Host-guest-driven copolymerization of tetraphosphonate cavitands

Article abstract of DOI:10.1002/chem.201002237

The outstanding complexing properties of tetraphosphonate cavitands towards N-methylpyridinium salts were exploited to realise a new class of linear and cyclic AABB supramolecular polymers through host-guest interactions. The effectiveness of the selected

Full text of DOI:10.1002/chem.201002237

FULL PAPER
DOI: 10.1002/chem.201002237
Host–Guest-Driven Copolymerization of Tetraphosphonate Cavitands
Francesca Tancini,[a] Roger M. Yebeutchou,[a] Laura Pirondini,[a] Rita De Zorzi,[b]
Silvano Geremia,[b] Oren A. Scherman,[c] and Enrico Dalcanale*[a]
Abstract: The outstanding complexing
properties of tetraphosphonate cavi-
tands towards N-methylpyridinium
salts were exploited to realise a new
class of linear and cyclic AABB supra-
molecular polymers through host–guest
interactions. The effectiveness of the
selected self-association processes was
crocalorimetric analyses clarified the
binding thermodynamics and revealed
the possibility of tuning entropic con-
tributions by acting on the flexibility of
the guest linker. Although the forma-
tion of linear polymeric chains for a
rigid system was demonstrated by X-
ray analysis, the presence of a concen-
tration-dependent ring–chain equilibri-
um was indicated by solution viscosity
measurements in the case of a very
flexible ditopic BB guest co-monomer.
Keywords: cavitands · copolymeri-
zation · host–guest systems · self-as-
sembly · supramolecular chemistry
1
tested by H NMR studies, whereas mi-
Introduction
molecular systems,[8] which allows for interconversion be-
tween different polymeric architectures.[9]
Supramolecular polymers[1] are constitutionally dynamic ma-
terials,[2] based on modular components reversibly linked
through non-covalent interactions. They occupy a special po-
sition among functional materials because they integrate the
remarkable properties of polymers with the key features of
self-assembly to give unique mechanical,[3] electronic,[4] bio-
logical[5] and self-healing[6] properties. Additionally, the
supramolecular approach offers the possibility of controlling
polymer topology and molecular-level mixing.[7] The incor-
poration of multiple switchable functionalities into a single
monomer leads to topological control of the realized supra-
The vast majority of supramolecular polymers reported so
far are assembled through hydrogen bonding or metal–
ligand coordination.[10] A less travelled route employs host–
guest interactions as the driving force for polymeri-
zation.[8,11,12,13] The main reason for its limited use is that
very high association constants (ꢀ105) are required to
obtain polymers with high molecular weight. This stringent
requirement greatly reduces the number of suitable host–
guest systems, out of the large number available.
As in the case of covalent polymers, the formation of
supramolecular copolymers widens the spectrum of synthet-
ic options and useful properties. Alternating copolymers
offer new opportunities for structural incorporation of func-
tional groups at very specific points along the chain. So far,
the number of supramolecular copolymers made by host–
guest interactions is rather small.[14] We previously reported
the design and synthesis of self-complementary heteroditop-
ic AB monomers[9] by exploiting the outstanding complexing
properties[15] of tetraphosphonate cavitands towards N-
methylpyridinium guests to form supramolecular homopoly-
mers. The designed monomers were cavitands bearing four
inward-facing P=O groups at the upper rim and a single N-
methylpyridinium unit at the lower rim. The corresponding
homopolymers featured guest-triggered reversibility, tem-
plate-driven conversion from linear to star-branched forms
and responsiveness to electrochemical stimuli.[16]
[a] Dr. F. Tancini, Dr. R. M. Yebeutchou, Dr. L. Pirondini,
Prof. Dr. E. Dalcanale
Dipartimento di Chimica Organica e Industriale and Unitꢀ INSTM
UdR Parma, Universitꢀ di Parma
Viale G. P. Usberti 17/a, 43124 Parma (Italy)
Fax : (+39)0521-905472
E-mail: enrico.dalcanale@unipr.it
[b] Dr. R. De Zorzi, Prof. Dr. S. Geremia
Centro di Eccellenza in Biocristallografia
Dipartimento di Scienze Chimiche
Universitꢀ di Trieste, Viale Giorgeri 1, 34127 Trieste (Italy)
[c] Dr. O. A. Scherman
Melville Laboratory for Polymer Synthesis
Department of Chemistry, University of Cambridge
Lensfield Road, CB2 1EW Cambridge (UK)
Herein we introduce cavitand-based supramolecular co-
polymers in which the host and guest functionalities are
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem201002237.
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present on two different species: 1) ditopic hosts (AA) with
two tetraphosphonate cavitands covalently attached at their
lower rim, and 2) ditopic guests (BB), in which flexible eth-
ylene oxide chains of different length are functionalized
with two N-methylpyridinium end groups (Scheme 1). The
formation of linear and cyclic supramolecular species with
the polymerization process and product. In the case of the
host, a more rigid heterocyclic tether was also introduced,
namely, pyridinedicarboxylate (1c), to ease crystal structure
determination. In the case of the guest, the presence of a
polyethylene glycol chain made the corresponding monomer
2c polymeric in nature.
Target hosts 1a, 1b and 1c
were synthesized in three steps,
starting from the already re-
ported monohydroxy-footed si-
lylcavitand I[9] (Scheme 2). Dif-
ferent dimerization protocols
were followed to bind together
two units of I. Esterification re-
actions with adipic acid and 3,5-
pyridinedicarboxylic acid in the
presence of 1,3-dichlorohexyl-
carbodiimide (DCC) and 4-di-
methylaminopyridine (DMAP),
were employed for IIb and IIc,
respectively. In the case of IIa,
silylcavitand I was treated with
dimethoxymethane in the pres-
ence of p-toluenesulfonic acid
monohydrate. Treatment of the
resulting intermediates IIa–c
with a 36% aqueous solution of
HF caused selective removal of
Scheme 1. AABB host–guest polymerization mode.
the dimethylsilyl bridges to give
an AABB copolymerization
motif was investigated by using
different techniques: the influ-
ence of the monomersꢂ struc-
tures on the thermodynamic
parameters of polymerization
was analyzed by isothermal ti-
tration calorimetry (ITC); the
linear polymer structure and
relative chain length were de-
termined by using X-ray analy-
sis and viscosity measurements,
respectively.
Results and Discussion
Synthesis of the building
blocks: Three ditopic hosts
(1a–c) and three ditopic guests
(2a–c) with different connect-
ing units were synthesized
(Schemes 2 and 3). The ali-
phatic spacers were chosen to
impart different lengths and
flexibilities to the correspond-
ing monomers to evaluate the
Scheme 2. Synthesis of target hosts. a) Dry CH2Cl2, DCC/DMAP, overnight, RT; b) DMF/CHCl3, HF, over-
influence of these factors on night, 458C; c) dry pyridine, PhPCl2, 3 h, 808C, then H2O2, 30 min, RT.
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Copolymerization of Tetraphosphonate Cavitands
FULL PAPER
Scheme 3. Synthesis of target guests. a) Pyridine, 3 h, 1008C; b) acetonitrile, CH3I, overnight, reflux.
the corresponding resorcinarenes IIIa–c, ready to be func-
tionalized with dichlorophenylphosphine. This reaction gave
rise to a tetraphosphonite intermediate, which was oxidized
to 8.39 ppm and from d=8.51 to about 7.98 ppm, respective-
ly.
The presence of complexed species was also confirmed by
ESI-MS spectrometry. Short ditopic guest 2b*, which is
[9]
in situ by addition of H2O2 to give tetraphosphonate cavi-
ꢁ
tands 1a–c. On account of the stereospecificity of this reac-
tion, only the isomers having four inward-facing phospho-
nate bridges were formed in all cases. The target guests 2a,
2b and 2c were prepared in two steps (Scheme 3) by treat-
ment of isonicotinoyl chloride hydrochloride with ethylene
glycol, 1,6-hexanediol and polyethylene glycol, respectively.
Subsequent methylation with iodomethane afforded the de-
sired products in quantitative yield.
structurally equivalent to 2b and features PF6 as the coun-
terion instead of Iꢁ, was chosen to give a suitable mass
range for ESI analysis. The ESI-MS spectrum in acetone/
methanol of a 1:1 mixture of 1b and 2b* showed two main
peaks at m/z 1451.1 and 3047.1, due to doubly and singly
charged ions of 1b·2b*, respectively (see Figure S1, Sup-
porting Information).
ITC measurements: ITC studies[17] were carried out to quan-
tify the thermodynamic parameters DH8, Kass, DG8 and DS8
associated with the inclusion process.[18] Preliminary experi-
ments performed with both monotopic and ditopic species
(see Figure S2 and Table S1,
Host–guest-driven complexation: Complexation of N-meth-
ylpyridinium-based guests inside the host cavity was first de-
termined by 1H NMR titration. Figure 1 shows 1H NMR
Supporting Information) re-
vealed that no cooperativity,
either positive or negative, is
present when multiple binding
occurs. More significant in this
context is the comparison be-
tween the data collected for di-
topic host 1b with the three di-
topic guests 2a, 2b and 2c.
As shown in Table 1, al-
though the Kass values remain
very close to each other, a clear
trend is seen for the entropic
contribution. On moving from
the short methylene linker to
the longer and flexible ones,
the negative TDS8 term first be-
comes almost neutral and then
positive. Particularly appealing
for the realization of robust
supramolecular architectures is
Figure 1. Section of 1H NMR spectra (CDCl3) monitoring host–guest complexation. Top: Free host (5 mm).
Middle: Free guest (5 mm). Bottom: Host–guest complex (1:1 stoichiometry).
spectra monitoring the system formed by 1b and 2c. Diag-
nostic upfield shifts of the guest signals were observed, as
expected for included species that experience the shielding
effect of the cavity. The CH3-pyridinium resonance moved
more than 3 ppm upfield; ortho and meta pyridinic protons
showed a smaller shift in the same direction, from d=8.60
the favourable thermodynamics of the 1b·2c system. In this
case, the high flexibility of the polyethylene glycol spacer
imparts conformational freedom in the final complex, which
reduces the entropy loss that generally occurs during self-as-
sociation and leads to a process that is both enthalpy- and
entropy-driven. As control experiments, the titration of 2c
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14315

E. Dalcanale et al.
Table 1. Thermodynamic parameters and Kass values for ITC titration of
1b with 2a, 2b and 2c in methanol at 258C. [1b]=0.5 mm; [guest]=
4 mm. All data fitted the 1:1 binding profile well.
Kass [mꢁ1
(1.3ꢂ0.1)ꢃ105 ꢁ34.8ꢂ0.6
(8.4ꢂ0.6)ꢃ104 ꢁ26.7ꢂ0.3
(4.9ꢂ0.2)ꢃ105 ꢁ25.4ꢂ0.1
]
DH8 [kJmolꢁ1
]
TDS8 [kJmolꢁ1
]
DG8 [kJmolꢁ1
]
1b·2a
1b·2b
1b·2c
N
ꢁ5.6ꢂ0.5
1.5ꢂ0.4
7.1ꢂ0.3
ꢁ29.2ꢂ0.2
ꢁ28.2ꢂ0.2
ꢁ32.5ꢂ0.1
Table 2. Thermodynamic parameters and Kass values for ITC titration of
2c with 1a and 1c in methanol at 258C. [host]=0.5 mm; [2c]=4 mm. All
data fitted well for a 1:1 binding profile.
Kass [mꢁ1
(2.3ꢂ0.2)ꢃ105 ꢁ25.4ꢂ0.5
(3.9ꢂ0.2)ꢃ105 ꢁ23.9ꢂ0.2
]
DH8 [kJmolꢁ1
]
TDS8 [kJmolꢁ1
]
DG8 [kJmolꢁ1
]
1a·2c
1c·2c ACHTUNGTRENNUNG
G
5.1ꢂ0.3
8.0ꢂ0.2
ꢁ30.6ꢂ0.2
ꢁ31.9ꢂ0.1
was repeated with 1a and 1c to test the efficiency of these
other hosts. As highlighted in Table 2, no significant differ-
ences are observed in comparison to 1b·2c. Therefore,
within the domain of the ditopic hosts the different flexibili-
ty of the spacers does not affect the thermodynamic signa-
ture of the host–guest interaction.
The most relevant result obtained from ITC measure-
ments is the solvent effect. When the titration between 1b
and 2c was repeated in dichloromethane, a gain of two
orders of magnitude for the Kass value was recorded on
moving from MeOH to CH2Cl2 (at 258C, [1b]=0.4 mm and
[2c]=2.5 mm,
K
ass =(1.8ꢂ0.5)ꢃ107 mꢁ1,
DH8=ꢁ35.3ꢂ
0.2 kJmolꢁ1,
TDS8=6.0ꢂ0.5 kJmolꢁ1,
DG8=ꢁ41.2ꢂ
Figure 2. a) Specific viscosity vs. concentration and b) log–log plot of spe-
0.6 kJmolꢁ1). The ITC data indicate that the gain is totally
enthalpic in origin. This result can be rationalized by taking
into account two factors: 1) the limited solvation exerted by
dichloromethane on the methylpyridinium moieties, which
leads to a preference for its inclusion in the cavity; 2) the
host affinity for MeOH, which competes with the guest for
cavity complexation.[19] The combination of the two factors
accounts for the large decrease in complexation observed in
MeOH. Because of the higher association constant assured
by chlorinated solvents, they were chosen as eligible media
for creation of polymeric chains.
cific viscosity vs. concentration for a solution of a mixture of 1b and 2c
ꢁ1
*
(1:1) in chloroform. : 31.5–1.8 gL (7.0–0.4 mm), y=1.3509xꢁ2.2602,
R2 =0.9982; : 237.1–45.0 gL (52.5–10.0 mm), y=1.7378xꢁ2.8984, R2 =
ꢁ1
&
ꢁ1
(77.5–57.5 mm), y=2.2841xꢁ4.1968, R2 =
^
0.9975;
0.9998.
: 350.3–248.3 gL
(Table 3). Below this threshold concentration, the low
number of connected monomer units N obtained is in agree-
ment with the presence of (H+G)1 or (H+G)2 cyclic oligo-
mers.
In the intermediate concentration regime (slope of 1.7)
the fraction of open oligomers increases at the expense of
the cyclic adducts. The formation of linear supramolecular
polymers was observed at higher concentrations, where a
further rise in viscosity was observed (slope of 2.28). The re-
corded final slope of the curve is comparable to that of urei-
dopyrimidone-based self-assembling systems reported by
Meijer, Schenning et al. (slope of 2.48).[21] This result is justi-
Viscosity and static light scattering measurements: To evalu-
ate the average degree of polymerization in the self-assem-
bly of 1b and 2c, viscosity measurements were carried out
in chloroform at 258C. While a linear relationship between
concentration and specific viscosity was initially observed
(1.8–31.5 gLꢁ1, 0.4–7 mm), a sharp rise in viscosity was re-
corded upon increasing the concentration (Figure 2a). Three
distinct regions can be distinguished in the corresponding
log–log plot (Figure 2b), indicative of a gradual transition
from cyclic to linear species.[20]
Table 3. SLS measurements of Mw for a 1:1 mixture of 1b and 2c in
chloroform (dn/dc=0.102 mLgꢁ1).
c [gLꢁ1
]
Mw
N
At low concentrations, the slope of the linear fit is about
1.4, as expected for cyclic oligomers with constant size.[20]
Further evidence for the formation of cyclic structures in
this concentration regime came from static light scattering
(SLS) measurements providing the average molecular
weight (Mw) in the concentration range of 1.5–4.0 mm
7 (1.5mm)
4500
4500
4700
8700
9500
out of scale
ACHTUNGTRENNUNG
7.8 (1.7mm)
8.8 (1.9mm)
16.6 (3.6mm)
18.5 (4.0mm)
20.7 (4.6mm)
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
–
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Copolymerization of Tetraphosphonate Cavitands
FULL PAPER
fied by the troublesome achievement of the exact 1:1 ratio
between host and guest due to the polydispersity of the
PEG-based monomer. Taking into account the detrimental
effect that even tiny deviations from the 1:1 ratio have on
the degree of polymerization,[1a] the obtained results are
consistent with the formation of reasonably long polymeric
chains.
The specific viscosity of a solution of unfunctionalized
PEG (Mw =1500 Da; 40 mm) in chloroform was measured to
be 0.4, and thus the higher value observed for the 1b·2c
system cannot be simply related to the presence of the PEG
spacer in the BB monomers. Moreover, control experiments
performed by measuring the viscosity of 1:2 mixtures of 1b
and monotopic N-methyl(propylisonicotinate) iodide (com-
pound 4, Supporting Information) at different concentra-
tions in CHCl3 revealed that the viscosity increased from 0.1
to 0.6 at 0.5 mm and 40 mm, respectively (see Figure S11,
Supporting Information). Thus, short oligomeric species
(trimers in this specific case) cannot account for the high
viscosities recorded for 1b·2c in the high-concentration
regime.
on the different oligomers, causing their assembly into long
polymeric species that are responsible for the recorded vis-
cosity increase. On cooling the solution and measuring its
viscosity again at 258C, a higher value than the starting one
is recorded (34.8 versus 26.7). This hysteresis is indicative of
the higher stability of the polymeric species with respect to
the corresponding cyclic adducts in a medium-high concen-
tration regime.
As a control experiment, the same temperature-depen-
dent measurements were performed on a solution of unfunc-
tionalized PEG (40 mm) in 1,1’,2,2’-tetrachloroethane. A
similar trend was observed, even though the viscosity en-
hancement above 508C was definitely less marked. It can be
attributed to elongation of the PEG chains (see Figure S12,
Supporting Information). This hypothesis is further support-
ed by the fact that when the solution was cooled at room
temperature, its initial viscosity was restored.
X-ray analysis: An equimolar mixture of rigid homoditopic
host 1c and methyl viologen hexafluorophosphate was crys-
tallized from acetonitrile/water (9:1). A section of the crys-
tal packing (Figure 4) highlights the eight P=O groups
facing inward toward the cavity and making ion–dipole in-
teractions with the positively charged nitrogen atom of the
methyl viologen guest. The average N+···O=P distance is
3.04ꢂ0.03 ꢄ, and the average distance between the protons
of the CH3-pyridinium moiety and the plane of the aromatic
Additional viscosity measurements were performed in
1,1’,2,2’-tetrachloroethane as a function of temperature. An
equimolar solution of 1b and 2c (40 mm) was heated from
25 to 808C, and first showed a decrease in specific viscosity,
followed by an increase above a critical temperature of
508C (Figure 3).
ꢁ
rings is 3.60ꢂ0.02 ꢄ. One PF6 counterion is located at the
bottom of the cavity and interacts with the alkyl chains at
ꢁ
the lower rim of the cavitand. Moreover, one of the P F
bonds points toward the centre of the cavity, stabilising the
ion pair with the complexed methylpyridinium moiety.[22]
Figure 3. Specific viscosity of a solution of a mixture of 1b and 2c (1:1)
in tetrachloroethane as a function of temperature.
This behaviour is in line with the thermodynamic signa-
ture of host–guest polymerization. As discussed in the ITC
section, complexation and polymerization of 1b·2c is both
enthalpy- and entropy-driven. However, enthalpy is more
effective at 258C, so that in the low-temperature regime
heating negatively affects polymerization by inducing rever-
sible formation of smaller oligomeric and cyclic species, and
accounts for the observed viscosity decrease. Nevertheless,
because entropy also plays a favourable role in the complex-
ation, a critical temperature should exist above which the
entropic contribution becomes dominant. At this tempera-
ture, sufficient energy is provided to the system to break
small rings, and consequently elongation of the PEG chains
is allowed. This occurs by exposing “reactive end groups”
Figure 4. Section of the linear polymer 1c·methyl viologen featuring ion–
dipole and CH–p interactions, and fitting of one PF6 counterion be-
tween the alkyl chains of the cavitands.
ꢁ
The crystal structure was obtained by the molecular re-
placement method with the atomic coordinates of a mono-
topic tetraphosphonate cavitand as search model.[23] The so-
lution showed two crystallographically independent mono-
topic molecules in the P21/n space group, in agreement with
a single molecule of 1c in the asymmetric unit. During re-
ꢁ
finement, two PF6 ions (one distributed over three sites at
partial occupancy) and 2.5 molecules of acetonitrile (placed
in four sites: one site at full occupancy and three sites at
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14317

E. Dalcanale et al.
half occupancy each) were detected in the asymmetric unit.
The analysis of electron density maps obtained after the ini-
tial refinement cycles revealed regions with residual electron
density. The electron density observed in the region between
the two resorcinarene cavities was successfully assigned to a
methyl viologen molecule. Moreover, another region of re-
sidual electron density was located close to an alkyl chain
on the lower rim of a resorcinarene moiety (Figure S13,
Supporting Information), assignable to residual 3,5-dicar-
boxypyridine, the linker between the two host moieties. In
the following refinement cycles, this fragment was intro-
duced into the model, but attempts to find its correct posi-
tion to interpret the electron density were hampered by the
high degree of disorder of this group. Seven possible posi-
tions for the 3,5-dicarboxypyridine residue were modelled
for the site of the linker. However, refined structures
showed high values for the thermal parameters of the atoms
of the 3,5-dicarboxypyridine and high values of the R factor
in all cases. Nonetheless, the seven positions that were not
excluded by topology considerations support a polymeric
supramolecular structure (Figure 5). In fact, in all these
models, the resorcinarene cavities linked by the dicarboxy-
pyridine face in opposite directions, as in the polymeric con-
figuration, rather than towards the same direction, as would
be expected for formation of tetrameric rings.
parent homopolymer.[9] Viscosity measurements demonstrat-
ed the strong influence that both monomer concentration
and temperature exert on the conversion of cyclic oligomer-
ic species to linear polymeric chains.[24] The crystal structure
of the copolymer between methyl viologen and 1a/1c vali-
dates the proposed interaction mode among the monomeric
units and shows the preference of the system for linear poly-
merization in the solid state.
The formation of supramolecular alternating copolymer
1b·2c is particularly significant, due to the polymeric nature
of monomer 2c. The dilution of the two interacting units at
the end of a long alkyl chain does not hamper polymer as-
sembly, on account of the positive entropic contribution to
binding. This bodes well for the use of this host–guest
system in topological and miscibility control of covalent
polymers. Moreover, the pyridine ligand embedded in ditop-
ic host linker 1c can be used as a ligand for metal-directed
switching from linear to cross-linked supramolecular net-
works.
Experimental Section
General: All reagents and chemicals were purchased from commercial
sources and used without further purification. Pyridine was dried before
use by distillation from KOH according to the standard procedures.
1H NMR spectra were obtained by using a Bruker AC-300 (300 MHz) or
a Bruker AVANCE 300 (300 MHz) spectrometer. All chemical shifts, d,
are reported in ppm relative to the proton resonances resulting from in-
complete deuteration of the NMR solvents. 31P NMR spectra were ob-
tained by using a Bruker AMX-400 (162 MHz) spectrometer.
Conclusion
Host–guest-driven self-assembly of complementary homodi-
topic molecules has been exploited to realize supramolec-
ular copolymers both in solution and in the solid state. An
accurate thermodynamic description of the binding events
leading to polymerization was obtained by ITC. The highly
desirable positive entropic contribution to binding requires
the introduction of a flexible spacer in the guest co-mono-
mer. However, the conformational mobility of the spacer
allows for the formation of cyclic species, absent in the
ESI-MS experiments were performed by using a Waters ZMD spectrom-
eter equipped with an electrospray interface. Exact masses were deter-
mined by using a LTQ ORBITRAP XL Thermo spectrometer equipped
with an electrospray interface. GC-MS analysis was performed by using a
(Hewlett Packard) HP 6890/5973 GC/MSD system.
Static light scattering (SLS) measurements were performed by using a
multi-angle laser light scattering (MALS) Dawn DSP-F photometer from
Wyatt (Santa Barbara, CA, USA) in off-line (batch) mode in freshly dis-
tilled chloroform at RT. All polymer solutions were accurately filtered
through 0.2 mm PTFE filters. The MALS photometer used a vertically
Figure 5. Structure of the alternate copolymer formed by self-assembly between methyl viologen and 1c. Experimental details are given in the Support-
ing Information.
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Copolymerization of Tetraphosphonate Cavitands
FULL PAPER
polarized He–Ne laser (l=632.8 nm) and simultaneously measured the
intensity of the scattered light at 18 angular locations ranging from 19.2
to 149.28. The MALS calibration constant was calculated by using tolu-
ered by solvent evaporation, was purified by silica column chromatogra-
phy (CH2Cl2) affording pure IIb (0.15 g, 42%). 1H NMR (300 MHz,
CDCl3, 258C): d=7.16 (s, 4H; ArH), 7.14 (s, 4H; ArH), 4.59 (t, 3J-
ene as a standard and assuming a Rayleigh factor of 1.406ꢃ10ꢁ5 cmꢁ1
.
ACHUTNGRENNUG CAHTUNGTRENNUNG
(H,H)=7.9 Hz, 8H; ArCH), 4.12 (t, 3J
The different photodiodes were normalized by measuring the scattering
intensity of a polystyrene standard of narrow molecular weight distribu-
tion (Mp =10.3 kgmolꢁ1, Mw/Mn =1.03, Rg =2.6 nm) in chloroform, as-
sumed to act as isotropic scatterer.
CH2CH2CH3), 0.96 (m, 18H; CH2CH2CH3), 0.50 (s, 24H; SiCH3,out),
ꢁ0.70 ppm (s, 24H; SiCH3,in); ESI-MS: m/z calcd for C110H150O20-
Si8Clꢁ: 2052.5; found: 2052.3 [M+Cl]ꢁ.
The incremental refractive index dn/dc for an equimolar mixture of 1b
and 2c in chloroform (n=1.446) at 258C was measured to be
0.102 mLgꢁ1 by using a KMX-16 differential refractometer from LDC
Milton Roy (Riviera Beach, FL, USA).
3,5-Pyridinedicarboxylic acid bis(silylcavitand) ester IIc: DCC (0.05 g,
2.61ꢃ10ꢁ4 mol) and DMAP (0.01 g, 8.73ꢃ10ꢁ5 mol) were added to a solu-
tion of 3,5-pyridinedicarboxylic acid (0.02 g, 1.20ꢃ10ꢁ4 mol) in dry
CH2Cl2/DMF (8:1, 9 mL). The resulting suspension was stirred at RT
until complete dissolution. Silylcavitand I (0.25 g, 2.61ꢃ10ꢁ4 mol) was
added. The reaction mixture was stirred at RT for 24 h and finally
quenched by solvent removal. The crude was suspended in water (10 mL)
and filtered. Purification by silica column chromatography (CH2Cl2/
EtOH 99:1) yielded desired product IIc (0.11 g, 41%). 1H NMR
ITC studies were performed by using an isothermal titration microca-
lorimeter MicroCal VP-ITC, thermostated at 258C. Experimental titra-
tion curves were analyzed by using the MicroCal Origin 5.0 program.
DH, DS and Kass values were calculated as the average of a set of inde-
pendent experiments; DG value is given by DG=DHꢁTDS. Standard de-
viations for DH, DS and K were calculated according to Equation (1):
(300 MHz, CDCl3, 258C): d=9.32 (d, 5J
(d, 5J
(H,H)=2.0 Hz, 1H; Ho-py), 7.16 (s, 4H; ArH), 7.14 (s, 4H; ArH),
4.62 (t, 3J(H,H)=8.1 Hz, 8H; ArCH), 4.45 (t, 3J
(H,H)=6.7 Hz, 4H;
ACHTUNGTREN(GNUN H,H)=2.0 Hz, 2H; Hp-py), 8.81
rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
n
ꢀ
Si¼1ðxi ꢁ xÞ
ð1Þ
AHCTUNGTRENNUNG
n ꢁ 1
A
ACHTUNGTRENNUNG
CH2OC(O)), 2.32 (m, 4H; CH2CH2CH2OC(O)), 2.17 (m, 12H;
ArCHCH2), 1.87 (s, 24H; ArCH3), 1.82 (m, 4H; CH2CH2CH2OC(O)),
1.27 (m, 12H; ArCHCH2CH2), 0.94 (m, 18H; CH2CH2CH3), 0.51 (s,
24H; SiCH3,out), ꢁ0.68 ppm (s, 24H; SiCH3,in); ESI-MS: m/z calcd for
C111H145NO20Si8Na+: 2061.0; found: 2060.8 [M+Na]+.
in which n is the number of three independent experiments, xi is the
ꢀ
value recorded in the i-experiment, and x is the average value for x. Stan-
dard deviation for DG was calculated according to Equation (2):
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
2
dðDGÞ ¼ ½ð@G=@KassÞdðKassÞꢃ
¼
½ꢁRTdðKassÞ=Kass
ꢃ
¼ RTdðKassÞ=Kass
ð2Þ
Methylenebis(resorcinarene) IIIa: An aqueous solution of HF (36%;
1.3 mL) was added to IIa (0.66 g, 3.44ꢃ10ꢁ4 mol) in CHCl3/DMF (1/1,
30 mL). The mixture was heated at 458C overnight. The solvent was re-
moved in vacuo and the product suspended in water. Vacuum filtration
afforded pure IIIa (0.46 g, 91%). 1H NMR (300 MHz, [D6]acetone,
258C): d=7.95 (s, 16H; ArOH), 7.44 (s, 4H; ArH), 7.43 (s, 4H; ArH),
Enthalpies of dilution of the hosts and the guests were determined in
separate experiments, and found to be negligible. All the measurements
were carried out by titrating a host solution (in the cell) with a guest so-
lution (in the syringe).
4.64 (s, 2H; OCH2O), 4.41 (t, 3J
(H,H)=7.5 Hz, 8H; ArCH), 3.57 (t, 3J-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Viscosity measurements were performed by using an Ubbelohde dilution
viscometer. Solutions of polymers were prepared in chloroform (HPLC
grade) or 1,1’,2,2’-tetrachloroethane (98%, GC grade). The temperature
was controlled by using a thermostated water bath (for the experiments
at 258C) or an oil bath (for measurements at variable temperature). Sol-
vents and solutions were filtered through 0.2 mm Teflon membrane filters
directly into the viscometer.
12H; CH2CH2CH3), 2.05 (s, 24H; ArCH3), 1.56 (m, 4H; CH2CH2CH2O),
1.31 (m, 12H; CH2CH2CH3), 0.95 ppm (m, 18H; CH2CH2CH3); ESI-MS:
m/z calcd for C89H111O18ꢁ: 1967.8; found: 1467.9 [MꢁH]ꢁ.
Adipic acid bis(resorcinarene) ester IIIb: An aqueous solution of HF
(36%; 0.4 mL) was added to IIb (0.42 g, 2.33ꢃ10ꢁ4 mol) in CHCl3/DMF
(1:1, 16 mL). The mixture was heated at 458C overnight. The solvent was
removed in vacuo and the product was suspended in water. Vacuum fil-
tration afforded pure IIIb (0.37 g, quantitative yield). 1H NMR
(300 MHz, (300 MHz, [D6]DMSO, 258C): d=8.63 (s, 16H; ArOH), 7.25
The molecular structure of C156H153N3O28P8·2PF6ꢁ·2.5CH3CN was deter-
mined by single-crystal X-ray diffraction. Experimental details are sum-
marized in Table S1 (see Supporting Information). Intensity data were
collected with CuKa radiation (l=1.54 ꢄ) and a CCD area detector at
ꢁ1738C. The structure was solved by direct methods with DENZO-SMN,
SCALEPACK and AMoRe SHELXL programs.
(s, 8H; ArH), 4.19 (t, 3J
6.2 Hz, 4H; CH2OC(O)CH2), 2.21 (m, 4H+16H; CH2OC(O)CH2 +
ArCHCH2), 1.90 (s, 24H; ArCH3), 1.47 (m, 4H+4H;
OC(O)CH2CH2CH2CH2(O)CO+CH2CH2CH2O), 1.17 (m, 12H;
(H,H)=7.3 Hz, 8H; ArCH), 4.01 (t, 3J
ACHUTGTNRNEUNG ACHTUNGTRENNUNG(H,H)=
Methylenebis(silylcavitand) IIa: Dimethoxymethane (0.86 mL, 9.72ꢃ10ꢁ3
mol) and p-toluenesulfonic acid monohydrate (0.02 g, 1.26ꢃ10ꢁ4 mol)
were added to a solution of silylcavitand I (2.06 g, 2.16ꢃ10ꢁ3 mol) in dry
CH2Cl2 (25 mL). The reaction mixture was heated to reflux overnight
under nitrogen by using a modified Soxhlet extractor filled with molecu-
lar sieves (3 ꢄ). The mixture was allowed to cool and washed with 0.3m
NaOH to neutralize the acid catalyst. Concentration of the organic phase
to dryness afforded the crude product, which was purified by silica
column chromatography (CH2Cl2/MeOH 99:1) to give pure IIa (0.66 g,
CH2CH2CH3), 0.88 ppm (m, 18H; CH2CH2CH3); ESI-MS: m/z calcd for
C94H117O20ꢁ: 1566.8; found: 1467.0 [MꢁH]ꢁ.
3,5-Pyridinedicarboxylic acid bis(resorcinarene) ester IIIc: An aqueous
solution of HF (36%; 0.8 mL) was added to IIc (1.0 g, 4.90ꢃ10ꢁ4 mol)
dissolved in CHCl3/DMF (1/1, 30 mL). The mixture was heated at 458C
overnight. The solvent was removed in vacuo and the product was sus-
pended in water. Vacuum filtration afforded pure IIIc (0.75 g, 96%).
1H NMR (300 MHz, [D6]DMSO, 258C): d=9.25 (d, 5J
2H; Hp-py), 8.63 (s, 16H; ArOH), 7.93 (d, 5J
(H,H)=2.0 Hz, 1H; Ho-py),
7.25 (s, 8H; ArH), 4.37 (t, 3J(H,H)=8.1 Hz, 8H; ArCH), 4.19 (t, 3J-
(H,H)=6.7 Hz, 4H; CH2OC(O)), 2.35 (m, 4H; CH2CH2CH2OC(O)),
ACHTUNGTREN(NUNG H,H)=2.0 Hz,
1
AHCTUNGTRENNUNG
32%). H NMR (300 MHz, CDCl3, 258C): d=7.19 (s, 4H; ArH), 7.18 (s,
4H; ArH), 4.71 (s, 2H; OCH2O), 4.61 (t, 3J
ACTHNUTRGNE(UNG H,H)=8.0 Hz, 8H; ArCH),
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
3.62 (brt, 4H; CH2CH2O), 2.27 (m, 4H; CH2CH2CH2O), 2.17 (m, 12H;
CH2CH2CH3), 1.91 (s, 24H; ArCH3), 1.58 (m, 4H; CH2CH2CH2O), 1.30
2.18 (m, 12H; ArCHCH2), 1.91 (s, 24H; ArCH3), 1.80 (m, 4H;
(m, 12H; CH2CH2CH3); 0.98 (t, 3J
ACHTUNTRGNE(UNG H,H)=6.6 Hz, 18H; CH2CH2CH3),
CH2CH2CH2OC(O)), 1.20 (m, 12H; ArCHCH2CH2), 0.87 ppm (m, 18H;
ꢁ
CH2CH2CH3); ESI-MS: m/z calcd for C95H112NO20
1587.8 [MꢁH]ꢁ.
: 1587.8; found:
0.71 (s, 24H; SiCH3,out), ꢁ0.69 ppm (s, 24H; SiCH3,in); ESI-MS: m/z calcd
for C105H144O18Si8Na+: 1941.8; found: 1941.5 [M+Na]+.
Methylenebis(tetraphosphonate cavitand) 1a: Dichlorophenylphosphine
(0.36 mL, 2.64ꢃ10ꢁ4 mol) was added slowly at RT to a solution of IIIa
(0.46 g, 3.10ꢃ10ꢁ4 mol) in freshly distilled pyridine (20 mL) under argon.
After stirring for 3 h at 708C, the solution was allowed to cool to RT and
a mixture of aqueous 35% H2O2 and CHCl3 (1:1, 12 mL) was added. The
Adipic acid bis(silylcavitand) ester IIb: Silylcavitand I (0.34 g, 3.57ꢃ
10ꢁ4 mol), DCC (0.07 g, 3.57ꢃ10ꢁ4 mol) and DMAP (0.02 g, 1.18ꢃ
10ꢁ4 mol) were added to a solution of adipic acid (0.03 g, 1.79ꢃ10ꢁ4 mol)
in dry CH2Cl2/DMF (95:5, 15 mL). The resulting suspension was stirred
overnight at RT. The mixture was filtered, and the crude product, recov-
Chem. Eur. J. 2010, 16, 14313 – 14321
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
14319

E. Dalcanale et al.
resulting mixture was stirred for 30 min at RT, and then the solvent was
removed in vacuo. Addition of water resulted in precipitation of a white
powder, which was collected by filtration to give pure 1a (0.74 g, 97%).
1H NMR (300 MHz, [D6]acetone, 258C): d=8.12 (m, 16H; P(O)ArHo),
7.74 (m, 8H; P(O)ArHp), 7.64 (m, 8H+8H; ArH+P(O)ArHm), 4.88 (t,
(0.60 g, 3.35ꢃ10ꢁ3 mol) in pyridine (25 mL). The reaction mixture was
stirred at 1008C for 3 h and then the solvent was removed under vacuum.
The crude product was washed with water and extracted with CH2Cl2.
Concentration to dryness of the organic phase afforded pure IVc (2.06 g,
69%). 1H NMR (300 MHz, CDCl3, 258C): d=8.72 (d, 3J
4H; Ho), 7.80 (d, 3J(H,H)=6.0 Hz, 4H; Hm), 4.45 (t, 3J
4H; CH2OCC(O)), 3.78 (m, 4H; CH2CH2OC(O)), 3.58 ppm (m, 116H;
(CH2CH2O)29).
ACHTUNGTRENNUNG
3J
ACHTUNGTRENNUNG(H,H)=7.6 Hz, 8H; ArCH), 4.71 (s, 2H; OCH2O), 3.64 (brt, 4H;
A
ACHTUNGTRENNUNG
CH2CH2O), 2.47 (m, 16H; ArCHCH2), 2.10 (s, 24H; ArCH3), 1.65 (m,
4H; CH2CH2CH2O), 1.42 (m, 12H; CH2CH2CH3), 1.00 ppm (m, 18H;
CH2CH2CH3); 31P NMR (162 MHz, CDCl3, 258C): d=5.64 ppm (s,
OACHTUNGTRENNUNG
Ditopic guest with ethylene glycol spacer 2a: CH3I (0.8 mL, 1.28ꢃ
10ꢁ2 mol) was added to a solution of IVa (0.82 g, 2.99ꢃ10ꢁ3 mol) dis-
solved in CHCl3/acetonitrile (2:1, 21 mL). The reaction mixture was
stirred at reflux overnight. The solvent was removed in vacuo and the
crude product was recrystallized from diethyl ether to give pure 2a
+
P(O)); HR-ESI-MS: m/z calcd for C137H140NO26P8 2462.75647; found:
2462.76380 [M+NH4]+.
Adipic acid bis(tetraphosphonate cavitand) ester 1b: Dichlorophenyl-
phosphine (0.25 mL, 1.83ꢃ10ꢁ3 mol) was added slowly to a solution of
IIIb (0.35 g, 2.23ꢃ10ꢁ4 mol) in freshly distilled pyridine (10 mL) at RT
under argon. After 3 h of stirring at 708C, the solution was allowed to
cool to RT and a mixture of aqueous 35% H2O2 and CHCl3 (1:1, 10 mL)
was added. The resulting mixture was stirred for 30 min at RT, then the
solvent was removed in vacuo. Addition of water resulted in the precipi-
tation of a white powder, which was collected by filtration to give pure
1b (0.55 g, 97%). 1H NMR (300 MHz, CDCl3, 258C): d=8.08 (m, 16H;
P(O)ArHo), 7.68–7.52 (m, 8H+16H; P(O)ArHp +P(O)ArHm), 7.25 (s,
(1.40 g, 84%). 1H NMR (300 MHz, [D6]DMSO, 258C): d=9.18 (d, 3J-
3
G
N
CH2), 4.43 ppm (s, 6H; NCH3); HR-ESI-MS: m/z calcd for C16H18-
N2O42+: 151.06278; found: 151.06267 [Mꢁ2I]2+
.
Ditopic guest with 1,6-hexanediol spacer 2b: CH3I (0.33 mL, 5.34ꢃ
10ꢁ3 mol) was added to a solution of IVb (0.40 g, 1.22ꢃ10ꢁ3 mol) in ace-
tonitrile (10 mL). The reaction mixture was stirred at reflux overnight.
The solvent was removed in vacuo and the crude product was recrystal-
lized from CH3CN/EtOAc (1:1) to give pure 2b (0.57 g, 76%). 1H NMR
8H; ArH), 4.78 (t, 3J(H,H)=7.8 Hz, 8H; ArCH), 4.21 (t, 3J
ACHTUNGTRENNUNG AHCTUNGTRNEN(UGN H,H)=
(300 MHz, [D6]DMSO, 258C): d=9.17 (d, 3J
8.49 (d, 3J
(H,H)=6.6 Hz, 4H; CH2O), 1.79 (m, 4H; CH2CH2O), 1.49 ppm (m, 4H;
ACHTUNGTRENNUNG
6.0 Hz, 4H; CH2OC(O)), 2.46–2.27 (m, 4H+16H; CH2OC(O)CH2 +
ArCHCH2), 2.13 (s, 24H; ArCH3), 1.74 (m, 4H; CH2CH2CH2O), 1.62
(m, 4H; OC(O)CH2CH2CH2CH2(O)CO), 1.42 (m, 12H; CH2CH2CH3),
1.06 ppm (m, 18H; CH2CH2CH3); 31P NMR (162 MHz, CDCl3/D2O,
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
CH2CH2CH2O); HR-ESI-MS: m/z calcd for C20H26N2O42+: 179.09408;
found: 179.09427 [Mꢁ2I]2+
.
258C): d=6.59 ppm (s, P(O)); HR-ESI-MS: m/z calcd for C142H143
O28P8+: 2543.76669; found: 2543.77453 [M+H]+.
-
Ditopic guest with 1,6-hexanediol spacer 2b*: NH4PF6 (0.45 g, 2.78ꢃ
10ꢁ3 mol) was added to a solution of 2b (0.56 g, 9.26ꢃ10ꢁ3 mol) in water
(10 mL). The mixture was stirred at RT for 1 h. Vacuum filtration afford-
ed pure 2b* (0.53 g, 88%). 1H NMR (300 MHz, [D6]DMSO, 258C): d=
3,5-Pyridinedicarboxylic acid bis(tetraphosphonate cavitand) ester 1c:
Dichlorophenylphosphine (0.14 mL, 1.03ꢃ10ꢁ3 mol) was added slowly to
a solution of IIIc (0.20 g, 1.26ꢃ10ꢁ4 mol) in freshly distilled pyridine
(10 mL) at RT under argon. After stirring for 3 h at 708C, the solution
was allowed to cool to RT and a mixture of aqueous 35% H2O2 and
CHCl3 (1:1, 8 mL) was added. The resulting mixture was stirred for
30 min at RT, then the solvent was removed in vacuo. Addition of water
resulted in the precipitation of a white powder, which was collected by
filtration to give pure 1c (0.31 g, 1.21ꢃ10ꢁ4 mol, 90%). 1H NMR
9.11 (d, 3J
(H,H)=6.5 Hz, 4H; Ho), 8.45 (d, 3J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
4.39 (s, 6H; NCH3), 4.37 (t, 3J
AHCTUNGTRENNUNG
CH2CH2O), 1.45 ppm (m, 4H; CH2CH2CH2O); 31P NMR (162 MHz,
[D6]DMSO, 258C): d=ꢁ141.2 ppm (s, PF6); HR-ESI-MS: m/z calcd for
C20H26N2O42+: 179.09408; found: 179.09375 [Mꢁ2PF6]2+
.
Ditopic guest with PEG spacer 2c: CH3I (0.32 mL, 5.06ꢃ10ꢁ3 mol) was
(300 MHz, CDCl3, 258C): d=9.25 (d, 5J
(H,H)=2.0 Hz, 2H; Hp-py), 8.80
added to
a
solution of IVc (2.06 g, 1.16ꢃ10ꢁ3 mol) in acetonitrile
5
(d, J
(H,H)=2.0 Hz, 1H; Ho-py), 8.05 (m, 16H; P(O)ArHo), 7.63–7.53 (m,
(10 mL). The reaction mixture was stirred at reflux overnight. The sol-
vent was removed in vacuo and the crude product was taken up with di-
8H+16H; P(O)ArHp +P(O)ArHm), 7.24 (s, 8H; ArH), 4.80 (t, 3J-
(H,H)=7.4 Hz, 8H; ArCH), 4.53 (t, 5J
(H,H)=6.3 Hz, 4H; CH2OC(O)),
ethyl ether (3ꢃ20 mL) to give pure 2c (1.86 g, 81%). 1H NMR
3
2.50 (m, 4H; CH2CH2CH2OC(O)), 2.33 (m, 12H; ArCHCH2), 2.20 (s,
24H; ArCH3), 1.92 (m, 4H; CH2CH2CH2OC(O)), 1.20 (m, 12H;
ArCHCH2CH2), 1.00 ppm (m, 18H; CH2CH2CH3); 31P NMR (162 MHz,
CDCl3, 258C): d=4.02 ppm (s, P(O)); HR-ESI-MS: m/z calcd for
(300 MHz, CDCl3, 258C): d=9.52 (d, J
G
3J
4H; CH2OCC(O)), 3.68 (m, 4H; CH2CH2OC(O)), 3.69–3.58 ppm (m,
ACHTUGTNERNNUG(H,H)=6.0 Hz, 4H; Hm), 4.73 (s, 6H; NCH3), 4.58 (t, JACHTUGNTREN(NUNG H,H)=4.9 Hz,
3
116H;
OAHCTNUGRTENG(NU CH2CH2O)29); HR-ESI-MS: m/z calcd for C80H146N2O36 :
+
C143H138NO28P8 2564.73065; found: 2564.73965 [M+H]+.
855.48222; found: 855.48242 [Mꢁ2I]2+
.
Ethylene glycol diisonicotinate (IVa): Ethylene glycol (1.16 mL, 2.81ꢃ
10ꢁ3 mol) was added to a solution of isonicotinoyl chloride hydrochloride
(1.50 g, 8.42ꢃ10ꢁ3 mol) in pyridine (15 mL). The reaction mixture was
stirred at 1008C for 3 h and the solvent was removed under vacuum. A
solution of potassium carbonate in water (20 mL) was added and the
mixture extracted with CH2Cl2. Concentration to dryness of the organic
phase afforded pure IVa (0.82 g, 71%). 1H NMR (300 MHz, CDCl3,
CCDC-787200 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
258C): d=8.79 (d, 3J(H,H)=6.1 Hz, 4H; Ho), 7.85 (d, 3J
ACHTUNGTRENNUNG ACHTUGNTREN(NUGN H,H)=6.1 Hz,
Acknowledgements
4H; Hm), 4.71 ppm (s, 4H; CH2); GC-MS: m/z calcd for C14H12N2O4:
272.2; found: 272 [M]+.
This work was supported by the EC through the Project BION (ICT-
2007-213219) and the Project FINELUMEN (PITN-GA-2008-215399).
Financial support from INSTM to F.T. is gratefully acknowledged. We
thank the Centro Interfacoltꢀ di Misure “G. Casnati” of the University of
Parma for the use of NMR and HR ESI-MS facilities, and Prof. J. de
Mendoza from ICIQ in Tarragona (Spain) for ITC facilities. Finally we
acknowledge Dr. R. Mendichi and A. Giacometti of CNR in Milano
(Italy) for the use of SLS instrument.
1,6-Hexanediol diisonicotinate (IVb): 1,6-Hexanediol (1.22 g, 1.87ꢃ
10ꢁ3 mol) was added to a solution of isonicotinoyl chloride hydrochloride
(1.00 g, 5.62ꢃ10ꢁ3 mol) in pyridine (10 mL). The reaction mixture was
stirred at 1008C for 3 h and then the solvent was removed under vacuum.
The crude product was washed with an aqueous solution of K2CO3.
Vacuum filtration afforded pure IVb (0.65 g, 70%). 1H NMR (300 MHz,
CDCl3, 258C): d=8.75 (d, 3J
6.0 Hz, 4H; Hm), 4.35 (t, 3J
AHCTUNGTRENNUNG
N
ACHTUNGTRNE(NUNG H,H)=
CH2CH2O), 1.51 ppm (m, 4H; CH2CH2CH2O); GC-MS: m/z calcd for
C18H20N2O4: 328.4; found: 328 [M]+.
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14320
www.chemeurj.org
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 14313 – 14321

Copolymerization of Tetraphosphonate Cavitands
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Received: August 4, 2010
Published online: December 1, 2010
Chem. Eur. J. 2010, 16, 14313 – 14321
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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