Electrochemical responsive arrays of sulfonatocalixarene groups prepared by free radical polymerization

Article abstract of DOI:10.1016/j.reactfunctpolym.2014.03.015

A styrene based water soluble polymer containing pendant sulfonated calix[4]arene groups has been synthesized by using free radical polymerization combined with post-polymerization sulfonation chemistry. The monomer 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene (VBC4A) was prepared in 3 steps: (1) reduction of 4-vinyl benzoic acid to the respective alcohol (2) formation of the bromide by the Appel reaction and (3) synthesis of the respective ether by Williamson O-alkylation reaction with calix[4]arene. Polymerization was accomplished by azobisisobutyronitrile (AIBN) initiated free radical polymerization technique to afford P(VBC4A) with Mn value of 7090 g/mol and moderate polydispersity. The resulting P(VBC4A) was subsequently reacted with acetyl sulfate to afforded the sulfonated polymer. The reaction was followed by nuclear magnetic resonance and infrared spectroscopy, and the results suggest that the sulfonation reaction lead to nearly quantitative functionalization of the calixarene functional polymer. Elemental analysis by X-ray photoelectron spectroscopy confirmed these findings on the degree of sulfonated functionalization. Electro-responsive properties of the sulfonated polymer were studied by cyclic voltammetry and isothermal titration calorimetry in phosphate buffer saline solution. A response to electrochemical stimulus is observed where guest molecules of methyl viologen incorporate and dissociate with P(VBSC4A).

Full text of DOI:10.1016/j.reactfunctpolym.2014.03.015

Accepted Manuscript
Electrochemical Responsive Arrays of Sulfonatocalixarene Groups Prepared by
Free Radical Polymerization
Uddhav Balami, Darlene K. Taylor
PII:
S1381-5148(14)00068-6
DOI:
http://dx.doi.org/10.1016/j.reactfunctpolym.2014.03.015
REACT 3362
Reference:
Reactive & Functional Polymers
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Revised Date:
Accepted Date:
23 October 2013
17 January 2014
29 March 2014
Please cite this article as: U. Balami, D.K. Taylor, Electrochemical Responsive Arrays of Sulfonatocalixarene
Groups Prepared by Free Radical Polymerization, Reactive & Functional Polymers (2014), doi: http://dx.doi.org/
10.1016/j.reactfunctpolym.2014.03.015
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Electrochemical Responsive Arrays of Sulfonatocalixarene Groups Prepared by Free
Radical Polymerization
Uddhav Balami and Darlene K. Taylor*
Department of Chemistry, North Carolina Central University, Durham, North Carolina 27707,
USA.
*Corresponding author:
Darlene K. Taylor, Ph.D.
Department of Chemistry
North Carolina Central University
3105 Mary Townes Science Complex
Durham, North Carolina 27707
Phone: 919-530-6463
Fax: 919-530-5135
Email: dtaylor@nccu.edu

ABSTRACT
A styrene based water soluble polymer containing pendant sulfonated calix[4]arene groups has
been synthesized by using free radical polymerization combined with post-polymerization
sulfonation chemistry. The monomer 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene
(VBC4A) was prepared in 3 steps: 1) reduction of 4-vinyl benzoic acid to the respective alcohol
2) formation of the bromide by the Appel reaction and 3) synthesis of the respective ether by
Williamson O-alkylation reaction with calix[4]arene. Polymerization was accomplished by
azobisisobutyronitrile (AIBN) initiated free radical polymerization technique to afford
P(VBC4A) with Mn value of 7090 g/mol and moderate polydispersity. The resulting P(VBC4A)
was subsequently reacted with acetyl sulfate to afforded the sulfonated polymer. The reaction
was followed by nuclear magnetic resonance and infrared spectroscopy, and the results suggest
that the sulfonation reaction lead to nearly quantitative functionalization of the calixarene
functional polymer. Elemental analysis by x-ray photoelectron spectroscopy confirmed these
findings on the degree of sulfonated functionalization. Electro-responsive properties of the
sulfonated polymer were studied by cyclic voltammetry and isothermal titration calorimetry in
phosphate buffer saline solution. A response to electrochemical stimulus is observed where guest
molecules of methyl viologen incorporate and dissociate with P(VBSC4A).
Keywords:
Calixarene, guest-host, redox potential, cyclic voltametry, isothermal calorimetry

1. Introduction
Dynamic bonds that respond to an applied electrical potential are gaining attention as a
way to modulate material properties [1-4]. Materials that dynamically assemble and disassemble
utilizing a host-guest driven interaction in response to electrochemical stimulus can be easily
controlled with no contamination to the system [5-7]. Host–guest complexes based on
calixarenes and neutral and ionic molecular guests as well as with metal ions have been
extensively investigated in solid and solution state studies [8,9]. As a class of materials,
calixarenes form the key component for selective electrodes and membranes, chemical and
biochemical sensors, and selective extraction of ions and neutral molecules [10-14]. Guo et.al.
recently reported a main chain supramolecular polymer where the dynamic bonds are those
supramolecular interactions between a bis-p-sulphonatocalix[4]arene and an electro-responsive
bis-viologen [15]. The viologen, in its oxidized state, binds to the calixarene moieties but does
not interact as strongly with the negatively charged calixarenes in its reduced neutral state.
These results coupled with our long interest in polymers with electric field responsive
side chains [16], lead us to design a polystyrene based polymer with pendant sulfonocalixarene
units. We describe herein details pertaining to the synthesis of a novel well-defined polystyrene-
based pendant functionalized sulfonated calix[4]arene polymer and show that its complexation
with methyl viologen can be controlled by electrochemical stimuli (Scheme 1). Unlike the
supramolecular calixarene polymer reported earlier by Guo et al, the backbone of our polymer
chain is kinetically less labile and thermodynamically more stable yet accommodating to the
dynamic interaction of a guest molecule. Thus, our new calixarene-derivatized polymer
combines the best attributes of conventional and supramolecular polymer platforms and may be a
useful material for drug delivery or chemical sensor devices. While there have been reports
focused on covalently bound calixarene main chain polymers [17-30], no report has focused on a
sulfonated calixarene unit immobilized as a pendant electrochemically-responsive system on a
polystyrene backbone.
Scheme 2 shows the overall synthetic methodology utilized to prepare the electro-
responsive polymer. The monomer, 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene
(VBC4A), has been designed using a three step reaction scheme with an overall yield of 30%.
Subsequent polymerization of VBC4A by free radical polymerization was straight forward. After
polymerization, the wide rim of the calix[4]arene ring was sulfonated.

2. Experimental Section
1H and 13C NMR spectra were recorded in deuterated chloroform (unless otherwise
noted) on a Varian spectrometer operating at 500 MHz using tetramethylsilane (TMS) as a
reference. IR spectra were recorded on a IR HCI by SensIR technologies. Molecular weights
were evaluated by a Waters Alliance GPC System, Waters 2695 Separations Module and Waters
2414 Refractive Index Detector (Waters Associates Inc., Milford, MA). Approximately 20-30
mg of sample was dissolved in THF and the GPC analysis was performed at 35 ºC using a
polystyrene standard kit for molecular weight elution volume calibration. 4-vinylbenzoic acid (1)
was used as received from VWR. All other solvents and reagents were used as supplied from
either Fisher Scientific or VWR. All solvents were purchased in the anhydrous form.
2.1 Synthesis of 4-vinylbenzyl alcohol (1)
As previously reported in the literature [31], a solution of 4-vinylbenzoic acid (500 mg,
3.37 mmol) in Et2O (25 mL) was drop-wise added to a 0 °C slurry of LiAlH4 (758 mg, 19.97
mmol) in THF (80 mL). The reaction mixture was warmed to room temperature and stirred for 1
h. The reaction was quenched via the following workup: 256 μL of water added slowly, 512 μL
of 10 wt % NaOH solution, and 768 μL of water. The mixture was stirred vigorously until a
white solid was formed. The crude reaction mixture was filtered, and the supernatant was dried
(anhydrous Na2SO4), and concentrated in vacuo. The resulting oil was purified by silica gel
column chromatography using an elutant of hexane:EtOAc, (4:1) to provide alcohol 1 (280 mg,
62%) as colourless oil. All the physical and spectral data were in accordance with the literature
1
[31]. H NMR (CDCl3, 500 MHz) δ: 4.66 (s, 2H), 5.24 (d, J = 11.5 Hz, 1H) 5.73 (d, J = 18.5 Hz,
1H) 6.69-6.75 (dd, J = 11.0, 6.5 Hz, 1H) 7.31 (d, J = 8.0 Hz, 2H) 7.39 (d, J = 8.0 Hz, 2H).
2.2 Synthesis of 4-vinylbenzyl bromide (2)
Using a reaction scheme adapted from literature [32], phosphorous tribromide (18.4 g,
6.4 ml, 68 mmol) dissolved in diethyl ether (10 ml) was added to alcohol 1 (5.9 g, 44.3 mmol) in
Et2O (500 ml) at 0°C under N2. After 1 h, additional phosphorous tribromide (18.4 g, 6.4 ml, 68
mmol) was added. The reaction mixture was stirred for 1 h at room temperature and
subsequently cooled to 0 ºC. Water (100 ml) was slowly added. The solution was extracted with
Et2O, and the Et2O layer was washed with saturated NaHCO3, brine and dried over MgSO4. The
crude product was purified by silica gel column chromatography using a hexane:EtOAc, (70:30)
elutant system to obtain product vinyl benzyl bromide 2. 1H NMR (CDCl3, 500 MHz) δ: 4.48 (s,

2H), 5.26(ddJ = 11.0, 1.0 Hz, 1H) 5.76 (dd, J = 17.6, 1.0 Hz, 1H) 6.69-6.75(dd, J = 17.6, 11.0
Hz, 1H), 7.32 (d, J = 8.0 Hz, 2H) 7.41 (d, J = 8.0 Hz, 2H). UV-Vis [chloroform, λmax(ε)]: 215
nm, 260 nm
2.3 Synthesis of 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene (VBC4A)
Calix[4]arene (1g, 2.36 mmol) and potassium tertbutoxide (528 mg, 4.71 mmol) were
dissolved in anhydrous acetonitrile (10 ml) by stirring at 65°C under N2. After 1 h, 4-vinyl
benzyl bromide 2 (460 mg, 2.35 mmol) was added and the mixture refluxed for 48 h. The
reaction mixture was concentrated under vacuum. The resulting solid was dissolved in DCM,
washed with 1M HCl, DI water, brine, and dried over anhydrous Na2SO4. The crude product was
purified by silica gel column chromatography using hexane:EtOAc, (90:10), providing monomer
VBC4A as a white crystalline solid (20% yield). 1H NMR (CDCl3, 500 MHz) δ: 3.27-3.32 (dd, J
= 10.0, 5.0 Hz, 4H, Ar-CH2-Ar), 4.09 (d, J = 15.0 Hz, 2H, Ar-CH2-Ar), 4.22 (d, J = 10.0 Hz, 2H,
Ar-CH2-Ar), 5.02 (s, 2H, -O-CH2), 5.13 (d, J = 15.0 Hz, 1H), 5.66 (d, J = 15.0 Hz, 1H), 6.51-
6.55 (dd, J = 5.0, 10 Hz, 3H, Ar-H), 6.59-6.65 (dd, J = 15.0, 5.0 Hz, 1H, C-H ) 6.74 (t, J = 5.0
Hz, 1H, Ar-H), 6.83-6,87 (dd, J = 10.0, 5.0 Hz, 4H, Ar-H), 6.90 (d, J = 10.0 Hz, 2H, Ar-H), 6.95
(d, J = 10.0 Hz, 2H, Ar-H), 7.41 (d, J = 5.0 Hz, 2H, Ar-H),7.55 (d, J = 10.0 Hz, 2H, Ar-H), 9.12
(s, 2H, Ar-OH), 9.45 (s, 1H, Ar-OH); 13C NMR (CDCl3, TMS, 125 MHz) δ: 32.11 (Ar-CH2-Ar),
79.18 (O-CH2), 114.9 (=CH2), 121.14-138.49(Ar), 136.6(-CH), 149.36(Ar-OH), 151.46(Ar-O-);
UV-Vis [DCM, λmax(ε)]: 230 and 254 nm; ESI/APCI – MS : m/z 540.1[M+H]+
2.4 Preparation of Poly (25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene) [P(VBC4A)]
Monomer VBC4A (1g, 1.85 mmol) and azobisisobutyronitrile (AIBN) (6.07 mg, 0.037
º
mmol) were dissolved in 10 mL of THF and stirred at 60 C under N2 for 48 h. The reaction
mixture was purified by silica gel flash column and recrystallized in MeOH providing
1
P(VBC4A), a white amorphous powder with 70% yield. H NMR (CDCl3, 500 MHz) δ : 1.26-
1.85 (broad 2H+1H, -CH2-CH-Ar-), 3.00-3.60 (broad 4H, Ar-CH2-Ar), 3.85-4.45 (broad 4H,
Ar-CH2-Ar), 4.65-5.20( broad, 2H, -O-CH2-), 6.25-7.80 (broad, 16H, Ar-H), 9.10-9.85 (broad,
3H, Ar-OH); 13C NMR (CDCl3, TMS, 125 MHz) δ: 31.80 (Ar-CH2-Ar), 40.35 (-CH2-C-Ar-),
79.10 (O-CH2), 120.93-130.35 (Ar), 134.35(-CH-Ar-), 149.07(Ar-OH), 151.14(Ar-O-); UV-Vis
[DCM, λmax(ε)]: 230, 276.

2.5 Preparation of poly(p-sulfo, 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene)
[P(VBSC4A)]
Acetyl sulfate was freshly prepared by adding acetic anhydride (1.77mL, 18.74 mmol) to
the DCE (10 mL) at -10 ºC. After 5 mins, 95% sulfuric acid (1mL, 18.77 mmol) was added to
º
DCE solution at -10 C, stirred, and allowed to equilibrate at room temperature. Subsequently,
acetyl sulfate (3.57mL freshly prepared) was added to the P(VBC4A) solution in DCE (50 mL)
(1:6 molar ratio, polymer : acetyl sulfate) at -10 ºC and stirred for 4 h. The reaction mixture was
filtered and the residue was dissolved in MeOH. The MeOH solution was washed with sodium
hydroxide solution (10% aqueous ) to neutralize the excess sulfuric acid and subsequently
dialyzed (<2000 MW cut off membrane) for 2 days and lyophilized until dry. The dry purple
1
amorphous powder was obtained in 10% yield. H NMR (D2O, 500 MHz) δ: 1.10-2.50 (broad
3H, -CH2-CH-Ar-), 3.25-3.64 (broad 4H, Ar-CH2-Ar), 3.65-4.03 (broad 4H, Ar-CH2-Ar), 4.20-
4.46 ( broad, 2H, -O-CH2-), 6.74-7.89 (broad, 16H, Ar-H); 13C NMR (CD3OH, TMS, 125 MHz)
δ: 21.03-22.01 (Ar-CH2-Ar), 31.33 (Ar-CH2-Ar), 32.99 (Ar-CH2-Ar), 38.42 (-CH2-C-Ar-), 64.33
(O-CH2), 124.97-130.49 (Ar), 135.08 (-CH-Ar-), 148-152 (Ar-O(H)); UV-Vis [DCM, λmax(ε)
210 nm.
3.Characterization
3.1 X-Ray Photoelectron Spectrometer (XPS)
XPS was performed with a Kratos Analytical Axis Ultra Photoelectron spectrometer using
monochromatic Al source, emission 10 mA and starting with 1200 eV energy. The pressure in
the analysis chamber was 1 X 10-8 torr. A spectrum was obtained as a function of binding energy
in eV. Casa XPS software was used for data processing.
3.2 Absorption and Emission Spectroscopy
Absorption spectra were measured with a Hewlett-Packard Model 8453 UV-Vis
spectrophotometer with HP Vectra Workstation. The fluorescence spectra were observed on a
Perkin Elmer LS 55 Fluorescence Spectrophotometer at ambient temperature. In both absorbance
and emission spectra, the samples were prepared in PBS (0.1 M, pH7) and measurements were
conducted in 1cm pathlength quartz cells.

3.3 Isothermal Titration Calorimetry (ITC)
The formation constant and thermodynamic parameters for the inclusion of MV in
P(VBSC4A) polymer were measured by titration calorimetry using a MicroCal iTC200
instrument. All solutions were prepared in phosphate buffer saline solution (0.1 M, pH 7). A
solution of P(VBSC4A) (250 µM) was placed in the sample cell. As a 2.00 mM solution of MV
was added in a series of 20 injections (3 µL each), the evolved heat was recorded. ITC
experiments were performed at 30 °C. The data were analyzed and fitted by using ORIGIN
software (MicroCal).
3.4 Cyclic Voltammetry(CV)
Cyclic voltammograms were recorded using a BAS potentiostat (CV-50W with C3 Cell
Stand) interfaced to a personal computer and software supplied by the manufacturer. All
experiments were conducted in phosphate buffer (pH 7.2, 0.1 M) at room temperature. A
working volume of 5 mL was transferred to the cell by syringe immediately prior to the start of
the experiment. A normal one-compartment cell was utilized with a Pt disk working electrode
(MF-2013, BAS), a Pt wire auxiliary electrode (MW-1032), and an Ag/AgCl reference electrode
(MF-2052, BAS). All potentials are reported versus Ag/AgCl. Electrochemical potentials were
converted to vacuum assuming the normal hydrogen electrode (NHE) to be at 4.7 eV versus
vacuum with an additional +0.2 V potential difference between Ag/AgCl and NHE. Before each
experiment, the cell was purged with N2 for 5-10 min and a blanket of N2 was maintained during
the experiment.
4. Results and Discussion
4.1 Synthesis
Scheme 1 shows the overall synthetic methodology utilized to prepare electro-responsive
P(VBSC4A). The VBSC4A monomer was prepared in 3 steps: 1) reduction of 4-vinyl benzoic
acid to alcohol 2) formation of bromide by the Appel reaction and 3) synthesis of the respective
ether by Williamson O-alkylation reaction with calix[4]arene. The monomer was polymerized by
AIBN initiated free radical polymerization and subsequently derivatized by sulfonation using
freshly prepared acetyl sulfate.

4.2 Characterization
4.2.1 NMR Spectroscopy
1
The H NMR spectra of VBC4A is shown in Figure 2.The polymer shows proton
resonances in regions similar to the monomer but substantially broadened. This is true for all the
peaks except the vinyl proton resonance peaks observed at 5.3 and 5.7 ppm in the monomer that
are not observed in the polymer. The lack of these two proton peaks confirms that the monomer
has reacted to form polymer.
To confirm the success of polymer derivatization, the FTIR spectra of unsulfonated and
sulfonated polymers were compared. The strong sulfur/oxygen stretching vibration observed at
1169 and 1038 cm-1 is characteristic of combined S=O and S-O stretches. This band region is
greatly enhanced in the spectra of P(VBSC4A) as compared to the spectra of the unsulfonated
analog polymer. Other features of the spectra are the prominent broad band at 3162-3400 cm-1
indicative of hydroxyl (OH) groups (Figure 3).
4.2.2 Molecular Weight Determination
Molecular weights were evaluated by Gel Permeation Chromotagraphy using a
polystyrene standard kit for molecular weight calibration. A broad peak was observed at 33.48
minutes retention time (Figure 4). The chromatogram of P(VBC4A) gives Mn, Mw, MP and PDI
as 7090, 11700, 10900 Daltons and 1.65 respectively. The unsulfonated P(VBC4A) was
prepared by free radical polymerization technique initiated by AIBN.
4.2.3 Elemental Analysis by XPS
The difficulty in confirming the degree of sulfonation of the calixarene ring of the
polymer by NMR and FT-IR led us to investigate films of the material by XPS. Residual sodium
was observed presumably from the residual counter ions in the dilute sodium hydroxide workup
(Figure 5). Based on the literature [33], we conclude that the oxygen bound to different elements
in the sulfonated polymer such as O-Na, O-S and showing an asymmetrical fused peak on O1s
scan ranging from 528-531eV and 531.5-532.5 eV respectively (Figure 6). The unsulfonated
polymer contains O-H bonding and the characteristic peak was observed in between O-Na and
O-S peak which matches with reference (Table 1 and Figure 6). The percentage of the other

atoms is reasonable if one considers remaining water molecules that exist in the final hydrophilic
material despite rigorous drying attempts.
Theoretically calculated element percentages for sulfonated VBC4A are close to the
experimental values of elemental analysis by XPS when it contains some water molecules that
are associated with the films (Table 2). The sulfur percentages determined experimentally are
reasonably identical to those calculated, indicating complete sulfonation on the lower rim of the
calix[4]arene pendent group.
4.2.4 Absorptions and Emission Measurements
The complexation properties of P(VBSC4A) were investigated by fluorescence
measurements. MV was employed as a guest molecule. P(VBSC4A) shows a broad emission
band that is strongest at 320 nm when excited at 210 nm. There is also a less intense emission
band at ~300 nm. This band at 300 nm was largely quenched when MV was added to
P(VBSC4A) in solution (20µM) (Figure 7). MV is a polynuclear aromatic compound and
P(VBSC4A) is largely composed of benzene rings, thus the driving force of the complex
formation is probably π-π interactions.
4.2.5 Isothermal Titration Calorimetry
ITC experiments supply the quantitative information for the host–guest complexation
between P(VBSC4A) and MV. As shown in Figure 8, the association constant was obtained as
4.56 x 104 M-1with an average 0.2% error in predicting a 3:10 complexation case of P(VBSC4A)
with MV (∆H= -30.16 kJ/mol; ∆S= -10.2 joules/mol/deg). The complexation appears to be
thermodynamically favorable as both the enthalpy and entropy are accompanied with negative
changes upon association. The resulting negative Gibbs free energy of formation for the complex
pushes the reversible assembly/disassembly equilibrium toward formation, an energetic state also
observed by Guo et et al. in the 1:1 complexation case of SC4A with bi-methyl viologen [34].

4.2.6 Cyclic Voltammogram
The electrochemical sensitivity of the P(VBSC4A) was further studied by CV. Typical
cyclic voltammograms of MV obtained in the absence and presence of P(VBSC4A) are shown
in Figure 9. It is well documented (and observed here) that free MV2+ undergoes two consecutive
one-electron reduction processes to its neutral form MV0. However, the voltammogram of MV2+
in the presence of P(VBSC4A) undergoes a noticeable shift in the peak potentials and a marked
decrease in the current levels.
For the first reduction potential (MV2+/MV+), the reversible shape of the half wave
potential is retained in the presence of P(VBSC4A)― just shifted to a more positive value by
E 16 mV compared to MV alone. This shift suggests that the species is slightly easier to be
½
reduced. In contrast, for the second reduction potential (MV+/MV0) the half-wave potential shifts
to more negative values in the presence of P(VBSC4A) by E  46 mV. This shift indicates
½
that MV cation radical is included into the cavity of P(VBSC4A) while the negative nature of the
shift indicates the species is more difficult to reduce.
Note the two peaks of MV observed at ca. -1296mV and -976mV. These two waves were
repeatedly observed even after cleaning the electrodes and degassing the solution. We
hypothesize that these peaks belong to the free MV radical accumulated in oxidation process
[35]. Upon complexation with P(VBSC4A), the second reduction peak undergoes a significant
negative shift, while the corresponding re-oxidation peak shifts by about the same amount (42
mV). Moreover, the first re-oxidation peak is now one peak located at -963 mV.
Taken together, the shifts in the half-wave potentials indicate the relative strength of the
association between the host and the guest MV in its different redox states. Thus, the cyclic
voltammetry results show that P(VBSC4A) prefers the charged species over the neutral species
of MV0 as a guest.
5. Conclusions
In summary, a novel styrene main chain polymer with pendant sulfonated calix[4]arene
groups has been synthesized. The polymer is sensitive to electrical stimuli as determined by its
ability to bind MV as a guest molecule. We are continuing to investigate this polymer for
potential drug delivery and sensor applications.

Acknowledgements
The authors acknowledge support from Triangle MRSEC Program and Research funded by the
National Science Foundation under Award Number DMR-1121107. We also thank Drs. LiJu
Yang and John Bang for discussions.

References
[1]
[2]
[3]
[4]
[5]
S.-i. Kawano, N. Fujita, S. Shinkai, A Coordination Gelator That Shows a Reversible
Chromatic Change and Sol−Gel Phase-Transition Behavior upon Oxidative/Reductive
Stimuli, Journal of the American Chemical Society 126 (2004) 8592-8593.
J. Chen, A.J. McNeil, Analyte-Triggered Gelation: Initiating Self-Assembly via
Oxidation-Induced Planarization, Journal of the American Chemical Society 130 (2008)
16496-16497.
I. Tomatsu, A. Hashidzume, A. Harada, Redox-Responsive Hydrogel System Using the
Molecular Recognition of β-Cyclodextrin, Macromolecular Rapid Communications 27
(2006) 238-241.
C. Wang, D. Zhang, D. Zhu, A Low-Molecular-Mass Gelator with an Electroactive
Tetrathiafulvalene Group: Tuning the Gel Formation by Charge-Transfer Interaction and
Oxidation, Journal of the American Chemical Society 127 (2005) 16372-16373.
W.S. Jeon, A.Y. Ziganshina, J.W. Lee, Y.H. Ko, J.-K. Kang, C. Lee, K. Kim, A
[2]pseudorotaxane-based molecular machine: reversible formation of a molecular loop
driven by electrochemical and photochemical stimuli., Angewandte Chemie 42 (2003)
4097-4100.
[6]
[7]
[8]
[9]
W. Wang, A.E. Kaifer, Electrochemical Switching and Size Selection in Cucurbit[8]uril-
Mediated Dendrimer Self-Assembly, Angew. Chem., Int. Ed. 45 (2006) 7042-7046.
C.A. Nijhuis, B.J. Ravoo, J. Huskens, D.N. Reinhoudt, Electrochemically controlled
supramolecular systems, Coord. Chem. Rev. 251 ( 2007) 1761-1780.
C.D. Gutsche, Calixarenes Revisited 1ed., Royal Society of Chemistry, The, Cambridge
1989.
V. Böhmer, Calixarenes, Macrocycles with (Almost) Unlimited Possibilities,
Angewandte Chemie International Edition in English 34 (1995) 713-745.
[10] W.F. Nijenhuis, E.G. Buitenhuis, F. De Jong, E.J.R. Sudholter, D.N. Reinhoudt,
Calixcrowns as selective potassium cation carriers in supported liquid membranes,
Journal of the American Chemical Society 113 (1991) 7963-7968.
[11] D. Diamond, M.A. McKervey, Calixarene-based sensing agents, Chem. Soc. Rev. 25
(1996 ) 15-24.
[12] K.B. Crawford, M.B. Goldfinger, T.M. Swager, Na+ Specific Emission Changes in an
Ionophoric Conjugated Polymer, Journal of the American Chemical Society 120 (1998)
5187-5192.
[13] S.I. Kim, T.J. Shin, M. Ree, G.T. Hwang, B.H. Kim, H. Han, J. Seo, Synthesis and
characterization of new polyimides containing calix[4]arenes in the polymer backbone,
Journal of Polymer Science Part A: Polymer Chemistry 37 (1999) 2013-2026.
[14] E. Malinowska, L. Gawart, P. Parzuchowski, G. Rokicki, Z. Brzózka, Novel approach of
immobilization of calix[4]arene type ionophore in ‘self-plasticized’ polymeric
membrane, Analytica Chimica Acta 421 (2000) 93-101.
[15] D.-S. Guo, S. Chen, H. Qian, H.-Q. Zhang, Y. Liu, Electrochemical stimulus-responsive
supramolecular polymer based on sulfonatocalixarene and viologen dimers, Chemical
Communications 46 (2010) 2620-2622.
[16] D.K. Taylor, E.T. Samulski, Synthesis and characterization of poly(p-phenylene)s with
nonlinear optical side chains. Macromolecules 33 (2000) 2355-2358.
[17] G. Uysal, S. Memon, M. Yilmaz, Synthesis and binding properties of polymeric calix [4]
arene nitriles, Reactive and Functional Polymers 50 (2002) 77-84.

[18] A. Katz, P. Da Costa, A.C.P. Lam, J.M. Notestein, The First Single-Step Immobilization
of a Calix-[4]-arene onto the Surface of Silica, Chemistry of Materials 14 (2002) 3364-
3368.
[19] S.D. Alexandratos, S. Natesan, Synthesis and Ion-Binding Affinities of Calix[4]arenes
Immobilized on Cross-Linked Polystyrene, Macromolecules 34 (2000) 206-210.
[20] C.W. Hall, J.S. Cockayne, M.J. Kan, G.P. Nicholson, Clean and efficient syntheses of
calix[4]arene modified polymer supports, Green Chemistry 3 (2001) 114-122.
[21] K. Ohto, Y. Tanaka, K. Inoue, Adsorptive Separation of Lead and Zinc Ions by Novel
Type of Calix[4]arene Carboxylate Resin Immobilized with Polyallylamine, Chemistry
Letters 26 (1997) 647-648.
[22] S. Shinkai, H. Kawaguchi, O. Manabe, Selective adsorption of UO22+ to a polymer resin
immobilizing calixarene-based uranophiles, Journal of Polymer Science Part C: Polymer
Letters 26 (1988) 391-396.
[23] L.-Z. Meng, H. Huang, Y.-B. He, Y.-Y. Chen, H. Wang, Preparation and behavior of
calix[4]arene-containing organosilicone resins (I), Journal of Applied Polymer Science
80 (2001) 58-64.
[24] A. Yilmaz, S. Memon, M. Yilmaz, Synthesis and binding properties of calix[4]arene
telomers, Journal of Polymer Science Part A: Polymer Chemistry 37 (1999) 4351-4355.
[25] M. T. Blanda, E. Adou, Syntheses and characterizations of two copolymers containing
cone conformations of calix[4]arenes in the polymer backbone, Chemical
Communications (1998) 139-140.
[26] Z.-L. Zhong, C.-P. Tang, C.-Y. Wu, Y.-Y. Chen, Synthesis and properties of calixcrown
telomers, Journal of the Chemical Society, Chemical Communications (1995) 1737-1738.
[27] P. Parzuchowski, E. Malinowska, G. Rokicki, Z. Brzozka, V. Bohmer, F. Arnaud-Neu, B.
Souley, Calix[4]arene derived tetraester receptors modified at their wide rim by
polymerizable groups, New Journal of Chemistry 23 (1999) 757-763.
[28] M.T. Blanda, E. Adou, Syntheses and characterizations of three vinyl copolymers
containing pendant calix[4]arenes, Polymer 39 (1998) 3821-3826.
[29] D.M. Gravett, J.E. Guillet, Synthesis and Photophysical Properties of a Novel Water-
Soluble, Calixarene-Containing Polymer, Macromolecules 29 (1996) 617-624.
[30] S.J. Harris, G. Barrett, M.A. McKervey, Polymeric calixarenes. Synthesis,
polymerisation and Na+ complexation of a calix[4]arene methacrylate, Journal of the
Chemical Society, Chemical Communications (1991) 1224-1225.
[31] K.S. Bloome, R.L. McMahen, E.J. Alexanian, Palladium-catalyzed Heck-type reactions
of alkyl iodides, J Am Chem Soc 133 (2011) 20146-20148.
[32] O. Shimomura, B. Se Lee, S. Meth, H. Suzuki, S. Mahajan, R. Nomura, K.D. Janda,
Synthesis and application of polytetrahydrofuran-grafted polystyrene (PS–PTHF) resin
supports for organic synthesis, Tetrahedron 61 (2005) 12160-12167.
[33] J.F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben, Hand book of X-ray Photoelectron
Spectroscopy, Physical Electronics Inc., 1993.
[34] D.S. Guo, L.H. Wang, Y. Liu, Highly effective binding of methyl viologen dication and
its radical cation by p-sulfonatocalix[4,5]arenes, Journal of Organic Chemistry 72 (2007)
7775-7778.
[35] H.J. Kim, W.S. Jeon, Y.H. Ko, K. Kim, Inclusion of methylviologen in cucurbit[7]uril,
Proc Natl Acad Sci U S A 99 (2002) 5007-5011.

Figure 1.Schematic representation of formation host–guest complexationbetweenviologen and
polystyrene-based pendant functionalized sulfonated calyx[4]arene.
Scheme 1. Synthesis of P(VBSC4A)
1
Figure 2. Comparison of H NMR peaks between (a) Monomer VBC4A and (b) Polymer
P(VBC4A)
Figure 3. Comparative IR absorption spectra of P(VBSC4A) with P(VBC4A)
Figure 4. GPC chromatogram for P(VBC4A)
Figure 5. XPS survey scan of P(VBSC4A) and elemental analysis.
Figure 6. Relative O1s peaks of sulfonatedP(VBSC4A) and non-sulfonated P(VBC4A)
polymers 5 scans of each by XPS.
Figure 7. Fluorescence observed after quenching P(VBSC4A) (20µM) by consecutive addition
of multiple of 3.2 µM MV in PBS solution.
Figure 8.(a) Raw ITC data for sequential 20 injections of MV solution (2.00 mM) injecting into
P(VBSC4A) (250µM) in aqueous solution. (b) Apparent reaction heat obtained from the
integration of calorimetric traces.
Figure 9. CV curve of MV (1.5mM) and mixture of MV and P(VBSC4A) solution (1.5mM
each, scan rate 200 mV/s) in PBS solution.

Fig. 1.

Scheme 1.
Fig. 2.

Fig. 3.

Fig. 4.
Fig. 5

Fig. 6

Fig. 7.
Fig.8.

Fig. 9

4.00E-05
3.00E-05
2.00E-05
1.00E-05
0.00E+00
-1.00E-05
-2.00E-05
-3.00E-05
-4.00E-05
-5.00E-05
-6.00E-05
MV
MV+PVBSC4A
0
-500
-1000
-1500
-2000
E (mV) vs Ag/AgCl

Scheme 1 New
OH
OH
OH HO
a) PBr3, Et2O,
0 oC - rt, 2 h
a) LiAlH4, Et2O,
0 oC, 4 h
b) 0 oC, H2O
b) KOtBu, CH3CN,
65 oC, 48 h
b) H2O, 5 % NaOH
O
OH
Br
OH
4-vinylbenzoic acid
[1]
[2]
n
n
Free Radical
Polymerization
a) Acetyl Sulfate,
-10 oC, 4 h
b) MeOH
AIBN initiator
OH
OH
OH
OH
O
HO
OH
O
HO
OH
O
HO
HO3S
HO3S
SO3H
SO3H
P(VBSC4A)
P(VBC4A)
VBC4A

Table 1.Percent elemental composition of P(VBSC4A) theory vs experiment (XPS).
Element
O 1s (%)
38.88
C 1s (%)
34.84
Na 1s (%)
16.22
S 2p (%)
10.06
Theoretical *
Experimental
39.24
34.15
16.41
10.21
*P(VBSC4A).8Na.15H2O
Table 2. Comparison of O1s peaks from different oxygen bonding with metal, hydrogen and
sulfur (adapted from book{Moulder, 1993, Hand book of X-ray Photoelectron Spectroscopy}).
eV
528
529
530
531
532
533
Metal oxide
hydroxide
Sulfates