)=15.9 Hz, 4H;
H4), 4.10–4.00 (m, 4H; H7), 4.03 (t, 3J
(H,H)=6.0 Hz, 4H; OCH2
(thread)), 3.74 (d, 2J
(H,H)=15.8 Hz, 4H; H4), 3.58–3.49 (m, 4H; H6),
ACHTUNGTRENNUNG(H,H)=8.0 Hz, JACHTNUGTRENNUNG
3
5
N
ACHTUNGTRNE(NUNG H,H)=8.5 Hz, 4H; H8), 7.03 (t, J-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
3.32 (bs, 4H; BipyCH2), 2.84–2.75 (m, 4H; H6), 1.87–0.8 (m, 36H; CH2
(thread)) 1.33 (s, 36H; CCH3), À2.81 ppm (s, 2H; H14); 13C NMR
(CDCl3, 125 MHz) d=158.7, 152.1, 146.2, 145.2, 142.4, 135.6, 132.9, 131.2,
130.6, 130.2, 128.7, 128.1, 123.5, 120.4, 116.6, 116.4, 114.8, 112.2, 108.8,
85.4,68.5, 67.8, 67.4, 44.0, 35.0, 31.5, 30.4, 29.6, 29.4, 28.8, 26.3 ppm; IR
(KBr) n˜ =3455, 2957, 2871, 1700, 1663, 1558, 1545, 1436, 1419, 1384,
1248, 1121, 1064, 968, 844, 668, 558 cmÀ1; MS (MALDI-TOF): m/z 2364.3
[MÀPF6]+, 2219.4 [MÀ2PF6]+.
Acknowledgements
´
Angew. Chem. Int. Ed. 2004, 43, 1959; f) J. D. Badjic, S. J. Cantrill,
This research was supported by the European Research Council in the
form of an ERC Starting grant for J.A.A.W.E (NANOCAT-259064) and
an ERC Advanced grant for R.J. M.N. (ALPROS-290886). The Dutch
National Research School for Combination Catalysis (NRSC-C) is ac-
knowledged for financial support to R.G.E.C and R.J.M.N. Further finan-
cial support was obtained from the Council for the Chemical Sciences of
the Netherlands Organization for Scientific Research (CW-NWO) (Vidi
grant for J.A.A.W.E and Vici grant for A.E.R) and from the Ministry of
Education, Culture and Science (Gravity program 024.001.035).
R. H. Grubbs, E. N. Guidry, R. Orenes, J. F. Stoddart, Angew. Chem.
2004, 116, 3335; Angew. Chem. Int. Ed. 2004, 43, 3273; g) P. G.
Clark, E. N. Guidry, W. Y. Chan, W. E. Steinmetz, R. H. Grubbs, J.
Am. Chem. Soc. 2010, 132, 3405; h) V. N. Vukotic, K. J. Harris, K.
Zhu, R. W. Schurko, S. J. Loeb, Nat. Chem. 2012, 4, 456; i) G. T.
Spence, P. D. Beer, Acc. Chem. Res. 2013, 46, 571.
[12] For some examples of other porphyrin containing catenanes, see:
a) M. J. Gunter, D. C. R. Hockless, M. R. Johnston, B. W. Skelton,
A. H. White, J. Am. Chem. Soc. 1994, 116, 4810; b) M. Linke, N.
Fujita, J. C. Chambron, V. Heitz, J.-P. Sauvage, New J. Chem. 2001,
25, 790; c) M. J. Gunter, S. M. Farquhar, Org. Biomol. Chem. 2003,
1, 3450; d) M. Beyler, V. Heitz, J.-P. Sauvage, Chem. Commun. 2008,
5396; e) M. J. Langton, J. D. Matichak, A. L. Thompson, H. L. An-
derson, Chem. Sci. 2011, 2, 1897.
[13] A similar statistical approach to the synthesis of simple molecular
necklaces by using Glaser–Hay coupling has been reported, see: F.
Bitsch, C. O. Dietrich-Buchecker, J. P. Khemiss, J.-P. Sauvage, A.
Van Dorsselaer, J. Am. Chem. Soc. 1991, 113, 4023.
[1] a) K. Kim, Chem. Soc. Rev. 2002, 31, 96; b) S. J. Cantrill, K. S. Chi-
chak, A. J. Peters, J. F. Stoddart, Acc. Chem. Res. 2005, 38, 1; c) J. D.
Crowley, S. M. Goldup, A.-L. Lee, D. A. Leigh, R. T. McBurney,
Chem. Soc. Rev. 2009, 38, 1530; d) R. S. Forgan, J.-P. Sauvage, J. F.
Stoddart, Chem. Rev. 2011, 111, 5434; e) From Non-covalent Assem-
blies to Molecular Machines (Eds.: J.-P. Sauvage and P. Gaspard),
Wiley-VCH, Weinheim, 2011; f) C.-F. Chang, C.-J. Chuang, C.-C.
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Interlocked Porphyrin Switches
FULL PAPER
[14] For some other examples of molecular necklaces, see: a) D. B. Ama-
bilino, P. R. Ashton, J. F. Stoddart, A. J. P. White, D. J. Williams,
Chem. Eur. J. 1998, 4, 460; b) D. Whang, K. M. Park, J. Heo, P.
Ashton, K. Kim, J. Am. Chem. Soc. 1998, 120, 4899; c) Y. H. Ko, K.
Kim, J. K. Kang, H. Vhun, J. W. Lee, S. Sakamoto, K. Yamaguchi,
J. C. Fettinger, K. Kim, J. Am. Chem. Soc. 2004, 126, 1932.
2296; e) D. A. Leigh, J. K. Y. Wong, F. Dehez, F. Zerbetto, Nature
2003, 424, 174; f) J. D. Badjic, V. Balzani, A. Credi, S. Silvi, J.-F.
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[17] I. O. Sutherland, Annu. Rep. NMR Spectrosc. 1972, 4, 71.
[18] For some other examples of switchable interlocked molecular ma-
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[15] M. J. Gunter, M. R. Johnston, J. Chem. Soc. Chem. Commun. 1994,
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[16] For some examples of induced motion in interlocked molecules, see:
a) A. S. Lane, D. A. Leigh, A. Murphy, J. Am. Chem. Soc. 1997, 119,
11092; b) P. R. Ashton, R. Ballardini, V. Balzani, I. Baxter, A.
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White, D. J. Williams, J. Am. Chem. Soc. 1998, 120, 11932; c) A. M.
Brouwer, C. Frochot, F. G. Gatti, D. A. Leigh, L. Mottier, F. Paoluc-
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Angew. Chem. 2003, 115, 2398; Angew. Chem. Int. Ed. 2003, 42,
Received: November 7, 2013
Revised: April 3, 2013
Published online: && &&, 0000
Chem. Eur. J. 2013, 00, 0 – 0
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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J. A. A. W. Elemans, A. E. Rowan, R. J. M. Nolte and R. G. E. Coumans
Olefin metathesis is used as an elegant
method to construct a series of cate-
nanes and rotaxanes based on olefin-
containing viologen threads and cavity-
containing porphyrin macrocycles. By
varying the olefin substituents of the
viologens, the outcome of the metathe-
sis reactions can be controlled. The
interlocked porphyrin structures show
acid/base-controlled switching behav-
ior (see figure).
Switchable Molecules
R. G. E. Coumans,
J. A. A. W. Elemans,* A. E. Rowan,*
R. J. M. Nolte* ................ &&&& — &&&&
Interlocked Porphyrin Switches
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!