Assembly of N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer films with catechol sensing selectivity

Article abstract of DOI:10.1039/c0jm01510e

The highly water insoluble N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate is synthesised and investigated for sensor applications. This amphiphilic molecule is immobilised by evaporation of an acetonitrile solution at a basal plane pyrolytic graphite (HOPG) electrode surface and is shown to provide a monolayer film. By varying the amount of deposit partial or full coverage can be achieved. The N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer acts as an active receptor for 1,2-dihydroxy-benzene (catechol) derivatives in aqueous media. The ability to bind alizarin red S is investigated and the Langmuirian binding constant determined as a function of pH. It is shown that the immobilised boronic acid monolayer acts as sensor film for a wider range of catechols. A comparison of Langmuirian binding constants for alizarin red S (1.4 × 10⁵ mol^-1 dm³), catechol (8.4 × 10⁴ mol ^-1 dm³), caffeic acid (7.5 × 10⁴ mol ^-1 dm³), dopamine (1.0 × 10⁴ mol ^-1 dm³), and l-dopa (8 × 10³ mol ^-1 dm³) reveals that a combination of hydrophobicity and electrostatic interaction causes considerable selectivity effects.

Full text of DOI:10.1039/c0jm01510e

View Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Assembly of N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate
monolayer films with catechol sensing selectivity
b
c
a
a
Yan-Jun Huang,ab Yun-Bao Jiang, John S. Fossey, Tony D. James and Frank Marken
*
Received 19th May 2010, Accepted 21st July 2010
DOI: 10.1039/c0jm01510e
The highly water insoluble N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate is synthesised
and investigated for sensor applications. This amphiphilic molecule is immobilised by evaporation of
an acetonitrile solution at a basal plane pyrolytic graphite (HOPG) electrode surface and is shown to
provide a monolayer film. By varying the amount of deposit partial or full coverage can be achieved.
The N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer acts as an active receptor
for 1,2-dihydroxy-benzene (catechol) derivatives in aqueous media. The ability to bind alizarin red S is
investigated and the Langmuirian binding constant determined as a function of pH. It is shown that the
immobilised boronic acid monolayer acts as sensor film for a wider range of catechols. A comparison of
Langmuirian binding constants for alizarin red S (1.4 ꢀ 105 molꢁ1 dm3), catechol (8.4 ꢀ 104 molꢁ1 dm3),
caffeic acid (7.5 ꢀ 104 molꢁ1 dm3), dopamine (1.0 ꢀ 104 molꢁ1 dm3), and L-dopa (8 ꢀ 103 molꢁ1 dm3)
reveals that a combination of hydrophobicity and electrostatic interaction causes considerable
selectivity effects.
phenylboronic acids,17 boronic acid functionalised TTF18 and
glutaraldehyde coupled boronic acids19 on glassy carbon. The
potential applications of boronic acid modified electrode surfaces
include the detection of glucose20–22 other saccharides (carbo-
hydrates),23–34 glycosylated proteins,35 chirality36–44 and oxidative
stress markers.45
1. Introduction
Boronic acids are capable of reversible formation of strong
covalent bonds with diol functionalities for example to form of 5-
or 6-membered cyclic esters with carbohydrates.1 This binding
process in aqueous media is important for sensor applications and
superior to other sensor systems involving weaker non-covalent
or hydrogen bonded interactions. Among the diols capable of
complexation with boronic acids, catechols are excellent candi-
dates2 due to the syn-peri-planar aromatic hydroxyl groups and
effective p-donation. Many biologically important species
contain catechol fragments, e.g. dopamine and caffeic acid, and
therefore boronic acids immobilised on sensor surfaces are
promising motifs for the detection of these molecule under
physiological condition.3,4 In aqueous media catechol can be
reversibly transformed into its oxidised form 1,2-benzoquinone.
The boronate esters formed by reaction of the aromatic 1,2-diol
with boronic acid are electrochemically oxidised at potentials
considerably more positive compared to those necessary to
oxidize free catechol at pH 7.4 An electrochemical sensor response
based on surface-immobilised boronate esters is therefore
expected to be distinct from the response for the free catechol.
Modified electrodes are widely used to detect analytes
including metal ions,5 DNA,6 and saccharides.7 Boronic acid
modified electrodes have been developed based on boronic acid
dendrimer nano-composites,8 boronic acid containing micro-
droplet deposits,9 carbon nanotubes modified with boronic
acids,10 conducting polymer films,11–13 self-assembled thiol
films on gold14,15 and on gold nanoparticles,16 diazo-coupled
Herein a novel boronic acid immobilisation strategy based on
a self-assembly process on basal plane pyrolytic graphite elec-
trode surfaces is reported. A highly hydrophobic boronic acid,
N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate, is
synthesised which is similar to boronic acid structures employed
by Mohler and Czarnik that allowed transmembrane drug
transport in living cells.46 The hydrophobicity of this new
boronic acid material allows facile assembly of monolayers on
hydrophobic electrode surfaces with potential applications in
sensors without covalent attachment. The physical monolayer
attachment allows rapid renewal of the sensor film and opens up
applications on many types of sensor surfaces without the need
for chemical attachment.
2. Experimental details
2.1. Chemical reagents
Dopamine hydrochloride and caffeic acid were purchased from
Sigma. L-Dopa, catechol, alizarin red S, 4-pyridineboronic acid
were obtained from Aldrich. KPF6 and 1-bromohexadecane
were obtained from Arcos, NaH2PO4 obtained from Fisher, and
ion-exchange resin amberlite IR-120 obtained from Merck. All
reagents were of analytical purity and used without further
purification.
aDepartment of Chemistry, University of Bath, Claverton Down, Bath, BA2
7AY, UK. E-mail: F.Marken@bath.ac.uk
bDepartment of Chemistry, College of Chemistry and Chemical
Engineering, and the MOE Key Laboratory of Analytical Sciences,
Xiamen University, Xiamen, 361005, China
cSchool of Chemistry, University of Birmingham Edgbaston, Birmingham,
B15 2TT, UK
2.2. Instrumentation
A micro-Autolab III (Ecochemie, NL) with GPES software was
employed for electrochemical measurements. A KCl-saturated
This journal is ª The Royal Society of Chemistry 2010
J. Mater. Chem., 2010, 20, 8305–8310 | 8305

View Online
calomel electrode (SCE) and platinum wire were the reference
and counter, respectively. A 4.9 mm diameter basal plane
pyrolytic graphite (Pyrocarbon, Le Carbone, UK) electrode was
the working electrode. The electrode surface was renewed by
polishing on fine caborundum paper. Solutions were de-aerated
with argon (BOC). All experiments were conducted at a temper-
ature of 20 ꢂ 2 ꢃC.
acid was deprotected simultaneously to give the alkyl pyridinium
as a chloride salt. Dropwise addition of aqueous saturated KPF6
solution into a methanol solution of the chloride salt formed
a precipitate. After washing the precipitate several times with
water, the desired product, N-hexadecyl-pyridinium-4-boronic
acid hexafluorophosphate 2, was obtained as a white solid in 52%
yield (128 mg). ESI-MS (m/z): [M+] calculated for C21H39NO2B,
1
348.31; found 348.31. H NMR (250 MHz methanol-d4) d 8.91
(d, 2H, J ¼ 6 Hz), 8.27 (d, 2H, J ¼ 6 Hz), 4.65 (t, 2H, J ¼ 7.5 Hz),
2.06 (m, 2H), 1.31 (m, 26H), 0.95 (t, 3H, J ¼ 6.5 Hz). 13C NMR
(300 MHz, methanol-d4) d 144.3, 133.5, 63.1, 33.5, 32.9, 31.2,
30.9, 30.5, 27.6, 24.2, 14.9, one carbon was not observed due to
quadropolar relaxation by the boron.
2.3. Synthesis of N-hexadecyl-pyridinium-4-boronic acid
hexafluorophosphate
4-Pyridineboronic acid (1.23 g, 10 mmol) and 2,2-dimethyl-1,3-
propanediol (1.04 g, 10 mmol) were mixed in toluene (150 mL). A
Dean–Stark head was fitted and the reaction mixture was heated
under reflux for 3 h. The mixture was allowed to cool to room
temperature. The solution was washed with water (3 ꢀ 30 mL),
then dried over sodium sulfate and filtered. Volatiles were
removed and resulting white solid dried in vacuo to yield 4-(5,
5-dimethyl-1, 3, 2-dioxanborinan-2-yl)pyridine 1 (see eqn (1)).
2.3. Electrode modification protocol
A solution of N-hexadecyl-pyridinium-4-boronic acid hexa-
fluorophosphate 2 in acetonitrile (0.2 mM concentration in
a 10 mL volume) was prepared and films on the basal plane
pyrolytic graphite electrode were formed by evaporation. In
a typical experiment, 5 mL stock solution was evaporated onto
a 4.9 mm diameter electrode to give a 1 nmol deposit (corres-
ponding to 5.3 nmol cmꢁ2).
(1)
3. Results and discussion
3.1. N-Hexadecyl-pyridinium-4-boronic acid monolayer films
I: binding and cathodic detection of alizarin red S
Alizarin red S is known to bind to boronic acids with a binding
constant of approximately 6000 molꢁ1 dm3 in aqueous media8
and has often been employed as a redox probe for electrodes
modified with boronic acids.8 Herein, we report initial investi-
gations on the binding of alizarin red S onto the bare basal plane
of HOPG. Fig. 1A shows a voltammogram for a clean graphite
electrode and an electrode after immersion in 1 mM alizarin red S
in aqueous 0.1 M phosphate buffer pH 7. The voltammograms
were recorded after transfer into clean 0.1 M phosphate buffer
pH 7. Two processes due to surface adsorbed alizarin red S can
be identified which correspond to the 2-electron 2-proton
reduction of alizarin red S (P1, see eqn (3)) and the 2-electron
2-proton oxidation of alizarin red S (P2, see eqn (4)).
(2)
A mixture of compound 1 (96 mg, 0.5 mmol) and 1-bromo-
hexadecane (152 mg, 0.5 mmol) in acetonitrile (10 mL) was
heated at reflux for 48 h under N2. After removal of the solvent
the mixture was dissolved in MeOH and treated with ion-
exchange resin, 0.2 mol Lꢁ1 HCl–MeOH as eluent. The boronic
From these measurements it is apparent that alizarin red S is
amphiphilic and readily adsorbed and the charge for a mono-
layer adsorption is approximately 40 mC (or 212 mC cmꢁ2). This
(3)
(4)
8306 | J. Mater. Chem., 2010, 20, 8305–8310
This journal is ª The Royal Society of Chemistry 2010

View Online
oxidation of alizarin red S (P2) is suppressed (shifted positive,
not shown). The new signal for the reduction of the boronic acid
bound alizarin red S is fully developed with ca. 0.5 nmol boronic
acid deposit (corresponding to 2.6 nmol cmꢁ2) and further excess
of boronic acid is shown to have no effect. This amount of the
boronic acid derivative is in good agreement with a monolayer at
the HOPG electrode surface. The boronic acid derivative has
a typical amphiphilic structure with a highly non-polar alkyl
chain and the cationic head group containing the boronic acid
binding site. At highly hydrophobic surfaces such as that of the
HOPG electrode spontaneous and reproducible monolayer
formation is possible.
The voltammetric response for the reduction of alizarin red S
in the presence of the boronic acid film (see Fig. 1B) is observed
with a considerable peak-to-peak separation of ca. 0.37 V and
ox
a midpoint potential Emid ¼ ½ (Ep + Epred) ¼ 0.54 V vs. SCE.
The midpoint potential is shifted positive when compared to the
reduction of adsorbed alizarin red S in the absence of boronic
acid, presumably due to the electron-withdrawing effect of the
pyridinium boronic acid. In order to obtain additional infor-
mation about the effect of the N-hexadecyl-pyridinium-4-
boronic acid monolayer on the rate of interfacial electron
transfer, experiments were conducted at a range of different scan
rates. Fig. 2A shows a typical set of voltammograms and Fig. 2B
summarises the effect of scan rate on peak current and peak
potentials.
Fig. 1 (A) Cyclic voltammograms (scan rate 0.1 V sꢁ1) for alizarin red S
(adsorbed from 1 mM solution in aqueous 0.1 M phosphate buffer pH 7)
at a 4.9 mm diameter basal plane HOPG electrode immersed in 0.1 M
phosphate buffer pH 7. (B) Conditions as in (A) but with N-hexadecyl-
pyridinium-4-boronic acid hexafluorophosphate (i) 3 ꢀ 10ꢁ10 mol, (ii) 5 ꢀ
10ꢁ10 mol, (iii) 1 ꢀ 10ꢁ9 mol, (iv) 2 ꢀ 10ꢁ9 mol, (v) 3 ꢀ 10ꢁ9 mol, and (vi)
5 ꢀ 10ꢁ9 mol pre-deposited onto the HOPG electrode surface. (C)
Schematic drawing of a graphite electrode with immobilised boronic acid
film and binding to alizarin red S.
corresponds to 1.2 ꢀ 1014 molecules (0.2 nmol) on the electrode
surface (corresponding to 6.4 molecules cmꢁ2) or a realistic
˚
˚
geometric area of 4 A ꢀ 4 A per alizarin red S molecule at the
surface of the graphite electrode (not taking into account elec-
trode roughness).
The estimated roughness factor as given by real surface area/
geometric surface area z 1.4 for the graphite surface and the
possible presence of different types of adsorption sites suggest
a more complex surface structure and indeed additional volt-
ammetric peaks are observed in Fig. 1A. However, throughout
this report the surface will be considered flat in order to facilitate
interpretation of data.
Fig. 2 (A) Cyclic voltammograms (scan rates (i) 0.02, (ii) 0.05, (iii) 0.1,
(iv) 0.2, and (v) 0.5 V sꢁ1) for alizarin red S (adsorbed from 1 mM solution
in aqueous 0.1 M phosphate buffer pH 7) at a 4.9 mm diameter basal
plane HOPG electrode with 1 nmol N-hexadecyl-pyridinium-4-boronic
acid hexafluorophosphate immobilised and immersed in 0.1 M phosphate
buffer pH 7. (B) Plot of the peak current versus peak potential for
reduction and re-oxidation and for a range of scan rates. The solid line
corresponds to simulation data (DigiSim) for a 1 nm thin film of redox
active molecules with two consecutive one-electron transfers with
Next, the experiment was repeated but with N-hexadecyl-
pyridinium-4-boronic acid hexafluorophosphate pre-deposited
at the graphite electrode surface. It can be seen that the shape of
the voltammetric response for the reduction of alizarin red S (P1)
is considerably different and the voltammetric response for the
a standard rate constant ks ¼ 10ꢁ10 m sꢁ1
.
This journal is ª The Royal Society of Chemistry 2010
J. Mater. Chem., 2010, 20, 8305–8310 | 8307

View Online
It can be seen that the increase in scan rate causes a further
increase in the peak-to-peak separation. In order to quantify this
effect a DigiSim simulation based on two consecutive one-elec-
tron transfer processes is employed. Thin film conditions are
employed (1 nm thickness, chosen tentatively) to represent the
adsorbed alizarin red S redox system and a heterogeneous
standard rate constant of 10ꢁ10 m sꢁ1 (see solid line in Fig. 2B) can
be seen to closely reproduce the peak positions for the reduction
process. For the re-oxidation and at low scan rates, the match of
simulation and experimental data is not satisfactory probably
due to additional complication such as a chemical step involving
deprotonation. A good match of simulation and experiment
confirms that slow electron transfer across the N-hexadecyl-
pyridinium-4-boronic acid monolayer is responsible for the
observed peak-to-peak separation. The corresponding standard
heterogeneous rate constant for the adsorbed alizarin red S layer
can be estimated as ks,immobilised ¼ 10ꢁ10 m sꢁ1/10ꢁ9 m ¼ 0.1 sꢁ1
which is in agreement for example with literature rate constant
data for electron transfer to immobilised redox systems observed
at catechol monolayer coated carbon surfaces.47 Alternatively, it
is possible to employ Laviron’s expressions48 for slow electron
transfer in immobilised redox systems (see eqn (5) for reduction
and eqn (6) for oxidation) to obtain mechanistic information. A
comparison of experimental and theoretical data for peak
potential versus logarithm of scan rate (not shown) is consistent
with the above mechanism (the first electron transfer is rate
limiting and therefore n ¼ 1, the transfer coefficient is approxi-
mately a z 0.5, and the standard rate constant is ks,immobilised
z
0.1 sꢁ1. In the equations R is the gas constant, T is the absolute
temperature, F is the Faraday constant, Ep,c and Ep,a are the
cathodic and anodic peak potentials, E00 is the formal potential,
and v denotes the scan rate.
Fig. 3 (A) Cyclic voltammograms (scan rate 0.1 V sꢁ1) for alizarin red S
(adsorbed from (i) 0, (ii) 1 ꢀ 10ꢁ6, (iii) 5 ꢀ 10ꢁ6, (iv) 1 ꢀ 10ꢁ5, (v) 5 ꢀ 10ꢁ5
,
(vi) 1 ꢀ 10ꢁ4, (vii) 5 ꢀ 10ꢁ4, and (viii) 1 mM solution in aqueous 0.1 M
ꢀ
ꢁ
phosphate buffer pH 7) at a 4.9 mm diameter basal plane HOPG elec-
RT
anFv
Ep;c ¼ E00
ꢁ
ln
(5)
trode with
1 nmol N-hexadecyl-pyridinium-4-boronic acid hexa-
anF
RTks;immobilised
fluorophosphate immobilised immersed in 0.1 M phosphate buffer pH 7.
(B) Plot of the charge under the reduction peak versus the concentration
of alizarin red S during adsorption (the solid line shows Langmuirian
binding with K ¼ 1.3 ꢀ 105 Mꢁ1). (C) Plot of the Langmuirian binding
constant versus pH during adsorption (with estimated errors).
ꢀ
ꢁ
RT
ð1 ꢁ aÞnFv
00
Ep;a ¼ E
þ
ln
(6)
ð1 ꢁ aÞnF
RTks;immobilised
Next, the effect of the alizarin red S concentration during the
binding process was investigated. Fig. 3A shows voltammograms
obtained for alizarin red S concentrations from 1 mM to 1 mM
and the plot in Fig. 3B demonstrates approximate agreement
with a Langmuirian binding process with K ¼ 1.3 ꢀ 105 Mꢁ1. The
transition from unbound to bound state appears to be slightly
more steep in the experimental data when compared to the
theory indicating some attractive interaction of alizarin red S
molecules when bound to the boronic acid film. Analysis of
alizarin red S binding as a function of solution pH (during the
adsorption step) (see Fig. 3C) is consistent with an only slight
trend towards weaker binding for more acidic or more alkaline
solutions and with a maximum at pH 5. The absence of a more
pronounced effect of pH may be attributed to a binding mech-
anism with significant contributions from electrostatic, disper-
sion, and covalent forces (vide infra). Attempts to replace alizarin
red S with analyte molecules such as fructose and glucose failed
even with high concentrations and this may be attributed to
a strong binding between alizarin red S and the N-hexadecyl-
pyridinium-4-boronic acid hexafluorophosphate monolayer
which may be due again to a combination of factors including (i)
binding to the boronic acid, (ii) electrostatic interactions, and (iii)
hydrophobic interactions of alizarin red S with the modified
electrode surface.
3.2. N-hexadecyl-pyridinium-4-boronic acid monolayer films
II: binding of and anodic detection of catechols
Voltammetric data in Fig. 1A and B demonstrate that the
oxidation of the catechol functional group of alizarin red S is
suppressed after binding to the boronic acid film. However, this
oxidation is only shifted to more positive potentials and it can be
employed for analytical purposes. In contrast to the reduction of
alizarin red S the oxidation is liberating the boronic acid bound
molecule due to the transformation of the catechol to an ortho-
diquinone. Therefore the N-hexadecyl-pyridinium-4-boronic
acid hexafluorophosphate monolayer modified electrode can be
employed for a much wider range of catechol analytes.
8308 | J. Mater. Chem., 2010, 20, 8305–8310
This journal is ª The Royal Society of Chemistry 2010

View Online
Voltammetry experiments conducted with a N-hexadecyl-
pyridinium-4-boronic acid hexafluorophosphate monolayer
modified basal plane HOPG electrode immersed in aqueous
0.1 M phosphate buffer solution in the presence of dopamine are
shown in Fig. 4A. A partially reversible process indicating
dopamine oxidation for dopamine in the solution phase is
observed at a potential of ca. 0.15 V vs. SCE (see P3, eqn (7)).
(8)
The shape of the oxidation peak P4 is characteristic for
a surface immobilised redox system and the fact that the process
is chemically irreversible is consistent with the oxidative removal
of bound dopamine during the oxidation. However, the adsorbed
layer quickly reforms and voltammetric analysis is possible
without removal of the sensor from the analyte solution. The
N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate
monolayer is stable over many potential cycles. However,
a further oxidation process at potential positive of 0.8 V vs. SCE
(not shown) occurs which destroys the boronic acid film irre-
versibly most likely via oxidative C–B bond cleavage.
(7)
An additional oxidation response with higher sensitivity at
lower dopamine concentration is observed at ca. 0.66 V vs. SCE
(see P4, eqn (8)).
The analysis of the charge under the oxidation peak P4 versus
the dopamine concentration is shown in Fig. 4B. Again a Lang-
muirian binding curve can be employed to extract an approxi-
mate binding constant of K ¼ 104 Mꢁ1. This binding constant is
considerably lower compared to that obtained for alizarin red S
and therefore a range of catechols was investigated. Fig. 4C
shows a table summarising binding constant data for catechol,
caffeic acid, dopamine, L-dopa, and alizarin red S. The strongest
binding constant is observed for alizarin red S followed by
catechol and caffeic acid. L-Dopa and dopamine show only
weaker binding.
Attempts to correlate the binding constants with hydropho-
bicity (log P values) or with the acidity of the first hydroxyl (pKa
values) were not successful. The more hydrophilic nature and the
positively charged amine functional groups on dopamine and
L-dopa as well as the combination of molecular charge and
hydrophobicity are likely to play a major and varying role in this
selectivity sequence.
4. Conclusions
It has been shown that N-hexadecyl-pyridinium-4-boronic acid
hexafluorophosphate can be readily deposited on basal plane
HOPG as a monolayer with boronic acid functional groups. The
amphiphilic nature of the molecule and the favourable interac-
tion of the hexadecyl alkyl chain with the hydrophobic graphite
substrate are responsible for this effect. Binding to the boronic
acid monolayer is demonstrated for alizarin red S and for a range
of catechol derivatives. Langmuirian binding is observed with
a strong preference for negatively charge hydrophobic molecules
such as alizarin red S. In future N-hexadecyl-pyridinium-4-
boronic acid hexafluorophosphate monolayer can be employed
on different types of sensor surfaces and in situ for the determi-
nation of dopamine or L-dopa directly in complex aqueous
sample solutions.
Fig. 4 (A) Cyclic voltammograms (scan rate 0.1 V sꢁ1) for the oxidation
of dopamine at a 4.9 mm diameter basal plane HOPG electrode with
1 nmol N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate
immobilised and immersed into aqueous 0.1 M phosphate buffer con-
taining (i) 1 ꢀ 10ꢁ5, (ii) 2 ꢀ 10ꢁ5, (iiii) 5 ꢀ 10ꢁ5, (iv) 1 ꢀ 10ꢁ4, (v) 2 ꢀ 10ꢁ4
,
Acknowledgements
(vi) 5 ꢀ 10ꢁ4, and (vii) 1 ꢀ 10ꢁ3 dopamine. (B) Plot of the charge under
the dopamine oxidation peak P4 versus dopamine concentration. Solid
line indicating Langmuirian binding with K ¼ 104 Mꢁ1. (C) Table of
Langmuirian binding constants K for catechols. Also shown are log P
estimates and the first pKa for the hydroxyl proton based on ACDlab
estimates.49
Y-JH wishes to acknowledge University of Bath for the oppor-
tunity to carry out research in the TDJ group and China
Scholarship Council for the grant supporting the visit. We would
also like to thank the CAtalysis and SEnsing for our Environ-
ment (CASE) Network and CASE08 (Bath) and CASE09
This journal is ª The Royal Society of Chemistry 2010
J. Mater. Chem., 2010, 20, 8305–8310 | 8309

View Online
25 T. D. James, K. R. A. S. Sandanayake and S. Shinkai, Angew. Chem.,
Int. Ed. Engl., 1996, 35, 1910–1922.
26 S. Arimori, M. L. Bell, C. S. Oh, K. A. Frimat and T. D. James, Chem.
Commun., 2001, 1836–1837.
(ECUST) for providing an environment where the basic ideas for
this research were discussed and developed.
27 S. Arimori, M. L. Bell, C. S. Oh, K. A. Frimat and T. D. James,
J. Chem. Soc., Perkin Trans. 1, 2002, 803–808.
References
28 T. D. James and S. Shinkai, Top. Curr. Chem., 2002, 218, 159–200.
29 T. D. James, M. D. Phillips and S. Shinkai, Boronic Acids in
Saccharide Recognition, RSC Publishing, The Royal Society of
Chemistry, Cambridge, 2006.
30 T. D. James, Top. Curr. Chem., 2007, 277, 107–152.
31 T. R. Jackson, J. S. Springall, D. Rogalle, N. Masurnoto, H. C. Li,
F. D’Hooge, S. P. Perera, A. T. A. Jenkins, T. D. James,
J. S. Fossey and J. M. H. van den Elsen, Electrophoresis, 2008, 29,
4185–4191.
32 D. K. Scrafton, J. E. Taylor, M. F. Mahon, J. S. Fossey and
T. D. James, J. Org. Chem., 2008, 73, 2871–2874.
33 W. M. J. Ma, M. P. P. Morais, F. D’Hooge, J. M. H. van den Elsen,
J. P. L. Cox, T. D. James and J. S. Fossey, Chem. Commun., 2009,
532–534.
1 J. M. Sugihara and C. M. Bowman, J. Am. Chem. Soc., 1958, 80,
2443–2446.
2 J. P. Lorand and J. O. Edwards, J. Org. Chem., 1959, 24, 769–774.
3 B. Fabre and L. Taillebois, Chem. Commun., 2003, 2982–2983.
4 L. Zhang, J. A. Kerszulis, R. J. Clark, T. Ye and L. Zhu, Chem.
Commun., 2009, 2151–2153.
5 V. E. Mouchrek, A. L. B. Marques, J. J. Zhang and G. O. Chierice,
Electroanalysis, 1999, 11, 1130–1136.
6 C. Berggren, P. Stalhandske, J. Brundell and G. Johansson,
Electroanalysis, 1999, 11, 156–160.
7 X. Y. Sun, B. Liu and Y. B. Jiang, Anal. Chim. Acta, 2004, 515,
285–290.
8 M. J. Bonne, E. Galbraith, T. D. James, M. J. Wasbrough,
K. J. Edler, A. T. A. Jenkins, M. Helton, A. McKee,
W. Thielemans, E. Psillakis and F. Marken, J. Mater. Chem., 2010,
20, 588–594.
34 X. Yang, C. Dai, A. D. C. Molina and B. Wang, Chem. Commun.,
2010, 46, 1073–1075.
35 M. P. P. Morais, J. D. Mackay, S. K. Bhamra, J. G. Buchanan,
T. D. James, J. S. Fossey and J. M. H. van den Elsen, Proteomics,
2010, 10, 48–58.
36 T. D. James, K. R. A. S. Sandanayake and S. Shinkai, Nature, 1995,
374, 345–347.
9 N. Katif, R. A. Harries, A. M. Kelly, J. S. Fossey, T. D. James and
F. Marken, J. Solid State Electrochem., 2009, 13, 1475–1482.
10 X. Zhong, H. J. Bai, J. J. Xu, H. Y. Chen and Y. H. Zhu, Adv. Funct.
Mater., 2010, 20, 992–999.
11 S. R. Ali, R. R. Parajuli, Y. Balogun, Y. F. Ma and H. X. He, Sensors,
2008, 8, 8423–8452.
€
37 J. Zhao, M. G. Davidson, M. F. Mahon, G. Kociok-Kohn and
T. D. James, J. Am. Chem. Soc., 2004, 126, 16179–16186.
38 J. Z. Zhao, T. M. Fyles and T. D. James, Angew. Chem., Int. Ed.,
2004, 43, 3461–3464.
39 J. Z. Zhao and T. D. James, J. Mater. Chem., 2005, 15, 2896–2901.
40 J. Z. Zhao and T. D. James, Chem. Commun., 2005, 1889–1891.
41 L. Chi, J. Z. Zhao and T. D. James, J. Org. Chem., 2008, 73,
4684–4687.
42 F. Han, L. N. Chi, X. F. Liang, S. M. Ji, S. S. Liu, F. K. Zhou,
Y. B. Wu, K. L. Han, J. Z. Zhao and T. D. James, J. Org. Chem.,
2009, 74, 1333–1336.
12 B. A. Deore, I. Yu, J. Woodmass and M. S. Freund, Macromol.
Chem. Phys., 2008, 209, 1094–1105.
13 E. Granot, R. Tel-Vered, O. Lioubashevski and I. Willner, Adv.
Funct. Mater., 2008, 18, 478–484.
14 X. T. Zhang, Y. F. Wu, Y. F. Tu and S. Q. Liu, Analyst, 2008, 133,
485–492.
15 R. K. Shervedani and M. Bagherzadeh, Electroanalysis, 2008, 20,
550–557.
16 M. Tanaka, R. Fujita and H. Nishide, J. Nanosci. Nanotechnol., 2009,
9, 634–639.
43 X. Zhang, L. N. Chi, S. M. Ji, Y. B. Wu, P. Song, K. L. Han,
H. M. Guo, T. D. James and J. Z. Zhao, J. Am. Chem. Soc., 2009,
131, 17452–17463.
44 X. Zhang, Y. B. Wu, S. M. Ji, H. M. Guo, P. Song, K. L. Han,
W. T. Wu, W. H. Wu, T. D. James and J. Z. Zhao, J. Org. Chem.,
2010, 75, 2578–2588.
45 A. Sikora, J. Zielonka, M. Lopez, J. Joseph and B. Kalyanaraman,
Free Radical Biol. Med., 2009, 47, 1401–1407.
46 L. K. Mohler and A. W. Czarnik, J. Am. Chem. Soc., 1993, 115,
2998–2999.
47 N. H. Nguyen, C. Esnault, F. Gohier, D. Belanger and C. Cougnon,
Langmuir, 2009, 25, 3504–3508.
48 E. Laviron, J. Electroanal. Chem., 1979, 101, 19–28.
49 ACD/Labs, Advanced Chemistry Development Inc., Toronto,
Canada, 2009, http://www.acdlabs.com.
17 R. Polsky, J. C. Harper, D. R. Wheeler, D. C. Arango and
S. M. Brozik, Angew. Chem., Int. Ed., 2008, 47, 2631–2634.
18 M. Shao and Y. Zhao, Tetrahedron Lett., 2010, 51, 2508–2511.
19 S. Q. Liu, B. Miller and A. C. Chen, Electrochem. Commun., 2005, 7,
1232–1236.
20 T. D. James, K. R. A. S. Sandanayake and S. Shinkai, Angew. Chem.,
Int. Ed. Engl., 1994, 33, 2207–2209.
21 T. D. James, K. R. A. S. Sandanayake, R. Iguchi and S. Shinkai,
J. Am. Chem. Soc., 1995, 117, 8982–8987.
22 A. Matsumoto, K. Yamamoto, R. Yoshida, K. Kataoka, T. Aoyagi
and Y. Miyahara, Chem. Commun., 2010, 46, 2203–2205.
23 T. D. James, K. R. A. S. Sandanayake and S. Shinkai, J. Chem. Soc.,
Chem. Commun., 1994, 477–478.
24 T. D. James, P. Linnane and S. Shinkai, Chem. Commun., 1996,
281–288.
8310 | J. Mater. Chem., 2010, 20, 8305–8310
This journal is ª The Royal Society of Chemistry 2010