Supramolecular Pseudorotaxane Polymers from Biscryptands and Bisparaquats

Article abstract of DOI:10.1021/jacs.8b01480

Five new bis(dibenzo-30-crown-10-based cryptand)s were synthesized, two of which (16 and 17) had long (12-atom), flexible spacers that led to cooperative complexation of dibenzyl paraquat TFSI (K_ave = 4.36 × 10⁵ M^-1 for 17

Full text of DOI:10.1021/jacs.8b01480

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SUPRAMOLECULAR PSEUDOROTAXANE POLYMERS
FROM BISCRYPTANDS & BISPARAQUATS
Terry Leon Price, and Harry William Gibson
J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 06 Mar 2018
Downloaded from http://pubs.acs.org on March 6, 2018
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SUPRAMOLECULAR PSEUDOROTAXANE POLYMERS FROM BISCRYPTANDS &
BISPARAQUATS
§
Terry L. Price, Jr., and Harry W. Gibson*
Department of Chemistry
Virginia Tech
Blacksburg, VA 24060
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ABSTRACT
Five new bis(dibenzoꢀ30ꢀcrownꢀ10ꢀbased cryptand)s were synthesized, two of
which (16 and 17) had long (12 atom), flexible spacers that led to cooperative
5
ꢀ1
complexation of dibenzyl paraquat TFSI (Kave = 4.36 x 10 M for 17ꢀ2b). Selfꢀassembly
of 16 and 17 with bisparaquats with similar spacers (18, 21 and 23) led to high
molecular weight supramolecular pseudorotaxane polymers in solution. Continuous,
flexible fibers were drawn from concentrated solutions. 17 with C ꢀlinked bisparaquat
10
2
3 in dichloromethane (DCM) produced a logꢀlog viscosity vs. concentration plot with
limiting slope 3.55, confirming high molecular weight; at 37 mM the degree of
polymerization was estimated to be 126 and M = 407 kDa. These are the first truly
n
polymeric pseudorotaxaneꢀtype AA/BB supramolecular polymers.
§
Present address: Zestron Corporation, 11285 Assett Loop, Manassas, VA 20109 USA
*
Corresponding author; eꢀmail: hwgibson@vt.edu
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INTRODUCTION
Supramolecular polymers are of particular interest because of their
1
dynamic character, which allows for reversibility and stimuli responsiveness. Polymers
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of this type are thus unique in the sense that they are “selfꢀhealing”. To prepare such
polymers containing pseudorotaxane linkages there are two approaches as outlined in
Scheme 1.
Scheme 1. Two routes to pseudorotaxaneꢀbased supramolecuar polymers: top) AA/BB approach and
bottom) AB approach.
The degree of polymerization (DP) is related to the association constant of the
complex and the concentrations (Eq. 1, Figure 1; [H] is the total concentration of an
o
2
AB monomer). When 4K [H ] >>1 the equation simplifies to Eq. 2, Figure 1. In general
a
o
the association constant can be controlled via stimuli such as temperature, solvent, pH,
electrochemistry, counter ion or light.
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Equation 1. Full equation.
Equation 2. Simplified equation.
1
/2
1/2
DP = 2 K [H] / {(1 + 4 K [H] ) – 1}
DP = (K [H] )
a
o
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o
a
o
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1000
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00
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log K
Figure 1. DP vs K at 1 M.
a
Among reported pseudorotaxane supramolecular polymers the crown ether host
2b,3
motif has been well studied.
In the meantime crown ether host systems, however,
4
have evolved into cryptands. Specifically, pyridyl cryptands have exceptionally high
binding constants with paraquat derivative guests (N,N’ꢀdialkylꢀ4,4’ꢀbipyridinium
4
c,4e,4gꢀ4j
salts).
Recently supramolecular polymers have been reported using cryptand
5
motifs of varying types, including an extremely high binding pyridyl cryptand motif in an
5a
AB or heteroditopic monomer.
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To illustrate the importance of strong complexation, consider that in Figure 1 DP
4
ꢀ1
=
100 is not achieved until K = 10 M at 1 M concentration. For stepꢀgrowth polymers,
a
which these are, the rule of thumb is that for good physical properties DP ≥ 100 is
3
ꢀ1
required. For most crown ether based complexes K ≤ 10 M , leading to maximum DP
a
=
32 at 1 M concentration assuming that no cyclics form, i. e., only oligomers will form.
The pyridyl dibenzoꢀ30ꢀcrownꢀ10 cryptand (1a) with dimethyl paraquat PF (2a) in
6
5
ꢀ1 4g
acetone has an association constant of 1 x 10 M , while the same cryptand with
6
ꢀ1 6
dibenzyl paraquat TFSI (2b) in DCM has an association constant of 1 x 10 M .
Appropriate monomers with these association constants would afford DP = 316 and DP
= 1,000 at 1 M concentration, respectively, i. e., truly high molecular weight polymers.
New templated synthetic pathways for cyclization of dibenzocrown ethers by the
4e,4g,4h,7
8
WangꢀPetersonꢀWessels protocol
and cryptands now allow more efficient
development of ditopic cryptands. Here we report our efforts to prepare pyridyl cryptand
AA monomers and bisparaquat BB monomers and their selfꢀassembly to
pseudorotaxaneꢀtype supramolecular polymers.
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RESULTS AND DISCUSSION
A. Synthesis of Biscryptand Monomers
Our initial attempts to synthesize a biscryptand employed the dibenzoꢀ30ꢀcrownꢀ
1
0ꢀbased pyridyl cryptand 1b with the intent of Heck coupling with a diolefin. These
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attempts were unsuccessful; coupling with the olefin was not observed. Instead
Ullmann coupling prevailed and biscryptand 3 was formed in 26% yield, with a large
fraction of 1 left unreacted after 36 h. Without the diolefin the Ullmann coupled product
was isolated in 25% yield with a large fraction of unreacted 1b. These conditions are
9
known to promote Ullmann couplings.
A similar reaction was carried out using the 32ꢀcrownꢀ10 bromocryptand 4 to
produce biscryptand 5 in 11% yield; the yield reduction vs. 3 is attributed to the small
reaction scale (18 mg). Once again a large fraction of the aryl bromide was unreacted.
Isothermal titration calorimetric (ITC) examination (Figure 2) of the complexation
of biscryptand 3 with dimethyl paraquat (2a) revealed a reasonably high average
5
ꢀ1
binding constant, 2.33 x 10 M . However, analysis of the isotherm revealed that K =
a1
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ꢀ1
4
ꢀ1
10
4
.50 x 10 M , while K = 1.78 x 10 M . For statistical complexation K = (1/4) K ,
a2 a2 a1
ꢀ2
so the system is antiꢀcooperative [Ka2 = (3.96 x 10 ) K ]. The antiꢀcooperative
a1
behavior of 3ꢀ2a is attributed to the close proximity of the two host cavities and the
rigidity of the linker, causing the complexation of the second paraquat to suffer a
repulsive electrostatic force from the first complexed paraquat. Thus, compounds 3 and
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were abandoned for constructs that contain longer, more flexible linkers between the
two cryptand units to avoid anticooperativity.
Time (min)
60
0
30
90
120
150
0
5
ꢀ1
K
∆
∆
1
= 4.50 x 10 M
G = ꢀ7.71 kcal/mol
H = ꢀ13.5 kcal/moꢀ1l
S = ꢀ19.4 cal mol K
ꢀ20
ꢀ1
ꢀ40
∆
0
ꢀ2
ꢀ4
4
ꢀ1
ꢀ6
K
2
= 1.78 x 10 M
∆G = ꢀ5.80 kcal/mol
H = ꢀ10.8 kcal/moꢀl
ꢀ8
ꢀ
10
12
14
∆
1
ꢀ1
ꢀ
∆ S = ꢀ16.8 cal mol K
ꢀ
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Molar Ratio
Figure 2. ITC titration of biscryptand 3 with dimethyl paraquat PF6
(2a) in CH COCH at 25 °C.
3
3
Since Ullmann coupling proved to be possible using aryl bromides 1b and 4, aryl
bromide 1c was prepared and subjected to those conditions to yield biscryptand 6,
whose longer linker would overcome the anticooperativity observed with 3. Synthesis of
6 was achieved in a yield of 12% after 17 h. Chromatography allowed recovery of
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unreacted starting material. At the same time progress had been made on templation of
8
the formation of cryptands and it became evident that biscryptands could be prepared
more readily by this method. Thus pursuit of 6 and analogs was abandoned.
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3c,11
Two biscryptands, 16 and 17, were chosen (Scheme 2). Our previous work
indicated that if the linker in the ditopic host is ≥ 10 atoms, the formation of cyclic
species, a side reaction in the formation of supramolecular polymers, is minimized. The
12
syntheses proceed from the known
diisopropyl chelidamate (7); the isopropyl ester
groups essentially eliminate Nꢀalkylation; this allowed formation of bischelidamates 9
and 12 in high yields. Their hydrolyses to tetraꢀacids 10 and 13 and thence conversion
to tetraꢀacid chlorides 11 and 14 proceeded smoothly. Finally their dual templated
cyclizations with dibenzoꢀ30ꢀcrownꢀ10 diol (15) afforded the biscryptands 16 and 17.
1
The H NMR spectrum of new biscryptand 17 is shown in Figure 3.
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H2
C
O
N
O
O
O
N
O
N
O
N
10
O
O
11
O
O
O
O
O
O
14
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
O
O
O
O
O
15
O
O
O
O
O
Pyridine
DCM
Pyridine
DCM
Pyridinium TFSI
HO
OH
Pyridinium TFSI
H2
C
O
N
O
O
O
N
O
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O
N
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16
17
O
O
O
O
O
O
O
O
2
3%
43%
O
O
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O
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O
O
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O
O
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O
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O
O
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O
O
O
O
Scheme 2. Synthesis of biscryptands 16 and 17.
a
CHCl3
e
OCH2
b,c
d
CꢀCH ꢀC
2
1
o
Figure 3. H NMR spectrum (500 MHz, CDCl , 23 C) of biscryptand 17.
3
As expected, ITC results revealed that the complexation of biscryptand 17 with
5
ꢀ1
dibenzyl paraquat TFSI (2b) was actually cooperative (Figure 4); Kavg = 4.36 x 10 M ,
5
ꢀ1
5
ꢀ1
K = 2.49 x 10 M and K = 6.23 x 10 M ; K = 2.5 K ! Cooperative behavior found
a1
a2
a2
a1
in other cryptand/paraquat systems has been attributed to conformational restrictions
13
promoting the complexation of a second site. The crystal structure of the complex of
2
,6ꢀpyridyl cryptand 1a with dimethyl paraquat PF (2a) revealed the guest π–stacked
6
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within the host in such a way that the paraquat methyl groups interact with the oxygen
4g
atoms of the host. It is likely that the electron poor benzyl moieties of paraquat 2b are
capable of interacting via hydrogen bonding with the adjacent uncomplexed cryptand
motif in 17, causing the latter moiety to adopt a conformation favorable for complexation
of the next paraquat guest. It is noteworthy that strong cooperativity was also
1
1
1
1
1
1
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demonstrated in a different solvent; in 1:1 CHCl :CH CN titration of biscryptand 17 with
3
3
3
ꢀ1
5
ꢀ1
dimethyl paraquat TFSI (2c) yielded K = 2.2 x 10 M and K = 1.3 x 10 M . K =
a2
a1
a2
5
5 K !
a1
5
ꢀ1
K = 2.49 x 10 M
1
∆
G = ꢀ7.36 kcal/mol
1
∆
H = ꢀ14.6 kcal/mol
1
ꢀ1 ꢀ1
∆
S = ꢀ 24.3 cal mol K
1
5
ꢀ1
K = 6.23 x 10 M
2
∆G = ꢀ7.90 kcal/mol
2
∆
H = ꢀ13.0 kcal/mol
2
ꢀ1
ꢀ1
∆S = ꢀ26.5 cal mol K
2
Figure 4. ITC titration of biscryptand 17 with dibenzyl paraquat TFSI (2b) in DCM at 25 °C.
B. Ditopic Guest Monomers
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5b
Bisparaquats used for this study, 18, 21, and 23, were synthesized in
acceptable yields by standard methods (Scheme 3).
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Scheme 3. Bisparaquat guest monomers 18, 21 and 23.
C. Self-Assembly of Supramolecular Polymers
Using the AA host monomers 16 and 17 along with the BB guest monomers 18,
2
1
1, and 23, five supramolecular polymers were selfꢀassembled in solution (Figure 5):
7 + 18 ꢁ P1, 16 + 18 ꢁ P2, 17 + 23 ꢁ P3, 17 + 21 ꢁ P4 and 16 + 21 ꢁ P5.
1
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0
1
2
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5
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1
2
3
4
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9
0
1
2
3
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0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 5. Left: Supramolecular polymers P1 – P5. Right: Films were cast via slow solvent evaporation
using the following solvents/substrates: P1 (CHCl :CH CN, 1:1 v/v on Teflon); P2 (ClCH CH Cl on
3
3
2
2
silicon); P3 (oꢀC H Cl on glass); P4 (ClCH CH Cl on Teflon); P5 (CHCl :CH CN, 1:1 v/v on glass).
6
4
2
2
2
3
3
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4
4
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4
4
4
4
4
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5
5
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5
5
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5
5
6
The polymers were selfꢀassembled by dissolving the host monomer in chloroform
and the guest monomer in acetone. The solutions of host and guest monomers
independently were either colorless or slightly yellow. However, upon mixing the
solutions instantly turned either a dark yellow or deep orange color, which persisted
after solvent evaporation, indicative of charge transfer binding between electron rich
cryptand hosts and electron poor paraquat guests.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
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5
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1
2
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1
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1
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8
9
0
It is a challenge to determine molecular weights for polyelectrolytes P1 – P5. Due
to the amount of material required to carry out viscosity experiments over a range of
dilutions, only polymer P3 was chosen for assessment. Figure 6 shows a logꢀlog plot of
specific viscosity vs. concentration of precursors for P3 in DCM; the critical
concentration where supramolecular polymer begins to form is where the two trend lines
cross (37 mM). This plot indicates that for equimolar concentrations of monomers 17
and 23 in DCM above 37 mM, a supramolecular polymer is present. Niu et al. reported
a supramolecular polymer made from a biscryptand/bisparaquat pair that displayed a
5b
critical monomer concentration of 53 mM. The lower critical monomer concentration
here is consistent with the ca. 100ꢀfold higher K of the present biscryptand/bisparaquat
a
system. Using the association constant of dibenzyl paraquat TFSI (2b) with 17 in DCM
5
ꢀ1
(
Ka average = 4.36 x 10 M ) DP is estimated by Eq. 2 to be 126 at 37 mM. With a repeat
unit of 3,229 Da, this gives a molecular weight of 407 kDa. Our previous report of an
AB selfꢀassembly from an analogous 32ꢀcrownꢀ10ꢀbased pyridyl cryptand and paraquat
5a
revealed a critical concentration of ca. 75 mM and a limiting slope of 3.54.
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Equimolar Concentration (M)
0
.001
0.01
0.1
1
1
00
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Slope = 3.55
10
1
0
0
.1
Slope = 1.17
.01
o
CH Cl @ 25 C
TFSI salt
2
2
Figure 6. Log(specific viscosity) vs. Log(concentration) for equimolar solutions of 17 and 23 in DCM.
The slope of Figure 6 at low concentrations is 1.17; this is attributed to the
2b,3b,3c,14
presence of cyclic dimeric species, acting as Einstein spheres.
Interestingly,
deviation from the line at low concentrations begins at 18 mM, indicating that large
oligomers are already beginning to form. The slope at high concentrations, 3.55, is
attributed to the formation of high molecular weight polymer and is the theoretical
15
5a
maximum, observed here for only the second time with a pseudorotaxane system.
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Films cast by slow solvent evaporation were brittle. Casting was attempted with
all polymers using the following solvent systems (as well as specifically indicated
solvents in Figure 5): DCM, CHCl :CH CN (1:1 v:v), and ClCH CH Cl.
3
3
2
2
ꢀ
6
0
1
2
3
4
5
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7
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1
2
3
4
5
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1
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1
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1
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P1 and P2, which employed PF counter ions, resulted in very brittle films that
could not be peeled from substrates (glass, silicon, or Teflon) in their entirety or even
pieces larger than small flakes. The picture of P2 is shown before removal from the
ꢀ
casting mold. Polymers with TFSI counter ions (P3 ꢀ P5) resulted in visually brittle
ꢀ
6
polymers, but unlike their PF counter parts these polymers were removable from the
surfaces of glass, silicon, and Teflon.
Castings of P3 and P4 were also carried out by redissolving the polymers in
CHCl and allowing slow solvent evaporation. The results for all attempts were the
3
same: brittle materials. Casting of P3 was carried out using oꢀC H Cl (Figure 5), which
6
5
2
resulted in a material that was bendable for approximately one day while the material
was plasticized. After this point, once oꢀC H Cl had time to evaporate, the film became
6
5
2
ꢀ
brittle. For polymers containing the TFSI counter ion and cast from CHCl :CH COCH
3
3
3
(50:50 v:v), it took 6 to 24 hours after casting for the film to reach its full brittleness.
During this time slight deformations could be made to the material, again attributable to
plasticization.
Polymers P1 to P4 resulted in the formation of optically clear films, indicating
amorphous polymers. P5 formed a monolith that seemed to be opaque as seen in
Figure 5.
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Fibers were pulled from high concentration solutions of all of the polymers.
Figure 7 shows images of a fiber (P3) pulled from a concentrated equimolar solution of
17 and 23. Fibers of P3 were flexible and strong enough to resist fracture while being
bent, as seen in images A and B. Films of P5 were brittle and fractured upon applying
mild force, while the corresponding fibers were capable of withstanding stress from
bending and pulling.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
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4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
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7
8
9
0
1
2
3
4
5
6
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8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
It is believed that as the films dry, one of the monomers precipitates. There is a
16
large solubility difference between the neutral cryptands and the paraquat salts. As the
paraquat precipitates, the biscryptand stays in solution and the stoichiometry of this
stepꢀgrowth process is thrown away from 1:1 and DP is greatly reduced. However, as
fibers are drawn, the solvent is more rapidly flashed off, negating precipitation. Fiber
formation can only occur above the entanglement molecular weight. Thus, these results
clearly demonstrate the selfꢀassembly of truly polymeric materials.
1
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9
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Figure 7. P3 fibers: A) color image taken on a black background, B) differential interference contrast
image at 10x magnification, C) differential interference contrast image at 40x magnification, D) differential
interference contrast image at 60x magnification.
Thermal measurements are summarized for P1 – P5 in Table 1. DSC traces
show a clear loss of monomer crystallinity and the formation of amorphous polymers.
For example, Figure 8 shows an overlay of DSC traces for monomers 17 and 23 along
with the resulting polymer P3. T values for polymers P1 – P5 vary in the range of 44 to
g
ꢀ
6
ꢀ
103 °C. By direct comparison of polymers P1 and P3, changing from a PF to a TFSI
counter ion results in lowering the T by 59 °C; such plasticization effects have been
g
17
observed in covalent polymers, particularly polymerized ionic liquids. This decrease
17d
ꢀ
could be ascribed to the larger volume
of the unsymmetrical, highly delocalized TFSI
anion and/or its lower ion pairing constant relative to the more symmetrical and compact
ꢀ
6
ꢀ
6
PF anion. P2 produced from guest monomer 18 (PF counter ion and C linker) and
10
host monomer 16 (a hydroquinone linkage) provided the highest T (112 °C). By
g
comparison of P2 and P1 there is no difference in thermal stability, but P2 has a 9 °C
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higher T than P1. However, comparing P5 and P4, both with the ditopic guest 21, the
g
T values are virtually identical for the hydroquinone linker vs. the C linker.
g
10
Table 1. Thermal Properties of Polymers P1 ꢀ P5.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
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8
9
0
1
2
3
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1
2
3
4
5
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0
1
2
3
4
5
6
7
8
9
0
Guest ꢀ
(linker X )
Tg
TGA 5 % wt loss
(°C)
Host
Polymer (°C)
1
7 (C )
18 (C PF )
P1
P2
P3
P4
P5
103
112
44
78
76
217
216
223
224
218
10
10
6
16 (HQ)*
18 (C PF )
10 6
17 (C )
23 (C TFSI)
10
10
17 (C )
21 (Bn TFSI)**
21 (Bn TFSI)
10
16 (HQ)
*
HQ = hydroquinone linkage.
** Bn = benzylic linkage.
Bisparaquat 23
Supramolecular
polymer P3
Biscryptand 17
Figure 8. DSC curves of third heating scans of monomer 17, monomer 23, and polymer P3 at 5 °C/min.
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6
Analysis via TGA showed 5 % weight losses for polymers P1 – P5 closely
grouped in the range of 216 to 224 °C (Figure 9). Degradation patterns varied,
dependent upon the guest monomer and counterion; c. f. P1 and P2 with “less stable”
ꢀ
6
0
1
2
3
4
5
6
7
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0
1
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PF counter ions vs. P3 ꢀ P5 with TFSI counter ions.
–
–ꢃ
–ꢄ
–ꢅ
–––––– Polymer P1
–––––– Polymer P4
–––––– Polymer P2
–––––– Polymer P5
–ꢆ –––––– Polymer P3
1
00
ꢅꢆꢂꢄꢃ
ꢅꢆ ꢃ
ꢅ
ꢆꢃ
ꢃ
ꢂ
ꢅꢆ
ꢄ
ꢄ
ꢆ
ꢅ
ꢂ
ꢂꢄ
ꢂꢄꢃ
ꢆꢃ
ꢅ
ꢄ
P3
ꢆ
ꢂ
ꢅꢃ
ꢂ
ꢆ
ꢄ
8
6
4
2
0
0
0
0
0
ꢅꢃ
ꢂ
ꢆ
ꢄ
ꢅ
ꢃ
P2
ꢂ
ꢆ
ꢄ
ꢅ
ꢃ
ꢂ
ꢆ
ꢄ
ꢄ
ꢅ
ꢄ
ꢆ
ꢃ
ꢄ
ꢆ
ꢂ
ꢆ
P1
ꢂ
ꢅ
ꢃ
ꢂ
ꢂ
ꢂ
ꢅ
ꢃ
P5
ꢅ
ꢃ
P4
ꢃ
0
100
200
300
400
500
600
Universal V4.5A TA Instruments
Temperature (°C)
Figure 9. TGA overlay of polymers P1 ꢀ P5 using a heating rate of 20 °C/min under N2.
CONCLUSIONS
Aryl bromide cryptands 1 and 3 produced the respective biscryptands 2 and 4
through Ullmann reactions. ITC results indicated that these ditopic hosts bind paraquats
antiꢀcooperatively and we thus abandoned this approach to biscryptands. Biscryptand 6
was similarly synthesized to extend the linkage between the cryptand units, but was
abandoned in favor of 16 and 17, which were produced directly from reactions of
tetra(acid chloride)s 11 and 14 with crown diol 15. Importantly, the complexation of
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ditopic biscryptand 16 with monotopic paraquat derivative 2b demonstrated highly
positive cooperativity.
Five high molecular weight supramolecular polymers, P1 – P5, were selfꢀ
assembled in solution from biscryptands and bisparaquats as AA/BB monomer pairs.
Fibers were drawn from concentrated solutions. Brittle films were cast from various
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ꢀ
solvents. The glass transition temperature was reduced by 59  by changing from PF6
ꢀ
to TFSI counterions in P1 vs. P3. T s ranged from 44 °C for P3 to 112 °C for P2; all 5
g
%
weight loss values were grouped in the range of 217 to 224 °C. P3 was found to
have a critical monomer concentration of 37 mM and the slope at high concentration,
3.55, was the theoretical maximum and the highest reported for an AA/BB
pseudorotaxane supramolecular polymer. Development of films suitable for mechanical
property evaluation will need to focus on processing techniques; one possible solution
may be spin casting, since the solvent is removed quickly.
EXPERIMENTAL
1
Measurements: HꢀNMR spectra were obtained on JEOL ECLIPSEꢀ500, BRUKERꢀ
o
13
5
00, and AGILENTꢀNMRꢀvnmrs400 spectrometers at 23 C.
CꢀNMR spectra were
o
collected at 125 MHz and 101 MHz on these instruments at 23 C. HRꢀMS were
obtained using an Agilent LCꢀESIꢀTOF system; CH CN was the solvent in all cases.
3
Reagents were purchased and used as received without further purification. TGA data
were obtained on a TA Instrument TGA Q500 under N . DSC data were obtained on a
2
TA Instrument Q2000 differential scanning calorimeter under N . Viscosities were
2
measured with a CannonꢀUbbelohde semiꢀmicro dilution viscometer. Light microscopy
was performed by Dr. Michelle B. Price using an Olympus IX81 Epifluorescene
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1
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1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
microscope. Fibers were H Oꢀmounted between two coverslips and imaged using
2
differential interference contrast (DIC) microscopy at 10X magnification (with a H Oꢀ
2
immersion objective), 40X magnification (using an oilꢀimmersion objective) and 60X
magnification (using an oilꢀimmersion objective). Images were captured with an EMCCD
RoleraꢀMGI FAST 1394 monochromatic camera (Olympus) and processed using
Slidebook 3I software.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
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1
2
3
4
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1
2
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0
General procedure 1.
4-Bromopyridine-2,6-dicarbonyl dichloride.
4ꢀ
18
Bromopyridineꢀ2,6ꢀdicarboxylic acid (0.724 g, 2.94 mmol) and SOCl (5 mL, 0.07 mol)
2
and DMF (1 drop) were held at reflux under N 4 h with magnetic stirring. Excess SOCl
2
2
was removed by distillation and the offꢀwhite material, 0.832 g (100 %), was used
without purification.
General procedure 2. Dibenzo-30-crown-10-based 4-bromopyridyl cryptand (1b).
4g
Crown ether diol 15 (0.257 g, 0.430 mmol) and freshly prepared 4ꢀbromopyridineꢀ2,6ꢀ
dicarbonyl dichloride (0.122 g, 0.430 mmol) were each dissolved in 50.0 mL of freshly
distilled DCM. The two solutions were loaded into plastic syringes whose metal needles
were replaced with HPLC tubing and added via syringe pump at 1 mL/h to pyridine (2.4
mL) in freshly distilled DCM (1.5 L). After additions were complete, the reaction mixture
was stirred for 3 days, after which time solvent was removed by rotary evaporation and
the resulting solid was dissolved in CHCl , washed with 1M HCl (x 1), H O (x 3),
3
2
followed by drying over Na SO . The mixture was filtered and solvent was removed by
2
4
rotary evaporation. The resulting residue was passed through a neutral Al O column,
2
3
eluting with CHCl :CH OH (97:3 v:v); the first eluting band contained the product: 81.1
3
3
1
mg (43%), mp 144.1 – 148.5 °C. H NMR (400 MHz, CDCl ) δ 8.48 (s, 2H), 6.94 (m,
3
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2
H), 6.93 (s, 2H), 6.78 (d, J = 9 Hz, 2H), 5.33 (s, 4H), 4.21 – 4.12 (m, 4H), 4.04 – 3.97
13
(m, 4H), 3.95 – 3.90 (m, 4H), 3.86 – 3.79 (m, 4H), 3.70 (m, 16H). C NMR (101 MHz,
CDCl ) δ 164.80, 148.99, 148.89, 148.40, 138.14, 128.17, 127.98, 121.60, 114.21,
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
13.94, 70.98, 70.75, 70.72, 70.61, 69.68, 69.46, 68.97, 68.79, 67.60 (19 signals
+1
expected and 19 signals found). High res MS: calc. for C H N O Br [M + NH ] m/z
37
48
2
14
4
8
23.2283, found m/z 823.2300 (error ꢀ2.1 ppm).
Biscryptand 3 (dibenzo-30-crown-10-based pyridyl cryptand linked directly at the
4
-pyridyl position). Bromocryptand 1b (34.7 mg, 0.0430 mmol), Pd(OAc) (2.1 mg,
2
0
.0094 mmol), PPh (18.9 mg, 0.072 mmol), and Na CO (21.8 mg, 0.206 mmol) in
3 2 3
DMF (20 mL) were stirred in an oil bath at 90 °C under N for 36 h. A portion of solvent
2
was removed by rotary evaporation and the remaining mixture was dissolved in CHCl3
and washed with 1M HCl (2x), H O (3x), and dried over Na SO . After filtration and
2
2
4
evaporation of the solvent, chromatography on neutral Al O was used to isolate the
2
3
coupled biscryptand product [EtOAc:DCM:CH OH (30:30:2 v:v:v)]: 15.8 mg (25%), mp
3
1
1
07.8ꢀ114.5 °C. H NMR (500 MHz, CDCl ) δ 8.71 (s, 2H), 6.98 (d, J = 8 Hz, 4H), 6.80
3
(d, J = 8 Hz, 2H), 5.40 (s, 4H), 4.18 (t, J = 4, 4H), 4.03 (t, J = 4, 4H), 3.93 (t, J = 4, 4H),
13
3
1
.84 (t, J = 4, 4H), 3.70 (m, 16H).
C NMR (126 MHz, CDCl ) δ 164.47, 150.02,
3
49.20, 149.04, 146.54, 128.06, 125.60, 121.94, 114.41, 114.01, 71.08, 70.80 (overlap
of two signals), 69.75, 69.56, 69.09, 68.89, 68.15 (18 peaks expected and 18 peaks
+
found). High res MS: calc. for C H N O [M+NH ] m/z 1470.5862, found m/z
74
92
3
28
4
1
470.5845 (error ꢀ1.2 ppm).
Bis(m-phenylene)-32-crown-10-based 4-bromopyridyl cryptand (4).
procedure 2 was used with the diacid chloride (0.153 g, 0.541 mmol), bis(5ꢀ
General
2
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1
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2
2
2
2
2
2
2
2
2
2
3
3
3
3
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3
3
3
3
3
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19
hydroxymethylꢀ1,3ꢀphenylene)ꢀ32ꢀcrownꢀ10
(0.323 g, 0.542 mmol) and pyridine (4.0
mL, 50 mmol) to produce a white solid that was purified by passing over neutral Al O ,
2
3
eluting with CHCl :CH OH (98:2 v:v) to give the desired product: 0.106 g (24%), mp
3
3
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
37.9 – 143.1 °C. H NMR (500 MHz, CDCl ) δ 8.48 (s, 2H), 6.52 (m, 4H), 6.45 (m,
3
13
H), 5.30 (s, 4H), 3.93 (m, 8H), 3.76 – 3.72 (m, 8H), 3.65 (m, 8H), 3.61 (m, 8H).
C
NMR (126 MHz, CDCl ) δ 163.92, 160.11, 149.25, 137.07, 134.97, 131.42, 106.49,
3
1
02.27, 71.03, 70.84, 69.69, 67.94, 67.71 (13 signals expected and 13 signals found).
79
14
+
High res MS: calc. for C H N O Br [M + NH ] m/z 823.2283, found m/z 823.2278
37
48
2
4
81
+
(
error 0.6 ppm); calc. for C H N O Br [M + NH ] m/z 825.2263, found m/z
37 48 2 14 4
825.2269 (error 0.7 ppm).
Biscryptand 5 [bis(m-phenylene)-32-crown-10-based pyridyl cryptand linked
directly at the 4-pyridyl position]. Bromocryptand 4 (18.0 mg, 0.0223 mmol),
Pd(OAc) (2.2 mg, 9.8 ꢁmol), PPh (5.2 mg, 20 ꢁmol), DMF (4 mL), and Na CO (22 mg,
2
3
2
3
0
.21 mmol) were stirred in an oil bath at 90 °C under N for 42 h, after which the mixture
2
was diluted with CHCl and washed with 1 M HCl (2x), H O (3x), and dried over
3
2
Na SO . The solution was filtered, followed by solvent removal. Product isolation was
2
4
achieved using preparative scale TLC [neutral Al O eluting with EtOAc:DCM:CH OH
2
3
3
1
(
30:30:1.5 v:v:v)]: 1.8 mg (11 %), mp: 96.1ꢀ105.4 °C. H NMR (500 MHz, CDCl ) δ 8.75
3
(
s, 3H), 6.58 (m, 6H), 6.50 – 6.47 (m, 7H), 5.39 (s, 8H), 4.05 – 4.00 (m, 9H), 3.82 (s,
11H), 3.79 – 3.74 (m, 18H), 3.72 – 3.61 (m, 70H). Integration was poor and indicated
impurities, but further purification was not possible due to the small amount of material;
+
also no 13C NMR spectrum was acquired.. High res MS: calc. for C H N O [M] m/z
74
88
2
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+
1
1
452.5524, found m/z 1452.5546 (error 1.6 ppm); calc. for C H N O [M + NH ] m/z
74 92 3 28 4
470.5862, found m/z 1470.5848 (error 0.95 ppm).
Biscryptand 6 (dibenzo-30-crown-10-based pyridyl cryptand employing a biphenyl
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
6
linkage). A mixture of DMF (5 mL), bromobenzyl 30ꢀcrownꢀ10 cryptand 1c (37.0 mg,
40.5 ꢁmol), Pd(OAc) (1.0 mg, 4.5 ꢁmol) and K CO (31.7 mg, 229 ꢁmol) under N was
2
2
3
2
held at reflux for 17 h and the solvent was removed by rotary evaporation. The crude
material was dissolved in DCM, washed with 1 M HCl (7x), H O (5x), and dried over
2
Na SO . The solution was filtered and rotary evaporation gave a material which was
2
4
passed over neutral Al O , eluting with CHCl :CH OH (97:3 v:v): 4.2 mg (12%), mp
2
3
3
3
1
1
13.4ꢀ120.1 °C. H NMR (500 MHz, CDCl ) δ 7.93 (s, 4H), 7.66 (d, J = 8 Hz, 4H), 7.54
3
(
d, J = 8 Hz, 4H), 6.94 (d, J = 8 Hz, 8H), 6. 77 (d, J = 8 Hz, 4H), 5.31 (s, 8H), 5.29 (s,
4
3
H), 4.18 – 4.14 (m, 8H), 4.02 – 3.97 (m, 8H), 3.95 – 3.90 (m, 8H), 3.83 – 3.79 (m, 8H),
13
.74 (m, 8H), 3.71 – 3.68 (m, 16H), 3.64 (m, 8H). C NMR spectrum not obtained due
+
to the small amount of material. High res MS: calc. for C H N O [M + NH ] m/z
88 104
3
30
4
1683.6733, found m/z 1683.6582 (error ꢀ8.97 ppm).
Tetraisopropyl 4,4'-(((p-phenylenebis(oxy))bis(ethane-2”,1”-
diyl))bis(oxy))bis(pyridine-2”’,6”’-dicarboxylate) (9). A mixture of CH CN (100 mL),
3
20
12
ditosylate 8 (5.78 g, 11.4 mmol), hydroxypyridine diester 7 (6.79 g, 25.4 mmol), and
K CO (5.85 g, 42.3 mmol) was held at reflux for 24 h with magnetic stirring under N .
2
3
2
After cooling to room temperature the mixture was filtered through Celite® p545 and
solvent was removed by rotary evaporation. The crude material was dissolved in DCM
and washed with aq. Na CO (x2), saturated NaCl (x3), and dried over Na SO . The
2
3
2
4
product was obtained after filtration and removal of solvent: 6.21 g (78%) of colorless
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2
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2
2
2
2
2
2
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3
3
3
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4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
solid, mp 193.1ꢀ195.4 °C. H NMR (500 MHz, CDCl ) δ 7.81 (s, 4H), 6.89 (s, 4H), 5.30
3
(
hept, J = 6 Hz, 4H), 4.52 – 4.46 (m, 4H), 4.37 – 4.32 (m, 4H), 1.43 (d, J = 6 Hz, 24H).
13
C NMR (126 MHz, CDCl ) δ 166.53, 164.10, 153.00, 150.64, 115.82, 114.18, 70.21,
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
6
7.32, 66.73, 21.81 (10 peaks expected and 10 peaks found). High res MS: calc. for
+
C H N O [M+H] m/z 697.2967, found m/z 697.3000 (error 4.7 ppm)
36
45
2
12
4
,4'-(((p-Phenylenebis(oxy))bis(ethane-2”,1”-diyl))bis(oxy))bis(pyridine-2”’,6’”-
dicarboxylic acid) (10). A mixture of tetraester 9 (0.379 g, 0.544 mmol) in THF (50
mL) and 10% aqueous KOH (50 mL) was stirred at reflux for 27 h. THF was removed
by rotary evaporation and conc. HCl was added until pH=1. The precipitate was
collected and washed with cool H O and dried: 0.287 g (100%) of a colorless solid, mp
2
1
2
60.0ꢀ265.0  (dec). H NMR (500 MHz, DMSOꢀd ) δ 7.78 (s, 4H), 6.93 (s, 4H), 4.57
6
13
(
s, 4H), 4.30 (s, 4H). C NMR (126 MHz, DMSOꢀd ) δ 166.53, 165.26, 152.42, 149.76,
6
115.49, 113.69, 67.61, 66.43 (8 peaks expected and 8 peaks found). HR MS: calc. for
+
C H O N [M + H] m/z 529.1089, found m/z 529.1084 (error 0.9 ppm); calc. for
24
21 12
2
+
C H O N Na [2M + Na] m/z 1079.1925, found m/z 1079.1926 (error 0.1 ppm).
48
40 24
4
4
,4'-(((p-Phenylenebis(oxy))bis(ethane-2”,1”-diyl))bis(oxy))bis(pyridine-2”’,6”’-
dicarbonyl dichloride) (11). Tetraꢀacid 10 (0.112 g, 0.212 mmol), SOCl (3 mL, 0.04
2
mol) and DMF (1 drop) were held at reflux under N for 12 h and the solvent was
2
removed under vacuum. The material was used directly without further purification; the
yield was assumed to be quantitative.
Tetraisopropyl
4,4'-(decane-1”,10”-diylbis(oxy))bis(pyridine-2,6-dicarboxylate)
(
12). A mixture of CH CN (200 mL), Br(CH ) Br (7.04 g, 23.5 mmol), 4ꢀhydroxypyridine
3
2 10
12
diester 7 (12.78 g, 47.82 mmol) and K CO (8.50 g, 61.5 mmol) under N was held at
2
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reflux for 4 days, after which it was filtered through Celite® p545 and the solvent was
removed by rotary evaporation. The crude material was dissolved in DCM and washed
with Na CO (2x), saturated NaCl (4x), and dried over Na SO . Filtration and removal
2
3
2
4
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
of the solvent provided the desired product as a colorless solid: 15.63 g (99%), mp 76.8ꢀ
1
7
=
1
8.0 °C. H NMR (500 MHz, CDCl ) δ 7.72 (s, 4H), 5.29 (hept, J = 6 Hz, 4H), 4.12 (t, J
3
13
6 Hz, 4H), 1.89 – 1.80 (m, 4H), 1.76 – 1.27 (m, 36H). C NMR (126 MHz, CDCl ) δ
3
66.92, 164.29, 150.52, 114.08, 70.13, 68.91, 29.44, 29.27, 28.80, 25.88, 21.81
+
(
11peaks expected and 11 peaks found). High res MS: calc. for C H N O [M+H]
36 53 2 10
m/z 673.3695, found m/z 673.3707 (error 1.8 ppm)
4,4'-(Decane-1”,10”-diylbis(oxy))bis(pyridine-2,6-dicarboxylic acid) (13). Tetraester
1
2 (1.86 g, 2.76 mmol), THF (50 mL) and 10 wt. % KOH (50 mL) were held at reflux for
2
4 h, followed by the removal of THF by rotary evaporation. The solution was acidified
to pH 1 using conc. HCl and the precipitate was collected via filtration: 1.08 g (78 %) of
1
a colorless solid, mp 192.8ꢀ196.1  . H NMR (500 MHz, DMSOꢀd ) δ 7.69 (s, 4H), 4.21
6
13
(
t, J = 6 Hz, 4H), 1.85 – 1.68 (m, 4H), 1.35 (m, 12H). C NMR (126 MHz, DMSOꢀd ) δ
6
1
66.71, 165.27, 149.65, 113.51, 68.69, 28.83, 28.59, 28.12, 25.21 (9 peaks expected
+
and 9 peaks found). HR MS: calc. for C H O N [M + H] m/z 505.1817, found m/z
24
29 10
2
5
05.1840 (error ꢀ4.6 ppm).
,4'-(Decane-1”,10”-diylbis(oxy))bis(pyridine-2,6-dicarboxylic acid chloride) (14).
4
Tetraꢀacid 13 (0.202 g, 0.401 mmol), SOCl (2.0 mL, 28 mmol) and DMF (1 drop) under
2
N were held at reflux for 12 h and the solvent was removed under vacuum. The
2
material was used directly without further purification, assuming the yield was
quantitative.
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2
2
2
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3
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3
4
4
4
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6
Biscryptand 16 (dibenzo-30-crown-10-based pyridyl cryptand containing a
4g
hydroquinone linkage). A mixture of dry DCM (700 mL), crown ether diol 15
(0.5291 g, 0.8868 mmol), pyridine (2 mL) and acidic Al O (1.00 g) was stirred for 1 h.
2
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Tetraꢀacid chloride 11 (0.2670 g, 0.4434 mmol) dissolved in 20 mL of DCM was added.
Stirring was continued for 32 h; the mixture was filtered through a small plug of neutral
Al O . The solvent was removed by rotary evaporation and the crude material was
2
3
taken up in DCM and washed with 1 M HCl (3x), H O (3x) and dried over Na SO . After
2
2
4
filtration the solvent was removed by rotary evaporation and the material was purified
using flash column chromatography, eluting with DCM to MeOH over neutral Al O :
2
3
1
0.1697 g (23%) of a colorless solid, mp 197.6ꢀ200.5 °C. H NMR (500 MHz, CDCl ) δ
3
7
4
.91 (s, 4H), 6.99 – 6.93 (m, 8H), 6.90 (m, 4H), 6.79 ꢀ 6.77 (m, 4H), 5.31 (s, 8H), 4.53 –
.48 (m, 4H), 4.36 (m, 4H), 4.20 – 4.14 (m, 8H), 4.03 – 3.99 (m, 8H), 3.96 – 3.92 (m,
13
8H), 3.85 – 3.80 (m, 8H), 3.75 (m, 8H), 3.73 – 3.68 (m, 16H), 3.65 (m, 12H). C NMR
126 MHz, CDCl ) δ 166.66, 164.84, 153.04, 150.10, 149.05, 148.94, 128.16, 121.73,
(
3
1
6
15.89, 114.61, 114.32, 114.00, 71.02, 70.79, 70.76, 70.65, 69.72, 69.49, 69.03, 68.84,
7.74, 67.46, 66.74 (23 signals expected and 23 signals found). High res MS: calc. for
+
2
C H N O [M + 2H] m/z 825.3203, found m/z 825.3223 (error 2.4 ppm); calc. for
84
102
2
32
+2
C H N O ꢀ2NH [M+2NH ] m/z 842.8484, found m/z 842.8493 (error 1 ppm); calc.
84
100
2
32
4
4
+
for C H N O [M] m/z 1648.6259, found m/z 1648.6256 (error ꢀ0.19 ppm).
84 100
2
32
Biscryptand 17 (dibenzo-30-crown-10-based pyridyl cryptand containing a C10
4g
linkage). A mixture of dry DCM (700 mL), crown ether diol 15
(0.4789, 0.8026
mmol), pyridine (2 mL) and acidic Al O (1.0 g) was stirred for 1 h. Tetraꢀacid chloride
2
3
1
4 (0.2025 g, 0.4014 mmol) dissolved in 20 mL of DCM was added. Stirring was
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continued for 32 h; the mixture was filtered and the solvent was removed by rotary
evaporation. The crude material was taken up in DCM and washed with 1 M HCl (3x),
H O (3x) and dried over Na SO . After filtration the solvent was removed by rotary
2
2
4
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
evaporation and the material was purified using flash column chromatography, eluting
with DCM to MeOH over neutral Al O : 0.2828 g (43%) of a colorless solid, mp 103.9ꢀ
2
3
1
1
06.2 °C. H NMR (500 MHz, CDCl ) δ 7.82 (s, 4H), 6.97 – 6.92 (m, 8H), 6.77 (d, J = 9
3
Hz, 4H), 5.31 (s, 8H), 4.16 (m, 12H), 4.01 (m, 8H), 3.93 (m, 8H), 3.81 (m, 8H), 3.75 (m,
H), 3.71 – 3.68 (m, 16H), 3.64 (m, 8H), 1.86 (m, 4H), 1.49 (m, 4H), 1.41 – 1.32 (s, 8H).
8
13
C NMR (126 MHz, CDCl ) δ 167.03, 165.00, 149.95, 149.04, 148.94, 128.19, 121.70,
3
114.52, 114.32, 114.02, 71.04, 70.81, 70.76, 70.66, 69.73, 69.49, 69.05, 68.86, 67.67,
9.43, 29.25, 28.76, 25.86 (24 peaks expected and 23 peaks found; it is believed that
2
one peak overlaps another in the 71.04 to 70.66 region). HR MS: calc. for
+
C H N O ꢀH [M+H] m/z 1625.7060, found m/z 1625.6921 (error ꢀ8.55 ppm); calc.
84
108
2
30
+
for C H N O ꢀNH [M+NH ] 1642.7325, found m/z 1642.7185 (error 2.4 ppm); calc.
84
108
2
30
4
4
+
for C H N O ꢀNa [M+Na] m/z 1647.6879, found m/z 1647.6753 (error 1.6 ppm).
84
108
2
30
1
-Benzyl-[4,4'-bipyridin]-1-ium TFSI (19). A solution of CH COC for H (200 mL),
3 3
4
,4’ꢀdipyridyl (5.02 g, 32.1 mmol) and C H CH Br (3.2 mL, 27 mmol) was held at reflux
6 5 2
for 45 min and cooled to room temperature. Half of the CH COCH was removed by
3
3
rotary evaporation and the solution was diluted with Et O and filtered. The solid was
2
washed with Et O, air dried and 3.01 g of the precipitate was dissolved in 30 mL of H O
2
2
and combined with a solution of LiTFSI (4.25 g, 14.0 mmol) in 10 mL of H O. The
2
resultant mixture was stirred and extracted with DCM twice. The organic layers were
combined and washed with H O (x3). Removal of solvent provided the desired product
2
2
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1
1
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1
1
1
1
1
1
1
2
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2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
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5
5
5
5
5
5
5
5
5
5
6
1
as a colorless solid: 4.71 g (97%), mp 90.8–92.5  . H NMR (500 MHz, CDCl ) δ 8.92
3
(
d, J = 7 Hz, 2H), 8.83 (d, J = 6 Hz, 2H), 8.22 (d, J = 7 Hz, 2H), 7.63 (d, J = 6 Hz, 2H),
13
7.51–7.39 (m, 5H), 5.75 (s, 2H). C NMR (126 MHz, CDCl ) δ 154.89, 151.48, 144.80,
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
40.83, 131.52, 130.59, 130.01, 129.45, 126.16, 121.46, 119.80 (q, J = 321 Hz), 65.00
+
(
12 peaks expected and 12 peaks found). High res MS: calc. for C H N [MꢀTFSI]
19 15 2
m/z 247.1230, found m/z 247.1223 (error ꢀ3 ppm).
1
',1'''-(((Pentane-1,5-diylbis(oxy))bis(4,1-phenylene))bis(methylene))bis(1-benzyl-
4,4'-bipyridine]-1,1'-diium) TFSI (21). solution of 1,5ꢀbis[p-
bromomethyl)phenoxy]pentane, (0.745 g, 1.68 mmol), CH CN (100 mL) and 1ꢀ
[
A
21
(
3
benzylꢀ[4,4'ꢀbipyridin]ꢀ1ꢀium TFSI (19, 1.86 g, 3.52 mmol) was held at reflux under N2
for 24 h. After it had cooled to room temperature, the mixture was filtered and the solid
was washed with CH CN, DCM, and dried on the filter. The precipitate was dissolved in
3
30 mL of boiling H O and mixed with a solution of LiTFSI (1.1 g, 4.2 mmol) in 10 mL of
2
H O. The mixture was cooled, the H O was decanted and the semiꢀsolid material was
2
2
triturated with H O (x3), filtered and dried in vacuum: a yellow solid, 2.90 g (91%), which
2
was purified by recrystallization from H OꢀCH COCH three times: 1.43 g (45%), mp
2
3
3
1
1
16.4–118.8  . H NMR (500 MHz, DMSOꢀd ) δ 9.49 (m, 8H), 8.73 (m, 8H), 7.61 (m,
6
8
H), 7.54–7.41 (m, 6H), 7.03 (d, J = 9 Hz, 4H), 5.96 (s, 4H), 5.86 (s, 4H), 4.00 (t, J = 6
1
3
Hz, 4H), 1.85–1.72 (m, 4H), 1.61–1.51 (m, 2H).
C NMR (126 MHz, DMSOꢀd ) δ
6
160.11, 149.85, 149.66, 146.13, 145.85, 134.51, 131.26, 129.98, 129.73, 129.36,
1
2
27.70, 127.63, 126.19, 119.94 (q, J = 323 Hz), 115.52, 68.01, 64.03, 63.73, 28.77,
2.60 (20 signals expected and 19 signals found, two peaks are believed to overlap at
+
126.19). High res MS: calc. for C H O F N NaS [M+Na] m/z 1919.0674, found
61
52 18 24
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+
m/z 1919.0505 (error –8.81 ppm); calc. for C H O F N NaS [MꢀTFSI] m/z
61
52 18 24
8
8
1
616.1604, found m/z 1616.1531 (error 4.5 ppm).
1',1'''-(Decane-1,10-diyl)bis(1-methyl-[4,4'-bipyridine]-1,1'-diium) TFSI (23).
1ꢀ
22
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Methylꢀ[4,4'ꢀbipyridin]ꢀ1ꢀium TFSI
(22, 6.10 g, 13.5 mmol) and Br(CH ) Br (1.64 g,
2
10
5
.47 mmol) in CH CN (75 mL) were held at reflux under N for 12 h. The mixture was
3 2
allowed to cool and the solid was collected on a glass frit and washed with cold CH CN
3
followed by DCM. The solid was dissolved in H O and mixed with a solution of LiTFSI
2
(
4.01 g, 14.0 mmol) in H O (10 mL). The precipitate was collected and recrystallized
2
from H O to yield an offꢀwhite product: 6.53 g (75 %), which was recrystallized from H O
2
2
1
ꢀCH COCH , mp 93.2–94.4  . H NMR (400 MHz, DMSOꢀd ) δ 9.32 (d, J = 7 Hz, 4H),
3
3
6
9
4
.24 (d, J = 7 Hz, 4H), 8.74 – 8.69 (m, 8H), 4.63 (t, J = 8 Hz, 4H), 4.40 (s, 6H), 1.94 (s,
13
H), 1.40–1.18 (m, 12H).
C NMR (101 MHz, DMSOꢀd ) δ 149.03, 148.62, 147.04,
6
146.15, 126.95, 126.49, 119.89 (q, J = 323 Hz), 61.37, 48.46, 31.24, 29.28, 28.90,
2
5.98 (13 signals expected and 13 signals found).
High res MS: calc. for
+
C H N O S F [M ꢀ TFSI] m/z 1322.0923, found m/z 1322.0839 (error 6.4 ppm);
40
42
7
12 6 18
+
calc. for C H N O S F [M ꢀ 2TFSI] m/z 521.0872, found m/z 521.0843 (error 5.6
36 42
6
8 4 12
ppm).
Example of an Isothermal Titration Microcalorimetry Experiment: Biscryptand 3
with Praquat 2a: The titration was run in CH COCH at 25 ºC using a Microcal MCS
3
3
ITC. The cryptand was in the cell and the paraquat was in the syringe. The
concentrations were 26.58 mM for the paraquat and 0.5002 mM for the cryptand.
Titration parameters were 50 injections of 2 ꢁl each. The time per injection was 3 min.
The primary filter period was 1 sec and lasted for 60 sec. The secondary filter period
2
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