Chloride-Anion-Templated Synthesis of a Strapped-Porphyrin-Containing Catenane Host System

Article abstract of DOI:10.1002/chem.201502721

The synthesis, structure and anion-recognition properties of a new strapped-porphyrin-containing [2]catenane anion host system are described. The assembly of the catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor-acceptor and coordinative pyridine-zinc interactions. The [2]catenane incorporates a three-dimensional, hydrogen-bond-donating anion-binding pocket; solid-state structural analysis of the catenane-chloride complex reveals that the chloride anion is encapsulated within the catenane's interlocked binding cavity through six convergent CH...Cl and NH...Cl hydrogen-bonding interactions and solution-phase ¹H NMR titration experiments demonstrate that this complementary hydrogen-bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution.

Full text of DOI:10.1002/chem.201502721

DOI: 10.1002/chem.201502721
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&
Catenanes |Hot Paper|
Chloride-Anion-Templated Synthesis of a Strapped-Porphyrin-
Containing Catenane Host System
Asha Brown,[a] Matthew J. Langton,[a] Nathan L. Kilah,[b] Amber L. Thompson,[a] and
Paul D. Beer*[a]
Abstract: The synthesis, structure and anion-recognition
properties of a new strapped-porphyrin-containing [2]cate-
nane anion host system are described. The assembly of the
catenane is directed by discrete chloride anion templation
acting in synergy with secondary aromatic donor–acceptor
and coordinative pyridine–zinc interactions. The [2]catenane
incorporates a three-dimensional, hydrogen-bond-donating
anion-binding pocket; solid-state structural analysis of the
catenane·chloride complex reveals that the chloride anion is
encapsulated within the catenane’s interlocked binding
cavity through six convergent CH····Cl and NH···Cl hydrogen-
bonding interactions and solution-phase 1H NMR titration
experiments demonstrate that this complementary
hydrogen-bonding arrangement facilitates the selective
recognition of chloride over larger halide anions in DMSO
solution.
halogen bonding,[11] and solvatophobic effects,[12] have been
successfully applied to catenane synthesis.
Introduction
[n]Catenanes, a class of mechanically bonded molecules com-
prising n interlocked ring components,[1] have received ever-
growing attention over recent decades on account of their
interesting topologies and aesthetic appeal, in addition to
their potential applications as molecular machines,[2] imaging
agents,[3] host systems[4] and functional nanomaterials.[5] How-
ever, despite the widespread interest in catenane compounds,
their synthesis remains challenging, usually relying on the use
of interweaving templating interactions to organise the molec-
ular precursor components in an orthogonal manner, before
performing the final ring-closing step. Since Sauvage’s pioneer-
ing use of a CuI-directed orthogonal assembly strategy,[6] much
synthetic effort has been devoted to the development of new
and efficient template-directed protocols for the preparation
of catenanes. Although coordinate metal–ligand bonds remain
the most widely exploited templating interactions,[7] a variety
of alternative noncovalent interactions, including p–p inter-
actions,[8] hydrogen bonding,[8c,9] radical–radical interactions,[10]
Our group[13] and others[14] have demonstrated that anions
can also be effectively employed as discrete interweaving tem-
plates during catenane synthesis, and that the preorganised
three-dimensional binding pockets contained within the resul-
tant interlocked architectures can subsequently be exploited
for selective anion-recognition purposes.[15] Incorporation of
a suitable optical or redox-active reporter group can give rise
to systems that produce a signalling response upon complexa-
tion of the target guest species. However, despite the promise
of this approach, anion-templation strategies remain under-
developed and examples of catenane-based host systems that
are capable of optically or electrochemically sensing the
presence of an anionic guest species are rare.[16]
Herein we describe the synthesis and solid-state structure of
a new strapped-porphyrin-containing [2]catenane anion host
system, which is assembled by using chloride anion templation
in combination with aromatic donor–acceptor interactions and
pyridine–zinc ligation.[17] After removal of the templating
anion, the catenane’s halide anion-recognition and sensing
1
properties were probed by H NMR, UV/Vis and fluorescence
titration experiments.
[a] Dr. A. Brown, Dr. M. J. Langton, Dr. A. L. Thompson, Prof. P. D. Beer
Department of Chemistry, University of Oxford
Chemistry Research Laboratory, Mansfield Road
Oxford, OX1 3TA (UK)
Results and Discussion
E-mail: paul.beer@chem.ox.ac.uk
[b] Dr. N. L. Kilah
Design and synthetic strategy
School of Physical Sciences – Chemistry, University of Tasmania
Hobart, Tasmania, 7001 (Australia)
We have previously employed a chloride-anion-templated,
amide-condensation-based clipping strategy to assemble
[2]catenane architectures in which bidentate hydrogen-bond-
donor groups from each of the interlocked macrocyclic com-
ponents converge towards a central, three-dimensional bind-
ing cavity, where the halide anion template is encapsulated.
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201502721.
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This is an open access article under the terms of the Creative Commons At-
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medium, provided the original work is properly cited.
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Upon removal of the template, the [2]catenanes
were shown to recognise halide anions selectively
over oxoanions in 1:1 CDCl3/CD3OD, which is primari-
ly attributed to the optimal size- and shape-comple-
mentarity between the halide anions and the hosts’
interlocked binding domains.[13d] In the current study
we have modified our previous catenane design by
incorporating a zinc(II) metalloporphyrin unit into
one of the interlocked macrocyclic components, and
a 3,5-pyridine bis(amide) motif into the second mac-
rocycle component, in order to introduce an inter-
component pyridine–zinc interaction into the final
interlocked structure (Figure 1).
We anticipated that this coordinative interaction
could be exploited in several ways: as well as provid-
ing an auxiliary templating interaction during cate-
nane assembly, the pyridine–zinc ligation process
was predicted to enhance the anion recognition
Scheme 1. Synthesis of the bis(amino)porphyrin 3. Reagents and conditions: i) BF3·OEt2,
EtOH, CH2Cl2, RT, 1 h; ii) p-chloranil, reflux, 1 h, 25%; iii) SnCl2·2H2O, 37% HCl(aq), RT, 16 h,
37% (3a) and 40% (3b); iv) Zn(OAc)2·2H2O, CH2Cl2, MeOH, RT, 18 h, 91%.
the corresponding a,a- and a,b-
bis(amino)porphyrin atropisom-
ers 3a and 3b, which were sepa-
rated by column chromatogra-
phy.[21] On the basis of molecular
dipole considerations, and by
analogy with related compounds
in the literature,[22] the more
polar compound was assigned
as the desired a,a-isomer 3a,
which was isolated in 37% yield.
The a,b-isomer 3b was isolated
in a comparable yield of 40%.[23]
Metallation of the a,a-bis(amine)
3a by treatment with excess
Figure 1. Cartoon representation of the intended synthetic route to the target strapped-porphyrin-containing
[2]catenane, which incorporates an intercomponent pyridine–zinc coordinative bond.
properties of the [2]catenane host system by increasing both
the overall preorganisation of the host system and the acidity
of the 3,5-pyridine bis(amide) hydrogen-bond-donor groups; it
was also envisaged that the pyridine–zinc bond would create
a direct through-bond communication pathway between the
anion recognition site and the porphyrin chromophore, which
could potentially enable the [2]catenane host system to opti-
cally sense the presence of an encapsulated guest anion.
Zn(OAc)2·2H2O afforded the corresponding zinc(II) metallopor-
phyrin Zn·3a in 91% yield.
The assignment of the atropisomers was confirmed by solid-
state structural characterisation of compounds Zn·3a and 3b
(Figure 2). In both structures, the meso-aryl substituents are ar-
Synthesis of pyridinium-strapped porphyrin
macrocycle
The synthesis of the new pyridinium bis(amide)-
strapped porphyrin macrocyclic fragment of the target [2]cate-
nane was carried out as outlined in Schemes 1 and 2. Initially
the bis(amino)porphyrin precursor Zn·3a was prepared
(Scheme 1). The trans-substituted dinitroporphyrin 2[18] was ob-
tained from a BF3-catalysed [2+2] condensation reaction be-
tween meso-unsubstituted dipyrromethane 2[19] and 2-nitro-
benzaldehyde, with subsequent p-chloranil oxidation.[20] Com-
pound 2 was obtained in 25% yield, as an approximately equi-
molar mixture of the a,a- and a,b-atropisomeric forms 2a and
2b. Reduction of this isomeric mixture with SnCl2/HCl afforded
Figure 2. Solid-state structures of the a,a- and a,b-aminoporphyrin deriva-
tives Zn(MeOH)·3a (top) and 3b (bottom). For clarity, nonpolar hydrogen
atoms have been omitted and only one of the two fractional occupancies of
the axially coordinated methanol solvate molecule is shown.
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ranged almost orthogonally to the planes of the porphyrins
(mean dihedral angle=86.78 and 67.88 for compounds Zn·3a
and 3b respectively). For compound Zn·3a, the desired cis ar-
rangement of the amino groups is observed, whereas for com-
pound 3b the meso-substituents adopt a trans conformation,
with the two amino groups diverging away from the porphyrin
plane. For both compounds, the hybridization states of the
aniline nitrogen atoms appear to be intermediate between sp3
and sp2, with all of the aniline nitrogen torsion angles falling
within the range 150–1658.[24] The structure of the metallopor-
phyrin Zn·3a confirms that the zinc(II) cation adopts the ex-
pected five-coordinate square pyramidal coordination environ-
ment in the solid state, with an axially coordinated methanol
molecule occupying the apical position of the square pyramid
bromooacetonitrile, followed by cyano-group reduction,
Boc-protection of the amino group and hydrogenative
debenzylation afforded the phenol derivative 7,[13a] which was
condensed with ethyl bromoacetate to provide compound 8.
Cleavage of the N-Boc protecting group by bubbling HCl(g)
through a solution of compound 8 in Et2O yielded the corre-
sponding amine as its hydrochloride salt, 9·HCl. This was con-
densed with 0.5 equivalents of the bis-acid chloride 10 to pro-
duce the bis-ester intermediate 11, which was subsequently
converted into the bis-acid-functionalised strap precursor 12 in
88% yield by base-mediated hydrolysis of the ester groups. An
EDC-promoted coupling reaction [EDC=N-(3-dimethylamino-
propyl)-N’-ethylcarbodiimide, which was added to the reaction
as a hydrochloride salt] between this bis-acid derivative and
the a,a-bis(amino)porphyrin Zn·3a in DMF afforded the pyri-
dine-strapped macrocycle 13 in 44% yield.[26] Finally, alkylation
of the pyridine group by treatment of macrocycle 13 with MeI
(mean
ZnÀN
distance:
2.048(2) Š; ZnÀO
distance:
2.166(20) Š).[25] The zinc(II) cation is located 0.174 Š above the
mean plane of the porphyrin, which is significantly ruffled, in
contrast to the highly planar free base porphyrin derivative
3b.
[27]
in the presence of NaHCO3 in DMF, followed by repeated ex-
traction with NH4Cl(aq), afforded the chloride salt of the target
pyridinium-strapped porphyrin macrocycle, 14·Cl, in 99% yield
(Scheme 2).
Having isolated the a,a-bis(amino)porphyrin precursor
Zn·3a, the strap component of the porphyrin-containing
macrocycle was constructed in ten steps from commercially
available 4-(benzyloxy)phenol. Reaction of this precursor with
Both of the new macrocycles 13 and 14·Cl were character-
ised by X-ray crystallography in the solid state. The crystal
Scheme 2. Synthesis of the pyridinium-strapped macrocycle 14·Cl. Reagents and conditions: i) Bromoacetonitrile, K2CO3, acetone, reflux, 18 h, 97%; ii) LiAlH4,
Et2O, reflux, 84%; iii) Boc2O, Et3N, CH2Cl2, RT, 87%; iv) H2, Pd/C, CHCl3, MeOH, RT, 95%; v) ethylbromoacetate, NaH, THF, RT, 1 h, 508C, 12 h, 94%; vi) HCl(g), Et2O,
RT, 97%; vii) (COCl)2, DMF (cat.), CH2Cl2, RT, quantitative yield; viii) Et3N, CH2Cl2, 08C to RT, 18 h, 73%; ix) KOH, CH2Cl2, MeOH, H2O RT, 88%; x) EDC·HCl, HOBt,
DMAP, DMF, RT, 44%; xi) MeI, NaHCO3, DMF, 808C, 2 h, then NH4Cl(aq), 99%.
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Figure 3. Orthogonal views of the solid-state structure of the pyridine-
strapped porphyrin macrocycle 13. Solvent molecules and nonpolar
hydrogen atoms have been omitted for clarity.
Figure 4. Solid-state structure of the pyridine solvate of the pyridinium-
strapped porphyrin macrocycle 14·Cl: content of the asymmetric unit (top)
and view of the head-to-tail dimer which forms as a result of crystal packing
(bottom). Nonpolar hydrogen atoms have been omitted for clarity.
Hydrogen bonds are represented as dashed lines.
structure of the pyridine-strapped macrocycle 13 (Figure 3) re-
veals the existence of an intramolecular coordinative interac-
tion between the pyridyl nitrogen atom and the zinc(II) cation
(ZnÀNpyr distance: 2.222(3) Š), which causes the strap to fold
inwards, inducing a parallel stacking arrangement between the
1,4-hydroquinone and 3,5-pyridine bis(amide) moieties.
A
saddle distortion of the porphyrin unit is also apparent. For
the N-methylpyridinium-strapped macrocycle 14·Cl, it is not
possible for an analogous intramolecular pyridine–zinc inter-
action to occur, and the axial coordination site is instead
occupied by a pyridine solvate molecule, which ligates to the
outer face of the porphyrin unit (ZnÀNpyr distance: 2.136(4) Š;
Figure 4). The macrocycle’s 3,5-pyridinium bis(amide) group
adopts a syn–syn conformation and the chloride counteranion
is held within the resultant binding cleft by three short NH···Cl
and CH···Cl contacts (N···Cl distances: 3.348(1) and 3.233(1) Š;
C···Cl distance: 3.231(2) Š). Examination of the crystal packing
reveals that the pyridinium macrocycle 14·Cl forms a head-to-
tail dimer in the solid state. Each dimeric unit appears to be
stabilised by two complementary intermolecular aromatic
stacking interactions between the pyridinium and porphyrin
groups, in addition to four NH···O amide–amide hydrogen
bonds.
Scheme 3. Synthesis of the [2]catenanes 16·Cl and 16·PF6. Reagents and
conditions: i) Et3N, CH2Cl2, RT, 2 h, 30%; ii) AgNO3, DMSO/H2O, RT, 45 min;
iii) NH4PF6(aq), 73%.
Synthesis of strapped-porphyrin-containing [2]catenane
Condensation of the bis(amine) derivative 15[28] with
3,5-bis(chlorocarbonyl) pyridine 10 in the presence of the
pyridinium-strapped porphyrin macrocycle 14·Cl in CH2Cl2 af-
forded the [2]catenane 16·Cl in 30% yield after purification by
preparative TLC and recrystallisation (Scheme 3). The chloride
anion template was removed by stirring compound 16·Cl with
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AgNO3 in 95:5 DMSO/H2O, before precipitation of the hexa-
of secondary aromatic-donor–acceptor interactions between
the electron-rich hydroquinone groups in the neutral macrocy-
cle and the electron-deficient pyridinium component of the
charged macrocycle.[30] In addition, a number of through-space
interactions between the two interlocked macrocyclic compo-
nents of the catenane were observed by 2D 1H NMR ROESY
spectroscopy in CD2Cl2 and [D6]DMSO, which provided further
supportive evidence for the interlocked nature and proposed
solution conformation of the [2]catenane (see the Supporting
Information, Figures S20 and S24).
fluorophosphate salt 16·PF6 in 73% yield by addition of
NH4PF6(aq)
.
[2]Catenane characterisation
The [2]catenanes 16·Cl and 16·PF6 were fully characterised by
1
electrospray mass spectrometry and H and 13C NMR spectros-
copy techniques in solution, and by X-ray crystallography in
1
the solid state. The H NMR spectrum of the [2]catenane 16·Cl
Single crystals of the [2]catenanes 16·Cl and 16·PF6 that
were suitable for X-ray structural determination were grown by
layered diffusion of hexane into a CH2Cl2/MeOH solution of the
chloride salt 16·Cl, and by layered diffusion of diisopropyl
ether into an acetone solution of the hexafluorophosphate salt
16·PF6. In both cases, the crystals were small and weakly
diffracting, and X-ray diffraction data were collected by using
synchrotron radiation.
in CD2Cl2 is compared with that of non-interlocked 3,5-pyridine
bis(amide)-functionalised macrocycle 17[29] in Figure 5.
The crystal structure of the chloride-complexed catenane
16·Cl (Figure 6) confirms the existence of an intercomponent
pyridine–zinc coordinative bond in the solid state (ZnÀNpyr dis-
tance: 2.138(2) Š). The chloride anion is encapsulated within
the pseudo-octahedral interlocked binding cavity defined by
the orthogonally disposed 3,5-pyridinium bis(amide) and 3,5-
pyridine bis(amide) moieties. The hydrogen atoms from each
of the six aromatic CH and amide NH hydrogen-bond-donor
groups are directed towards the encapsulated chloride anion,
and six short X···Cl (X=C, N) contacts are observed, with X···Cl
distances ranging from 3.285 to 3.353(2) Š and XÀH···Cl angles
ranging from 159 to 1808. A parallel donor–acceptor–donor
aromatic stacking arrangement between the electron-rich 1,4-
1
Figure 5. Partial H NMR spectra (500 MHz) of macrocycle 17 (top spectrum)
and the [2]catenane 16·Cl (bottom spectrum) in CD2Cl2 at 293 K.
A dramatic >6 ppm upfield shift in the signal for the aro-
matic ortho pyridine proton a is observed upon incorporation
of macrocycle 17 into the [2]catenane, with concomitant 0.3–
1.2 ppm upfield shifts in the signals corresponding to the para
pyridine proton b and aliphatic CH2 protons d and e. This indi-
cates that the pyridyl group is located within the shielding
region created by the porphyrin ring currents, and therefore
strongly suggests that the [2]catenane is stabilised by an inter-
component pyridine–zinc interaction in solution. In contrast,
the resonance for amide proton c shifts downfield, which is
consistent with the pyridine bis(amide) group participating in
NH···Cl hydrogen-bonding interactions with the chloride anion,
since these interactions would be expected to polarise the
amide NH bonds. The pronounced upfield shift and splitting of
the resonances for hydroquinone protons f and g is diagnostic
Figure 6. Solid-state structures of the [2]catenane 16·Cl (top) and the [2]cat-
enane 16·PF6 (bottom). Solvent molecules and nonpolar hydrogen atoms
have been omitted for clarity. Hydrogen bonds are represented as dashed
lines.
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hydroquinone and electron-deficient pyridinium motifs is also
observed, with centroid-to-centroid distances of 3.493 and
3.822 Š.
fast-exchange complexation of the chloride anion within the
[2]catenane’s interlocked binding domain. A 1:1 stoichiometric
association constant of K=2144(149) mÀ1 was determined by
analysis of the chloride-concentration-dependent shifts of the
external pyridinium proton 16 with WinEQNMR2[32] software
(Figure 8). In contrast, comparable titration experiments using
The diffraction data obtained for the hexafluorophosphate
catenane 16·PF6 were unusually weak and the structure was
found to incorporate a significant degree of disorder, necessi-
tating the use of extensive restraints during minimisation. Nev-
ertheless, it is evident from the structure that the conformation
of the hexafluorophosphate catenane 16·PF6 is largely un-
changed from that of the chloride catenane 16·Cl in the solid
state (Figure 6). In the absence of an encapsulated chloride
anion, the pyridine–zinc coordinative bond and approximate
interlocked co-conformation of the two macrocycles are
preserved, but the 3,5-pyridinium bis(amide) and 3,5-pyridine
bis(amide) groups adopt a syn–anti conformation, which is sta-
bilised by two intercomponent NH···O amide–amide hydrogen
bonds. The hexafluorophosphate counteranion is not involved
in short contacts with the hydrogen-bond-donor groups from
either of the bis(amide) motifs, which is in accordance with its
assumed non-coordinating role.[31]
Figure 8. Changes in the chemical shift of the pyridinium proton 16 on addi-
tion of the TBAX salts (X=ClÀ, BrÀ and IÀ) to 1.5 mm solutions of compound
16·PF6 in [D6]DMSO at 298 K. Square data points represent experimental
data; continuous line represents the calculated binding curve for
Halide recognition and sensing experiments
Encouraged by the crystallographic evidence that the chloride
counteranion is encapsulated within the interlocked binding
cavity of the [2]catenane 16·Cl in the solid state, we employed
1H NMR, UV/Vis and fluorescence spectroscopic titration experi-
ments to investigate the ability of the [2]catenane host system
to recognise and sense halide anions in solution.
K=2144mÀ1
.
TBAI and TBABr salts produced no convincing evidence of
a binding interaction between the larger halide anions and the
catenane’s interlocked cavity. Addition of up to 10 equivalents
of TBABr and TBAI to a [D6]DMSO solution of the catenane re-
sulted in only slight (Ddꢀ0.11 ppm) perturbations in the
1H NMR signals for the cavity protons 14, 15 and c (Figure 8),
which could not be definitively assigned to a binding event.
The [2]catenane host system 16·PF6 therefore appears to dis-
play an impressive selectivity for chloride over bromide and
iodide anions in DMSO, which may reflect an optimal
host–guest complementarity relationship between the chloride
anion and the catenane’s preorganised hydrogen-bond-
donating binding pocket.[33]
1H NMR titration experiments
Addition of an increasing concentration of tetrabutylammoni-
um (TBA) chloride to a 1.5 mm solution of compound 16·PF6 in
1
[D6]DMSO induced progressive shifts in the H NMR signals for
protons 14, 15 and c (Figure 7), which is consistent with
UV/Vis and fluorescence experiments
UV/Vis and fluorescence spectroscopic titration experiments re-
vealed that the [2]catenane exhibits modest optical chloride-
sensing capabilities: upon titration of TBACl into solutions of
the catenane in DMSO a gradual hypsochromic shift of approx-
imately 1 nm was observed in the Soret band absorbance,
with the formation of a single isosbestic point at 418.5 nm,[34]
along with approximately 9 and 4% increases in the intensities
of the emission maxima at 595 nm and 650 nm, respectively
(Figure 9). Analysis of the UV/Vis titration data by using
Specfit[35] software revealed a 1:1 stoichiometric association
constant of logK=3.38Æ0.04 (K=2396mÀ1), which is in good
1
agreement with the value determined by H NMR spectrosco-
1
Figure 7. Partial H NMR spectra of a 1.5 mm solution of the [2]catenane
py. By comparison, addition of increasing concentrations of
TBABr and TBAI to DMSO solutions of the catenane produced
16·PF6 in [D6]DMSO at 293 K after addition of a) 0, b) 1 and c) 5 equivalents
of TBACl.
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Experimental Section
All solvents and reagents were purchased from commercial suppli-
ers and used as received, unless otherwise stated. Dry solvents
were obtained by purging with N2 and then passing through an
MBraun MPSP-800 column. H2O was deionised and microfiltered by
using a Milli-Q Millipore machine. Et3N was distilled and stored
over KOH. TBA salts were stored in a vacuum desiccator containing
1
P2O5 prior to use. H, 13C, 19F and 31P NMR spectra were recorded
on a Varian Mercury-VX 300, a Varian Unity Plus 500, a Bruker
AVD500 or a Bruker AVII500 with cryoprobe at 293 K. Chemical
shifts are quoted in parts per million relative to the residual solvent
peak. Mass spectra were obtained by using a Micromass LCT
(ESMS) instrument or a MALDI Micro MX instrument. Electronic
absorption spectra were recorded on a PG instruments T60U
spectrometer.
X-ray crystallography
Single crystal diffraction data for compounds 3b and Zn·3a were
collected at 150(2) K using graphite monochromated MoKa
radiation (l=0.71073 Š) on a Nonius Kappa CCD diffractometer.
Cell parameter determination and refinement and raw frame data
integration were carried out by using the DENZO-SMN package.[36]
Diffraction data for compounds 13, 14·Cl, 16·Cl and 16·PF6 were
collected at 100(2) K by using silicon double crystal monochromat-
ed synchrotron radiation (l=0.68890 Š) at Diamond Light Source,
beamline I19,[37] with a custom-built Rigaku diffractometer.[38] Cell
parameter determination and refinement and raw frame data inte-
gration were carried out by using the CrysAlisPro[39] package. The
structures were solved by charge-flipping methods using SUPER-
FLIP[40] and refined by full matrix least squares on F2 using the
CRYSTALS[41] suite. All non-hydrogen atoms were refined with ani-
sotropic displacement parameters. Where appropriate, disordered
regions were modelled by using refined partial occupancies, geo-
metric restraints were applied to ensure a physically reasonable
model, and thermal and vibrational restraints were applied to
maintain sensible ADPs; in addition, when present, diffuse disor-
dered solvent and counteranions were modelled by treating the
discrete Fourier transform of the void region as contributions to
the calculated structure factors with PLATON/SQUEEZE.[42] Hydro-
gen atoms were generally visible in the difference map and were
treated in the conventional manner.[43] CCDC 1412108–1412113
contain the supplementary crystallographic data (excluding struc-
ture factors) for this paper. These data are provided free of charge
by The Cambridge Crystallographic Data Centre.
Figure 9. a) Changes in the Soret band absorbance of a 2 mm solution of the
[2]catenane 16·PF6 in DMSO upon addition of an increasing concentration of
TBACl (final TBACl concentration: 4.9 mm). Inset: change in absorbance at
420 nm as a function of [TBACl]; square data points represent experimental
data; continuous line represents the calculated binding curve for
K=2396mÀ1. b) Changes in the fluorescence emission spectrum of a 40 mm
solution of the the [2]catenane 16·PF6 in DMSO upon addition of an
increasing concentration of TBACl (final TBACl concentration: 6.1 mm).
lex =548 nm. Inset: change in emission at 600 nm as a function of [TBACl].
no discernible shifts in the maximum of the Soret band ab-
sorbance and only slight, random fluctuations in the intensities
of the fluorescence emission spectra (see the Supporting Infor-
1
mation, Figures S27 and S28), which corroborates the H NMR
evidence that these larger halides do not significantly interact
with the [2]catenane host system in DMSO.
Synthetic procedures and characterisation data
The syntheses of the known compounds 2[18] and 4–7[13a,44] are de-
scribed in the supporting information. Compounds 1,[19] 15[28] and
17[29] were prepared by slight modification of previously reported
procedures.
Conclusions
A new strapped-porphyrin-containing [2]catenane anion-host
system was prepared through an amide-condensation-based
clipping reaction, which was directed by chloride anion tem-
plation in combination with pyridine–zinc ligation and aromat-
ic donor–acceptor interactions. Upon removal of the halide
template, the catenane was shown to selectively recognise
chloride (K=2144(149) mÀ1) over larger halide anions in the
competitive solvent [D6]DMSO. The [2]catenane also exhibits
a modest ability to optically sense chloride anions in DMSO
through small but detectable changes in the absorption and
emission spectra of the porphyrin chromophore.
a,a- and a,b-Bis(amino)porphyrins 3a and 3b: 5,15-Bis-(2-nitro-
phenyl)porphyrin 2 (0.47 g, 0.84 mmol) was suspended in 37%
HCl(aq) (35 mL). The mixture was sonicated briefly and then stirred
at room temperature for 20 min. SnCl2·2H2O (0.10 g, 4.42 mmol)
was added and the reaction mixture was stirred vigorously under
N2 for 16 h. After cooling to 08C, saturated NH4OH(aq) was added
cautiously until the pH reached 7. CH2Cl2 (30 mL) was added. The
mixture was stirred vigorously at room temperature for 30 min and
then transferred to a separating funnel. The layers were separated
and the aqueous layer was extracted with CH2Cl2 (3”25 mL). The
combined CH2Cl2 extracts were washed with H2O (2”50 mL), dried
Chem. Eur. J. 2015, 21, 17664 – 17675
www.chemeurj.org
17670 ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
over MgSO4 and concentrated on a rotary evaporator to give
a purple solid, which contained a mixture of the a,a- and a,b-bis(a-
mino)porphyrin derivatives 3a and 3b. This atropisomeric mixture
was separated by column chromatography. The a,b-isomer 3b was
eluted with 98:2 CH2Cl2/EtOAc and obtained as a purple solid
(0.165 g, 40%). 9:1 CH2Cl2/EtOAc was then used to elute the a,a-
isomer 3a, which was also obtained as a purple solid (0.152 g,
37%).
Ethyl 2-(4-{2-[(tert-butoxycarbonyl)amino]ethoxy}phenoxy)ace-
tate 8: tert-Butyl[2-(4-hydroxyphenoxy)ethyl]carbamate 7 (0.75 g,
2.96 mmol) was dissolved in dry THF (100 mL) and NaH (0.148 g of
a 60% dispersion in mineral oil, 3.70 mmol) was added. The mix-
ture was stirred at room temperature under N2 for 20 min. Ethyl
bromoacetate (0.99 g, 0.66 mL, 5.92 mmol) was added and the re-
action mixture was heated to 508C, and maintained at this temper-
ature under N2 for 18 h, before being cooled to room temperature,
diluted with H2O (30 mL) and extracted with CH2Cl2 (4”30 mL).
The combined organic extracts were washed with brine (50 mL),
dried over MgSO4 and concentrated under reduced pressure. Purifi-
cation of the residue by column chromatography (2% MeOH in
CH2Cl2) afforded the product as a viscous, pale yellow oil (0.95 g,
94%). 1H NMR (300 MHz; [D6]acetone) : d=6.87–6.83 (m, 8H, hy-
droquinone-ArÀH), 6.14 (br s, 1H, NH), 4.63 (s, 2H, OCH2CO2Et),
4.19 (quartet, 3J=7.0 Hz, 2H, CH2CH3), 3.98 (t, 3J=5.58 Hz, 2H,
OCH2CH2NH) 3.45–3.39 (m, 2H, OCH2CH2NH), 1.40 (s, 9H, tBu-CH3),
1.24 ppm (t, 3J=7.0 Hz, 3H, CH2CH3); 13C NMR (75 MHz;
[D6]acetone): d=169.7, 156.8, 154.5, 153.4, 116.5, 116.2, 78.8, 68.2,
66.5, 61.4, 40.8, 28.7, 14.5 ppm; ESMS m/z: 362.15 ([M+Na]+;
C17H25NNaO6 requires 362.16); 701.32 ([2M+Na]+; C34H50N2NaO12
requires 701.33); HRMS m/z: 362.1569. ([M+Na]+; C17H25NNaO6
requires 362.1572).
Characterisation data for a,a-5,15-bis(2-aminophenyl)porphyrin
1
3a: H NMR (500 MHz; CDCl3): d=10.31 (s, 2H, porphyrin-meso-H),
3
3
9.41 (d, J=4.6 Hz, 4H, b-pyrrole-H), 9.12 (d, J=4.6 Hz, 4H, b-pyr-
role-H), 7.97 (d, 3J=8.2 Hz, 2H, ArÀH), 7.67–7.64 (m, 2H, ArÀH),
3
7.25–7.22, (m, 2H, ArÀH), 7.17 (d, J=8.2 Hz, 2H, ArÀH), 3.56 (br s,
4H, NH2), À3.15 ppm (br s, 2H, pyrrole-NH); 13C NMR (75 MHz;
CDCl3): d=147.3, 146.9, 145.6, 134.8, 132.0, 130.8, 129.7, 126.3,
117.7, 115.3, 114.9, 105.0 ppm; UV/vis (CH2Cl2): lmax (e)=405
(250000), 501 (18000), 536 (5000), 574 (6000), 628 nm
(1500 molÀ1 m3 cmÀ1); ESMS m/z: 493.21 ([M+H]+; C32H25N6 re-
quires 493.21); HRMS m/z: 493.2133 ([M+H]+; C32H25N6 requires
493.2135).
Characterisation data for a,b-5,15-bis(2-aminophenyl)porphyrin
1
3b: H NMR (500 MHz; CDCl3): d=10.31 (s, 2H, porphyrin-meso-H),
3
3
9.40 (d, J=3.8 Hz, 4H, b-pyrrole-H), 9.12 (d, J=3.8 Hz, 4H, b-pyr-
role-H), 7.92 (d, 3J=7.6 Hz, 2H, ArÀH), 7.67–7.64 (m, 2H, ArÀH),
Ethyl 2-[4-(2-aminoethoxy)phenoxy]acetate hydrochloride 9·HCl:
Ethyl 2-(4-{2-[(tert-butoxycarbonyl)amino]ethoxy}phenoxy)acetate 8
was dissolved in Et2O (25 mL). Gaseous HCl was bubbled slowly
through the solution for a period of 2 h, during which time a white
precipitate formed. The mixture was then stirred at room tempera-
ture under N2 for an additional 2 h. The precipitate was collected
by filtration, washed with Et2O (5”5 mL) and dried under vacuum
to afford the product as a white solid (0.75 g, 97%). 1H NMR
(300 MHz; [D6]DMSO): d=8.12 (br s, 3H, NH3·Cl), 6.94–6.87 (m, 4H,
hydroquinone-ArÀH), 4.71 (s, 2H, OCH2CO2Et), 4.15 (quartet, 3J=
3
7.24–7.21, (m, 2H, ArÀH), 7.18 (d, J=8.2 Hz, 2H, ArÀH), 3.59 (br s,
4H, NH2), À3.16 ppm (br s, 2H, pyrrole-NH); ESMS m/z: 493.22
([M+H]+; C32H25N6 requires 493.21; UV/vis (CH2Cl2): lmax (e)=405
(268000), 502 (19000), 536 (5500), 574 (6000), 629 nm
(1000 molÀ1 m3 cmÀ1); HRMS m/z: 493.2134 ([M+H]+; C32H25N6 re-
quires 493.2135). Single crystals suitable for X-ray structural deter-
mination were grown by slow evaporation from CH2Cl2. Single crys-
tal data: C32H24N6, Mr=492.57; monoclinic, P21/c; a=8.5216(2),
b=10.9750(3), c=13.7764(4) Š; a=g=908, b=102.6958(14)8; V=
1256.96(6) Š3; data/restraints/parameters: 2399/0/172; Rint =0.024;
3
7.0 Hz, 2H, CH2CH3), 4.10 (t, J=5.3 Hz, 2H, OCH2CH2NH), 3.19–3.15
(br m, 2H, OCH2CH2NH), 1.20 ppm (t, 3J=7.0 Hz, 3H, CH2CH3);
13C NMR (75 MHz; [D6]DMSO) : d=168.9, 152.4, 152.1, 115.7, 115.5,
65.2, 64.8, 60.6, 38.3, 14.1 ppm; ESMS m/z: 240.12 ([MÀCl]+;
C12H18NO4 requires 240.12); 262.10 ([MÀHCl+Na]+; C12H17NaNO4
requires 262.11); HRMS m/z: 240.1236 ([MÀCl]+; C12H18NO4 requires
240.1230).
final R1 =À03.047 (I>2s(I)); wR2 =0.118 (I>2s(I)); D1min max
,
=À0.24,
+0.35 eŠ
.
ZnII a,a-bis(amino)porphyrin Zn·3a: The a,a-bis(amino)porphyrin
3a (0.15 g, 0.30 mmol) was dissolved in CH2Cl2 (25 mL) and a solu-
tion of Zn(OAc)2·2H2O (0.33 g, 1.52 mmol) in MeOH (25 mL) was
added. The solution was stirred at room temperature under nitro-
gen for 18 h, before being concentrated on a rotary evaporator
without applying heat. The residual solid was dissolved in DMF
(2 mL) and H2O (40 mL) was added. The resulting precipitate was
collected by filtration, washed with H2O (8”15 mL) followed by
MeOH (2”2.5 mL) and dried under high vacuum. After recrystalli-
zation (CH2Cl2/hexane), the product was obtained as a pink/purple
Compound 11: 3,5-Pyridinedicarboxylic acid (0.197 g, 1.18 mmol)
was suspended in dry CH2Cl2 (30 mL). Oxalyl chloride (0.75 g,
0.50 mL, 5.89 mmol) and DMF (1 drop) were added. The mixture
was stirred at room temperature under N2 for 18 h, by which time
it had formed a homogenous solution. The solvent was removed
on a rotary evaporator and the residue dried under high vacuum
for 60 min to afford 3, 5-bis(chlorocarbonyl) pyridine 10 as a waxy,
off-white solid, which was redissolved in dry CH2Cl2 (20 mL). The
solution was cooled to 08C in an ice bath and a solution of 9·HCl
in dry CH2Cl2 (20 mL) and dry Et3N (2.5 mL) was added dropwise by
syringe. After addition was complete, the reaction mixture was
stirred at 08C under N2 for 15 min. The ice bath was then removed
and the reaction mixture was allowed to stir at room temperature
for 18 h. The solution was washed with 10% citric acid(aq) (2”
50 mL), followed by saturated NaHCO3(aq) (2”50 mL) and H2O
(50 mL). The organic layer was dried over MgSO4 and concentrated
under reduced pressure. Purification of the residue by column
chromatography (2–4% MeOH in CH2Cl2 afforded the product as
1
solid (0.15 g, 91%). H NMR (300 MHz; [D6]DMSO): d=10.29 (s, 2H,
meso-H), 9.46 (d, 3J=4.7 Hz, 4H, b-pyrrole-H), 8.93 (d, 3J=4.7 Hz,
3
4
4H, b-pyrrole-H), 7.77 (dd, J=7.3 Hz, J=1.5 Hz, 2H, meso-ArÀH),
7.58–7.53 (m, 2H, meso-ArÀH), 7.16 (d, 3J=7.6 Hz, meso-ArÀH),
7.09–7.04 (m, 2H, meso-ArÀH), 4.36 ppm (s, 4H, NH2); 13C NMR
(75 MHz; [D6]DMSO): d=149.5, 149.0, 148.2, 148.1, 134.3, 132.2,
131.4, 129.0, 126.7, 115.6, 115.4, 114.6, 105.6 ppm; ESMS m/z:
555.15 ([M+H]+; C32H23N6Zn requires 555.13); HRMS m/z 555.1280
([M+H]+; C32H23N6Zn requires 555.1270); UV/vis (CH2Cl2): lmax (e)=
406 (107000), 535 (7000), 570 nm (2000 molÀ1 m3 cmÀ1). Single crys-
tals of the methanol solvate suitable for X-ray structural determina-
tion were grown by slow evaporation from CH2Cl2/MeOH. Single
1
¯
crystal data: C33H26N6OZn, Mr=587.99; triclinic, P1, a=10.3352(2),
a white solid (0.52 g, 73%). H NMR (500 MHz; CDCl3): d=9.14 (d,
4
b=11.5808(2), c=12.3227(3) Š; a=75.5368(8), b=69.8504(9), g=
88.4691(10)8; V=1337.91(5) Š3; data/restraints/parameters: 5470/0/
388; Rint =0.022; final R1 =À03.032 (I>2s(I)); wR2 =0.066 (I>2s(I));
4J=2.2 Hz, 2H, py-ArÀH), 8.48 (t, J=2.2 Hz, 1H, py-ArÀH), 6.80 (t,
3J=5.6 Hz, 2H, amide-NH), 6.87–6.83 (m, 8H, ArÀH), 4.55 (s, 4H,
OCH2CO2Et), 4.25 (quartet, 3J=7.1 Hz, 4H, CH2CH3), 4.10 (t, 3J=
5.1 Hz, 4H, NHCH2CH2O), 3.88–3.85 (m, 4H, NHCH2CH2O), 1.26 ppm
D1min max
,
=À0.52, +0.50 eŠ
.
Chem. Eur. J. 2015, 21, 17664 – 17675
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17671 ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
(t, 3J=7.1 Hz, 6H, CH2CH3); 13C NMR (75 MHz; CDCl3): d=169.2,
165.0, 153.2, 152.4, 150.7, 133.6, 129.7, 115.8, 115.4, 66.9, 66.1, 61.4,
MeI was removed on a rotary evaporator. The remaining DMF solu-
tion was diluted with CH2Cl2 (100 mL) and then washed with 1m
NH4Cl(aq) (6”75 mL) followed by H2O (2”75 mL). After concentra-
tion of the organic layer under reduced pressure, and recrystallisa-
tion of the residual solid (CH2Cl2/MeOH/hexane), the product was
obtained as a purple solid (0.11 g, 99%). 1H NMR (500 MHz,
+
39.8, 14.1 ppm; ESMS m/z: 632.21 ([M+Na]+; C31H35N3NaO10
requires 632.22); 1241.47 ([2M+Na]+; C62H70N6NaO20 requires
1241.45); HRMS m/z: 632.2216 ([M+Na]+; C31H35N3NaO10 requires
632.2215).
3
[D6]DMSO): d=10.42 (s, 2H, porphyrin-meso-H), 9.48 (d, J=4.4 Hz,
Compound 12: Compound 11 (0.50 g, 0.82 mmol) was dissolved in
CH2Cl2 (40 mL) and MeOH (40 mL). A solution of KOH (0.18 g,
3.28 mmol) in H2O (7 mL) was added. The solution was stirred at
RT under N2 for 60 h, during which time a white precipitate
formed. H2O (40 mL) was added and the organic solvents were re-
moved on a rotary evaporator. The pH of the remaining aqueous
suspension was adjusted to 7 by addition of 10% citric acid(aq) and
the solid was collected by filtration, washed with H2O (4”15 mL),
MeOH (3”5 mL) and CH2Cl2 (3”10 mL) and dried under high
vacuum to afford the product as a white solid (0.40 g, 88%).
1H NMR (300 MHz; [D6]DMSO): d=9.06 (d, 4J=2.2 Hz, 2H, py-ArÀ
4H, porphyrin-b-pyrrole-H), 9.40 (s, 2H, pyridinium-ArÀH), 9.14 (br
3
s, 2H, amide-NH), 8.99 (s, 1H, pyridinium-ArÀH), 8.75 (d, J=4.4 Hz,
4H, porphyrin-b-pyrrole-H), 8.57 (d, 3J=9.2 Hz, 2H, porphyrin-
meso-ArÀH), 8.34 (s, 2H, amide-NH), 8.03 (d, 3J=7.6 Hz, 2H, por-
phyrin-meso-ArÀH), 7.90–7.86 (m, 2H, porphyrin-meso-ArÀH), 7.62–
3
7.58 (m, 2H, porphyrin-meso-ArÀH), 6.30 (d, J=9.0 Hz, 4H, hydro-
quinone-ArÀH), 5.29 (d, 3J=9.0 Hz, 4H, hydroquinone-ArÀH), 4.30
3
(s, 3H, methylpyridinium-CH3), 3.98 (t, J=4.8 Hz, 4H, CH2), 3.80 (s,
4H, CH2), 3.69–3.66 ppm (m, 4H, CH2); 13C NMR (125 MHz;
[D6]DMSO): d=166.5, 161.3, 152.6, 150.1, 149.4, 149.2, 147.1, 140.3,
137.6, 135.2, 133.2, 132.8, 132.7, 131.0, 128.9, 123.1, 121.0, 114.9,
114.4, 113.1, 106.3, 66.6, 66.4, 48.4 ppm, one 13C signal is coincident
with [D6]DMSO; ESMS m/z: 1086.32 ([MÀCl]+; C60H48N9O8Zn re-
quires 1086.29); HRMS m/z: 1086.2929 ([MÀCl]+; C60H48N9O8Zn re-
quires 1086.2912). Single crystals of the pyridine solvate suitable
for X-ray structural determination were grown by layered diffusion
of hexane into a CH2Cl2/MeOH/pyridine solution of the macrocycle.
Single crystal data: C65H53N10O8Zn·Cl, Mr=1203.03; monoclinic, P21/
c; a=10.1084(3), b=21.8767(7), c=31.8505(12) Š; a=g=908, b=
4
H), 8.98 (t, 3J=5.3 Hz, 2H, amide-NH), 8.57 (t, J=2.2 Hz, 1H, py-
ArÀH), 6.85 (d, 3J=9.1 Hz, 4H, hydroquinone-ArÀH), 6.75 (d, 3J=
9.1 Hz, 4H, hydroquinone-ArÀH), 4.38 (s, 4H, OCH2CO2H), 4.07 (t,
3J=5.3 Hz, 4H, OCH2CH2NH), 3.64–3.59 ppm (m, 4H, OCH2CH2NH);
ESMS m/z: 554.16 (M+H]+; C27H28N3O10 requires 554.18); 576.15
([M+Na]+; C27H27N3NaO10 requires 576.16); HRMS m/z: 576.1641
([MÀH]À; C27H26N3O10 requires 552.1624).
3,5-Pyridine bis(amide)-strapped porphyrin macrocycle 13: Dry,
de-gassed DMF was added to a flask containing Zn·3a (0.14 g,
0.25 mmol), compound 12 (0.14 g, 0.25 mmol), N-(3-dimethylami-
nopropyl)-N’-ethylcarbodiimide hydrochloride (0.12 g, 0.63 mmol),
1-hydroxybenzotriazole hydrate (0.077 g, ca. 0.57 mmol) and 4-(di-
methylamino)pyridine (0.030 g, 0.25 mmol). The mixture was soni-
cated briefly and then stirred vigorously at room temperature
under N2 for 60 h. After removal of the solvent under reduced
pressure, the residual solid was dissolved in 9:1 CH2Cl2/MeOH mix-
ture (100 mL), dry-loaded onto silica and purified by column chro-
matography (1–5% MeOH in CH2Cl2) to afford the product as
a purple solid (0.12 g, 44%). 1H NMR (500 MHz; [D6]DMSO): d=
90,349(3)8;
11 350/0/766; Rint =0.100; final R1 =À03.077 (I>2s(I)); wR2 =0.182
(I>2s(I)); D1min max
=À0.61, +0.51 eŠ
V=7043.2(4) Š3;
data/restraints/parameters:
,
.
Chloride catenane 16·Cl: 3,5-Pyridinedicarboxylic acid (0.014 g,
0.081 mmol) was suspended in dry CH2Cl2 (3 mL). Oxalyl chloride
(0.051 g, 0.034 mL, 0.41 mmol) and DMF (1 drop) were added and
the mixture was stirred at room temperature under N2 until it had
formed a homogenous solution (2.5 h). After removal of the sol-
vent on a rotary evaporator, the residual off-white solid was dried
under high vacuum for 3 h and then re-dissolved in dry CH2Cl2
(2.5 mL). Et3N (0.041 g, 0.057 mL, 0.41 mmol) was added and the
solution was added dropwise to a solution of compound 15
(0.038 g, 0.081 mmol) and macrocycle 14·Cl (0.040 g, 0.032 mmol)
in dry CH2Cl2 (10 mL). The reaction mixture was stirred at room
temperature under N2 for 90 min, then diluted with CH2Cl2 (5 mL).
The solution was washed sequentially with H2O (10 mL), saturated
NaHCO3(aq) (10 mL) and brine (10 mL), dried over MgSO4 and con-
centrated on a rotary evaporator. The residue was purified by prep-
arative thin layer chromatography (SiO2; 8% MeOH in CH2Cl2, then
5% MeOH in EtOAc) and recrystallisation (CH2Cl2/MeOH, then
CH2Cl2/MeOH/hexane) to give the product as a purple solid
3
10.43 (s, 2H, porphyrin-meso-H), 9.51 (d, J=4.4 Hz, 4H, porphyrin-
3
b-pyrrole-H), 8.83 (d, J=4.4 Hz, 4H, porphyrin-b-pyrrole-H), 8.70 (s,
3
2H, amide-NH), 8.60 (d, J=8.3 Hz, 2H, ArÀH), 8.46 (s, 2H, py-ArÀ
3
H), 8.43 (br t, 2H, amide-NH), 8.15 (s, 1H, py-ArÀH), 8.04 (dd, J=
7.3 Hz, 4J=1.5 Hz, 2H, ArÀH), 7.93–7.89 (m, 2H, ArÀH), 7.65–7.61
(m, 2H, ArÀH), 6.21 (d, 3J=9.0 Hz, 4H, hydroquinone-ArÀH), 5.28
(d, 3J=9.0 Hz, 4H, hydroquinone-ArÀH), 3.92 (t, 3J=4.9 Hz, 4H,
OCH2CH2NH), 3.76 (s, 4H, OCH2CONH), 3.56–3.53 ppm (m, 4H,
OCH2CH2NH); 13C NMR (75 MHz, [D6]DMSO): d=166.5, 164.6, 152.7,
150.2, 150.1, 149.4, 149.3, 137.6, 135.3, 133.2, 133.1, 132.8, 131.0,
129.1, 128.9, 123.1, 121.1, 114.9, 114.5, 113.2, 106.3, 66.7, 66.6 ppm,
one 13C signal is coincident with [D6]DMSO; ESMS m/z: 1094.29
([M+Na]+; C59H45N9NaO8Zn requires 1094.26); HRMS m/z:
1094.2452 ([M+Na]+; C59H45N9NaO8Zn requires 1094.2575). Single
crystals suitable for X-ray structural determination were grown by
layered diffusion of hexane into a CH2Cl2/MeOH solution of the
macrocycle. Single crystal data: C59H45N9O8Zn·CH2Cl2, Mr=1158.37;
1
(0.017 g, 30%). H NMR (500 MHz; [D6]DMSO): d=10.34 (s, 2H, por-
phyrin-meso-H), 9.52 (d, 3J=4.6 Hz, 4H, porphyrin-ß-pyrrole-H),
9.04 (s, 1H, pyridinium-ArÀH), 8.97 (s, 2H, pyridinium-ArÀH), 8.96
3
(s, 2H, amide-NH), 8.91 (d, 4H, J=4.6 Hz, porphyrin-ß-pyrrole-H),
8.52 (d, 3J=8.0 Hz, 2H, ArÀH), 8.31 (br s, 2H, amide-NH), 8.28 (s,
3
3
1H, py-ArÀH), 7.91 (t, J=8.0 Hz, 2H, ArÀH), 7.86 (d, J=7.4 Hz, 2H,
ArÀH), 7.72 (br s, 2H, amide-NH), 7.59 (t, 3J=7.4 Hz, 2H, ArÀH),
6.28 (d, 3J=9.0 Hz, 4H, hydroquinone-ArÀH), 6.14 (d, 3J=8.2 Hz,
4H, hydroquinone-ArÀH), 6.03 (d, 3J=9.0 Hz, 4H, hydroquinone-
ArÀH), 5.45 (d, 3J=8.2 Hz, 4H, hydroquinone-ArÀH), 4.47 (s, 3H,
methylpyridinium-CH3), 3.76 (br t, 4H, CH2), 3.72 (s, 4H, CH2), 3.56
(br t, 4H, CH2), 3.50–3.46 (m, 16H, CH2), 3.44–3.42 (m, 4H, CH2),
3.02–2.99 ppm (m, 4H, CH2), signal corresponding to the external
pyridinium proton 16 is not observed in [D6]DMSO owing to signal
broadening; 13C NMR (125 MHz; [D6]DMSO): d=166.4, 162.4, 159.9,
152.3, 152.2, 151.5, 150.3, 149.4, 149.2, 147.2, 145.8, 137.2, 136.0,
¯
triclinic, P1; a=14.0873(8), b=14.2958(7), c=15.5922(9) Š; a=
63.513(5), b=71.193(5), g=82.978(4)8; V=2659.6(3) Š3; data/re-
straints/parameters: 7853/0/721;
(I>2s(I)); wR2 =0.147 (I>2s(I)); D1min max
R
int =0.085; final R1À=3 0.057
,
=À0.77, +0.86 eŠ
.
3,5-Pyridinium bis(amide)-strapped porphyrin macrocycle 14·Cl:
Macrocycle 13 (0.105 g, 0.098 mmol) was dissolved in dry, de-
gassed DMF (6 mL). NaHCO3 (0.058 g, 0.68 mmol) was added, fol-
lowed by MeI (0.34 g, 0.15 mL, 2.41 mmol). The reaction mixture
was heated at 808C under N2 for 2 h, using a reflux condenser to
prevent loss of MeI. After cooling to room temperature, the excess
Chem. Eur. J. 2015, 21, 17664 – 17675
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17672 ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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134.2, 132.8, 132.1, 131.7, 131.2, 128.7, 126.7, 123.6, 122.9, 114.6,
114.4, 114.3, 114.0, 113.8, 106.2, 69.9, 69.8, 69.0, 67.3, 65.0,
48.6 ppm, one 13C signal is coincident with [D6]DMSO; ESMS m/z:
1681.49 ([MÀCl]+; C91H85N12O17Zn requires 1681.54); HRMS m/z:
1683.5339 ([MÀCl]+; C91H85N12O17Zn requires 1683.5419). Single
crystals suitable for X-ray structural determination were grown by
layered diffusion of hexane into a CH2Cl2/MeOH solution of the cat-
for collection of a preliminary single crystal data set and Prof.
Stephen Faulkner for the use of spectrometers.
Keywords: anion binding · catenanes · porphyrins · self-
assembly · supramolecular chemistry
enane.
Single
crystal
data:
C91H85N12O17Zn·2(CH2Cl2)·Cl,
¯
Mr=1889.44; triclinic, P1; a=14.5199(2), b=16.4604(2), c=
21.6127(4) Š; a=99.0338(12), b=104.2010(14), g=92.0154(11)8;
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V=4930.86(13) Š3; data/restraints/parameters: 15424/0/1153; Rint
=
0.025; final R1 =0.037 (I>2s(I)); wR2 =0.087 (I>2s(I));
À3
D1min,max
=À0.69, +0.90 eŠ
.
Hexafluorophosphate catenane 16·PF6: The chloride catenane
16·Cl (0.009 g, 0.005 mmol) was dissolved in DMSO (4 mL). The
flask was wrapped with foil to protect the contents from light and
a solution of AgNO3 (0.004 g, 0.026 mmol) in H2O (0.16 mL) was
added. After stirring at room temperature under N2 for 45 min, the
solution was filtered through a plug of celite and then added drop-
wise to 0.05m NH4PF6(aq) (60 mL), which resulted in the formation
of a purple precipitate. The precipitate was collected by filtration,
washed with H2O (6”7.5 mL), EtOH (3”2 mL) and hexane (3”
5 mL) and dried under vacuum to yield the product as a purple
solid (0.007 g, 73%). 1H NMR (500 MHz, [D6]DMSO): d=10.33 (s,
2H, porphyrin-meso-H), 9.49 (d, 3J=4.2 Hz, 4H, porphyrin-b-pyr-
role-H), 9.08 (s, 2H, pyridinium-ArÀH), 8.84–8.81 (m, 5H, 4 porphy-
rin-b-pyrrole-H+1 pyridinium-ArÀH), 8.72 (s, 2H, amide-NH), 8.63
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3
(br s, 2H, amide-NH), 8.49 (br s, 2H, amide-NH), 8.39 (d, J=8.0 Hz,
2H, porphyrin-meso-ArÀH), 8.32 (s, 1H, py-ArÀH), 7.93 (d, 3J=
6.9 Hz, 2H, porphyrin-meso-ArÀH), 7.88–7.85 (m, 2H, porphyrin-
3
meso-ArÀH), 7.61–7.58 (m, 2H, porphyrin-meso-ArÀH), 6.39 (d, J=
3
7.8 Hz, 4H, hydroquinone-ArÀH), 6.28 (d, J=8.0 Hz, 4H, hydroqui-
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3
none-ArÀH), 6.00 (d, J=8.0 Hz, 4H, hydroquinone-ArÀH), 5.87 (d,
3J=7.8 Hz, 4H, hydroquinone-ArÀH), 4.23 (s, 3H, methylpyridini-
um-CH3), 3.83–3.81 (m, 4H, CH2), 3.71–3.69 (m, 4H, CH2), 3.64 (s,
4H, CH2), 3.55–3.51 (m, 4H, CH2), 3.42–3.39 (m, 4H, CH2), 3.08–3.02
(m, 8H, CH2), 2.99–2.97 3.83–3.81 ppm (m, 4H, CH2); 19F NMR
(470 MHz, [D6]DMSO): d=À70.1 ppm (d, 2J(F,P)=711 Hz), 31P NMR
(203 MHz, [D6]DMSO): d=À144.2 ppm (septet, 2J(F,P)=711 Hz);
ESMS m/z: 1683.51 ([MÀPF6]+; C91H85N12O17Zn requires 1683.54).
Single crystals suitable for X-ray structural determination were
grown by layered diffusion of di-isopropyl ether into an acetone
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solution
of
the
catenane.
Single
crystal
data:
C91H85N12O17Zn·0.5(PF6), Mr=1756.59; tetragonal, P4/ncc; a=
41.5009(6), b=41.5009(6), c=24.4007(5) Š; a=b=g=908, V=
42025.9(15) Š3; data/restraints/parameters: 10933/3740/1415;
R
int =0.110; final R1 =0.091 (I>2s(I)); wR2 =0.237 (I>2s(I));
À3
D1min,max
=À0.51, +0.87 eŠ
.
Acknowledgements
We thank the Wellcome Trust and the European Research
Council (under the European Union’s 7th Framework Program;
FP7/2007-2013), ERC Advanced Grant Agreement (no. 267426)
for postdoctoral funding (A.B.) and the Engineering and Physi-
cal Sciences Research Council for studentships (A.B., M.J.L.).
N.L.K. thanks the Royal Commission for the Exhibition of 1851
for a Research Fellowship. We also thank Diamond Light
Source for an award of beam time on I19 (MT9981), the beam-
line scientists (Drs. David Allan, Harriott Nowell, Sarah Barnett
and Mark Warren) for technical support, Dr. Richard Knighton
Chem. Eur. J. 2015, 21, 17664 – 17675
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À
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1
the H NMR timescale at 500 MHz up to temperatures of at least 1508C,
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.
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Chem. Eur. J. 2015, 21, 17664 – 17675
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17675 ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim