Chemistry Letters 2000
941
methylglucoside. iii) The electrode had a response to methyl-β-
xylopyranoside, a compound that has no binding site with
phenylboronic acid, at the relatively higher concentrations.
Possible hydrogen bonding between the phenylboronic acid
moiety in 1 with the 2,3-and 4-hydroxy moieties in methyl-β-
xylopyranoside may explain the shift.
In conclusion, we have found, for the first time, that
phenylboronic acid-terminated redox active SAMs on gold
electrodes respond to a variety of saccharides at relatively low
concentration (ppm order). Intense effort is currently underway
in our laboratory to reveal fully the characteristics of 1-
SAMs/Au electrodes including the mechanism of the observed
potential shift in the CVs and explore potential applications of
the electrodes as highly sensitive sensors for biological oligo-
and poly(saccharides).
This work was supported in part by the Nagasaki
Advanced Technology Development Council (for H. M.).
References and Notes
1
a) S. Shinkai and M. Takeuchi, NATO ASI Ser., Ser. C,
527, 157 (1999). b) T. D. James, K. R. A. Samankumara
Sandanayake, and S. Shinkai, Angew. Chem., Int. Ed.
Engl., 35, 1911 (1996).
stronger binding of the saccharide with the oxidized form of 1
than the reduced form. On the contrary, no such shift in the for-
mal potential was observed for a 2-SAM/Au electrode. CVs at
1-SAM/Au electrodes were measured in the presence of given
concentrations of galactose, fructose, mannose, glucose, xylose,
α-methylglucoside and methyl-β-xylopyranoside, and the
observed shifts in E0’ were plotted as a function of saccharide
concentration in Figure 3. Interesting features observed are as
follows. i) 1-SAM/Au electrodes exhibited a response for
xylose, mannose and fructose at the concentration range of
10–6–10–3 mol dm–3. ii) CV response of the electrode was also
occurred to α-methylglucoside, a compound possessing no 1,2-
diol moiety. This might be due to the binding of the phenyl-
boronic acid moiety in 1 with the 4- and 6-hydroxy groups in α-
2
3
a) A. Ori and S. Shinkai, J. Chem. Soc., Chem. Commun.,
1995, 1771. b) N. J. Moore and D. D. M. Wayner, Can. J.
Chem., 77, 681 (1999).
K. D. Pavey, C. J. Olliff, J. Baker, and F. Paul, Chem.
Commun., 1999, 2223.
N. Kanayama and H. Kitano, Langmuir, 16, 577 (2000).
S. Arimori, H. Murakami, M. Takeuchi, and S. Shinkai, J.
Chem. Soc., Chem. Commun., 1995, 961.
mp >300 ˚C. Anal. Found: C, 40.10; H, 4.01; N, 4.02%.
Calcd for C46H56N4O4B2F24P4S2: C, 39.6; H, 4.04; N,
4.02%. IR (KBr): 3400 (OH), 3058 (CH, Ar), and 2942
(CH) cm–1. 1H NMR (200 MHz, CD3CN, TMS); δ 1.3–1.8
(m, 16H, SC(CH2)4CN+), 2.70 (m, 4H, SCH2), 4.60 (t, 4H,
CH2N+), 5.84 (s, 4H, N+CH2Ph), 6.43 (s, 4H, OH), 7.49
(d, 4H, ArH), 7.88 (d, 4H, ArH), 8.37 (m, 8H, PyH), 8.89
(d, 4H, PyH), 8.98 (d, 4H, PyH).
4
5
6
7
mp >300 °C. Anal. Found: C, 38.93; H, 4.31; N, 4.41%.
Calcd for C46H54N4F24P4S2·5.7H2O: C, 39.19; H, 4.68;
N,3.97%. IR (KBr): 3139 (CH, Ar), and 2931 (CH) cm–1.
1H NMR (200 MHz, DMSO-d6, TMS); δ 1.30 (m, 8H, SC2
(CH2)2C2N+), 1.63 (m, 4H, SCCH2C4N+), 1.95 (m, 4H,
SC4CH2CN+), 2.70 (m, 4H, SCH2), 4.65 (t, 4H, CH2N+),
5.94 (s, 4H, N+CH2Ph), 7.47 (d, 6H, ArH), 7.61 (d, 4H,
ArH), 8.75 (m, 8H, PyH), 9.36 (d, 4H, PyH), 9.52 (d, 4H,
PyH).
8
The surface roughness factor determined by the anodic oxi-
dation of chemisorbed iodine on bare Au electrodes was
ca. 1.4, whose value was used to calculate the surface cov-
erage. Detailed for the anodic oxidation of chemisorbed
iodine, see: J. F. Rodriguez, T. Mebrahtu, and M. P.
Soriaga, J. Electroanal. Chem., 233, 283 (1987).