As we have previously reported, the fluorescence response of
Thus, the PD-1/g-CyD complex was found to exhibit high
the PD-1/g-CyD complex must be dependent on g-CyD
selectivity for Pb2+ ion in water.
15
concentration. Preliminary experiments revealed that selectiv-
In summary, a supramolecular PD-1/g-CyD complex sensor
2+
2+
ity for Pb /Cu increased monotonically with an increase in g-
CyD concentration from 2.0 mM to 14.0 mM.† In this study, a
g-CyD concentration of 12.0 mM was selected for subsequent
experiments. The pH of the sample solutions was adjusted to 4.3
by 0.010 M acetate buffer with an ionic strength of 0.10 by
that exhibited the monomer/dimer emission ratio response with
markedly high selectivity for Pb2+ in water was successfully
designed. It should be noted that the observed detection limit of
10 mM is evidently insufficient for practical Pb2+ ion analysis
1
(0.02–1.0 mM) in water. Although we selected the pseudo-
2+
2+
NaNO
3
. No significant difference in the selectivity for Pb /
18-crown-6 structure as the Pb binding site, the podand
2+
Cu was noted in the pH range from 3.7 to 5.5.†
structure as well as the alkyl spacer design in the fluoro-
Fig. 3a shows changes in the fluorescence spectra of the PD-
ionophore is an important factor for enhancing the Pb2+
2+
2+
1
/g-CyD complex with the addition of Pb . As the Pb
recognition efficiency of the g-CyD complex sensors by several
concentration was increased, the intensity of the monomer
emission decreased whereas that of the dimer emission
increased. Fig. 3b shows plots of the intensity ratio (I471/I378) as
a function of Pb2+ concentration. When the change in
fluorescence is induced only by the 2 : 1 complex formation
order of magnitude.15 Such modifications are being actively
undertaken in our laboratory in order to develop more advanced
fluoroionophore/g-CyD complex sensors for heavy metal ion
recognition in water.
This work was supported by Grants-in-Aid for Scientific
Research (B) (Nos. 12440208 and 14340230) from the Ministry
of Education, Culture, Sports, Science and Technology of
Japan.
2+
between PD-1 and the metal ion (M ), the fluorescence ratio
471/I378) can be expressed by the following equations:11
(I
(
1)
2)
Notes and references
1
2
3
A. Fetch, Crit. Rev. Anal. Chem., 1998, 28, 267; X. Yu, H. Yuan, T.
Górecki and J. Pawliszyn, Anal. Chem., 1999, 71, 2998.
Quantitative Trace Analysis of Biological Materials, H. A. Mckenzie
and L. E. Smythe, eds., Elsevier, New York, 1988.
A. P. de Silva, D. B. Fox, A. J. M. Huxley and T. S. Moody, Coord.
Chem. Rev., 2000, 205, 41; V. Adendota, L. Fabbrizzi, M. Licchelli, C.
Mangano, P. Pallavicini, L. Parodi and A. Poggi, Coord. Chem. Rev.,
(
0
where [PD-1] is the initial concentration of the fluoro-
2
000, 192, 649; Chemosensors of Ion and Molecule Recognition, J. P.
ionophore, and ff1 and ff2 are the fluorescence quantum yields
for PD-1 at 471 and 378 nm, respectively. Similarly, fc1 and fc2
are those for the 2 : 1 complex at 471 and 378 nm, respectively.
Desvergne and A. W. Czarnik, eds., Kluwer Academic Publishers,
Dordrecht, 1997.
4 A. Minta and R. Y. Tsien, J. Biol. Chem., 1989, 264, 19449; H. He, M.
A. Mortellaro, M. J. P. Leiner, R. J. Fraats and J. K. Tusa, J. Am. Chem.
Soc., 2003, 125, 1468; T. Hayashita, S. Taniguchi, Y. Tanamura, T.
Uchida, S. Nishizawa, N. Teramae, Y. S. Jin, J. C. Lee and R. A.
Bartsch, J. Chem. Soc., Perkin Trans. 2, 2000, 1003; H. Ueyama, M.
Takagi and S. Takenaka, J. Am. Chem. Soc., 2002, 124, 14286.
5 G. Grynkiewicz, M. Poenie and R. Y. Tsien, J. Biol. Chem., 1985, 260,
3440; A. Miyawaki, J. Llopis, R. Heim, J. M. McCaffery, J. A. Adams,
M. Ikura and R. Y. Tsien, Nature, 1997, 388, 882; K. R. Gee, E. A.
Archer, L. A. Lapham, M. E. Leovard, Z.-L. Zhou, J. Bingham and Z.
Diwu, Bioorg. Med. Chem. Lett., 2000, 10, 1515.
2+
K
21 is the apparent 2 : 1 binding constant of PD-1 with M . As
shown in Fig. 3b, the observed values are well fitted by eqn. (1)
(
0
solid line), and the binding constant is calculated as (1.17 ±
9
22
.75) 3 10 M . Also shown in Fig. 3b are the fluorescence
2+
responses of the PD-1/g-CyD complex in the presence of Zn
2+
and Cu . The PD-1/g-CyD complex did not show any obvious
spectral changes upon the addition of Zn2 and Cu , indicating
+
2+
that fluorescence quenching by heavy metal ions was negli-
gible. No fluorescence response upon the addition of 1.0 mM
6
M. C. Kinber, I. B. Mahadevan, S. F. Lincoln, A. D. Ward and E. R. T.
Tiekink, J. Org. Chem., 2000, 65, 8204; T. Hirano, K. Kikuchi, Y.
Urano, T. Higuchi and T. Nagano, J. Am. Chem. Soc., 2000, 122, 12399;
T. Hirano, K. Kikuchi, Y. Urano and T. Nagano, J. Am. Chem. Soc.,
+
2+
2+
2+
2+
2+
K , Mg , Ca , Ni , Co , and Cd was also confirmed.†
2
002, 124, 6555; S. Maruyama, K. Kikuchi, T. Hirano, Y. Urano and T.
Nagano, J. Am. Chem. Soc., 2002, 124, 10650; K. R. Gee, Z.-L. Zhou,
W.-J. Qian and R. Kennedy, J. Am. Chem. Soc., 2002, 124, 776; S. C.
Burdette and S. J. Lippard, Inorg. Chem., 2002, 41, 6816; S.
Bhattacharya and A. Gulyani, Chem. Commun., 2003, 1159.
7
C.-T. Chen and W.-P. Huang, J. Am. Chem. Soc., 2002, 124, 6246; S.
Deo and H. A. Godwin, J. Am. Chem. Soc., 2000, 122, 174; W.-S. Xia,
R. H. Schmehl, C.-J. Li, J. T. Mague, C.-P. Luo and D. M. Guldi, J.
Phys. Chem. B, 2002, 106, 833; M. Minagawa, T. Hayashita, Q. Dai, R.
A. Bartsch and N. Teramae, Bunseki Kagaku, 2002, 51, 681; R. S.
Addleman, J. Bennett, S. H. Tweedy, S. Elshani and C. M. Wai, Talanta,
1
998, 46, 573.
8
9
R. Métivier , I. Leray and B. Valeur, Chem. Commun., 2003, 996.
T. Koike, T. Watanabe, S. Aoki, E. Kimura and M. Shiro, J. Am. Chem.
Soc., 1996, 118, 12696; D. S. McClure, J. Chem. Phys., 1952, 20,
6
82.
1
1
0 L. Fabbrizzi, M. Licchelli, P. Pallavicini, D. Sacchi and A. Taglietti,
Analyst, 1996, 121, 1763.
1 A. Yamauchi, T. Hayashita, S. Nishizawa, M. Watanabe and N.
Teramae, J. Am. Chem. Soc., 1999, 121, 2319; A. Yamauchi, T.
Hayashita, A. Kato, S. Nishizawa, M. Watanabe and N. Teramae, Anal.
Chem., 2000, 72, 5841.
1
1
2 T. Hayashita, H. Sawano, T. Higuchi, M. Indo, K. Hiratani, Z.-Y. Zhang
and R. A. Bartsch, Anal. Chem., 1999, 71, 791.
3 F. Cramer, W. Saenger and H.-C. Spatz, J. Am. Chem. Soc., 1967, 89,
14.
Fig. 3 (a) Fluorescence spectra of PD-1. [PD-1] = 2.0 3 102 M in 98%
6
water/2% MeOH (v/v); [g-CyD] = 12.0 mM. Excitation wavelength, 328
14 A. Ueno, I. Suzuki and T. Osa, J. Am. Chem. Soc., 1989, 111, 6391.
15 A. Yamauchi, T. Hayashita, A. Kato and N. Teramae, Bull. Chem. Soc.
Jpn., 2002, 75, 1527.
3
nm. pH = 4.3 adjusted with 0.010 M acetate buffer (I = 0.10 by NaNO ).
(
b) Dependence of I471/I378 on the concentration of Pb , Cu , and Zn2+.
2+
2+
CHEM. COMMUN., 2003, 2160–2161
2161