1
354
Vol. 53, No. 10
ꢁ
1
1
18)
Table 1. Association Constants (Ka [M ] in CDCl3 at 24 °C) for 1 : 1
H-NMR Titration Experiemnt
Association constants (K ) were ob-
a
1
Complexes of Phenols (1, 4) and Quaternary Ammonium Salts (5) and Free tained by H-NMR titration experiments, performed directly in the NMR
Energy (ꢁDG [kJ/mol] in CDCl at 24 °C) tube using a micropipette to add known amounts (0, 10, 50, 100, 150, 200,
3
2
50, 300, 400, 500, 600 ml) of a phenol’s (1 or 4) stock solution (concentra-
tionꢂ20.0 mM (1) or 82.6 mM (4)) in CDCl to a solution of quaternary am-
ꢁ
1 a)
Association constants (K ) [M
]
a
3
(free energy (ꢁDG [kJ/mol]))
monium salt (5) (700 ml, concentrationꢂ2.88 mM for 1 or 11.9 mM for 4) in
CDCl . A 1 : 1 association of phenols and quaternary ammonium salts was
b)
3
Anion
Receptor
previously demonstrated, therefore, experimental data were fit to the equa-
tion of the 1 : 1 binding isotherm by a nonlinear regression method. All titra-
1
4
tion experiments were performed in CDCl at 24 °C and 500 MHz.
3
ꢁ
ꢁ
Cl
5a
5b
5c
5d
5e
5f
310 (14.2)
85 (11.0)
11 (5.9)
1530 (18.0)
95 (11.2)
530 (15.5)
130 (12.1)
95 (11.2)
75 (10.7)
28 (8.2)
210 (13.1)
43 (9.3)
References and Notes
Br
1) Seel C., de Mendoza J., Reetz M. T., “Comprehensive Supramolecular
Chemistry,” Vol. 2, ed. by Atwood J. L., Davies J. E., MacNicol D. D.,
Voegtle F., Elsevier Science Ltd., Oxford, 1996, pp. 519—562.
2) Gale P. A., Anzenbacher P., Sessler J. L., Coord. Chem. Rev., 222,
57—102 (2000).
ꢁ
I
ꢁ
H PO
2
4
ꢁ
HSO4
ꢁ
2
CH CO
70 (10.5)
57 (10.0)
3
ꢁ
NO3
5g
3) Beer P. D., Gale P. A., Angew. Chem., Int. Ed. Engl., 40, 486—516
(
2001).
ꢅ
a) Errors were estimated to be ꢃ10%. b) Anions were used as their n-Bu N
salts.
4) Motomura T., Aoyama Y., J. Org. Chem., 56, 7224—7228 (1991).
4
5)
6)
7)
Manabe K., Okamura K., Date T., Koga K., J. Am. Chem. Soc., 114,
940—6941 (1992).
Jeong K.-S., Hahn K.-M., Cho Y. L., Tetrahedron Lett., 39, 3779—
782 (1998).
6
3
Arduini A., Giorgi G., Pochini A., Secchi A., Ugozzoli F., J. Org.
Chem., 66, 8302—8308 (2001).
8
9
)
)
Smith D. K., Org. Biomol. Chem., 1, 3874—3877 (2003).
Ito K., Miki H., Ohba Y., Yakugaku Zasshi, 122, 413—417 (2002).
1
1
1
1
1
0) Ito K., Nagase K., Morohashi N., Ohba Y., Chem. Pharm. Bull., 53,
0—94 (2005).
1) Yamato T., Hasegawa K., Saruwatari Y., Doamekpor L. K., Chem. Ber.,
26, 1435—1439, (1993).
2) Yamato T., Hideshima C., Prakashi G. K., Olah G. A., J. Org. Chem.,
6, 3192—3194 (1991).
3) Sone T., Ohba Y., Yamazaki T., Bull. Chem. Soc. Jpn., 62, 1111—1116
1989).
9
1
5
Fig. 5. Plausible Structure of Complex (1—5d)
(
4) The downfield shift of phenolic OH protons was negligible in more
ing the high reactivity of phenol moiety, the unique binding
motif of biphenol is expected to be use more useful in the de-
velopment of new anion receptor/sensors with enhanced
binding affinity and substrate specificity.
polar solvent such as 10% methanol-d in CDCl . Such solvent effects
4
3
are characteristic of interaction involving polar groups and hence sup-
port involvement of the phenolic OH group in the interaction with an
anion.
15) IR spectra of biphenol (1) were measured in the presence or absence of
Experimental
quaternary ammonium salts (5) in CHCl at 24 °C. With the addition
3
1
13
ꢁ1
H- and C-NMR spectra were measured with a Varian Mercury 200
of 5, the intensity of the initial OH stretching band of 1 at 3550 cm
1
13
1
ꢁ1
(
1
200 MHz for H, 50 MHz for C) and/or an INOVA 500 (500 MHz for H,
decreased and that of a new band around 3400 cm increased. The IR
1
3
25 MHz for C) spectrophotometer, using tetramethyl silane as an internal
spectral change was ascribed to hydrogen bonding between phenolic
OH protons and anion component of quaternary ammonium salts.
standard. IR spectra were collected on a Horiba FT-720 spectrophotometer.
Tetra-n-butyl ammonium salts (5) were purchased from Tokyo Kasei Indus- 16) Ogoshi H., Hayashi T., “Encyclopedia of Experimental Chemistry,”
tries and Kanto Kagaku Co., Ltd. Biphenols (1—3) and phenol-formalde-
4th ed., Vol. 27, ed. by Iguchi H., The Chemical Society of Japan,
Maruzen Co., Ltd., Tokyo, 1991, pp. 19—25.
11—13)
hyde dimer (4) were prepared according to the literature.
16)
1
Job Plot
or 4)/quaternary ammonium salts (5) under the condition that [1 or
]ꢅ[5]ꢂ10 mM, and [1 or 4] varied from 0 to 9 mM in 1 mM steps. The ex-
The H-NMR sample solutions were made of phenols (1 17) Although similar downfield shifts of OH protons were observed for 5d
ꢁ ꢁ ꢁ
2
(H PO ), 5e (HSO ), 5f (CH CO ), and 5g (NO ), the changes of the
2
4
4
3
3
4
shifts were not determined accurately because of the exclusive broad-
ening of OH proton signals during titration.
1
perimentally observed parameter was the H-NMR chemical shift (Dd) of
methyl protons of n-butyl groups of 5 that is sensitive to complex 18) Hirose K., J. Inc. Phenom. Macrocycl. Chem., 39, 193—209 (2001).
17)
formation. The data were plotted in the form Ddꢆ[1 or 4] versus [1 or 4]/
[1 or 4]ꢅ[5]), and the position of the maximum indicated the stoichiometry
of the complex.
19) The association constant between p-tert-butyl phenol and
ꢁ ꢅ
ꢁ1
(
H PO Bu N (5d) was 405ꢇ10 M , supporting that the biphenol
2 4 4
ꢁ
skeleton was an important factor in the binding of H PO anion.
2
4