The Topological and Chemical Implications of Introducing Oriented Rings to
[3]Catenanes
Ross S. Forgan, Anthea K. Blackburn, Megan M. Boyle, Severin T. Schneebeli,
and J. Fraser Stoddart*
Center for the Chemistry of Integrated Systems and Department of Chemistry,
Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (USA)
Supramolecular Chemistry Special Edition – ISMSC-8
REVISED VERSION
SUPPLEMENTARY INFORMATION
*Correspondence Address
Professor J Fraser Stoddart
Center for the Chemistry of Integrated Systems
Northwestern University
2145 Sheridan Road, Evanston, IL 60208 (USA)
UNITED STATES OF AMERICA
Tel: +1-847-467-3326
Fax: +1-847-491-1009
E-Mail: stoddart@northwestern.edu
Table of Contents
S1.
General Methods
S2
S2.
Synthesis
S3
S3.
Electrospray Ionization Mass Spectrometry
S6
S4.
Single Crystal X-Ray Diffraction Analysis of Monoazido[2]Catenane
S8
S5.
Single Crystal X-Ray Diffraction Analysis of Monoazido[3]Catenane
S10
S6.
Single Crystal X-Ray Diffraction Analysis of Bisazido[3]Catenane
S11
S7.
1H
S12
S8.
References
NMR Spectroscopy
S18
S1. General Methods
All chemicals and reagents were used as received from Sigma Aldrich. Bis-1,5dioxynaphtho[50]crown-14 (DN50C14) (S1), 4·2PF6 (S2), and 5·2PF6 (S3) were synthesized
according to literature procedures. Nuclear magnetic resonance (NMR) spectra were recorded
at 298 K unless otherwise stated on Bruker Avance 500 and 600 spectrometers, with working
frequencies of 500 and 600 MHz for 1H and 125 MHz for 13C. Chemical shifts are reported in
ppm relative to signals corresponding to residual non-deuterated solvents. All
13
C
experiments were performed with simultaneous decoupling of 1H nuclei. Electrospray
ionization (ESI) mass spectra were obtained on an Agilent 6210 LC-TOF high-resolution
mass spectrometer. X-Ray diffraction data for 1·4PF6 and 2·8PF6 were collected at 100 K on
a Bruker d8-Apex II fitted with a CCD area detector (CuKα, λ = 1.5418 Å). X-Ray
diffraction data for 3·8PF6 were collected at 100 K using a Bruker Apex Prospector fitted
with a CCD area detector (CuKα, λ = 1.5418 Å). Intensity data in all cases were collected
using ω and φ scans spanning at least a hemisphere of reciprocal space for all structures; data
were integrated using SAINT (S4). Absorption effects were corrected on the basis of multiple
equivalent reflections (SADABS). Using Olex2 (S5), structures were solved with the ShelXM
structure solution program (S6) using direct methods and refined with the ShelXL refinement
package (S6) using least squares minimization. Hydrogen atoms were assigned riding
isotropic displacement parameters and constrained to idealized geometries. CCDC
depositions 937910–937912 contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, by
S2
emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic
Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
S2. Synthesis
The azide-substituted catenanes were prepared (Scheme S1) by a high pressure self-assembly
protocol utilized previously in the synthesis of the analogous unsubstituted catenanes (S7).
Both the monoazido[2]catenane 1·4PF6 and the bisazido[3]catenane 3·8PF6 could be isolated
from the same reaction, and then 1·4PF6 was reacted further to produce the
monoazido[3]catenane 2·8PF6.
Scheme S1. Synthesis of the three azide-substituted catenanes
S3
1·4PF6 / 3·8PF6. Bis-1,5-dioxynaphtho[50]crown-14 (DN50C14) (60.0 mg, 74 μmol), 1,4bis(bromomethyl)benzene (98.0 mg, 371 μmol) and 4·2PF6 (277.0 mg, 371 μmol) were
dissolved in DMF (10 ml) and subjected to 15 kbar in a high pressure reactor for 6 days. The
solvent was removed from the reaction mixture under vacuum to yield a purple solid. The
solid was purified by silica-60 wet flash column chromatography (Me2CO to 2% w/v NH4PF6
in Me2CO) to yield the monoazido[2]catenane 1·4PF6 as a reddish solid (93 mg, 64%) in the
first fraction and the desired bisazido[3]catenane 3·8PF6 as a purple solid in the second
fraction (34 mg, 15%).
Analytical data for 1·4PF6. 1H NMR (CD3SOCD3, 363 K, 600 MHz): δ 3.51 (m, 8H, OCH2),
3.57 (m, 8H, OCH2), 3.71 (m, 8H, OCH2), 3.81 (m, 8H, OCH2), 4.00 (m, 8H, OCH2), 4.28
(m, 8H, OCH2), 4.9-5.2 (br s, 4H, H4/8), 5.77-5.82 (m, 8H, CH2), 6.54 (br, m, 8H, H2/6 + H3/7),
7.51 (m, 4H, Hβ), 7.55 (d, 3J = 6.8 Hz, 2H, Hβ), 7.58 (d, 3J = 7.0 Hz, 2H, Hβ), 7.93 (d, 3J = 8.2
Hz, 1H, N3-xylylene-H), 8.08 (m, 4H, xylylene-H), 8.12 (s, 1H, N3-xylylene-H), 8.13 (d, 3J =
8.0 Hz, 1H, N3-xylylene-H), 8.93 (d, 3J = 6.9 Hz, 2H, Hα), 9.02 (d, 3J = 6.8 Hz, 4H, Hα), 9.11
(d, 3J = 6.9 Hz, 2H, Hα). HR-ESI-MS (MeCN): m/z 1809.5551 [M – PF6]+ calc 1809.5555 for
C80H91N7O14P3F18, 831.7954 [M – 2PF6]2+ calc 831.7959 for C80H91N7O14P2F12.
Crystal data for 1·4PF6: (C80H91N7O14)·4(PF6)·4(C3H7NO); purple block, 0.209 × 0.134 ×
0.115 mm3; triclinic, space group P1̅; a = 13.4315(5), b = 17.0611(6), c = 27.829(1) Å; α =
73.839(2), β = 77.641(2), γ = 77.667(2)°; V = 5902.0(4) Å3; Z = 2; ρcalcd = 1.464 g cm-3; 2θmax
= 64.81°; T = 100(2) K; 13804 reflections collected, 11354 independent, 1554 parameters; μ
= 1.805 mm-1; R1 = 0.1319 [I > 2.0σ(I)], wR2 = 0.4384 (all data); CCDC deposition number
937912. Three of the PF6– counterions were highly disordered. Distance and angle restraints
were applied to these molecules. The solvent masking procedure as implemented in Olex2
(S5) was used to remove the electronic contribution of solvent molecule from the refinement.
Only the atoms used in the refinement model are reported in the formula here. Total solvent
accessible volume / cell = 1081.3 Å3 [18.3 %] Total electron / cell = 29.8.
S4
Analytical data for 3·8PF6. 1H NMR (CD3SOCD3, 363 K, 600 MHz): δ 2.51 (d, partially
obscured by solvent peak, ArH4/8), 3.35 (t, 3J = 5.2 Hz, 8H, OCH2), 3.51 (t, 3J = 5.2 Hz, 8H,
OCH2), 3.80 (m, 8H, OCH2), 3.91 (m, 8H, OCH2), 4.14 (m, 8H, OCH2), 4.39 (m, 8H, OCH2),
5.81 (m, 20H, ArH3/7 + CH2), 6.27 (d, 3J = 7.8 Hz, 4H, ArH2/6), 7.52 (m, 8H, Hβ), 7.58 (d, 3J
= 6.8 Hz, 4H, Hβ), 7.62 (d, 3J = 6.6 Hz, 4H, Hβ), 7.94 (d, 3J = 8.3 Hz, 2H, N3-xylylene-H),
8.08 (m, 8H, xylylene-H), 8.13 (d, 3J = 8.4 Hz, 2H, N3-xylylene-H), 8.15 (s, 2H, N3-xylyleneH), 8.98 (d, 3J = 6.8 Hz, 4H, Hα), 9.07 (m, 8H, Hα), 9.17 (d, 3J = 6.8 Hz, 4H, Hα). HR-ESIMS (MeCN): m/z 1402.3563 [M – 2PF6]2+ calc 1402.3564 for C116H122N14O14P6F36, 886.5824
[M – 3PF6]3+ calc 886.5830 for C116H122N14O14P5F30.
Crystal data for 3·8PF6: (C58H61N7O7)·4(PF6); purple block, 0.352 × 0.119 × 0.068 mm3;
triclinic, space group P1̅; a = 13.9730(4), b = 14.0470(4), c = 22.1298(6) Å; α = 106.387(1),
β = 105.195(1), γ = 91.581(1)°; V = 3997.2(2) Å3; Z = 2; ρcalcd = 1.264 g cm-3; 2θmax = 67.10°;
T = 100(2) K; 19418 reflections collected, 14882 independent, 985 parameters; μ = 1.805
mm-1; R1 = 0.1918 [I > 2.0σ(I)], wR2 = 0.5410 (all data); CCDC deposition number 937910.
One of the azide moieties was highly disordered, and was restrained using distance and angle
(SADI) restraints. Two of the PF6– counterions were also highly disordered over three
positions. Distance and angle restraints were applied to these molecules. The solvent masking
procedure as implemented in Olex2 (S5) was used to remove the electronic contribution of
solvent molecule from the refinement. Only the atoms used in the refinement model are
reported in the formula here. Total solvent accessible volume / cell = 783.1 Å3 [19.6 %] Total
electron / cell = 171.4.
2·8PF6. 1·4PF6 (86 mg, 44 μmol), 1,4-bis(bromomethyl)benzene (177 mg, 250 μmol) and
5·2PF6 (66 mg, 250 μmol) were dissolved in DMF (10 ml) and subjected to 15 kbar in a high
pressure reactor for 4 days. The solvent was removed from the reaction mixture under
vacuum to yield a purple solid. The solid was purified by two successive silica-60 wet flash
column chromatography (Me2CO to 1.5% w/v NH4PF6 in Me2CO) to yield the
monoazido[3]catenane 2·8PF6 (20 mg, 15%) as a purple solid.
S5
Analytical data for 2·8PF6. 1H NMR (CD3SOCD3, 363 K, 600 MHz): δ 2.28 (d, partially
obscured by solvent peak, ArH4/8), 3.38 (m, 8H, OCH2), 3.52 (m, 8H, OCH2), 3.80 (m, 8H,
OCH2), 3.95 (m, 8H, OCH2), 4.15 (m, 8H, OCH2), 4.38 (m, 8H, OCH2), 5.81 (m, 16H, CH2),
5.86 (t, 4H, 3J = 8.1 Hz, ArH3/7), 6.26 (t, 3J = 7.8 Hz, 4H, ArH2/6), 7.58 (d, 3J = 7.1 Hz, 4H,
Hβ), 7.6-7.7 (m, 12H, Hβ), 7.95 (d, 3J = 8.1 Hz, 1H, N3-xylylene-H), 8.09 (m, 12H, xylyleneH), 8.15 (d, 3J = 8.1 Hz, 1H, N3-xylylene-H), 8.19 (s, 1H, N3-xylylene-H), 9.00 (d, 3J = 6.9
Hz, 2H, Hα), 9.10 (m, 12H, Hα), 9.20 (d, 3J = 6.9 Hz, 2H, Hα). HR-ESI-MS (MeCN): m/z
1381.8540 [M – 2PF6]2+ calc 1381.8556 for C116H123N11O14P6F36, 872.9155 [M – 3PF6]3+ calc
872.9159 for C116H123N11O14P5F30.
Crystal data for 2·8PF6: (C58H61.5N5.5O7)·4(PF6)·(CH3CN); purple block, 0.195 × 0.121 ×
0.08 mm3; triclinic, space group P1̅; a = 14.0648(5), b = 14.0747(5), c = 21.9768(9) Å; α =
106.804(2), β = 104.655(2), γ = 90.978(2)°; V = 4010.1(3) Å3; Z = 2; ρcalcd = 1.299 g cm-3;
2θmax = 59.88°; T = 100(2) K; 13990 reflections collected, 7000 independent, 982 parameters;
μ = 1.804 mm-1; R1 = 0.145 [I > 2.0σ(I)], wR2 = 0.4194 (all data); CCDC deposition number
937911. Four of the PF6– counterions were highly disordered. Distance and angle restraints
were applied to these molecules. Two of the PF6– counterions were also disordered over two
positions. The solvent masking procedure as implemented in Olex2 (S5) was used to remove
the electronic contribution of solvent molecule from the refinement. Only the atoms used in
the refinement model are reported in the formula here. Total solvent accessible volume / cell
= 634.4 Å3 [15.8 %] Total electron / cell = 178.1.
S3.
Electrospray Ionization Mass Spectrometry
High-resolution electrospray ionization mass spectra (Figures S1–S3) of the azido-substituted
catenanes were collected from diluted MeCN solutions, with multiple peaks corresponding to
each cationic catenane, accompanied by varying numbers of PF6– anions, observed in each
case.
S6
Figure
S1.
High
resolution
electrospray
ionization
mass
spectrum
of
the
monoazido[2]catenane, 1·4PF6, with peak envelopes marked for [M – 2PF6]2+ (expansion in
inset) and [M – PF6]+.
Figure
S2.
High
resolution
electrospray
ionization
mass
spectrum
of
the
monoazido[3]catenane, 2·8PF6, with peak envelopes marked for [M – 3PF6]3+ and [M –
2PF6]2+ (expansion in inset).
S7
Figure S3. High resolution electrospray ionization mass spectrum of the bisazido[3]catenane,
3·8PF6, with peak envelopes marked for [M – 3PF6]3+ and [M – 2PF6]2+ (expansion in inset).
S4.
Single Crystal X-Ray Diffraction Analysis of Monoazido[2]Catenane
A single crystal, suitable for X-ray diffraction, of the monoazido[2]catenane 1·4PF6 was
grown by the slow diffusion of Et2O into a DMF solution of the compound. The solid-state
structure (Figure S4) shows many similarities with its unsubstituted analogue (S7). The
catenane crystallizes in the triclinic space group P1̅, with one N3-CBPQT4+, one DN50C14
macrocycle, four PF6– counterions and four DMF solvent molecules in the asymmetric unit.
The unit cell consists of a dimer of 14+, which are related through an inversion centre sitting
between the xylylene units of the two CBPQT4+ rings. These sets of dimers are held together
through complementary [C–H···π] interactions (3.61 Å) between the CBPQT4+ methylene of
one molecule and the xylylene moiety of a second molecule.
S8
Figure S4. The crystal structure of 14+. The CBPQT4+ rings are depicted in blue and the
crown ethers in red. H atoms not involved in interactions, counterions and solvent molecules
are omitted for the sake of clarity. (a) Extensive [C–H···O] interactions are observed within
each molecule between the polyether loops of the crown ether and the hydrogens of the
cyclophane, as well as π-stacking between the donor and acceptor aromatic units in the two
mechanically interlocked rings. (b) [C–H···π] interactions between the para-xylylene protons
of one molecule and the phenyl ring of a second molecule form head-to-head dimers of
[2]catenanes, which are then held in a two-dimensional sheet through infinite donor-acceptor
between neighboring dimers.
As with previously reported donor-acceptor [2]catenanes (S7, S8), one DNP unit of the crown
ether macrocycle sits (Figure S4a) inside the CBPQT4+ ring where it is stabilised in the same
manner by [C–H···π] interactions (3.38 and 3.44 Å) between the peri-hydrogen atoms of the
DNP unit and the aromatic xylylene components of the CBPQT4+ ring. A second DNP–
CBPQT4+ interaction is also present in the molecule, in so far as the second DNP unit sits on
the outside of the catenane and is stabilized through [π···π] interactions (3.59 Å) with the
bipyridinium units of the CBPQT4+ ring. Again, further stabilising [C–H···O] interactions are
present between the polyether loop and the pyridinium (3.20–3.51 Å) and methylene (3.17–
3.78 Å) protons of the CBPQT4+ ring. As a result of the long polyether chains in the
molecule, the extent of bifurcated H-bonding interactions present in the molecule is much
greater than in the subsequent [3]catenanes, with the majority of oxygen atoms present in the
chains interacting with the CBPQT4+ ring. Interestingly, sheets of catenanes are formed
(Figure S4b) in the (010) plane as a result of alternating donor-acceptor [π···π] interactions
between 14+ molecules in one direction, and [C–H···π] interactions in the second direction.
S9
S5.
Single Crystal X-Ray Diffraction Analysis of Monoazido[3]Catenane
Single crystals of the monoazido[3]catenane, 2·8PF6, were isolated by vapor diffusion of
Et2O into a MeCN solution of the catenane. Unsurprisingly, the structural features observed
(Figure S5) in the solid-state are related to those observed in the multiple single crystal
structures, which have been solved for the parent [3]catenane (S7). The catenane crystallizes
in the triclinic space group 𝑃1̅, with one half of a molecule, four PF6– counterions and one
MeCN solvent molecule in the asymmetric unit. The complete molecule is generated through
an inversion center, which sits between the planes containing the methylene carbons of both
CBPQT4+ rings in the structure. As a result the two CBPQT4+ rings sit 3.74 Å apart (with
respect to the planes of the rings).
Figure S5. The crystal structure of 28+. The CBPQT4+ rings are depicted in blue and the
crown ether in red (H atoms not involved in interactions, counterions and solvent molecules
are omitted for the sake of clarity). (a) [C–H···O] interactions are observed within each
molecule between the polyether loops of the crown ether and the hydrogens of the CBPQT4+
rings, as well as π-stacking between the donor and acceptor aromatic units of the three
mechanically interlocked rings’ interactions. (b) [C–H···π] interactions between the
methylene protons of one molecule and the phenylene bridge of a second molecule form
stacks of the catenanes.
As is commonly observed in solid-state structures containing the CBPQT4+ rings, the
bipyridinium units are twisted from planarity, with torsional angles of 12º and 21º observed
between neighboring pyridinium rings on the outer and inner sides of the catenane,
respectively. The DNP units sit (Figure S5a) inside the CBPQT4+ rings, with [C–H···π]
S10
interactions (3.33 Å) present between the peri-hydrogen atoms of the DNP unit and the
aromatic xylylene components of the CBPQT4+ ring. The stability of the compound is further
enhanced by the presence of multiple bifurcated [C–H···O] interactions between the
methylene and bipyridinium protons of the CBPQT4+ ring and the oxygen atoms of the glycol
chains. These interactions range in distance from 3.37 to 3.48 Å and act to hold the polyether
loops in close proximity to the CBPQT4+ ring. Offset stacks of 28+ are generated along the c
axis, through weak [C–H···π] interactions (3.65 Å) between (Figure S5b) the methylene
protons of one CBPQT4+ ring and the CBPQT4+ phenylene bridge in a neighboring catenane.
Sheets are formed along the (001) plane as a result of the parallel stacking of neighboring
stacks of catenanes.
S6.
Single Crystal X-Ray Diffraction Analysis of 3·8PF6
Finally, crystals of the bisazido[3]catenane 3·8PF6 were grown from the slow diffusion of
iPr2O into a MeCN solution of the compound, which crystallizes (Figure S6) in a triclinic
space group P1̅, with half a molecule of 38+ and four PF6– counterions in the asymmetric unit.
The unit cell parameters are very similar to those of 2·8PF6; whilst the two species are not
isostructural, the catenanes themselves adopt very similar structural arrangements in the
solid-state. The complete molecule is generated through an inversion center, which, as in the
case of the 28+, which sits between the planes containing the methylene carbons of both
CBPQT4+ rings. As a result, the CBPQT4+ rings sit 3.68 Å apart (with respect to the planes of
the rings), which is closer than that observed for 28+.
In a manner similar to 28+, the CBPQT4+ bipyridinium rings of 38+ are twisted (Figure S6a) at
angles of 12º (outer side of catenane) and 23º (inner side of catenane), respectively. As
expected, the DNP unit sits inside the N3-CBPQT4+ rings, and is stabilized by [C–H···π]
interactions (3.36 Å and 3.41 Å) between the two ring components. Multiple bifurcated [C–
H···O] interactions occur between the bipyridinium (3.31 – 3.90 Å) and methylene (3.44 Å)
protons of the CBPQT4+ ring with the oxygen atoms of the polyether loops of the crown
ether, adding to the stability of the compound. Slightly offset stacks of 38+ molecules along
the crystallographic a axis are formed (Figure S6b) through complementary interactions (2.97
Å) between the glycol chain of one catenane and the azide moiety of a second catenane.
Sheets of these stacks propagate along the (010) plane.
S11
Figure S6. The crystal structure of 38+. The CBPQT4+ rings are depicted in blue and the
crown ethers in red. H atoms not involved in interactions, counterions and solvent molecules
are omitted for the sake of clarity. (a) [C–H···O] interactions are observed within each
molecule between the polyether loops of the crown ether and the hydrogens of the CBPQT4+,
as well as π-stacking between the donor and acceptor aromatic units of the three interlocked
rings interactions. (b) [C–H···N] interactions between the azide moiety of one molecule and
the polyether loop of a second molecule form stacks of the catenanes.
S7.
1H
NMR Spectroscopy
For each azide-functionalized catenane, 1H NMR spectroscopy was carried out over a range
of temperatures in an attempt to characterize the solution-state structure and dynamics of the
mechanically interlocked molecules. The monoazido[2]catenane 1·4PF6 was examined as a
useful model compound to aid subsequent characterization of the [3]catenanes. 1H NMR
Spectra (Figure S7) recorded in CD3CN at 10 degree increments from 233 K to 333 K
demonstrate a number of features. At lower temperatures in CD3CN, a minor coconformation is observed along with the major one. There are two possible orientations of the
DNP unit within the N3-CBPQT4+ ring – one presumably more stable than the other as a
result of steric interactions between the polyether loop with the azide – and so the two coconformations are observed in slow exchange at low temperature solutions (S9), through exit,
rotation and re-entry of the DNP unit (see main text figure 4b), which is slower than the
NMR timescale. These signals for the different co-conformations coalesce upon heating to
333 K, but their exchange cannot be rendered fast on the NMR timescale because of the
limitation of the boiling point of CD3CN, and so a spectrum recorded in CD3SOCD3 is
utilized instead for full characterization of the molecule (see main text Figure 5).
S12
Figure S7. 1H NMR (600 MHz, CD3CN) spectra of the monoazido[2]catenane 1·4PF6
recorded in 10 degree increments from 233 to 333 K.
The spectrum recorded at 253 K in CD3CN can still provide useful information on the
solution structures of the two co-conformations, particularly when aided by a 1H-1H COSY
spectrum (Figure S8). The introduction of the azide group onto the CBPQT4+ ring renders all
Hα and Hβ protons on the BIPY2+ units heterotopic, and, as such, we see the expected eight
resonances for the Hα protons, each of which correlates well with its adjacent Hβ proton in the
1
H-1H COSY spectrum under the same conditions, for each co-conformation. Likewise, two
distinct resonances are observed far upfield (2.1–2.4 ppm) for the H4 and H8 protons of the
encapsulated DNP unit of each co-conformation, which correlate with the signals of their
adjacent H3 and H7 protons, found at 5.5–6.0 ppm. These signals are characteristic for DNP
encapsulation within CBPQT4+ rings, and also confirm that reorientation of the DNP units
within the asymmetric N3-CBPQT4+ ring is slow on the 1H NMR timescale.
S13
Figure S8. Partial 1H-1H COSY NMR (600 MHz, CD3CN, 253 K) spectra of the
monoazido[2]catenane 1·4PF6 with significant correlations labeled.
In the 1H NMR spectrum in CD3CN of the major isomer at 253 K, it is also possible to
observe three resonances which correspond to the three heterotopic protons of the azidoxylylene bridge, whilst two larger peaks correspond to the four protons of the opposite
xylylene bridge, which is presumably located too far from the azide group to induce
significant shifting of the signals.
At 233 K, the signals are slightly broadened, as a “super-rotation” process (see main text
Figure 4a), wherein the outer DNP unit can rotate by 180 degrees to take up a position on
either CBPQT4+ ring face, is beginning to slow towards the 1H NMR timescale under these
conditions. The asymmetric nature of the N3-CBPQT4+ ring means that another two coconformations of 1·4PF6 are possible for the observed major and minor species based on this
dynamic process – one with the azide group pointing towards the outside DNP unit and one
with it pointing away – but we have not been able to observe these species in the solution
state. Overall, the 1H NMR data allow us to predict the co-conformations of 1·4PF6 under
various conditions, and, importantly, endow us with a greater understanding of the 1H NMR
spectra of the azido-substituted [3]catenanes.
S14
The variable temperature 1H NMR spectra of the monoazido[3]catenane 2·8PF6 in CD3CN
show similar behavior to that of 1·4PF6 when recorded from 233 to 333 K (see main text
Figure 6). Again, the heating of the sample simplifies the resulting spectra by inducing fast
co-conformational exchange and averaged resonances. The 1H NMR spectrum (Figure S9) of
a sample of 2·8PF6 recorded at 363 K in CD3SOCD3 shows similar characteristic peaks
comparable to that of 1·4PF6.
Figure S9. 1H NMR (600 MHz, CD3SOCD3, 363 K) spectrum of the monoazido[3]catenane
2·8PF6, with limited signal assignments based on the structural formula. Small intensity peaks
are visible as a result of thermal degradation of 2·8PF6 under these conditions.
Resonances can be easily assigned to differing components in the molecule by reference to
the assignments for 1·4PF6. The fact that only three resonances are observed for the aromatic
DNP protons (the signal assigned to the H4/8 protons is obscured by the residual solvent peak
and not shown) confirms that exchange of both DNP units of the crown ether between the
functionalized and unfunctionalized CBPQT4+ rings is occurring fast on the NMR timescale
and hence give rise to averaged signals.
S15
Finally, for the bisazido[3]catenane 3·8PF6 the 1H NMR spectra (Figure S10) recorded at low
(233–253 K) temperatures in CD3CN are complex as a result of the two topological isomers
presumed to be present, as well as the various accessible co-conformations of each under
these experimental conditions. Collecting spectra at 10 degree increments from 233 to 333 K
in CD3CN illustrates well the dynamic behavior of 3·8PF6.
Figure S10. 1H NMR (600 MHz, CD3CN) spectra of the bisazido[3]catenane 3·8PF6
recorded at 10 degree increments from 233 K to 333 K.
The large numbers of complex overlapping resonances that are observed at low temperatures
simplify upon heating the sample in a manner similar to those observed for 1·4PF6 and
2·8PF6, with the spectrum at 333 K simple enough to assign, but still with some broad
resonances. The 1H NMR spectrum recorded in CD3SOCD3 at 363 K (main text Figure 7)
exhibits sharp, distinct resonances, which can easily be assigned.
S16
Figure S11. Partial
1
H NMR (600 MHz, CD3SOCD3, 363 K) spectra of the
bisazido[3]catenane 3·8PF6 collected as soon as the temperature has stabilized (bottom) and
recollected approximately 10 minutes afterwards (top). Thermal degradation of 3·8PF6 is
evident as small resonances appear throughout the spectrum. Close scrutiny of the methylene
protons of the polyether loop indicates the presence of at least two new species.
Whilst examination of the variable temperature 1H NMR spectra of the catenanes can impart
significant knowledge of the solution structure and dynamics of the topologically complex
MIMs, it is the high temperature spectra, particularly those recorded in CD3SOCD3 at 363 K,
which are most informative. The averaging of signals as a result of fast dynamic processes
yield simplified spectra, with the caveat that the catenanes are inherently unstable to thermal
degradation under these conditions. As an example, Figure S11 shows 1H NMR spectrum of
a sample of 3·8PF6 that had been left in the spectrometer at 363 K for approximately 10
minutes after an initial spectrum had been collected. The appearance of additional small
peaks clearly demonstrates the thermal breakdown of 3·8PF6, with careful examination of the
polyether protons’ resonances revealing at least two new species are present in the sample.
S17
S8.
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