Structural Homology and Dynamic Variation in a Series of Porphyrin Bipyridinium Receptors and their [2]Catenanes

Article abstract of DOI:10.1002/ejoc.200300493

We describe the successful of the porphyrin [2]catenanes, which completes a set of six structures where the length of the polyethylene glycol strap over the porphyrin is regularly increased from diethylene to triethylene to tetraethylene, and the central

Full text of DOI:10.1002/ejoc.200300493

FULL PAPER
Structural Homology and Dynamic Variation in a Series of Porphyrin
Bipyridinium Receptors and Their [2]Catenanes
Maxwell J. Gunter,*[a] Tyrone P. Jeynes,[a] and Peter Turner[b]
Keywords: Porphyrins / Catenanes / Dynamics / Bipyridinium / Receptors
We describe the successful synthesis of the porphyrin [2]ca- observed for related members of the series. The temperature-
tenanes, which completes a set of six structures where the
length of the polyethylene glycol strap over the porphyrin is
regularly increased from diethylene to triethylene to tetra-
ethylene, and the central electron-donor component is either
hydroquinol- or naphthoquinol-based. In the synthetic route
to the strapped porphyrin precursors, co-formation of
‘‘straight’’ and ‘‘twisted’’ atropisomers in the longer strapped
derivatives, and dimeric and higher oligomeric structures for
the shorter straps, has been observed. Catenation results in
only a single [2]catenane in each case. X-ray crystal struc-
dependent dynamic properties of the catenanes have been
examined by 1H NMR methods, and the rates of rotation in-
crease from 50 to 25 000 to 340 000 s−1 at room temperature
as the length of the strap increases by one ethylene glycol
unit on each side. For the similarly sized naphthoquinol de-
rivatives, the rotation rates are reduced by many orders of
magnitude, ranging from essentially zero to 10 to 100 times
per second at 25 °C through the same increase in chain
length as for the hydroquinol analogues. The rates for a se-
cond process described as ‘‘out, turn around and in again’’,
tures of two representative strapped porphyrins are de- range from 2 to 400 to 110 000 s−1 at 25 °C in this naphthoqui-
scribed. For each of the untwisted singly-strapped porphyr- nol porphyrin series. The electronic spectra of the catenanes
ins, there is significant binding of paraquat within the cavity
formed by the strap, and the binding constants range over
about two orders of magnitude. For the catenanes, in each
case the overall structural motif is similar to that previously
themselves do not show any significantly enhanced charge-
transfer bands over the hydroquinol counterparts.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
(3n ϩ8)-crown-n] ethers. Since π-stacking interactions are
a fundamental requirement in paraquat complexation and
catenane synthesis, we reasoned that by replacing one of
the electron-rich hydroquinol- or naphthoquinol- compo-
nents of the crown ether with a large extended π-electron-
rich porphyrin ring, we should be able not only to enhance
paraquat complexation, but also facilitate catenane forma-
tion. Indeed with a hydroquinol- or naphthoquinol-ring
centrally located within a polyether chain over-arching the
porphyrin, we have shown that these porphyrin hosts com-
plex paraquat, a concept which subsequently has led to the
self-assembly of the corresponding porphyrinic [2]ca-
tenanes.
The use of a catenane as a component of a molecular
device,[1] or a molecular-scale machine[2,3] requires the
ability to exercise precise control over its dynamics and
chemistry by such external stimuli as protonation, electro-
chemistry, or photochemistry. In these cases, the catenane
is required to have an in-built addressable component.[3,4]
Porphyrins are excellent candidates for this, as they provide
a particularly useful range of controlled functionality that
can be accessed through chemical, electrochemical, or pho-
tochemical means, and there have been several examples
where they are incorporated into catenated structures.[5Ϫ9]
Previously, we embarked on a program to synthesise a
complete series of porphyrin hosts which are capable of
complexing paraquat in a manner analogous to the [bis-(p-
phenylene)-(3n ϩ4)-crown-n] or [bis-(1,5-dinaphtho)-
The strategy for catenane self-assembly was based on that
employed by Stoddart and co-workers for analogous non-
porphyrinic assemblies. Thus we synthesised a number of
strapped porphyrins 1a and their [2]catenanes 1c and have
examined in some detail the effects on their dynamics,
chemical and photophysical behaviour.[7Ϫ10] Structural
variations proved to have a profound influence on the ob-
served dynamic behaviour of the catenanes synthesised thus
far as evidenced by the wide range in the calculated thermo-
dynamic parameters for the diethylene to triethylene series
of strapped porphyrin catenanes.
[a]
Chemistry, School of Biological and Biomedical Sciences,
University of New England,
Armidale, NSW 2351, Australia
Fax: (internat.) ϩ 612-6773-3268
E-mail: mgunter@metz.une.edu.au
[b]
School of Chemistry, University of Sydney,
Sydney, NSW 2006, Australia
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
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DOI: 10.1002/ejoc.200300493
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193

M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
Ar ϭ phenyl) and 1a (n ϭ 1 and 3; Ar ϭ naphthyl) is out-
lined in Schemes 1 and 2 and follows a similar methodology
to that employed for the synthesis of the previously re-
ported tri- and diethylene glycol-strapped analogues.[8] The
dialdehyde strap precursor 4 was condensed with the dipyr-
rylmethane 5 using acid catalysis; trifluoroacetic acid with
[14]
Cs2CO3
in methanol for 6 and 7, p-toluenesulfonic acid
in the case of 8 and 9, and trifluoroacetic acid for 10, fol-
lowed in each case by oxidation of the porphyrinogen with
o-chloranil to give the desired porphyrin products which
were then separated by column (silica) chromatography.
In the case of the two longer strapped derivatives (n ϭ
3), two atropisomers 6 and 7; and 8 and 9, were isolated in
each case (Scheme 1). These were identified on the basis of
NMR spectral evidence, as the ‘‘twisted’’ or α,β-isomer, and
the ‘‘over-the-top’’ α,α-isomer respectively. This type of
isomerism has been previously reported by us, and others,
and it appears to be commonly observed for porphyrins
strapped by long chains.[13,15,16]
With this set of catenanes in hand, our next aim was to
delineate the structure-activity profile of these intriguing
porphyrin catenanes by probing their behaviour under a
range of stimuli, including chemical (acid/base), redox, and
photochemical studies[6,11,12] as both the length of the over-
arching strap, and the central electron-rich unit were varied.
We have previously described the synthesis, solution state,
and in some instances solid-state properties, bipyridinium
binding behaviour, and [2]catenanes for the members of the
series 1aϪc: n ϭ 1 and 2, Ar ϭ phenyl; and 1aϪc: n ϭ 2,
Ar ϭ naphthyl.[8,9,13] For a more rational assessment of
these factors, we now report the remaining three members
of this series, 1aϪc: n ϭ 3, Ar ϭ phenyl; and 1aϪc: n ϭ 1
and 2, Ar ϭ naphthyl, which completes a set of porphyrin
catenanes where two factors are varied systematically Ϫ the
chain length of the strap and the nature of the central π-
donor unit (hydroquinol or naphthoquinol). In completion
of this series, we have encountered some new structural
types involving atropisomers and oligomers, and these are
also described.
Scheme 1
We are now in a position to provide a complete catalogue
of their fundamental properties, to allow a more systematic
and rational structure-activity relationship within the series.
Several pieces of evidence confirm the atropisomeric re-
lationship between 6 and 7, and 8 and 9. Firstly, the pairs
of isomers have the same pattern in their electrospray mass
spectra with peaks observed for the parent ion (singly and
doubly charged). Secondly, the H NMR resonance of the
hydroquinol (HQ) ring protons at δ ϭ 6.91 ppm in the
Results and Discussion
1
Porphyrin Synthesis and Solution Structures
The synthesis of the hydroquinol- and naphthoquinol- ‘‘twisted’’ strapped porphyrin isomer 6a are shifted signifi-
containing crown ether-strapped porphyrins 1a (n ϭ 3; cantly downfield (deshielded ϩ0.78 ppm) compared to
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A Series of Porphyrin Bipyridinium Receptors
FULL PAPER
Table 1. Selected 1H NMR spectroscopic data for the hydroquinol-
and naphthoquinol-strapped free base and zinc porphyrins and
their isomers at 300 MHz in CDCl3 at 298 K
hence the HQ protons are deshielded by the porphyrin ring
current, while the meso-H proton is shielded by the presence
of the aromatic HQ ring, which is presumably held edge-
to-face with the porphyrin ring. Furthermore, the chemical
shifts of the methylene protons of the polyether strap in
6a span a wider range compared to the α,α-isomer 7a. For
example the protons H-7 and H-8 (Table 1) are shifted sig-
nificantly downfield in the α,β-isomer 6a (∆δ ϩ0.64 and
ϩ0.78, respectively) compared to 7a, indicative of deshield-
ing as a result of twisting around the side of the porphyrin.
In contrast, the protons H-3 and H-4 are shifted upfield in
the isomer 6a compared to 7a (∆δ Ϫ0.25 and Ϫ0.30 respec-
tively) since these protons would be shielded by the porphy-
rin as a result of being held closer to the porphyrin macro-
cycle as the strap twists from one face to the other. Similar
trends are also observed for the naphthoquinol analogues 8
and 9, and the comparative shifts are also shown in Fig-
ure 1.
Similar trends were also noted for the zinc derivatives (b,
Table 1), with some notable exceptions. For example the H-
3 and H-4 protons of the polyether strap in the twisted iso-
mer 8b are deshielded (∆δ ϩ0.40 and ϩ0.32) compared to
its zinc isomer 9b, whereas the corresponding protons in the
free base derivatives are shielded (∆δ ϭ Ϫ0.22 and Ϫ0.38).
Also the deshielding of the methylene strap protons closest
to the meso-phenyl rings in 8b compared to 9b is greater
than those of the corresponding free base derivatives, 8a
and 9a, while those closest to the NQ ring in the zinc de-
rivative are more shielded. This is consistent with the poly-
ether chain of the zinc derivative in 9b being folded in over
the face of the same or a second porphyrin moiety (similar
to the crystal structure of 9b in Figure 3 Ϫ see below) and
being shielded by the porphyrin, whereas on forming the
zinc twisted isomer 8b, the protons H-1 and H-2 are further
deshielded, while H-3 and H-4 are now deshielded as a re-
sult of movement away from the porphyrin.
Position
6a
7a
9a
9b
8a
8b[a]
10a 10b
meso-H
10.10 10.17
3.93 4.00
1.69 1.78
2.50 2.55
10.18 10.12
4.00 3.99
1.78 1.77
2.56 2.52
10.02 10.02 10.14 9.92
3.80 3.87 3.98 3.94
1.58 1.65 1.75 1.77
2.42 2.39 2.57 2.52
porph. CH2CH3
porph. CH2CH3
porph. CH3
Pyrrole NH
meso-ϕ o-
meso-ϕ m-
meso-ϕ p-
meso-ϕ mЈ-
OCH2 H-1[b]
OCH2 H-2[b]
OCH2 H-3[b]
OCH2 H-4[b]
OCH2 H-5[b]
OCH2 H-6[b]
OCH2 H-7[b]
OCH2 H-8[b]
HQ
Ϫ2.42 2.37 Ϫ2.33
Ϫ
Ϫ2.47
Ϫ
Ϫ
Ϫ
7.73 7.65
7.32 7.31
7.74 7.74
7.34 7.33
4.14 4.16
3.18 3.15
2.28 2.53
2.19 2.49
2.67 2.64
3.01 2.64
3.44 2.80
3.93 3.15
6.91 6.13
7.61 7.74
7.29 7.27
7.73 7.73
7.31 7.28
4.08 4.02
3.05 2.84
2.47 1.99
2.54 1.99
2.70 2.67
2.70 2.67
2.91 2.67
3.23 2.91
7.69 7.58 7.69 7.73
7.26 7.19 7.34 7.34
7.71 7.69 7.74 7.76
7.31 7.34 7.32 7.28
4.11 4.12 4.28 4.11
3.15 3.18 3.47 3.04
2.25 2.39 3.20 2.33
2.16 2.31 2.82 1.88
2.75 2.52
3.18 2.81
3.70 3.34
4.23 3.85
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
NQ(α)
NQ(β)
NQ(γ)
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
5.88 6.03
6.74 6.90
7.37 7.34
6.86 6.76 3.77 3.79
7.41 7.39 4.11 5.17
7.95 7.80 6.24 6.39
[a]
[b]
Recorded at 303 K.
Numbering H-1 to H-8 refers to OCH2
protons commencing at the meso-aryl ring, and increasing to the
central naphthoquinol or hydroquinol ring of the strap.
It was surprising that there was no apparent splitting of
the porphyrin resonances, particularly for the meso-H, HQ,
methyl and ethyl side-chain protons as a result of the appar-
ent asymmetry in structures 6 and 8. However, an examin-
ation of molecular models revealed that the polyether strap
is long and flexible enough to allow facile interconversion
of conformers which maintains equivalence of the porphy-
rin protons.[17] Even down to 220 K, no asymmetric split-
ting was observed, although the HQ protons in 6a and 8a
did broaden considerably, whereas the HQ and NQ ring
protons in 7a and 9a remained sharp at this temperature.
Nevertheless, interconversion of 6 and 7, and of 8 and 9,
by free rotation of the meso-phenyl ring around the C9Ϫ10
axis can be observed readily: solutions of pure samples of
either 6a or 7a were found to reach an equilibrium mixture
Figure 1. Schematic representation of the differences in the chemi-
cal shifts of the ‘‘twisted’’- or α,β-strapped porphyrins 6a and 8a
compared to their α,α-atropisomers 7a and 9a. Numbering is as
indicated in Table 1
those in 7a at δ ϭ 6.13 ppm (Table 1 and Figure 1). Similar of approximately 12:88 at room temperature over 30 days,
1
trends were also observed for the zinc derivatives 6b and 7b. when monitored by either TLC or H NMR spectroscopy.
Also, the meso proton (meso-H) chemical shift at δ ϭ 10.10 Alternatively, this equilibration process was complete
1
ppm in 6a is shielded (∆δ ϭ Ϫ0.07) in the H NMR spec- within one hour in refluxing acetonitrile solution. Likewise
trum compared to that in 7a. These chemical shift differ- for the naphthoquinol analogues 8b and 9b, equilibration
ences, represented schematically in Figure 1 imply that the was complete (8:92) after 30 days at room temperature, or
HQ ring is held at the side of the porphyrin ring in 6a and 3 h in refluxing acetonitrile.
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M. J. Gunter, T. P. Jeynes, P. Turner
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The synthesis of the ‘‘tighter’’ naphthoquinol-strapped diethylene glycol chains, compared to the longer strapped
porphyrin 10 resulted in the formation of several oligomeric analogues. A more detailed analysis of the NMR assign-
and isomeric porphyrins in significant quantities, in ad- ments for the dimeric 11 and 12 and trimeric species at both
dition to the monomeric, single-strapped derivative 10 high and low temperatures, and aspects of their electronic
(Scheme 2). The oligomeric nature of these were proven by spectra, are given in the supplementary material.
MS in the first instance, which showed that monomeric 10,
dimeric and atropisomeric 11 and 12, and trimeric porphy-
rin products had been isolated from the reaction. In the
Solid-State Structures
electrospray mass spectrum of the monomeric 10b only one
Single crystal structures of 10b and 7b were determined
parent ion peak was seen at 1025.8 (calcd. 1025.4), whereas by X-ray diffraction, and ORTEP[18] depictions are shown
the dimeric 11b and 12b produced a very large peak in the in Figure 2 and 3. A closely related analogue of 7b, with a
FAB-mass spectrum at 2051.9 (calcd. 2052.85) as well as a naphthoquinol unit linked across the face of the porphyrin
monomer peak at 1026.4 (calcd. 1026.43), whereas the by triethylene glycol chains rather than the tetraethylene
FAB-MS for the trimeric species had peaks with the same glycol units of 7b, has been reported previously.[13] Likewise
mass values as 10b and 11b/12b as well as a peak (with the a paraquat PQ2؉ complex of 1: n ϭ 2, Ar ϭ naphthyl has
same intensity as the monomeric peak) at 3078.24 (calcd. been described previously.[13]
3079.28) corresponding to a porphyrin trimer.
The metal coordination geometry of the 10b complex is
square pyramidal with an apical dimethyl sulfoxide ligand
bound within the porphyrin cavity. The metal to apical oxy-
˚
gen distance is typical at 2.125(1) A. The pyrrole nitrogens
of the metalloporphyrin are essentially co-planar, with no
˚
deviation greater than 0.006(2) A. The metal ion is dis-
˚
placed 0.300(1) A from this plane towards the axial ligand.
The porphyrin strap appears to be responsible for the C(10)
˚
and C(20) meso carbons being 0.320(3) and 0.257(3) A
above the square pyramid basal plane, and the C(5) and
˚
C(15) atoms being correspondingly 0.288(3) and 0.324(3) A
below that plane. Adjacent pyrrole groups are accordingly
slightly tilted towards each other, with respect to the basal
plane. The strap of the inversion centre related neighbour-
ing metalloporphyrin immediately above the complex is in
van der Waals contact with the N(1) and N(2) pyrrole
groups. The intruding strap is responsible for the metallo-
porphyrin strap being offset from the porphyrin centre and
inclined at 26.80(3) ° with respect to the 24 atom porphyrin
least-squares plane. The cavity bound dimethyl sulfoxide li-
gand prevents any intramolecular interaction between strap
and porphyrin.
Surprisingly the 7b metalloporphyrin forms discrete di-
mers in the solid state, such that the Zn of one porphyrin
is coordinated by a polyether chain oxygen of an inversion
related complex (Figure 4).[19] The coordination geometry
is again square pyramidal, with the metal to ether oxygen
˚
distance being 2.257(5) A. In contrast to 10b the porphyrin
ring is essentially planar, with no deviation from the 24
Scheme 2
˚
atom least-squares plane greater than 0.078(9) A, and the
˚
pyrrole nitrogens deviate no more than 0.011(8) A from the
equatorial coordination least-squares plane. The metal ion
Assignment of the 1H NMR resonances for both the free is drawn 0.209(1) A from the core least-squares plane
base 10a and zinc 10b monomeric strapped porphyrin de- towards the coordinating polyether oxygen. Accommodat-
rivatives are shown in Table 1. The shifts of the relevant ing the coordinating neighbour, the polyether strap of 10b
resonances for the strap and the porphyrin are consistent is folded away from the porphyrin core, with the closest
with the strapped structure, as now a clear pattern has em- distance between the phenyl chain residue and the ring cen-
˚
˚
erged across the range of strapped porphyrins both in this tre being approximately 8.7 A. The phenyl residue in the
and other studies. The most significant aspect of the spectra strap forms a dihedral angle of 50.2(3) ° with the 24 atom
of 10a and 10b are the large upfield (shielded) resonances porphyrin least-squares plane, and clearly there is no pos-
for the naphthoquinol protons as a result of an enforced sibility for any intramolecular interaction between strap
close proximity to the porphyrin face by the relatively short and porphyrin.
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A Series of Porphyrin Bipyridinium Receptors
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Figure 2. An ORTEP depiction, with 50 % displacement ellipsoids, of the naphthoquinol-containing diethylene-strapped zincporphyrin
10b
Strapped Porphyrins as Receptors for Paraquat
followed the same trend as observed previously,[8,12,13] indi-
cating a similar binding geometry in each case.[21] The cal-
culated association constants, K, determined by the direct
1H NMR titration method in [D6]acetone/[D6]DMSO
(20:80) are collected in Table 2, together with values re-
ported previously for other members of the series.
These results show that binding of paraquat is strongest
in the tight diethylene-strapped naphthoquinol porphyrin
10b. As expected, the strength of binding in the naphtho-
quinol-strapped porphyrin series is weaker as the length of
the strap increases (entropic effect). Furthermore, the re-
placement of a naphthoquinol unit for a hydroquinol in
analogous length strapped porphyrins reduces the effective-
ness of πϪπ interactions and this is reflected in an approxi-
mate order of magnitude decrease in the strength of bind-
ing.
As a prelude to the synthesis of the porphyrin [2]ca-
tenanes, binding studies were carried out for this new series
of strapped porphyrin receptors. Previous complexation
studies with paraquat for the analogous hydroquinol and
naphthoquinol strapped porphyrins had established that
these porphyrin hosts complex paraquat in a manner anal-
ogous to that of BPP34C10, ie with an inclusion geometry
in which the hydroquinol (or naphthoquinol), paraquat,
and porphyrin rings are held in a co-parallel manner, as
indicated by 1b.[8,12,13] At the same time, we wished to com-
pare the binding strengths of a series of di-, tri-, and tetra-
ethylene-strapped porphyrins to gauge the effect of increas-
ing the length of the strap on the binding constant. This
would reflect the importance of πϪπ interactions as a stabi-
lizing force in noncovalent interactions and in subsequent
template-directed synthesis. In addition, we wished to deter-
mine the effect of solvent polarity on the strength of bind-
ing in these systems.
Also, this series of complexation studies highlights the
solvent effect in the strength of binding (compare rows 3
and 5 in Table 2), which generally decreases as the polarity
of the solvent increases, as we have also found in related
crowned porphyrins.[13,22]
To this end, a series of complexation studies was carried
out in [D6]acetone/[D6]DMSO (20 %)[20] on the hydroqui-
nol-strapped porphyrin host 7b and the naphthoquinol-
strapped porphyrin hosts 9b and 10b as well as the pre-
viously reported naphthoquinol triethylene-strapped por-
Porphyrin [2]Catenanes
The synthetic methodology employed for the self-as-
phyrin 1a (n ϭ 2, Ar ϭ naphthyl) whose association con- sembly of the [2]catenanes used a modification of Stoddart’s
1
stant was previously determined in DMF by H NMR ti- clipping strategy, as we have described previously for related
tration. The NMR shifts of both host and guest on binding porphyrin catenanes, and is outlined in Scheme 3. In the
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M. J. Gunter, T. P. Jeynes, P. Turner
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Figure 3. A labelled ORTEP[18] depiction, with 20 % displacement ellipsoids, of the hydroquinol-containing tetraethylene-strapped
zincporphyrin 7b. Axial coordination from an inversion related complex molecule is not shown (see Figure 4), and the hydrogen atoms
have been removed for clarity
case of the longer (n ϭ 3) strapped porphyrins (both hydro- The 1H NMR resonances of the previously reported hydro-
quinol and naphthoquinol), equilibrium mixtures of the quinol-strapped porphyrin [2]catenanes 1c: n ϭ 1, Ar ϭ
atropisomeric 6b (12 %) and 7b (88 %), or the naphthoqui- phenyl, and 1c: n ϭ 2, Ar ϭ phenyl, as well as the naphtho-
nol-strapped porphyrin isomers 8b (8 %) and 9b (92 %), or quinol-strapped porphyrin [2]catenane 1c: n ϭ 2, Ar ϭ
the naphthoquinol-strapped porphyrin 10b were used. In naphthyl are included in Table 3. All previously reported
each case only a single catenane product was identified and catenanes show an increased chemical shift difference com-
isolated, indicating that atropisomersiation had occurred pared to the BPP34C10-based [2]catenane 2a, due to the
under the catenation conditions (12Ϫ14 days at 1 atm, or influence of the large magnetic anisotropy of the porphyrin
3Ϫ4 days at 12 KBar pressure in DMF).[23]
macrocycle. However, the change in chemical shift for the
Mass spectroscopic data were typical and diagnostic for hydroquinol ring proton (HQ) resonance upon catenane
catenanes of this type:[8,24] in FAB MS spectra, ion peaks formation in 14 is very similar to the BPP34C10-based
for the stepwise loss of one to four counterions and the [2]catenane 2a, which reflects the increased distance of the
parent porphyrin were observed, with very few other frag- HQ ring away from the effects of porphyrin nucleus upon
ment ions.
catenane formation. A similar effect is seen for the naphthyl
1H NMR spectra for the porphyrin [2]catenanes were col- derivative 15.
lected under conditions of either fast or slow exchange, with
As evidenced previously, these spectra support a struc-
the exception of the diethylene-strapped naphthoquinol ture in which the bipyridinium moiety, hydroquinol (or
porphyrin [2]catenane 16 since the fast exchange limit could naphthoquinol) and porphyrin macrocycle are held co-par-
not be reached, indicating a large steric barrier for tetracat- allel (see 1c in Scheme 3) in a similar fashion to that shown
ion rotation in this tightly strapped catenane; instead this for the complexation of paraquat: (i) the β-bipyridinium
catenane decomposed above temperatures of about 380 K. and α-bipyridinium protons (∆δ ϭ Ϫ1.10 and Ϫ0.51) are
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A Series of Porphyrin Bipyridinium Receptors
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Figure 4. A ‘‘straw’’ depiction[19] of the strapped porphyrin 7b showing the dimer formed by coordination of the O(8) ether oxygen of
one porphyrin to the zinc atom of an inversion related metalloporphyrin
Table 2. Binding constants (Ka) for several hydroquinol and naph-
thoquinol containing crown-ether-strapped porphyrin hosts with
paraquat determined by 1H NMR titration in CD3COCD3/
CD3SOCD3 (20 %) at 303 K
[a]
Host
K
(Ϫ1
)
∆G° (kJ·molϪ1 [b]
)
a
1a: n ϭ 3, Ar ϭ phenyl (7b)
3.1 ϫ 102
Ϫ14.3
Ϫ21.5
Ϫ19.3
Ϫ17.2
Ϫ24.7
1a: n ϭ 1, Ar ϭ naphthyl (10b) 5.6 ϫ 103
1b: n ϭ 2, Ar ϭ naphthyl[c]
2.3 ϫ 103
1a: n ϭ 3, Ar ϭ naphthyl (9b) 1.0 ϫ 103
1b: n ϭ 2, Ar ϭ naphthyl[d]
2.1 ϫ 104
[a]
Binding constants are averaged values from several protons
[b]
monitored during the titration. ∆G° values calculated from Ka.
[c] Ka also measured in CH3CN by fluorescence technique to be 1.0
ϫ 104 Ϫ1
.
Measured in [D7]DMF at 298 K by 1H NMR ti-
[d]
tration using a dilution method.
more affected by catenane formation then either the
ϩNCH2 (∆δ ϭ Ϫ0.86 and Ϫ0.42) or phenylene (ϪC6H4Ϫ)
protons (∆δ ϭ Ϫ0.33 and ϩ0.11) which are least affected;
(ii) under conditions of slow exchange, the β-bipyridinium
resonances in the naphthoquinol porphyrin catenanes 16
and 15 are split into four peaks with a very large separation
(∆δ ϭ 3.77 and 3.74) for 16; 3.38 and 4.36 ppm for 15),
Scheme 3
which is significantly greater than the splitting observed for are co-parallel (as in structures 1c) rather than orthogonal,
α-bipyridinium resonances (∆δ ϭ 1.12 and 1.67 for 16; 0.91 as described previously.[8]
and 0.67 ppm for 15) and the phenylene resonances (∆δ ϭ
The diastereotopicity that was observed within the meth-
0.13 and 0.23 ppm for 16 and 15 respectively). This implies ylene protons of the porphyrin periphery following para-
that the α- and β-bipyridyl protons of the bipyridinium quat complexation, is again seen in each of the porphyrin
1
moiety are held closest to the porphyrin, and thus most [2]catenane H NMR spectra. NOE correlations were ob-
affected by the porphyrin magnetic anisotropy on catenane served between hydroquinol or naphthoquinol, and adjac-
formation, and supports a structure in which the bipyridin- ent methylene protons of the strap and phenylene, bipyridi-
ium, hydroquinol (or naphthoquinol) and porphyrin units nium and methylene protons of the macrocycle.
Eur. J. Org. Chem. 2004, 193Ϫ208
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M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
1, Ar ϭ phenyl, M ϭ Zn) (50 sϪ1 at 25 °C) or 1c: (n ϭ 2,
Ar ϭ phenyl, M ϭ Zn) (2.5 ϫ 103 sϪ1 at 25 °C) and implies
that the major influence on the observed rotation rate of
the tetracationic macrocycle in this series of porphyrin ca-
tenanes are steric factors. As this series demonstrates
(Table 4), the short hydroquinol ether strap porphyrin ca-
tenane has a significant steric barrier to tetracation ro-
tation, whereas the longer strapped derivatives are not as
sterically restricted allowing free rotation of the macrocycle,
particularly in 14, which shows much less inhibited dynamic
behaviour than the simpler, nonporphyrinic analogous ca-
tenanes 2a of the Stoddart type.
In the case of the naphthoquinol porphyrin catenanes, a
second exchange process was observed. In the case of the
longer strapped naphthoquinol analogue 15, tetracation
resonances were broad at 30 °C, and only at 360 K in
[D6]DMSO were sharp resonances for all protons observed.
At Ϫ80 °C in [D6]acetone, eight bipyridinium peaks and
two phenylene (ϪC6H4Ϫ) peaks as well as multiplets for
the ϩNCH2 resonances were observed for the tetracation
macrocycle. As was observed in the triethylene-strapped
analogue 1c: (n ϭ 2, Ar ϭ naphthyl, M ϭ Zn), at Ϫ80 °C
the ethyl and methyl groups of the porphyrin periphery are
split into two methyl singlets and two ethyl multiplets, with
the diastereotopic methylene resonances remaining as mul-
tiplets. These results can be rationalised in terms of two
processes. The first is the slowing of the tetracation rotation
about the naphthoquinol axis to distinguish between ‘‘in-
side’’ and ‘‘outside’’ tetracation environments, as for the
hydroquinol porphyrin catenane. This rotation rate of the
tetracation macrocycle was found to be 1.0 ϫ 102 times per
second at 25 °C.
Table 3. Selected proton chemical shift values (δ, ppm) for the
naphthoquinol-containing strapped porphyrin [2]catenanes 14, 15,
and 16 under conditions of fast and slow exchange
[a]
16 (slow)[b]
15 (slow)
15 (fast)[c] 14 (fast)[d]
α
β
‘‘outside’’ 8.52 ‘‘outside’’ 9.1 8.28
‘‘inside’’ 7.40 ‘‘inside’’ 8.22
‘‘outside’’ 8.50 ‘‘outside’’ 8.78
‘‘inside’’ 6.83 ‘‘inside’’ 8.11
‘‘outside’’ 6.99 ‘‘outside’’ 7.59 6.66
‘‘inside’’ 3.28
‘‘inside’’ 4.21[e]
8.35
6.59
‘‘outside’’ 7.13 ‘‘outside’’ 7.40
‘‘inside’’ 3.39
‘‘inside’’ 3.04[e]
7.89
7.66
5.83
5.68
ϪC6H4Ϫ 7.80
7.67
7.43
5.29
7.63
5.32
ϩNCH2 5.60
5.12
5.02
5.45
NQ(α)
NQ(β)
NQ(γ)
5.60[f]
5.83[f]
5.66
5.70
5.18
1.84
Ϫ
Ϫ
Ϫ
5.30
1.47
1.75[f]
[a] Spectra were recorded at 300 MHz using the appropriate residual
solvent as reference. [b] The [2]catenane 15 decomposed at tempera-
tures above 380 K in [D6]DMSO before the fast exchange limit
[c]
[d]
could be attained. Spectrum recorded in (CD3)2SO at 360 K.
Spectrum recorded in (CD3)2CO at 298 K; the slow exchange limit
could not be reached at temperatures below Ϫ80 °C for 14. [e] Hid-
[f]
den protons identified by saturation transfer techniques. These
proton resonances were hidden under larger peaks, but were ident-
ified from gradient NOE experiments.
From dynamic NMR measurements, it was possible to
calculate rates for various processes observed in these ca-
tenanes, as we have established for the previous members
of the series (Table 4). For the hydroquinol catenane 14, a
rotation rate of the macrocycle around the central hydro-
The second effect that results in the additional splitting
quinol of the strap (equivalent to an ‘‘inside’’ to ‘‘outside’’ that is observed in the tetracation resonances in 15 over that
exchange process for the bipyridinium rings on each side of observed for 14 has been interpreted in both porphyrin and
the macrocycle) was calculated as 3.4 ϫ 105 times per se- nonporphyrinic catenanes as a local twofold symmetry of
cond at 25 °C. This relatively high value for the rotation of the naphthalene ring affecting both the tetracation and por-
the tetracation is significantly greater than either 1c: (n ϭ phyrin moieties in the catenane. In 15, the effects of this
Table 4. Kinetic and thermodynamic parameters from the dynamic 1H NMR studies on the porphyrin [2]catenanes for tetracation rotation
and reorientation
Catenane
∆ν (Hz)
Tc (°C)
kc (sϪ1
)
∆G‡c (kJ·molϪ1
)
Rates at 25 °C (Hz)[a]
Rotation[a]
2a
2000[a]
50[a]
1c: n ϭ 1, Ar ϭ ϕ
1c: n ϭ 2, Ar ϭ ϕ
1c: n ϭ 3, Ar ϭ ϕ (14)
2b
1c: n ϭ 1, Ar ϭ naphthyl (16)
1c: n ϭ 2, Ar ϭ naphthyl
1c: n ϭ 3, Ar ϭ naphthyl (15)
Reorientation[b]
2500[a]
340 000[a]
1200[a]
0[a]
62
57
Ϫ80
ϩ19
138
127
39
60
10[a]
100[a]
2b
10[b]
1c: n ϭ 1, Ar ϭ naphthyl (16)
1c: n ϭ 2, Ar ϭ naphthyl
1c: n ϭ 3, Ar ϭ naphthyl (15)
18
79
ϩ58
Ϫ55
40
71
43
2[b]
400[b]
110 000[b]
175
[a]
[b]
Data obtained by the coalescence method as previously reported. Refers to the ‘‘out, turn around, and in again’’ process observed
in naphthoquinol catenanes.
200
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A Series of Porphyrin Bipyridinium Receptors
FULL PAPER
symmetry disappear from the spectrum at Ϫ55 °C as the rinic counterpart, namely, the 1,5-DN38C10-based [2]ca-
two methyl singlet resonances coalesce, which has been ex- tenane 2b. The observed tetracation rotation rate in the lat-
plained before as a process involving the decomplexation of ter was found to be 1200 times per second at ambient tem-
the naphthalene ring from within the tetracation macrocy- perature with a ∆Gc‡ of 53.1 kJ·molϪ1, whereas the ‘‘out,
cle, a reorientation of the ring, followed by recomplexation. turn around, and in again’’ process occurred at a rate of 10
This phenomenon, dubbed the ‘‘out, turn around, and in times per second at 25 °C. By comparison, the porphyrin
again’’ process was measured using the coalescence method catenane analogue 15 (Table 4) has a substantially increased
by following the methyl resonances, and was found rate of removal-reorientation-recomplexation for the naph-
(Table 4) to have a rate at 25 °C of 1.1 ϫ 105 times per se- thoquinol ring (about four orders of magnitude) due to a
cond.
lower activation energy, yet has a slower tetracation ro-
In contrast to 15, the tight strapped analogue 16 was tation rate (about one order of magnitude) resulting from a
found to have eight bipyridinium resonances, two phenylene higher free energy of activation. This implies that the pres-
singlets and ϩNCH2 peaks at 30 °C (as opposed to Ϫ80 °C ence of the porphyrin subunit leads to a higher activation
for 15), which indicates that this catenane undergoes slow energy for tetracation rotation due to either a steric or elec-
exchange on the NMR time scale at this temperature, and tronic influence. However, the origin of the lower activation
not unexpectedly, reflects the severe steric restriction im- energy for the naphthoquinol decomplexation is not as evi-
posed by the short-strapped porphyrin on tetracation ro- dent, but it has been suggested that this may be as a result
tation. Hence, the rotation rate of the tetracation subunit in of the porphyrin catenane being conformationally less flex-
this catenane could not be measured since the ‘‘inside’’ and ible than its nonporphyrinic counterpart, and that the num-
‘‘outside’’ bipyridinium environments failed to coalesce be- ber of sites available for [CH···O] hydrogen bonding (which
fore decomposition started to set in above 380 K in as has been identified as an important stabilising force in
[D6]DMSO. Nevertheless, the naphthalene ‘‘out, turn noncovalent interactions) has been halved.[8]
around, and in again’’ exchange process could still be meas-
UV/Vis Spectra
ured at lower temperatures by following the coalescence of
the two ‘‘outside’’ β-bipyridinium resonances. This process
The absorption data for the catenanes are collected in
was found to be about 2 rotations per second at ambient Table 5 together with the data of the related porphyrin
temperatures and can be compared to the other naphtho- models 1a, and the complexes with paraquat 1b.[6,12] It is
quinol porphyrin catenanes, where the rates for this process interesting to note that the ground state spectrum of 10b
increase from 4.0 ϫ 102 sϪ1 to 1.1 ϫ 105 sϪ1 at 25 °C as shows few if any anomalous features, although the solid-
the length of the strap increases from triethylene to the state structure clearly identifies a planar distortion in the
tetraethylene glycol derivatives. This reflects the stronger form of a ruffling of the porphyrin nucleus undoubtedly as
πϪπ interaction of the naphthoquinol ring within the tetra- a result of the ‘‘tight’’ strap; the less constrained 7b shows
cation in the tighter-strapped porphyrin catenane.
no significant related distortion. The origins of a red shift
In comparison to the hydroquinol porphyrin catenane 14, in the absorption spectra of both B and Q bands as either
the tetracation rotation rate (3.4 ϫ 105 sϪ1 at 25 °C), the a cause or effect relationship of distortions of the porphyrin
naphthoquinol porphyrin catenane 15 rotation rate is signif- nucleus from planarity, either in a ruffling or saddling
icantly slower. This is hardly surprising considering the rela- mode, have been argued for several years, until very recently
tive sizes of the π-clouds and thus the expected stronger Ghosh and co-workers[25] have shown that such a corre-
πϪπ interactions between the naphthoquinol ring and the lation is not definitive, especially for free base or zinc
tetracations.
(amongst others) derivatives. Nevertheless, even previous
An interesting comparison can also be made between the calculations by DiMagno et al[26] have implied that spectral
naphthoquinol porphyrin catenane 15 and its nonporphy- red-shifts are a result of distortions allowing some rotation
Table 5. UV/Vis absorption properties of the porphyrins, the complexes and the catenanes at 298 K in acetonitrile solution. The charge-
transfer bands (CT) arise from the interaction of the porphyrin with the paraquat or cyclobis-paraquat unit
Soret bands
λmax/nm
Q bands
Q bands
CT bands
λmax/nm
λmax/nm
(10Ϫ3ε/ Ϫ1cmϪ1
)
(10Ϫ3ε/ Ϫ1cmϪ1
)
(10Ϫ3ε/ Ϫ1cmϪ1
)
10b
414 (420)
413 (420)
413 (370)
420 (224)
418 (257)
418 (234)
425 (199)
425 (210)
425 (201)
542 (17.6)
542 (19.0)
542 (17.3)
546 (15.0)
544 (17.0)
543 (15.0)
548 (21.1)
548 (18.8)
548 (21.7)
577 (6.0)
577 (6.0)
577 (5.7)
578 (5.1)
578 (6.7)
578 (5.8)
582 (7.4)
583 (5.8)
582 (6.9)
7b
9b
10b Ϫ PQ2ϩ
720 (260)
720 (230)
720 (380)
765 (600)
760 (400)
760 (500)
7b Ϫ PQ2ϩ
9b Ϫ PQ2ϩ
16
14
15
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201

M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
of the meso aryl groups from a perpendicular orientation a dipyrromethane with a pre-formed dialdehyde strap, is the
with respect to the porphyrin plane to allow some degree co-formation of ‘‘straight’’ and ‘‘twisted’’ atropisomers in
of π-overlap with the porphyrin system. Clearly in the case the longer strapped derivatives, and dimeric and higher oli-
of 10b, the strap coming from both o-positions of the aryl gomeric structures for the shorter straps. Although the atro-
groups will effectively prevent any such rotation, even in a pisomers for both the hydroquinol and naphthoquinol-
distorted structure (and it is not unreasonable to assume strapped porphyrins with tetraethylene glycol-based straps
that the solution structure of 10b would show similar dis- can be separated and structurally identified, they can be
tortion, given the restrictions of the diethylene glycol strap). equilibrated in solution, and catenation under high pressure
Thus the absence of a red shift is consistent with expla- conditions of either an equilibrated mixture or the individ-
nations advanced by both Ghosh and DiMagno, and ex- ual isomers, results in only a single [2]catenane in each case.
plains the similarity in absorption spectra for all the deriva-
tives described here.
For each of the untwisted singly-strapped porphyrins,
there is significant binding of the paraquat within the cavity
The catenane spectra display typical porphyrin Soret and formed by the strap, and the binding constants range over
Q bands but they appear broader, shifted to lower energies about two orders of magnitude. Nevertheless, the template-
and with lower molar absorption coefficients than the par- directed self-assembly process operates successfully in all
ent porphyrins and, to some extent, also with respect to the cases, and good to moderate yields of catenanes are ob-
complexes 1b.[6] In addition, for the catenanes new spectral tained under high pressure conditions.
features appear at lower energies than the Q-bands. These,
For the catenanes, in each case the overall structural mo-
displaying maxima around 760 nm and extinction coef- tif is the same, with the bipyridinium side of the macrocyclic
ficients in the range 102Ϫ103 Ϫ1·cmϪ1, are assigned to CT ring oriented parallel to the porphyrin plane, so that the
bands originated from the interaction between the porphy- bipyridinium rings, the quinol, and the porphyrin are
rin component and the paraquat units of the macrocycle in stacked in a face-to-face fashion. This is similar to the
the catenanes. Similar bands, though less intense and with structures observed for the simple complexes between the
maxima at higher energies, were also observed for the com- corresponding strapped porphyrins and paraquat.
plexes.[11] A stronger interaction is detected in the catenanes
The temperature-dependent dynamic properties of the ca-
with respect to the complexes as revealed by the higher sta- tenanes described here indicate a trend within the rates of
bilization in the energy of the CT bands (lower wavelength), rotation of the macrocycle around the central quinol axis,
and higher absorption coefficients. The reason for such bet- which are critically dependent on the length of the strap on
ter stabilization in catenanes could be the higher oxidizing the one hand, and on the nature of the quinol unit on the
ability of the tetracationic macrocycle cyclo-bispara- other. Within the hydroquinol serries, the rates of rotation
quat(4,4Ј-biphenylene) (CBPQ4ϩ) compared to paraquat increase from 50 to 25 000 to 340 000 sϪ1 at room tempera-
PQ2ϩ),[12] but to some extent geometric factors could also ture as the length of the strap increases by one ethylene
play a role. In fact the rigidity of the catenane can ensure a glycol unit on each side. This compares with a rate of about
better parallel orientation of the electron acceptor with the 2 000 for the related nonporphyrinic analogue from the sim-
porphyrin plane, compared to the looser complex. Other ple BPP34-C-10 [2]catenane, and indicates that the rela-
CT bands deriving from the interaction between the tively large π-surface of the porphyrin provides an effective
CBPQ4ϩ and the dimethoxy-aromatic group in the ЈbrakeЈ on the macrocycle rotation in the tight-strapped de-
450Ϫ520 region, in agreement with previous obser- rivatives, but has little influence when the strap is loose en-
vations,[27] are also detectable, but mostly obscured by the ough not to impose any steric restriction.
intense Soret bands. The above features in the absorption
For the similarly sized naphthoquinol derivatives, which
spectra are indicative of interactions between the various have an increased π-surface area, the rotation rates are re-
components. Nonetheless, the units maintain their own in- duced by many orders of magnitude, ranging from essen-
dependent spectral features, indicating that the interaction tially zero to 10 to 100 times per second at 25 °C through
between components can be considered weak, although ac- the same increase in chain length as for the hydroquinol
tive in promoting electronic coupling as evidenced by fluor- analogues. This compares to the modest decrease in rate
escence and electrochemical studies.[6]
for the simple nonporphyrinic 1,5-DN38-C-10 [2]catenane
compared to its phenyl analogue (1 200 vs. 2 000). It is thus
apparent that π-π interactions between the naphthoquinol
and porphyrin are sufficiently strong to cause a significant
barrier to rotation. Nevertheless, a second process needs to
Conclusion
The successful synthesis of the porphyrin [2]catenanes de- be considered in the naphthoquinol cases Ϫ that of a bar-
scribed here completes a set of six structures where the rier imposed by a process described as ‘‘out, turn around
length of the polyethylene glycol strap over the porphyrin and in again’’, as a mechanism by which the naphthoquinol
is regularly increased from diethylene to triethylene to tetra- unit can rotate only by slipping out from the enclosing mac-
ethylene, and the central electron-donor component is rocycle first. This ranges from 2 to 400 to 110 000 sϪ1 at 25
either hydroquinol- or naphthoquinol-based.
A complication that has been encountered with the nonporphyrinic analogue. Clearly, this is not a significant
°C in this porphyrin series, compared to about 10 for the
chosen ‘‘2ϩ2’’ route to the porphyrins, by condensation of barrier to rotation in the porphyrin catenanes, and may
202
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A Series of Porphyrin Bipyridinium Receptors
FULL PAPER
separated, washed (H2O), and dried (MgSO4). The product was
purified using column chromatography (silica) by eluting with
CH2Cl2/petroleum ether (1:1), CH2Cl2/petroleum ether (2:1), and
then CH2Cl2 to remove impurities, followed by MeOH/CH2Cl2 (1
%) to give 4 (n ϭ 3) as a yellow oil (9.41 g, 67 %). C36H46O12
arise from the porphyrin catenane being conformationally
less flexible than its nonporphyrinic counterpart, and hav-
ing fewer sites available for [CH···O] hydrogen bonding.
A stronger π-π interaction as a the major influence in
restricting rotation in the naphthoquinol series compared to
the hydroquinol series, is indicated by the stronger binding
constants of the corresponding strapped porphyrins for the
simple guest paraquat. However, the electronic spectra of
the catenanes themselves do not show any significantly en-
1
(670.74): calcd. C 64.46, H 6.91; found C 64.20, H 6.84. H NMR
(300 MHz. CDCl3, 25 °C): δ ϭ 10.50 (d, J ϭ 1 Hz, 2 H, CHO),
7.81 (dd, J ϭ 8, 2 Hz, 2 H, Ar-H), 7.51 (dt, J ϭ 8, 2 Hz, 2 H, Ar-
H), 7.01 (t J ϭ 8 Hz, 2 H,, Ar-H), 6.96 (d, J ϭ 8Hz, 2 H, Ar-H),
6.80 (s, 4 H, Ar-H), 4.22 (t, 4 H, J ϭ 5 Hz, OCH2), 4.04 (t, J ϭ 5
hanced charge-transfer bands over the hydroquinol Hz, 4 H, OCH2), 3.90 (t, J ϭ 5 Hz, 4 H, OCH2), 3.80 (t, J ϭ 5
Hz, 4 H, OCH2), 3.72Ϫ3.65 (m, 16 H, OCH2) ppm.
counterparts.
With this set of catenanes in hand, we are now in a posi-
tion to delineate their structure-activity profile by studying
their behaviour under a range of stimuli, including chemical
(acid/base), redox, and photochemical studies. This has
Hydroquinol-Strapped Porphyrins 6 and 7: Hydroquinol dialdehyde
4: n ϭ 3 (2.55 g, 3.80 mmol) and 3,3Ј-diethyl-4,4Ј-dimethyl-2,2Ј-
dipyrrylmethane (5) (1.75 g, 7.60 mmol) were dissolved with stir-
ring in MeOH (380 mL), then bubbled with N2 for 10 min, before
been commenced with certain members of the series,[6,9,12] adding a solution of Cs2CO3 (1.49 g, 4.56 mmol) and TFA (1.04 g,
9.12 mmol) in MeOH (15 mL). The reaction mixture was bubbled
with N2 for a further 5 min, before adding catalytic amounts of
TFA (ഠ 0.5 g), stirring for 5 h (room temp., N2, dark), adding o-
chloranil (1.87 g, 7.60 mmol) in THF (62 mL) all at once, and stir-
ring continued overnight (room temp., dark). Then Et3N (10 mL)
was added, stirred for 30 min, and the solution taken to dryness by
rotary evaporation. An initial purification was carried out on an
alumina column using CH2Cl2 as the eluent to obtain several por-
phyrin fractions. A final purification was carried out by column
chromatography (silica), eluting initially with C Cl2 and CH2Cl2/
Et2O (5 %) to remove impurities followed by CH2Cl2/Et2O (8 %)
and then CH2Cl2/Et2O (10 %) to obtain the porphyrin isomer 6a,
and then CH2Cl2/Et2O (15 %) and CH2Cl2/Et2O (20 %) to obtain
7a.
but we are now in a position to provide a complete cata-
logue of their fundamental properties, to allow a more sys-
tematic and rational structure-activity relationship across
the whole series.
Experimental Section
General Remarks: All solvents were distilled before use, using
standard procedures: tetrahydrofuran (THF) was distilled from
over benzophenone and sodium under N2; triethylamine (Et3N)
was distilled from over CaH2; dimethylformamide (DMF) was
˚
dried with type 4A molecular sieves. Column chromatography used
Aldrich silica gel (grade 9385, 230Ϫ400 mesh). Preparative TLC
was performed on 20 ϫ 20 cm plates coated with 0.5 mm thick Art.
7731 Kieselgel 60 G Merck silica. Analytical TLC was carried out
on Merck Silica Gel 60 G254 precoated aluminium sheets.
6a was recrystallised to obtain a purple/red solid (101 mg, 2 %),
m.p. 185Ϫ188 °C (from CH2Cl2/MeOH). C66H80N4O10·H2O
(1107.38): calcd. C 71.58, H 7.46, N 5.06; found C 71.71, H 7.42,
N 4.66. ESMS: m/z ϭ [M ϩ H]ϩ 1089.6002 (calcd. 1089.5957), [M
ϩ 2H]2ϩ 545.3011 (calcd. 545.3018). UV (CHCl3): λ ϭ 410, 508,
1H NMR spectra were acquired using a 300 MHz Bruker Avance
300 spectrometer at 303 K, unless otherwise stated. Chemical shifts
(δ) are reported in parts per million relative to residual solvent.
Coupling constants (J) are reported in Hz. Deuterated solvents
1
541, 575, 627 nm. H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.10
(s, 2 H, meso-H), 7.74 (t, J ϭ 7 Hz, 2 H, Ar-H), 7.73 (d, J ϭ 7 Hz,
2 H, Ar-H), 7.34 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.32 (t, J ϭ 7 Hz, 2
H, Ar-H), 6.91 (s, 4 H, Ar-H), 4.14 (t, J ϭ 5 Hz, 4 H, OCH2),
3.98Ϫ3.88 (m, 12 H, CH2CH3 ϩ OCH2), 3.44 (t, J ϭ 5 Hz, 4 H,
OCH2), 3.18 (t, J ϭ 5 Hz, 4 H, OCH2), 3.01 (t, J ϭ 5 Hz, 4 H,
OCH2), 2.67 (t, J ϭ 5 Hz, 4 H, OCH2), 2.50 (s, 12 H, CH3), 2.28
(t, J ϭ 5 Hz, 4 H, OCH2), 2.19 (m, 4 H, OCH2), 1.69 (t, J ϭ 8 Hz,
12 H, CH2CH3), 1.24 (s, 2 H, H2O), Ϫ2.42 (br. s, 2 H, pyrrole
NH) ppm. 13C NMR (CDCl3): δ ϭ 158.52, 153.15, 145.28, 144.12,
140.79, 135.65, 134.54, 131.11, 129.942, 120.87, 115.93, 113.95,
111.79, 95.86, 70.64, 70.08, 69.89, 69.66, 69.47, 69.33, 68.79, 68.22,
19.82, 17.69, 13.64 ppm.
˚
were purchased from Aldrich and stored over type 3A molecular
sieves after opening. COSY-45, gradient COSY, one-bond CϪH
correlation (HMQC), long-range CϪH correlation (HMBC),
NOESY, gradient NOESY two-dimensional NMR experiments
employed the standard Bruker parameters. DEPT, NOE difference
and saturation transfer experiments, as well selective gradient NOE
experiments utilised standard Bruker pulse programs. UV/Vis spec-
tra were recorded with a Varian Cary IE UVϪVIS spectrophoto-
meter. Melting points were determined using a Reichert micro-
scopic hot-stage apparatus. FAB and ESI mass spectrometry was
carried out by CSIRO Molecular Science at the Ian Wark Labora-
tory, Clayton and the Australian National University, Canberra,
and high resolution ESI was performed at the Centre for Molecular
Architecture, Rockhampton.
7a was recrystallised to obtain a purple/red solid (294 mg, 7 %),
m.p. 166Ϫ169 °C (from CH2Cl2/MeOH). C66H80N4O10.H2O
(1107.38): calcd. C 71.58, H 7.46, N 5.06; found C 71.74, H 7.34,
N 5.00. ESMS: m/z ϭ [M ϩ H]ϩ 1090.0 (calcd. 1089.6), [M ϩ2H]2ϩ
545.6 (calcd. 545.3). UV (CHCl3): λ ϭ 410, 507, 541, 575, 626 nm.
1H NMR (300 MHz. CDCl3, 25 °C): δ ϭ 10.17 (s, 2 H, meso-H),
7.74 (t, J ϭ 7 Hz, 2 H, Ar-H), 7.65 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.33
1,4-Bis[2-(2-{2-[2-(o-formylphenoxy)ethoxy]ethoxy}ethoxy)-
ethoxy]benzene (4, n ؍ 3): The hydroquinol bistosylate 3 (n ϭ 3)
(16.1 g, 2.08 ϫ 10Ϫ2 mol) in dry CH3CN (220 mL) was added all
at once to a stirred mixture of salicylaldehyde (5.6 g, 4.58 ϫ 10Ϫ2 (d, J ϭ 9 Hz, 2 H, Ar-H), 7.31 (t, J ϭ 7 Hz, 2 H, Ar-H), 6.13 (s,
mol) and K2CO3 (11.5 g, 8.32 ϫ 10Ϫ2 mol) in dry CH3CN
(180 mL) with heating under an atmosphere of N2 for 4 days. Upon
cooling, the reaction mixture was filtered, the solid washed
(CH2Cl2), the solvent removed by rotary evaporation, and the resi-
due partitioned between CH2Cl2 and H2O. The organic layer was
4 H, Ar-H), 4.14 (t, J ϭ 5 Hz, 4 H, OCH2), 4.05Ϫ3.93 (m, 8 H,
CH2CH3), 3.15 (m, 8 H, OCH2), 2.80 (t, J ϭ 4 Hz, 4 H, OCH2),
2.64 (s, 8 H, OCH2), 2.55 (s, 12 H, CH3), 2.55Ϫ2.48 (m, 8 H,
OCH2), 1.78 (t, J ϭ 8 Hz, 12 H, CH2CH3), 1.24 (s, 2 H, H2O),
Ϫ2.37 (br. s, 2 H, pyrrole NH) ppm.
Eur. J. Org. Chem. 2004, 193Ϫ208
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
203

M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
Zinc Hydroquinol-Strapped Porphyrin 6b: Zinc was inserted into the
hydroquinol porphyrin isomer 6a to give 6b, which was recrystal-
OCH2), 3.75 (br. s, 4 H, OCH2), 3.66 (br. s, 8 H, OCH2), 3.55 (br.
s, 8 H, OCH2), 3.15 (br. s, 4 H, OCH2), 3.00 (s, 4 H, Ar-H), 2.62
lised to obtain a purple/pink solid, m.p. 198Ϫ200 °C (from CH2Cl2/ (s, 12 H, CH3), 1.73 (t, 12 H, J ϭ 7 Hz, CH2CH3) ppm.
MeOH). UV (CHCl3): λ ϭ 412, 504, 540, 574 nm. 1H NMR
1,5-Bis[2-(2-{2-[2-(o-formylphenoxy)ethoxy]ethoxy}ethoxy)-
(300 MHz. CDCl3, 25 °C): δ ϭ 10.06 (s, 2 H, CHO), 7.71 (t, J ϭ
ethoxy]naphthalene (4, n ؍ 3, Ar ؍ naphthyl): Salicylaldehyde
8 Hz, 2 H, Ar-H), 7.61 (d, J ϭ 9 Hz, 2 H, Ar-H), 7.38 (d, J ϭ 8
(1.27 g, 10.4 mmol) and K2CO3 (2.61 g, 18.9 mmol) were stirred in
dry CH3CN (40 mL) with heating under N2 for 1 h. Then naphtho-
Hz, 2 H, Ar-H), 7.26 (t, J ϭ 8 Hz, 2 H, Ar-H), 6.72 (s, 4 H, Ar-
H), 4.16 (t, J ϭ 5 Hz, 4 H, OCH2), 3.94 (q, J ϭ 8 Hz, 8 H,
quinol bistosylate 3 (n ϭ 3, Ar ϭ naphthyl) (4.01 g, 6.22 mmol) in
CH2CH3), 3.53 (t, J ϭ 5 Hz, 4 H, OCH2), 3.24 (t, J ϭ 5 Hz, 4 H,
dry CH3CN (120 mL) was added all at once, and the resulting solu-
OCH2), 3.03 (t, J ϭ 5 Hz, 4 H, OCH2), 2.62 (t, J ϭ 5 Hz, 4 H,
OCH2), 2.48 (s, 12 H, CH3), 2.42 (m, 8 H, OCH2), 2.29 (t, J ϭ 5
Hz, 4 H, OCH2), 1.70 (t, J ϭ 8 Hz, 12 H, CH2CH3) ppm.
tion refluxed under N2 for 3 days. Upon cooling, the solvent was
removed by rotary evaporation, and the residue partitioned be-
tween CH2Cl2 and H2O. The organic layer was separated, washed
(H2O), and dried (MgSO4). The product was purified using column
chromatography (silica) by eluting with C Cl2 to remove impurit-
ies, followed by MeOH/CH2Cl2 (1 %) to give 4 (n ϭ 3, Ar ϭ naph-
thyl) as a yellow oil (2.37 g, 70 %); found C 66.48, H 7.01.
C40H48O12 (720.80) requires C, 66.65, H 6.71 %. 1H NMR
(300 MHz. CDCl3, 25 °C): δ ϭ 10.49 (s, 2 H, CHO), 7.84 (d, J ϭ
8 Hz, 2 H, Ar-H), 7.80 (dd, J ϭ 8, 2 Hz, 2 H, Ar-H), 7.49 (dt, J ϭ
7, 2 Hz, 2 H, Ar-H), 7.31 (t, J ϭ 8 Hz, 2 H, Ar-H), 6.70 (t, J ϭ 8
Hz, 2 H, Ar-H), 6.91 (d, J ϭ 8 Hz, 2 H, Ar-H), 6.80 (d, J ϭ 8 Hz,
2 H, Ar-H), 4.26 (t, J ϭ 5 Hz, 4 H, OCH2), 4.17 (t, J ϭ 5 Hz, 4
H, OCH2), 3.97 (t, J ϭ 5 Hz, 4 H, OCH2), 3.86 (t, J ϭ 5 Hz, 4 H,
OCH2), 3.79 (m, 4 H, OCH2), 3.69 (m, 12 H, OCH2) ppm.
Zinc Hydroquinol-Strapped Porphyrin 7b: Zinc was inserted into the
hydroquinol (4)-porphyrin H2HQ4P (17a) to give (17b), which was
recrystallised to obtain a purple/pink solid, m.p. 166Ϫ168 °C (from
CH2Cl2/MeOH). UV (CHCl3 (1 %)/MeCN): λ (ε, Ϫ1cmϪ1) ϭ 413
(4.26 ϫ 105), 504 (3.64 ϫ 103), 542 (1.94 ϫ 104), 576 (7.58 ϫ 103)
nm. 1H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.09 (s, 2 H, CHO),
7.74 (t, J ϭ 8 Hz, 2 H, Ar-H), 7.71 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.32
(t, J ϭ 7 Hz, 2 H, Ar-H), 7.31 (d, J ϭ 8 Hz, 2 H, Ar-H), 6.12 (s,
4 H, Ar-H), 4.10 (t, J ϭ 5 Hz, 4 H, OCH2), 3.99 (m, 8 H, CH2CH3),
3.09 (t, J ϭ 5 Hz, 4 H, OCH2), 2.84 (t, J ϭ 4 Hz, 4 H, OCH2),
2.52 (s, 12 H, CH3), 2.46 (t, J ϭ 5 Hz, 4 H, OCH2), 2.34 (m, 8 H,
OCH2), 2.12 (s, 8 H, OCH2), 1.76 (t, J ϭ 7 Hz, 12 H, CH3CH2)
ppm.
Naphthoquinol-Strapped Porphyrins 8 and 9: Naphthoquinol dicar-
baldehyde 4 (n ϭ 3, Ar ϭ naphthyl) (0.97 g, 1.35 mmol) and 3,3Ј-
diethyl-4,4Ј-dimethyl-2,2Ј-dipyrrylmethane (5) (0.62 g, 2.7 mmol)
were dissolved with stirring in MeOH (135 mL), bubbled with N2
for 10 min, and then catalytic amounts of TFA (ഠ 10 drops) were
added. The reaction mixture was then stirred for 5 h (room temp.,
N2, dark), before adding o-chloranil (0.66 g, 2.7 mmol) in THF
(21 mL) all at once and stirring was continued overnight (room
temp., dark). Then was added Et3N (4 mL) and the mixture stirred
for 30 min, before taking the solution to dryness by rotary evapor-
ation. An initial purification was carried out on an alumina column
using CH2Cl2 and then CH2Cl2/Et2O (10 %) to remove impurities,
followed by CH2Cl2/Et2O (15 %) to elute several porphyrin frac-
tions. A final purification was carried out by column chromatogra-
phy (silica), eluting initially with C Cl2 and CH2Cl2/Et2O (5 %)
followed by CH2Cl2/Et2O (10 %) to obtain the porphyrin isomer
8a, and then CH2Cl2/Et2O (15 %) to obtain 9a.
Zinc Hydroquinol-Strapped Porphyrin [2]Catenane 14b: A mixture
of the hydroquinol-strapped porphyrin isomers 6a and 7a were re-
fluxed in MeCN for 1 h to reach equilibrium, before zinc was in-
serted to produce a mixture of 6b and 7b. The mixed isomers [6b
1
(12 %) and 7b (88 %), from H NMR] (130 mg, 1.13 ϫ 10Ϫ4 mol),
1,1Ј-[1,4-phenylenebis(methylene)]-bis(4,4Ј-bipyridinium) bis(hexa-
fluorophosphate) (13)[28] (96 mg, 1.36 ϫ 10Ϫ4 mol), 1,4-bis(bromo-
methyl)benzene (45 mg, 1.70 ϫ 10Ϫ4 mol), and catalytic amounts
of NaI and NH4PF6 were dissolved in DMF (7 mL), deoxygenated
with N2 for 20 min, and then stirred at room temperature at 12
kbar for 3 days. The solvent was then removed under vacuum with
heating, and the residue was washed well with CH2Cl2, followed by
hot H2O. Purification was carried out by column chromatography
(silica) by eluting initially with CH2Cl2/MeOH (10 %), followed
by MeOH/2  NH4Cl solution/MeNO2 (7:2:1, v/v). The product
fractions were taken to dryness, the residue dissolved in a minimum
amount of MeOH/H2O and acetone, and a solution of Zn(OAc)2
in MeOH was added and allowed to stir at room temperature for
one hour. The solvent was then removed, the residue dissolved in
MeOH, and the product precipitated with H2O. The material was
then filtered, the solid dissolved in a minimum amount of MeOH,
and saturated NH4PF6 solution added until no further precipi-
tation was evident. The catenane product was collected by fil-
tration, washed (H2O), and pumped dry. The product was recrystal-
lised to obtain 14b as a dark purple solid (33 mg, 13 %), m.p.
230Ϫ234 °C (from acetone/iPr2O). C102H110N8O10P4F24Zn
8a was recrystallised to obtain a purple/red solid (99 mg, 6 %), m.p.
186Ϫ189 °C (from CH2Cl2/MeOH). C70H82O10N4·2H2O (1175.45):
calcd. C 71.52, H 7.38, N 4.77; found C 71.05, H 7.07, N 4.68.
ESMS: m/z ϭ [M ϩ H]ϩ 1140.0 (calcd. 1139.6). UV (CHCl3): λ ϭ
410, 507, 541, 575, 626 nm. 1H NMR (300 MHz, CDCl3, 25 °C):
δ ϭ 10.02 (s, 2 H, meso-H), 7.95 (d, J ϭ 8 Hz, 2 H, Ar-H), 7.71
(dt, J ϭ 8, 2 Hz, 2 H, Ar-H), 7.69 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.41
(t, J ϭ 8 Hz, 2 H, Ar-H), 7.31 (d J ϭ 8 Hz, 2 H, Ar-H), 7.26 (t,
J ϭ 7 Hz, 2 H, Ar-H), 6.86 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.23 (t, J ϭ
4 Hz, 4 H, OCH2), 4.11 (t, J ϭ 4 Hz, 4 H, OCH2), 3.80 (q, J ϭ 7
H, 8 Hz, CH2CH3), 3.70 (t, J ϭ 4 Hz, 4 H, OCH2), 3.20Ϫ3.13 (m,
8 H, OCH2), 2.75 (t, J ϭ 5 Hz, 4 H, OCH2), 2.42 (s, 12 H, CH3),
2.25 (m, 4 H, OCH2), 2.16 (m, 4 H, OCH2), 1.58 (t, J ϭ 7 Hz,
12 H, CH2CH3), 1.52 (s, 4 H, 2 H2O), Ϫ2.47 (br. s, 2 H, pyrrole
NH) ppm.
(2253.26): calcd. C 54.37, H 4.92, N 4.97; found C 54.01, H 5.26,
Ϫ ϩ
N 4.66. FAB MS: m/z ϭ [M Ϫ PF6
] 2106.3 (calcd. 2105.7), [M
Ϫ ϩ
Ϫ ϩ
Ϫ2PF6
]
1961.3 (calcd. 1960.7), [M Ϫ3PF6
]
1816.4 (calcd.
1815.7), [M Ϫ 4PF6Ϫ]ϩ, [M Ϫ tetracation Ϫ 4PF6
]
Ϫ ϩ 1149.9 (calcd.
1150.5). UV (acetone): λ ϭ 408, 506, 540, 574 nm. 1H NMR
(300 MHz, [D6]acetone, 25 °C): δ ϭ 9.99 (s, 2 H, meso-H), 8.28 (d,
J ϭ 7 Hz, 8 H, α-bipy), 7.86 (dt, J ϭ 8 Hz, 2 Hz, 2 H, Ar-H), 7.63
9a was recrystallised to obtain a purple/red solid (207 mg, 14 %),
(d, J ϭ 8 Hz, 2 H, Ar-H), 7.43 (s, 8 H, ϪC6H4Ϫ), 7.42 (d, J ϭ 8 m.p. 178Ϫ180 °C (from CH2Cl2/MeOH). C70H82N4O10·2H2O
Hz, 2 H, Ar-H), 7.36 (t, J ϭ 7 Hz, 2 H, Ar-H), 6.66 (d, J ϭ 7 Hz, (1175.45): calcd. C 71.52, H 7.38, N 4.77; found C 71.63, H 7.02,
8 H, β-bipy), 5.29 (s, 8 H, ϩNϪCH2), 4.53 (br. s, 4 H, OCH2), 4.17 N 4.58. ESMS: m/z ϭ [M ϩ H]ϩ 1140.1 (calcd. 1139.6), [M ϩ
(m, 4 H, CH2CH3), 3.87 (m, 4 H, CH2CH3), 3.83 (br. s, 4 H,
2H]2ϩ 570.7 (calcd. 570.3). UV (CHCl3): λ ϭ 410, 507, 541, 574,
204
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 193Ϫ208

A Series of Porphyrin Bipyridinium Receptors
FULL PAPER
626 nm. 1H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.18 (s, 2 H, 4.78; found C 54.06, H 4.96, N 4.84. ESMS: m/z ϭ [M ϩ H Ϫ
meso-H), 7.73 (dt, J ϭ 7, 2 Hz, 2 H, Ar-H), 7.61 (dd, J ϭ 7, 2 Hz,
PF6]ϩ 2156.3 (calcd. 2156.7), [M ϩ H Ϫ tetracation Ϫ 4PF6]ϩ
2 H, Ar-H), 7.37 (d, J ϭ 8 Hz, 2 H, Ar-H), 7.31 (d, J ϭ 8 Hz, 2 1201.4 (calcd. 1201.5), [M ϩ 2H Ϫ 2PF6]2ϩ 1006.6 (calcd. 1006.4),
H, Ar-H), 7.30 (t, J ϭ 8 Hz, 2 H, Ar-H), 6.74 (t, J ϭ 8 H, 2 Hz,
[M Ϫ 3PF6]3ϩ 622.3 (calcd. 621.9), [M Ϫ tetracation Ϫ 4PF6]2ϩ
Ar-H), 5.88 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.08 (t, J ϭ 5 Hz, 4 H, 600.1 (calcd. 600.3), [M ϩ 4H]4ϩ 576 (calcd. 576.2), [M ϩ 4H Ϫ
OCH2), 4.00 (q, J ϭ 7 Hz, 8 H, CH2CH3), 3.23 (t, J ϭ 4 Hz, 4 H, Zn]4ϩ 560.2 (calcd. 560.2), [M Ϫ 4PF6]4ϩ 430.1 (calcd. 430.2). UV
OCH2), 3.05 (t, J ϭ 5 Hz, 4 H, OCH2), 2.91 (t, J ϭ 4 Hz, 4 H, (acetone): λ ϭ 418, 545, 576 nm. 1H NMR (300 MHz, [D6]DMSO,
OCH2), 2.70 (s, 8 H, OCH2), 2.56 (s, 12 H, CH3), 2.54 (m, 4 H, 360 K): δ ϭ 9.89 (s, 2 H, meso-H), 8.35 (d, J ϭ 6 Hz, 8 H, α-bipy),
OCH2), 2.47 (m, 4 H, OCH2), 1.78 (t, J ϭ 7 Hz, 12 H, CH2CH3), 7.82 (t, J ϭ 7 Hz, 2 H, Ar-H), 7.63 (s, 8 H, ϪCH4Ϫ), 7.51 (d, J ϭ
1.52 (s, 4 H, 2H2O), Ϫ2.33 (br. s, 2 H, pyrrole NH) ppm.
7 Hz, 2 H, Ar-H), 7.49 (dd, J ϭ 7, 2 Hz, 2 H, Ar-H), 7.36 (t, J ϭ
7 Hz, 2 H, Ar-H), 6.59 (d, J ϭ 6 Hz, 8 H, β-bipy), 5.65 (d, J ϭ 8
Hz, 2 H, Ar-H), 5.32 (s, 8 H, ϩNϪCH2), 5.18 (t, J ϭ 8 Hz, 2 H,
Ar-H), 4.12 (t, J ϭ 5 Hz, 4 H, OCH2), 2.46 (s, 12 H, CH3), 1.91
(s, 4 H, 2H2O), 1.84 (d, J ϭ 8 Hz, 2 H, Ar-H), 1.70 (t, J ϭ 7 Hz,
12 H, CH2CH3) ppm.
Zinc Naphthoquinol-Strapped Porphyrin 8b: Zinc was inserted into
the free base 8a to give 8b, which was recrystallised to obtain a
purple/pink solid, m.p. 251Ϫ252 °C (from CH2Cl2/MeOH).
C70H80O10N4Zn·2H2O (1238.83): calcd. C 67.86, H 6.84, N 4.52;
found C 68.18, H 6.68, N 4.22. UV (CHCl3): λ ϭ 415, 542, 577
1
nm. H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.02 (s, 2 H, meso-
1,5-Bis{2-[2-(o-formylphenoxy)ethoxy]ethoxy}naphthalene (4, n ؍ 1,
H), 7.80 (d, J ϭ 8 Hz, 2 H, Ar-H), 7.70 (t, J ϭ 8 Hz, 2 H, Ar-H), Ar ؍ naphthyl): Salicylaldehyde (1.67 g, 13.7 mmol) and K2CO3
7.58 (d, J ϭ 8 Hz, 2 H, Ar-H), 7.38 (m, 4 H, Ar-H), 7.19 (t, J ϭ
8 Hz, 2 H, Ar-H), 6.76 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.14 (m, 4 H,
(3.44 g, 24.9 mmol) were stirred in dry CH3CN (55 mL) with heat-
ing under N2 for 1 h. Then naphthoquinol bistosylate 3 (n ϭ 1,
OCH2), 3.92Ϫ3.82 [m, 12 H, CH2CH3 (8 H), OCH2 (4 H)], 3.34 Ar ϭ naphthyl) (4.01 g, 6.22 mmol) in dry CH3CN (190 mL) was
(t, J ϭ 4 Hz, 4 H, OCH2), 3.20 (m, 4 H, OCH2), 2.82 (t, J ϭ 4 Hz, added all at once, and the resulting solution refluxed under N2 for
4 H, OCH2), 2.54 (m, 4 H, OCH2), 2.40 [s, 16 H, CH3 (12 H), 4 days. Upon cooling, the solvent was removed by rotary evapor-
OCH2 (4 H)], 2.32 (t, J ϭ 3 Hz, 4 H, OCH2), 1.65 (t, J ϭ 8 Hz, ation, and the residue partitioned between CH2Cl2 and H2O. The
12 H, CH2CH3), 1.28 (s, 4 H, 2 H2O) ppm.
organic layer was separated, washed (H2O), and dried (MgSO4).
The product was purified using column chromatography (silica) by
eluting with C Cl2 and then CH2Cl2/petroleum ether (5 %) to
remove impurities, followed by CH2Cl2/Et2O (2 %) to give 4 (n ϭ
1, Ar ϭ naphthyl) as a yellow solid, which was recrystallised to
yield a beige solid (2.69 g, 79 %), m.p. 121Ϫ123 °C (from CHCl3/
ethyl acetate). C32H32O8 (544.59): calcd. C 70.58, H 5.92; found C
Zinc Naphthoquinol-Strapped Porphyrin 9b: Zinc was inserted into
9a to give 9b, which was recrystallised to obtain a purple/pink solid,
m.p. 109Ϫ111 °C (from CH2Cl2/MeOH). C70H80O10N4Zn·2H2O
(1238.83): calcd. C 67.86, H 6.84, N 4.52; found C 67.50, H 6.77,
1
N 4.41. UV (CHCl3): λ ϭ 415, 542, 576 nm. H NMR (300 MHz,
CDCl3, 25 °C): δ ϭ 10.15 (s, 2 H, meso-H), 7.77 (d, J ϭ 6 Hz, 2
H, Ar-H), 7.76 (t, J ϭ 8 Hz, 2 H, Ar-H), 7.38Ϫ7.28 (m, 6 H, Ar-
H), 6.93 (t, J ϭ 8 Hz, 2 H, Ar-H), 6.07 (d, J ϭ 7 Hz, 2 H, Ar-H),
4.07Ϫ3.98 [m, 12 H, CH2CH3 (8 H), OCH2 (4 H)], 2.94 (t, J ϭ 4
Hz, 4 H, OCH2), 2.88 (t, J ϭ 6 Hz, 4 H, OCH2), 2.56 (s, 12 H,
CH3), 2.31 (s, 12 H, OCH2), 2.02 (s, 8 H, OCH2), 1.80 (t, J ϭ 8
Hz, 12 H, CH2CH3), 1.28 (s, 4 H, 2 H2O) ppm.
1
70.05, H 5.96. H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.53 (s,
2 H, CHO), 7.83 (dt, J ϭ 7, 2 Hz, 4 H, Ar-H), 7.50 (dt, J ϭ 8, 2
Hz, 2 H, Ar-H), 7.32 (t, J ϭ 8 Hz, 2 H, Ar-H), 7.00 (dt, J ϭ 8, 2
Hz, 2 H, Ar-H), 6.98 (d, J ϭ 8 Hz, 2 H, Ar-H), 6.83 (d, J ϭ 8
Hz, 2 H, Ar-H), 4.33Ϫ4.27 (m, 8 H, OCH2), 4.08Ϫ4.04 (m, 8 H,
OCH2) ppm.
Naphthoquinol-Strapped Porphyrin 10b: Naphthoquinol dialdehyde
4 (n ϭ 1, Ar ϭ naphthyl) (0.5 g, 0.99 mmol) and 3,3Ј-diethyl-4,4Ј-
dimethyl-2,2Ј-dipyrrylmethane (5) (0.45 g, 1.98 mmol) were dis-
solved with stirring in THF (100 mL). The solution was bubbled
with N2 for 20 min before adding catalytic amounts of p-tolu-
enesulfonic acid. Stirring was continued for 48 h (room. temp., N2,
dark), and o-chloranil (485 mg, 1.97 mmol) in THF (10 mL) was
added all at once, and stirring was further continued overnight
(room. temp., dark). Then Et3N (4 mL) was added, stirred for
45 min, and the solution taken to dryness by rotary evaporation.
An initial purification was carried out on an alumina column using
CH2Cl2 as the eluent, followed by a silica column using the same
eluent. Zinc was then inserted into the porphyrin fractions, before
a final purification was carried out on preparative TLC plates using
CH2Cl2 as the eluent to obtain 3 different porphyrin fractions 10b,
11b, and a trimeric product.
Naphthoquinol-Strapped Porphyrin [2]Catenane 15: A mixture of
the naphthoquinol-strapped porphyrin isomers 8a and 9a were re-
fluxed in MeCN and CHCl3 for 3 h to obtain an equilibrium mix-
ture, before zinc was inserted to produce a mixture of 8b and 9b (8
% and 92 %, respectively, from 1H NMR integrations) (146 mg,
1.21 ϫ 10Ϫ4 mol), 1,1Ј-[1,4-phenylenebis(methylene)]-bis(4,4Ј-bipy-
ridinium) bis(hexafluorophosphate) 13[28] (107 mg, 1.52 ϫ 10Ϫ4
mol), 1,4-bis(bromomethyl)benzene (50 mg, 1.91 ϫ 10Ϫ4 mol), and
catalytic amounts of NaI and NH4PF6 were dissolved in DMF
(7 mL), deoxygenated with N2 for 20 min, and then stirred at room
temperature at 12 KBar for 4 days. The solvent was then removed
under vacuum with heating, and the residue was washed well with
CH2Cl2, followed by hot H2O. Purification was carried out by col-
umn chromatography (silica) by eluting initially with CH2Cl2/
MeOH (10 %), followed by MeOH/2  NH4Cl solution/MeNO2
(7:2:1, v/v). The product fractions were taken to dryness, the resi-
due dissolved in a minimum amount of MeOH/H2O and acetone, 10b was recrystallised to obtain a bright red solid (41.6 mg, 5 %),
and a solution of Zn(OAc)2 in MeOH was added and the mixture
allowed to stir at room temperature for one hour. The acetone was
then removed, the solution filtered, the solid dissolved in a mini-
mum amount of MeOH/H2O, and saturated NH4PF6 solution ad-
ded until no further precipitation was evident. The catenane prod-
uct was collected by filtration, washed (H2O), and pumped dry.
The product was then recrystallised to obtain catenane 15 as a dark
purple solid (97 mg, 35 %), m.p. 221Ϫ224 °C (from acetone/iPr2O).
m.p. 318Ϫ322 °C, (from CH2Cl2/MeOH). C62H64O6N4Zn·2H2O
(1062.62): calcd. C 70.08, H 6.45, N 5.27; found C 70.12, H 6.51,
N 5.05. ESMS m/z ϭ [M ϩ H]ϩ 1025.8 (calcd. 1025.4). UV (CHCl3
(1 %)/MeCN): λ ϭ 414, 504, 542, 576 nm. 1H NMR (300 MHz,
CDCl3, 25 °C): δ ϭ 9.92 (s, 2 H, meso-H), 7.76 (dt, J ϭ 8, 2 Hz, 2
H, Ar-H), 7.54 (dd, J ϭ 8, 2 Hz, 2 H, Ar-H), 7.32Ϫ7.25 (m, 4 H,
Ar-H), 5.55 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.65 (t, J ϭ 8 Hz, 2 H, Ar-
H), 4.30 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.26 (t, J ϭ 4 Hz, 4 H, OCH2),
C106H112O10N8P4F24Zn·2H2O (2339.35): calcd. C 54.33, H 4.99, N 3.94 (q, J ϭ 7 Hz, 8 H, CH2CH3), 3.48 (t, J ϭ 4 Hz, 4 H, OCH2),
Eur. J. Org. Chem. 2004, 193Ϫ208
www.eurjoc.org  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 205

M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
3.27 (t, J ϭ 4 Hz, 4 H, OCH2), 2.83 (t, J ϭ 4 Hz, 4 H, OCH2) 2.52 ‘‘inside’’), 7.46 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.40 (d, J ϭ 6 Hz, 2 H,
(s, 12 H, CH3), 1.77 (t, J ϭ 7 Hz, 12 H, CH2CH3), 1.50 (s, 4 H, α-bipy ‘‘inside’’), 7.34 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.13 (d, J ϭ 4 Hz,
2H2O) ppm.
2 H, β-bipy ‘‘outside’’), 6.99 (d, J ϭ 5 Hz, 2 H, βЈ-bipy ‘‘outside’’),
6.83 (d, J ϭ 6 Hz, 2 H, αЈ-bipy ‘‘inside’’), 5.60 [s, 6 H, ϩNCH2
‘‘outside’’ (4 H), Ar-H (2 H)], 5.30 (t, J ϭ 8 Hz, 2 H, Ar-H), 5.17
(t, J ϭ 7 Hz, 2 H, OCH2), 5.12 (d, J ϭ 13 Hz, 2 H, ϩNCH2
‘‘inside’’), 5.02 (d, J ϭ 13 Hz, 2 H, ϩNCH2Ј ‘‘inside’’), 4.78 (d, J ϭ
9 Hz, 2 H, OCH2), 4.33Ϫ4.22 (m, 4 H, CH2CH3), 4.11Ϫ4.02 (m,
10 H, OCH2), 3.87Ϫ3.82 (m, 4 H, CH2CH3), 3.64 (dd, J ϭ 10 Hz,
4 Hz, 2 H, OCH2), 3.39 (d, J ϭ 5 Hz, 2 H, βЈ-bipy ‘‘inside’’), 3.28
(d, J ϭ 5 Hz, 2 H, β-bipy ‘‘inside’’), 2.65 (s, 6 H, CH3), 2.60 (s, 6
H, CH3), 1.96Ϫ1.84 (m, 12 H, CH2CH3), 1.47 (d, J ϭ 8 Hz, 2 H,
Ar-H) ppm.
11b was recrystallised to obtain a red solid (9.6 mg, 1 %), m.p.
210Ϫ214 °C, (from CH2Cl2/MeOH). C124H128O12N8Zn2·4H2O
(2125.23): calcd. C 70.08, H 6.45, N 5.27; found C 70.15, H 6.09,
N 5.31. FAB MS: m/z ϭ [M ϩ 4H]ϩ 2051.9 (calcd. 2052.85), [M
ϩ 4H]2ϩ 1026.4 (calcd. 1026.43). UV (CHCl3): λ ϭ 412, 541, 576
1
nm. H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 10.20 (s, 2 H, meso-
H), 9.80 (s, 2 H, meso-H), 7.75 (t, J ϭ 6 Hz, 2 H, Ar-H), 7.72 (d,
J ϭ 6 Hz, 2 H, Ar-H), 7.66 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.60 (d, J ϭ
6 Hz, 2 H, Ar-H), 7.38Ϫ7.25 (m, 8 H, Ar-H), 7.02 (d, J ϭ 9 Hz, 2
H, Ar-H), 6.69 (d, J ϭ 9 Hz, 2 H, Ar-H), 6.50 (t, J ϭ 8 Hz, 2 H,
Ar-H), 6.21 (t, J ϭ 8 Hz, 2 H, Ar-H), 5.75 (d, J ϭ 8 Hz, 2 H, Ar-
H), 4.99 (d, J ϭ 8 Hz, 2 H, Ar-H), 4.25 (t, J ϭ 5 Hz, 4 H, OCH2),
4.09 (t, J ϭ 5 Hz, 4 H, OCH2), 4.04 (m, 8 H, CH2CH3), 3.65 (m,
8 H, CH2CH3), 3.39 (t, J ϭ 5 Hz, 4 H, OCH2), 3.19 (t, J ϭ 5 Hz,
4 H, OCH2), 2.93 (t, J ϭ 5 Hz, 4 H, OCH2), 2.59 (s, 12 H, CH3),
2.38 (s, 12 H, CH3), 2.35 (t, J ϭ 5 Hz, 4 H, OCH2), 2.26 (t, J ϭ 5
Hz, 4 H, OCH2), 1.79 (t, J ϭ 7 Hz, 12 H, CH2CH3), 1.54 (s, 4 H,
2H2O), 1.48 (t, J ϭ 7 Hz, 12 H, CH2CH3) ppm.
X-ray Crystallographic Study: The structure models were refined
with SHELXL-97,[29] and teXsan,[30] WinGX[31] and XTAL[32] were
used for analysis and graphics. In general non-hydrogen atoms were
modelled with anisotropic displacement parameters and a riding
atom model was used for the hydrogen atoms. The refinement re-
siduals are defined as R1 ϭ Σ||Fo| Ϫ |Fc||/Σ|Fo| for Fo Ͼ 2σ(Fo) and
wR2 ϭ [Σw(F2o Ϫ F2c)2/Σ(wF2c)2]1/2 for all reflections, with w ϭ
1/[σ2(F2o) ϩ (AP)2 ϩ BP] where P ϭ (F2o ϩ 2F2c)/3 where A and B
are given in the crystal data below.
The trimeric product was recrystallised to obtain a red solid
(10.5 mg, 1 %), m.p. Ͼ 350 °C, (from CH2Cl2/MeOH): FAB MS:
m/z ϭ [M ϩ 6H]ϩ 3078.24 (calcd. 3079.28), [M Ϫ M/3 ϩ 4H]ϩ
2051.9 (calcd. 2052.85), [M/3 ϩ 2H]ϩ 1026.0 (calcd. 1026.43). UV
The single crystals obtained for 10b were too small to provide an
acceptable data set from a conventional laboratory diffarctometer.
Data were obtained during commissioning studies at the Chem-
MatCARS facility at the Advanced Photon Source of the Argonne
National Laboratory, Argonne USA. Double diamond (111) reflec-
1
(CHCl3): λ ϭ 411, 541, 576 nm. H NMR (300 MHz, CDCl3, 25
°C): δ ϭ 10.09 (s, 2 H, meso-H), 7.76 (t, J ϭ 8 Hz, 2 H, Ar-H),
7.73 (d, J ϭ 7 Hz, 2 H, Ar-H), 7.34 (t, J ϭ 7 Hz, 2 H, Ar-H), 7.28
(d, J ϭ 8 Hz, 2 H, Ar-H), 6.39 (d, J ϭ 8 Hz, 2 H, Ar-H), 5.17 (t,
J ϭ 8 Hz, 2 H, Ar-H), 4.11 (t, J ϭ 4 Hz, 4 H, OCH2), 3.93 (q, J ϭ
7 Hz, 8 H, CH2CH3), 3.79 (d, J ϭ 8 Hz, 2 H, Ar-H), 3.04 (t, J ϭ
4 Hz, 4 H, OCH2), 2.51 (s, 12 H, CH3), 2.33 (t, J ϭ 4 Hz, 4 H,
OCH2), 1.88 (t, J ϭ 4 Hz, 4 H, OCH2), 1.67 (t, J ϭ 7 Hz, 12 H,
CH2CH3) ppm.
˚
tions were used to obtain monochromated 0.56356 A radiation
from the synchrotron source, and harmonics were eliminated with
mirrors. A red prismatic crystal was attached with Exxon Paratone
N, to a short length of fibre supported on a thin piece of copper
wire inserted in a copper mounting pin. The pin and crystal were
mounted on a unique BrukerϪKappa diffractometer equipped
with a 4-chip mosaic CCD detector, and an Oxford Scientific
Cryojet. Data were collected at 123(2) Kelvin with ϕ scans to 44.3°
2θ, and cell constants were obtained from a least-squares refine-
ment against 1020 reflections located between 6 and 44° 2θ. The
intensities of 268 standard reflections recollected at the end of the
experiment changed by 7.38 % during the data collection and a
correction was accordingly applied with SADABS.[33] The data in-
tegration and reduction were undertaken with SAINT and
XPREP.[34]
Zinc Naphthoquinol-Strapped Porphyrin [2]Catenane 16: Naphtho-
quinol-strapped zincporphyrin 10b (92 mg, 8.96 ϫ 10Ϫ5 mol), 1,1Ј-
[1,4-phenylenebis(methylene)]bis(4,4Ј-bipyridinium) bis(hexafluoro-
phosphate) (13) (76 mg, 1.08 ϫ 10Ϫ4 mol), 1,4-bis(bromomethyl)-
benzene (35 mg, 1.34 ϫ 10Ϫ4 mol), and catalytic amounts of NaI
and NH4PF6 were stirred at room temperature in DMF (2 mL) for
14 days. The solvent was then removed under vacuum with heating,
and the residue was washed well with CH2Cl2, followed by hot
H2O. Purification was carried out by column chromatography (sil-
ica) by eluting initially with MeOH, followed by MeOH/2  NH4Cl
solution/MeNO2 (7:2:1, v/v). The product fractions were taken to
dryness, the residue dissolved in a minimum amount of MeOH/
H2O, and a solution of Zn(OAc)2 in MeOH/H2O added and al-
lowed to stir at room temperature for one hour. The solution was
then filtered and saturated NH4PF6 solution added to the filtrate
until no further precipitation was evident. The catenane product
was collected by filtration, washed (H2O), and pumped dry. The
product was recrystallised to obtain catenane 16 as a dark purple
The structure was solved by direct methods with SIR97,[35] and
the asymmetric unit contains the metalloporphyrin, a solvent site
modelled with a 60 % occupancy dimethylsufoxide molecule and
two 20 % occupancy water oxygen atoms. Initially a fully occupied
but disordered DMSO model was used for the solvent site, with
the sulfur disordered over two positions related by sp3 inversion.
However this model was unsatisfactory, having very high displace-
ment parameters for the second sulfur site relative to the oxygen
site and higher refinement residuals. Accordingly this model was
abandoned, and the residual peaks were treated as partial occu-
pancy water sites. In general the non-hydrogen atoms were mod-
elled with anisotropic displacement parameters and a riding atom
model was used for the hydrogen atoms. The partially occupied
carbon and oxygen sites were modelled with isotropic displacement
parameters. An ORTEP[18] depiction of the molecule with 50 %
displacement ellipsoids is provided in Figure 2.
solid (37 mg, 19 %), m.p.
C99H100F24N8O6P4Zn·H2O (2161.17): calcd. C 55.02, H 4.76, N
5.18; found C 54.74, H 4.94, N 4.98. FAB MS: m/z ϭ [M Ϫ PF6
Ͼ 350 °C (from acetone/iPr2O).
Ϫ ϩ
]
Ϫ ϩ
1981.3 (calcd. 1979.6), [M Ϫ 2PF6
]
1835.2 (calcd. 1834.6), [M
1545.1 (calcd.
1023.9 (calcd. 1024.4). UV
Ϫ ϩ
Ϫ ϩ
Ϫ 3PF6
]
1689.7 (calcd. 1689.6), [M Ϫ 4PF6
]
Ϫ ϩ
1544.7), [M Ϫ tetracation Ϫ 4PF6
]
(acetone): λ ϭ 422, 544, 580 nm. 1H NMR (300 MHz, CD3CN, 25
°C): δ ϭ 10.02 (s, 2 H, meso-H), 8.50 (m, 4 H, α,αЈ-bipy ‘‘outside’’),
Crystal Data for 10b: Model formulation C65.20H73.60N4O8S1.60Zn,
¯
˚
8.01 (t, J ϭ 7 Hz, 2 H, Ar-H), 7.80 (d, J ϭ 8 Hz, 4 H, ϪC6H4Ϫ M ϭ 1157.95, triclinic, space group P1 (No. 2), a ϭ 15.0962(13),
‘‘outside’’), 7.74 (d, J ϭ 8 Hz, 2 H, Ar-H), 7.67 (m, 4 H, ϪC6H4Ϫ
b ϭ 17.1660(19), c ϭ 14.6118(17) A, α ϭ 113.150(4), β ϭ
206
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 193Ϫ208

A Series of Porphyrin Bipyridinium Receptors
FULL PAPER
J.-P. Sauvage, Acc. Chem. Research 1998, 31, 611.
[3]
[4]
3
˚
118.166(5), γ ϭ 64.067(5)°, V ϭ 2917.6(5) A , Z ϭ 2, crystal
P. R. Ashton, V. Baldoni, V. Balzani, A. Credi, H. D. A.
Hoffmann, M.-V. Martinez-Diaz, F. M. Raymo, J. F. Stoddart,
M. Venturi, Chem. Eur. J. 2001, 7, 3482. V. Balzani, A. Credi,
S. J. Langford, F. M. Raymo, J. F. Stoddart, M. Venturi, J. Am.
Chem. Soc. 2000, 122, 3542. P. R. Ashton, S. E. Boyd, A.
Brindle, S. J. Langford, S. Menzer, L. Perez-Garcia, J. A. Pre-
ece, F. M. Raymo, N. Spencer, J. F. Stoddart, A. J. P. White, D.
J. Williams, New J. Chem. 1999, 23, 587. M. Asakawa, P. R.
Ashton, V. Balzani, A. Credi, C. Hamers, G. Mattersteig, M.
Montalti, A. M. Shipway, N. Spencer, J. F. Stoddart, M. S.
Tolley, M. Venturi, A. J. P. White, D. J. Williams, Angew. Chem.
Int. Ed. 1998, 37, 333. P. R. Ashton, J. A. Preece, J. F. Stoddart,
M. S. Tolley, A. J. P. White, D. J. Williams, Synthesis 1994,
1344. Z.-T. Li, P. C. Stein, J. Becher, D. Jensen, P. Mørk, N.
size 0.110
ϫ
0.084
ϫ
0.029 mm, colour red, habit prism,
Ϫ1
˚
λ(synchrotron) ϭ 0.56356 A, µ(synchrotron) ϭ 0.289 mm
,
T(SADABS)min.,max. ϭ 0.763, 1.000, 2θmax. ϭ 44.30, hkl range Ϫ20/
20, Ϫ22/22, Ϫ19/19, N ϭ 96208, Nind. ϭ 13889(Rmerge ϭ 0.0428),
Nobsd. ϭ 13207[I Ͼ 2σ(I)], Nvar. ϭ 736, residuals R1(F) 0.0426,
wR2(F2) 0.1171 with A ϭ 0.06 and B ϭ 2.255, GoF(all) ϭ 1.098,
Ϫ3
∆ρmin.,max. Ϫ0.918, 1.315 eϪ
A .
˚
A dark purple prismatic crystal of 7b was attached to a thin glass
fibre and mounted on a Rigaku AFC7R diffractometer employing
graphite-monochromated Cu-Kα radiation generated from a Ri-
gaku rotating anode. Cell constants were obtained from a least-
squares refinement against 25 reflections located between 19.30 and
33.50° 2θ. Data were collected at 294(2) Kelvin with ω-2θ scans to
120.18° 2θ. The data processing was undertaken with the UNIX
version of teXsan.[30] The intensities of 3 standard reflections meas-
ured every 150 reflections did not change significantly during the
data collection. The structure by direct methods with SHELXS-
86.[36] Large displacement parameters in the porphyrin strap indi-
cate significant disorder and/or thermal motion. An ORTEP[18] de-
piction of the molecule with 20 % displacement ellipsoids is pro-
vided in Figure 3.
´
Svenstrup, Chem. Eur. J. 1996, 2, 624. D. J. Cardenas, A. Livor-
eil, J.-P. Sauvage, J. Am. Chem. Soc. 1996, 118, 11980.
D. B. Amabilino, J.-P. Sauvage, New J. Chem. 1998, 395. M.
Linke, N. Fujita, J. C. Chambron, V. Heitz, J. P. Sauvage, New
J. Chem. 2001, 25, 790. J.-C. Chambron, C. O. Dietrich-Bu-
checker, V. Heitz, J.-F. Nierengarten, J.-P. Sauvage, C. Pascard,
J. Guilhem, Pure Appl. Chem. 1995, 67, 233. D. B. Amabilino,
J.-P. Sauvage, Chem. Commun. 1996, 2441. M. J. Gunter, S. M.
Farquhar, Org. Biomol. Chem. 2003, 1, 3450.
[5]
[6]
L. Flamigni, A. M. Talarico, S. Serroni, F. Puntoriero, M. J.
Gunter, M. R. Johnston, T. P. Jeynes, Chem. Eur. J. 2003, 9,
2649.
M. J. Gunter, M. R. Johnston, J. Chem. Soc., Chem. Commun.
1992, 1163.
M. J. Gunter, D. C. R. Hockless, M. R. Johnston, B. W. Skel-
ton, A. H. White, J. Am. Chem. Soc. 1994, 116, 4810.
M. J. Gunter, M. R. Johnston, J. Chem. Soc., Chem. Commun.
1994, 829.
M. J. Gunter, R. N. Warrener, Chem. Aust. 1997, 25.
I. Willner, E. Kaganer, E. Joselevich, H. Durr, E. David, M. J.
Gunter, M. R. Johnston, Coord. Chem. Rev. 1998, 171, 261.
L. Flamigni, A. M. Talarico, M. J. Gunter, M. R. Johnston, T.
P. Jeynes, New J. Chem. 2003, 27, 551.
M. J. Gunter, T. P. Jeynes, M. R. Johnston, P. Turner, Z. P.
Chen, J. Chem. Soc., Perkin Trans. 2 1998, 21, 1945.
Cs2CO3 was added to the reaction to aid in the formation of
the this large macrocycle by a cation templating effect, the so
called ‘‘cesium effect’’, see: G. Dijkstra, W. H. Kruizinga, R.
M. Kellogg, J. Org. Chem. 1987, 52, 4230. The modification of
Maruyama’s procedure (A. Osuka, F. Kobayashi, K. Maruy-
ama, Bull. Chem. Soc. Jpn. 1991, 64, 1213. A. Osuka, T. Na-
gata, F. Kobayashi, K. Maruyama, J. Heterocycl. Chem. 1990,
27, 1657) that was used for some previous related porphyrin
synthesis was unsuccessful in this case.
Crystal Data for 10b: C66H78N4O10Zn, M ϭ 1152.69, monoclinic,
[7]
[8]
[9]
space group: P21/c (No. 14), a ϭ 13.353(2), b ϭ 34.280(6), c ϭ
3
˚
˚
14.824(2) A, β ϭ 116.510(10), V ϭ 6072.1(16) A , Dc ϭ 1.261 g
cmϪ3, Z ϭ 4, crystal size: 0.20 ϫ 0.10 ϫ 0.10 mm, colour: dark
˚
purple, habit: prismatic, T ϭ 294(2) Kelvin, λ(Cu-Kα) 1.54178 A,
µ(Cu-Kα) ϭ 1.054 mmϪ1, T(ϕ-scans)min.,max. ϭ 0.855, 0.998,
2θmax. ϭ 120.18, hkl range: 0/14, 0/38, Ϫ16/14, N ϭ 9339, Nind.
ϭ
[10]
[11]
8507 (Rmerge ϭ 0.1208), Nobsd. ϭ 2901 [I Ͼ 2σ(I)], Nvar. ϭ 726,
residuals R1(F) ϭ 0.0662, wR2(F2) ϭ 0.1750 with A ϭ 0.03 and
B ϭ 0.0, GoF(all) ϭ 1.159, ∆ρmin.,max. ϭ Ϫ0.474, 0.674 eϪ
A .
Ϫ3
˚
[12]
[13]
[14]
CCDC-216542 and -216543 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK; Fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
Acknowledgments
Funding for part of this project by the Australian Research Council
is acknowledged. Use of the ChematCARS Sector 15 at the Ad-
vanced Photon Source, was supported by the Australian Synchro-
tron Research Program, which is funded by the Commonwealth of
Australia under the Major National Research Facilities Program.
ChemMatCARS Sector 15 is also supported by the National Sci-
ence Foundation/Department of Energy under grant numbers
CHE9522232 and CHE0087817 and by the Illinois board of higher
education. The Advanced Photon Source is supported by the U.S.
Department of Energy, Basic Energy Sciences, Office of Science,
under Contract No. W-31-109-Eng-38.
[15]
M. J. Gunter, S. M. Farquhar, T. P. Jeynes, Org. Biomol. Chem.
2003, 1, 4097.
[16]
[17]
J. E. Redman, J. K. M. Sanders, Org. Lett. 2000, 2, 4141.
Conformational interchange can occur by rotation around the
CϪC and CϪO bonds in the strap, and not around the
mesoϪC to phenyl bond; rotation around this bond is restric-
ted and interconverts the two atropisomeric 6 and 7, or 8 and 9.
C. K. Johnson, ORTEP: ORTEPII. Report ORNL-5138, Oak
Ridge National Laboratory, Oak Ridge, Tennessee, 1976.
A Multipurpose Crystallographic Tool, 1998,
Utrecht University, Utrecht, The Netherlands. A. L. Spek,
Acta Crystallogr., Sect. A 1990, 46, C34.
Some DMSO was found necessary to improve the solubility of
7b which otherwise tended to crystallize during the course of
the NMR titration experiment. For consistency, the association
constants of the other porphyrin receptors were also deter-
mined in this solvent.
A table of chemical shift changes and detailed rationale for the
indicated structures of the complexes is given in the Sup-
plementary Data.
[18]
[19]
PLATON,
[20]
[1]
A. R. Pease, J. O. Jeppesen, J. F. Stoddart, Y. Luo, C. P. Collier,
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M. Venturi, Chem. Eur. J. 2002, 8, 5525.
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V. Balzani, M. Gomez-Lopez, J. F. Stoddart, Acc. Chem. Re-
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[22]
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Eur. J. Org. Chem. 2004, 193Ϫ208
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
207

M. J. Gunter, T. P. Jeynes, P. Turner
FULL PAPER
Chem. Soc., Perkin Trans. 1 1994, 1009. M. J. Gunter, M. R.
Johnston, J. Chem. Soc., Perkin Trans. 1 1994, 995.
A modification of the originally reported workup procedure
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