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J Incl Phenom Macrocycl Chem (2012) 72:221–225
Table 1 The constants (Ka) and correlation coefficients (R) of sensor
1 with various anions in DMSO
O
H
O
H
Aniona
Ka (M-)b
R^d
AcO-
HC
HC
N
N
AcO-
7.83 9 104
7.89 9 103
2.72 9 103
NDc
0.97161
0.98661
0.96512
ND
N
S
H
N
-
HN
H2PO4
F-
H
O
N
S
H
C
Cl-
Br-
I-
O
ND
ND
ND
ND
Scheme 2 The proposed host–guest binding mode in solution
a
The anion were added as their tetrabutylammonium salts at
298.2 0.1 K
Scheme 2. It was noteworthy that excess acetate ion added
results the deprotonation of sensor 1, which agreed well
with the Fabbrizzi paradigm for anion-induced urea de-
protonation process [20].
b
Ka was determined in dry DMSO
c
ND indicated that the spectra showed little or no change with the
addition of anion so that the association constants cannot be deter-
mined using the spectra
d
Correlation coefficient (R^) determined by non-linear fitting
The calculation of Ka from UV–vis titration spectra
analyses
For a complex of 1:1 stoichiometry, the constants (Ka) can
be calculated by non-linear fitting analyses of the titration
curves according to the following Eq. 1 reported before
[21], where CG and CH represent the corresponding con-
centration of the guest and host, and A is the intensity of
absorbance at certain concentration of the host and guest.
A0 represents the intensity of absorbance of host only and
Alim is the maximum intensity of absorbance of host when
guest is added. Kass is the affinity constant of host–guest
References
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ization of indolocarbazole-quinoxalines with flat rigid structure
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complexation by a family of easy-to-make ortho-phenylenedi-
amine based bis-ureas: studies in solution and the solid state. New
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ꢀ
A ¼ A0 þ ðAlim ꢂ A0Þ ꢃ CH þ CG þ 1=Kass
ꢁꢂ
h
i
1=2
2
ꢂ ðCH þ CG þ 1=KassÞ ꢂ4CHCC
2CH
ð1Þ
The non-linear curve fitting results of the absorbance of
the interaction between sensor 1 and guests were shown in
Table 1. The disassociation constants (Ka) illustrated in
Table 1 showed that Ka (AcO-) was much higher than
other anions.
7. Camiolo, S., Gale, P.A., Hursthouse, M.B., Light, M.E.: Nitro-
phenyl derivatives of 2, 5-diamidopyrroles: structural behaviour,
anion binding and colour change signaled deprotonation. Org.
Biomol. Chem. 1, 741–744 (2003)
8. Pfeffer, F.M., Lim, K.F., Sedgwick, K.J.: Indole as a scaffold for
anion recognition. Org. Biomol. Chem. 5, 1795–1799 (2007)
9. Sessler, J.L., Davis, J.M.: Sapphyrins: versatile anion binding
agents. Acc. Chem. Res. 34, 989–997 (2001)
Conclusions
10. Jose, D.A., Kumar, D.K., Kar, P., Verma, S., Ghosh, A., Ganguly,
B., Ghosh, H.N., Das, A.: Role of positional isomers on receptor-
anion binding and evidence for resonance energy transfer. Tet-
rahedron 63, 12007–12014 (2007)
11. Gunnlaugsson, T., Davis, A.P., O’Brien, J.E., Glynn, M.: Fluo-
rescent sensing of pyrophosphate and bis-carboxylates with
charge neutral PET chemosensors. Org. Lett. 4, 2449–2452
(2002)
12. Liu, S.Y., Fang, L., He, B.Y., Chan, W.H., Yeung, K.T., Cheng,
Y.K., Yang, R.H.: Cholic acid based fluorescent sensor for
dicarboxylates and acidic amino acids in aqueous solutions. Org.
Lett. 7, 5825–5828 (2005)
In conclusion, the thiourea-based sensor 1 which shows
good recognition for acetate ion has been successfully
synthesized. UV–vis spectral titration experiments showed
that the sensor formed 1:1 stoichiometric complexes with
anions in DMSO solution and it is an excellent sensor for
AcO-. Furtheremore, the proposed binding mode of sensor
1 with acetate was shown in Sheme 2 according to the
proton NMR titration experiments.
Acknowledgment This project was supported by the National
Natural Science Foundation of China (20371028 and 20671052).
13. Kim, S.K., Singh, N.J., Kim, S.J., Swamy, K.M.K., Ki, S.H., Lee,
K.H., Kim, K.S., Yoon, J.: Anthracene derivatives bearing two
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