Chromogenic anion receptors based on 4-nitrophenylhydrazone and phenylhydrazone

Article abstract of DOI:10.1007/s10847-013-0328-8

Chromogenic anion receptors based on 4-nitrophenylhydrazone and phenylhydrazone have been designed and synthesized. UV-Vis and 1H NMR titration showed that receptor 1 responded to anions according to their basicity. Although the nature of hydrogen bonds i

Full text of DOI:10.1007/s10847-013-0328-8

J Incl Phenom Macrocycl Chem
DOI 10.1007/s10847-013-0328-8
ORIGINAL ARTICLE
Chromogenic anion receptors based on 4-nitrophenylhydrazone
and phenylhydrazone
•
Yusun Choi Jongmin Kang
Received: 1 February 2013 / Accepted: 19 April 2013
Ó Springer Science+Business Media Dordrecht 2013
Abstract Chromogenic anion receptors based on 4-nitro-
phenylhydrazone and phenylhydrazone have been designed
because anions play a major role in biological, medical,
environmental, and chemical sciences [1–10].Many chemical
sensors follow the approach of the covalent attachment of
signaling subunits and binding sites [11, 12]. Chromogenic or
fluorogenic groups that are covalently linked to the receptor
moiety as signaling subunits and multiple hydrogen-bonding
interactions as binding sites have been utilized in this regard.
For binding sites, molecules containing highly polarized N–H
fragments such as ureas [13–18], thioureas [19–25],pyrroles
[26–28], and amides [29–36] have been widely used as
receptors for recognition and sensing purposes in aprotic
solvents such as CHCl3, CH3CN, and DMSO. Extreme
polarization of these groups may lead to deprotonation from
the receptor. On deprotonation, a substantial delocalization of
negative charge usually leads to drastic color changes of
solution. In consequence, naked eye detection of the anion
becomes possible [37–44]. Artificial receptors utilizing
amines [45] and C–H—anion hydrogen bonds [46–54] are
still scarce as their polarization and binding ability is usually
weak. However, theyplayan important role in nature [55–60].
As an attempt to anion receptors using only these weak
hydrogen bonds, we designed receptor 1 and 2 based on
4-nitrophenylhydrazone and phenylhydrazone. The recep-
tor 1 and 2 would bind anion utilizing one hydrazone N–H
hydrogen bond and one C–H hydrogen bond as shown in
Fig. 1. Here we would like to report the synthesis and
binding properties of receptors 1 and 2 with various anions.
1
and synthesized. UV–Vis and H NMR titration showed
that receptor 1 responded to anions according to their
basicity. Although the nature of hydrogen bonds in
hydrazone N–H and vinylic C–H is weak, receptor 1 bound
weakly basic anions such as chloride, bromide, iodide and
hydrogen sulfate utilizing only hydrogen bond in CH3CN.
No color change was observed with these anions. However,
for more basic anions such as acetate dihydrogen phos-
phate and fluoride, color change due to deprotonation
observed. Furthermore, the solution color of 1 changed to
deep blue with fluoride. Fluoride could be distinguished
from acetate and dihydrogen phosphate with naked eye.
However, phenylhydrazone based receptor 2 showed only
hydrogen bonding association with all anions investigated
except fluoride. Due to low deprotonation tendency and its
structure, color change of solution 2 was not observed.
Keywords Chromogenic anion receptor ꢀ Weak
hydrogen bonds ꢀ Deprotonation
Introduction
The design and synthesis of receptors capable of binding and
sensing anions selectively have drawn considerable attention
Electronic supplementary material The online version of this
article (doi:10.1007/s10847-013-0328-8) contains supplementary
material, which is available to authorized users.
Experimental
Synthesis and characterization
Y. Choi ꢀ J. Kang (&)
Department of Chemistry, Sejong University, Seoul 143-747,
South Korea
e-mail: kangjm@sejong.ac.kr
Receptor 1 was obtained from the reaction between
4-nitrobenzaldehyde and 4-nitrophenylhydrazine in dry
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J Incl Phenom Macrocycl Chem
R
Receptor 2
To a solution of 4-nitrobenzaldehyde (200 mg, 1.32 mmol)
in dry ethanol (13 ml) at 40 °C was added phenylhydrazine
(251 mg, 1.32 mmol) and stirred for 3 h. Filtering and
washing the precipitated solid gave the desired receptor 2
1
N
H
(187 mg) in 58 % yield. H NMR (DMSO-d6, 500 MHz)
N
H
10.87(s, 1H), 8.21(d, J = 9, 2H), 7.93(s, 1H), 7.88(d,
J = 9, 2H), 7.26(t, J = 7.5, 2H), 7.15 (d, J = 7.5, 2H),
6.83(t, J = 7.5, 1H) 13C NMR(DMSO-d6, 500 MHz)
146.00 144.42 142.59 133.58 129.21 125.99 124.3 119.91
112.54 calcd for C13H11N3O2 m/z 241.09 found for 241.04.
A_
O2N
R = NO2
1
2
= H
Results and discussion
Fig. 1 The expected binding mode of receptor 1 and 2 with anion
The receptor 1 displayed strong absorption bands at
414 nm in CH3CN. Figure 2 shows the family of spectra
obtained over the course of the titration of solution 1 with
tetrabutylammonium chloride in CH3CN. When chloride
were added to the 10 lM solution of 1, kmax of 1 is moved
to the longer wavelength slightly up to 430 nm and
intensity of absorption band at 414 nm decreased. This
result suggests that a typical hydrogen bonding complex
forms between receptor 1 and chloride. The formation of
ethanol in 60 % yield. Receptor 2 was obtained using
phenylhydrazine in 58 % yield.
Receptor 1
To a solution of 4-nitrobenzaldehyde(200 mg, 1.32 mmol)
1
hydrogen bonding could be confirmed by H NMR titra-
and
4-nitrophenylhydrazine
hydrochloride(251 mg,
tion. In CD3CN, both hydrazone N–H peak and vinylic C–H
peak moved to downfield. For example, hydrazone N–H
peak moved from 9.64 to 13.38 ppm and vinylic C–H peak
moved from 8.00 to 8.55 ppm (Fig. 3). We believe that
such measurable downfield chemical shifts of vinyl C–H
and hydrazone N–H are caused by the formation of a weak
C–HꢀꢀꢀCl- and N–HꢀꢀꢀCl- hydrogen bonds. The stoichi-
ometry between the receptor 1 and chloride was deter-
mined by Job plot using 1H NMR in CD3CN, which
showed evident 1:1 stoichiometry (Fig. 4).
1.32 mmol) in dry ethanol (12 ml) at 40 °C was added
N-ethyldiisopropylamine(227 ll, 1.32 mmol) and refluxed
for 3 h. Filtering and washing the precipitated solid gave
1
the desired receptor 1 (227 mg) in 60 % yield. H NMR
(DMSO-d6, 500 MHz) 11.64(s, 1H), 8.27(d, J = 9, 2H),
8.17(d, J = 9, 2H), 8.13(s, 1H), 7.99(d, J = 9, 2H), 7.27
(d, J = 9, 2H) 13C NMR(DMSO-d6, 500 MHz) 151.23
148.26 142.48 140.55 140.23 128.35 127.32 125.29 113.21
LRMS(ESI): calcd for C13H10N4O4 m/z 286.07 found for
286.05.
Fig. 2 Family of spectra
recorded over the course of
titration of 10 lM CH3CN
solution of the receptor 1 with
the standard solution
tetrabutylammonium chloride
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Fig. 3 1H NMR spectra
of 2 mM of 1 with increased
amounts of
tetrabutylammonium chloride
(0–16 equiv.) in CD3CN
Table 1 The association constants (M-1) of the receptor 1 with
various anions in acetonitrile
NMR
Ka
UV
Ka
Keq
Keq
-
CH3CO2
-
H2PO4
F-
6.4 9 102
6.2 9 102
6.4 9 103
6.6 9 102
6.0 9 102
7.0 9 103
Cl-
Br-
I-
3.0 9 102
6.1 9 10
9.5
3.4 9 102
4.4 9 10
9.0
-
HSO4
4.0
4.3
Fig. 4 The Job plots of 1 with tetrabutylammonium chloride and
1
tetrabutylammonium hydrogen sulfate using H NMR
1
The association constant of chloride for the receptor 1
could be calculated from Benesi–Hildebrand plot [61] in
the case of UV–Vis titration and analysis of chemical shift
receptor 1 was confirmed through H NMR titration. For
example, in CD3CN, hydrazone N–H hydrogen peak
appearing at 9.64 ppm completely disappeared with
2.8 equiv. of acetate ion (Fig. 6) and 17 equiv. of acetate ion
were required to reach saturation point. Assuming 1:1 stoi-
chiometry, the deprotonation equilibrium constant of
receptor for acetate was calculated as 6.6 9 102 from UV–
1
utilizing EQNMR [62] in the case of H NMR titration.
The association constants calculated were 3.4 9 102 from
1
UV–Vis titration and 3.0 9 102 from H NMR titration
respectively.
Vis titration and 6.4 9 102 from H NMR titration respec-
1
Almost same phenomena were observed with weakly
basic anions such as bromide, iodide and hydrogen sulfate in
titration. Despite of their weak hydrogen bonding ability,
receptor 1 bound these anions through 2 hydrogen bonds
even in polar solvent such as CH3CN. The association con-
stants of these anions simply reflect their basicity (Table 1).
However, with basic anions such as acetate, dihydrogen
phosphate and fluoride drastic spectral changes were
observed. A new intense peak was developed. For example,
when acetate was added to the 10 lM solution of the
receptor 1, kmax at 430 nm shifted slightly and a new peak at
635 nm appeared (Fig. 5a). This phenomenon indicated the
occurrence of N–H deprotonation. The deprotonation of
tively. While these anions showed similar behavior, the
deprotonation due to fluoride was faster and much less
equivalents of anion were required to reach saturation point
(Figs. 5b, 7). For example, 17 equiv. of fluoride and 2 equiv.
of fluoride were required to reach saturation point in UV–Vis
1
titration and H NMR titration respectively. Therefore, the
deprotonation equilibrium constants of these anions also
reflect their basicity (Table 1).
During experiments, it was observed that solution color
of receptor 1 changed. Therefore, the chromogenic sensing
ability of 1 was studied in CH3CN in the presence of seven
different anions such as Cl-, Br-, I-, HSO4-, CH3COO-,
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Fig. 5 Family of UV–Vis spectra recorded over the course of titration of 10 lM CH3CN solutions of the receptors 1 with the standard solution
tetrabutylammonium acetate (a) and tetrabutylammonium fluoride (b)
Fig. 6 1H NMR spectra
of 2 mM of 1 with increased
amounts
of tetrabutylammonium acetate
(0–17 equiv.) in CD3CN
Fig. 7 1H NMR spectra
of 2 mM of 1 with increased
amounts
of tetrabutylammonium fluoride
in CD3CN
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Fig. 8 UV–Vis spectra of 1
(10 lM) upon the addition of
various anions (20 equiv.) in
CH3CN
Fig. 9 The color changes of solution of 1 (a) and 2 (b) in the presence of various anions (20 equiv.) in CH3CN. The concentration of solution
was 100 lM
H2PO4 and F-. Figure 8 shows induced spectral changes
with addition of these anions. As expected, spectral chan-
ges depend on the basicity of anions. For example, weakly
basic anions such as chloride, bromide, iodide and hydro-
gen sulfate did not induce any spectral change. Therefore,
there were no color changes in the solution of receptor 1.
However, the changes of spectra were increased as the
basicity of anions increased. Figure 9a shows the color
change of the solutions of the receptors 1 upon additions of
various anions in CH3CN. It can be seen that the color
changes from yellow to green in the presence of dihydrogen
phosphate and acetate. With more basic fluoride, the color of
solution turned into green first. As more fluoride was added,
the color of solution finally turned into deep blue. When
tetrabutylammonium hydroxide ion was added to the solu-
tions of receptor 1, deep blue color was observed too.
Therefore, we believe that deprotonated receptor 1 appears
as blue color. In the case of acetate and dihydrogen phos-
phate, receptor 1 and deprotonated receptor 1 existed as a
mixture. Therefore, the solution appears as green. It is
interesting that the receptor 1 can differentiate anions
according to the basicities of anions with naked eye.
-
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Fig. 10 Family of UV–Vis spectra recorded over the course of titration of 10 lM CH3CN solutions of the receptors 2 with the standard solution
tetrabutylammonium acetate (a) and tetrabutylammonium fluoride (b)
Fig. 11 1H NMR spectra of
2 mM of 2 with increased
amounts of
tetrabutylammonium acetate
(0–22 equiv.) in CD3CN
To investigate the effect of deprotonation on the chro-
mogenic sensing ability, receptor 2 was synthesized, which
does not have nitro group. In UV–Vis titration condition, it
was found that receptor 2 formed only a hydrogen bonding
complex even with basic acetate and dihydrogen phos-
phate. For example, the receptor 2 displayed strong
absorption bands at 410 nm in CH3CN. Figure 10a shows
the family of spectra obtained over the course of the
titration of solution 2 with tetrabutylammonium acetate in
CH3CN. When acetate were added to the 10 lM solution
of 2, kmax of 2 is moved to the longer wavelength slightly
up to 420 nm. No new peak due to deprotonation was
developed. However, the deprotonation of receptor 2 was
observed in 1H NMR titration condition (2 mM). For
example, in CD3CN, hydrazone N–H hydrogen peak
appearing at 9.11 ppm completely disappeared with
22 equiv. of acetate ion (Fig. 11).
Weakly basic anions such as chloride, bromide, iodide
and hydrogen sulfate bound receptor 2 with low association
constant or did not bind at all to receptor 2. (Table 2) Only
fluoride showed a new band from deprotonation (Fig. 10b).
However, many equivalents of fluoride were needed for
deprotonation. In 1H NMR titration, the receptor 2
decomposed to unknown compounds with fluoride.
Therefore, the color of solution 2 did not change with most
of anions investigated. (Fig. 9b).
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Table 2 The association
constants (M-1) of the receptor
2 with various anions in
acetonitrile
NMR
Ka
UV
Ka
Keq
Keq
-
CH3CO2
-
H2PO4
F-
1.1 9 102
7.4 9 10
7.0 9 102
6.4 9 102
5.1 9 102
Cl-
Br-
I-
4.3 9 10
1.6 9 10
nb
9.1 9 10
3.4 9 10
nb
-
HSO4
nb
nb
nb nonbinding
8. Haryley, J.H., James, T.D., Ward, C.J.: Synthetic receptors.
J. Chem. Soc. Parkin Trans. 1(19), 3155–3184 (2000)
9. de Silva, A.P., Nimal Gunaratne, H.Q., Gunnlaugsson, T., Hux-
ley, A.J.M., McCoy, C.P., Rademacher, J.T., Rice, T.E.: Signal-
ing recognition events with fluorescent sensors and switches.
Chem. Rev. 97, 1515–1566 (1997)
10. Czarnik, A.W. (ed.): Fluorescent chemosensors for ion and
molecule recognition. American Chemical Society Books,
Washington, DC (1993)
11. Kwon, J.Y., Jang, Y.J., Kim, S.K., Lee, K.-H., Kim, J.S., Yoon,
J.: Unique hydrogen bonds between 9-anthracenyl hydrogen and
anions. Org. Chem. 69, 5155–5157 (2004)
12. Kim, S.K., Singh, N.J., Kim, S.J., Kim, H.G., Kim, J.K., Lee,
J.W., Kim, K.S., Yoon, J.: New fluorescent photoinduced electron
transfer chemosensor for the recognition of H2PO4-. Org. Lett. 5,
2083–2086 (2003)
13. Kim, Y.K., Lee, H.N., Singh, N.J., Choi, H.J., Xue, J.Y., Kim,
K.S., Yoon, J., Hyum, M.H.: Anthracene derivatives bearing
thiourea and glucopyranosyl groups for the highly selective chiral
recognition of amino acids: opposite chiral selectivities from
similar binding units. J. Org. Chem. 73, 301–304 (2008)
14. Jun, E.J., Swamy, K.M.K., Bang, H., Kim, S.-J., Yoon, J.:
Anthracene derivatives bearing thiourea group as fluoride selec-
tive fluorescent and colorimetric chemosensors. Tetrahedron Lett.
47, 3103–3106 (2006)
Conclusion
We have designed and synthesized a new chromogenic
anion receptor 1 and 2 based on 4-nitrophenylhydrazone
and phenylhydrazone structure. UV–Vis and 1H NMR
titration showed that receptor 1 respond anions according
to their basicity. Receptor 1 binds to weakly basic anions
such as chloride, bromide, iodide and hydrogen sulfate
only through hydrazone N–H and vinylic C–H hydrogen
bonds in polar solvent such as CH3CN despite of their
weak hydrogen bonding ability. However, drastic color
change occurs when receptor 1 interact with basic acetate,
dihydrogen phosphate and fluoride due to deprotonation. In
addition, receptor 1 can differentiate anions according to
the basicities of anions with naked eye. However, phen-
ylhydrazone based receptor 2 showed only hydrogen
bonding association except fluoride. The color change of
solution 2 was not observed due to low deprotonation
tendency and its structure.
Acknowledgments This research was supported by Basic Science
Research Program through the National Research Foundation of
Korea (NRF) funded by the Ministry of Education, Science and
Technology (2010-0021333).
15. Boiocchi, M., Boca, L.D., Gomez, D.E., Fabbrizzi, L., Licchelli,
M., Monzani, E.: Nature of urea-fluoride interaction: incipient
and definitive proton transfer. J. Am. Chem. Soc. 126,
16507–16514 (2004)
16. Ayling, A.J., Perez-Payan, M.N., Davis, A.P.: New ‘‘cholapod’’
anionophores; high-affinity halide receptors derived from cholic
acid. J. Am. Chem. Soc. 123, 12716–12717 (2001)
References
17. Werner, F., Schneider, H.-J.: Complexation of anions including
nucleotide anions by open-chain host compounds with amide,
urea, and aryl function. Helv. Chim. Acta 83, 465–478 (2000)
18. Snellink-Ruel, B.H.M., Antonisse, M.M.G., Engbersen, J.F.J.,
Timmerman, P., Reinhoudt, D.N.: Neutral anion receptors with
multiple urea-binding sites. Eur. J. Org. Chem. 165–170 (2000)
19. Gunnlaugsson, T., Davis, A.P., O’Brien, J.E., Glynn, M.: Syn-
thesis and photophysical evaluation of charge neutral thiourea or
urea based fluorescent PE sensors for bis-carboxylates and
pyrophosphate. Org. Biomol. Chem. 3, 48–56 (2005)
1. Xu, Z., Kim, S.K., Yoon, J.: Revisit to imidazolium receptors for
the recognition of anions: highlighted research during
2006–2009. Chem. Soc. Rev. 39, 1457–1466 (2010)
2. Haugland, R.P.: The handbook. A guide to fluorescent probes and
labeling technologies, vol. 10th ed. Molecular Probes Inc, Eugene
(2005)
3. Stibor, I. (ed.): Anion sensing. Springer, Berlin (2005)
4. Lhotak, P.: Anion receptors based on calixarenes. Top. Curr.
Chem. 255, 65–95 (2005)
20. Kim, S.K., Singh, N.J., Kim, S.J., Swamy, K.M.K., Kim, S.H.,
Lee, K.H., Kim, K.S., Yoon, J.: Anthracene derivatives bearing
two urea groups as fluorescent receptors for anions. Tetrahedron
61, 4545–4550 (2005)
21. Gunnlaugsson, T., Davis, A.P., Hussey, G.M., Tierney, J., Glynn,
M.: Design, synthesis and photophysical studies of simple fluo-
rescent anion PET sensors using charge neutral thiourea recep-
tors. Org. Biomol. Chem. 2, 1856–1863 (2004)
5. Matthews, S.E., Beer, P.D.: Calixarene-based Anion receptors.
Supramol. Chem. 17, 411–435 (2005)
6. Martinez-Manez, R., Sancenon, F.: Fluorogenic and chromogenic
chemosensors and reagents for anions. Chem. Rev. 103,
4419–4476 (2003)
7. Beer, P.D., Gale, P.A.: Anion recognition and sensing: the state
of the art and future perspectives. Angew. Chem. Int. Ed. 40,
486–516 (2001)
123

J Incl Phenom Macrocycl Chem
22. Dryfe, R.A.W., Hill, S.S., Davis, A.P., Joos, J.-B., Roberts,
E.P.L.: Electrochemical quantification of high-affinity halide
binding by a steroid-based receptor. Org. Biomol. Chem. 2,
2716–2718 (2004)
23. Benito, J.M., Gomez-Garcia, M., Blanco, J.L.J., Mellet, C.O., Fer-
nandez, J.M.G.: Carbohydrate-based receptorswith multiple thiourea
binding sites. Multi-point hydrogen bond recognition of dicarboxyl-
ates and monosaccharides. J. Org. Chem. 66, 1366–1372 (2001)
24. Buhlmann, P., Nishizawa, S., Xiao, K.P., Umezawa, Y.: Strong
hydrogen bond-mediated complexation of H2PO4- by neutral bis-
thiourea hosts. Tetrahedron 53, 1647–1654 (1997)
25. Fan, E., Van Arman, S.A., Kincaid, S., Hamilton, A.D.: Molecular
recognition: hydrogen-bonding receptors that function in highly
competitive solvents. J. Am. Chem. Soc. 115, 369–370 (1993)
26. Panda, P.K., Lee, C.-H.: Metalloporphyrin-capped calix[4]pyr-
roles: heteroditopic receptor models for anion recognition and
ligand fixation. J. Org. Chem. 70, 3148–3156 (2005)
27. Gale, P.A.: Amidopyrroles: from anion receptors to membrane
transport agents. Chem. Commun. 30, 3761–3772 (2005)
28. Sessler, J.L., Camiolo, S., Gale, P.A.: Pyrrolic and polypyrrolic
anion binding agents. Coord. Chem. Rev. 240, 17–55 (2003)
29. Bao, X., Zhou, Y.: Synthesis and recognition properties of a class
of simple colorimetric anion chemosensors containing OH and
CONH groups. Sens. Actuators B 147, 434–441 (2010)
30. Chmielewski, M.J., Jurczak, J.: Anion recognition by neutral
macrocyclic amides. Chem. Eur. J. 11, 6080–6094 (2005)
31. Kondo, S.-I., Hiraoka, Y., Kurumatani, N., Yano, Y.: Selective
recognition of dihydrogen phosphate by receptors bearing pyridyl
moieties as hydrogen bond acceptors. Chem. Commun. 13,
1720–1722 (2005)
nitrophenyl group as a signaling group. Supramol. Chem. 22,
267–273 (2010)
43. Kang, J., Jang, S.P., Kim, Y.-H., Lee, J.H., Park, E.B., Lee, H.G.,
Kim, J.H., Kim, Y., Kim, S.-J., Kim, C.: Novel receptors with
quinoline and moieties for the biologically important ions. Tet-
rahedron Lett. 51, 6658–6662 (2010)
44. Amedola, V., Esteban-Gomez, D., Fabbrizzi, L., Licchelli, M.:
What anions do to N–H containing receptors. Acc. Chem. Res.
39, 343–353 (2006)
45. Wichmann, K., Antonioli, B., Sohnel, T., Wenzel, M., Gloe, K.,
Gloe, K., Price, J.R., Lindoy, L.F., Blake, A.J., Schroder, M.:
Polyamine-based anion receptors: extraction and structural stud-
ies. Coord. Chem. Rev. 250, 2987–3003 (2006)
46. Kang, J., Lee, H.G., Han, Y., Hwang, I.J., Kim, C., Cho, S.J.: A
new anion receptor utilizing aromatic and aliphatic C–H hydro-
gen bonds. Supramol. Chem. 24(10), 738–742 (2012)
47. Kondo, S.: Anion recognition by 2,20-binaphthalene bearing imi-
dazoliumgroupsinMeCN. Supramol. Chem. 23(1–2), 29–36 (2011)
48. Garcia, F., Torres, M.R., Matesanz, E., Sanchez, L.: Open aryl
triazole receptors: planar sheets, spheres and anion binding.
Chem. Commun. 47, 5016–5018 (2011)
49. Hua, Y., Ramabhadran, R.O., Uduehi, E.O., Karty, J.A., Ragh-
avachari, K., Flood, A.H.: Aromatic and aliphatic CH hydrogen
bonds fight for chloride while competing alongside ion pairing
within triazolophanes. Chem. Eur. J. 17, 312–321 (2011)
50. Li, Y., Flood, A.H.: Pure C–H hydrogen bonding to chloride ions:
a preorganized and rigid macrocyclic receptor. Angew. Chem.
Int. Ed. 47, 2649–2652 (2008)
51. Li, Y., Flood, A.H.: Strong, size-selective, and electronically
tunable C–H—halide binding with steric control over aggregation
from synthetically modular, shape-persistent [34]triazolophanes.
J. Am. Chem. Soc. 130, 12111–12122 (2008)
32. Sessler, J.L., An, D., Cho, W.-S., Lynch, V., Marquez, M.:
Calix[n]bispyrrolylbenzenes: synthesis, characterization, and pre-
liminary anion binding studies. Chem. Eur. J. 11, 2001–2011 (2005)
33. Chellappan, K., Singh, N.J., Hwang, I.-C., Lee, J.W., Kim, K.S.:
A calix[4]imidazolium[2]pyridine as an anion receptor. Angew.
Chem. Int. Ed. 44, 2899–2903 (2005)
52. Berryman, O.B., Sather, A.C., Hay, B.P., Meisner, J.S., Johnson,
D.W.: Solution phase measurement of both weak r and C–H—
X-hydrogen bonding interactions in synthetic anion receptors.
J. Am. Chem. Soc. 130, 10895–10897 (2008)
34. Nishiyabu, R., Anzenbacher Jr, P.: Sensing of antipyretic car-
boxylates by simple chromogenic calix[4]pyrroles. J. Am. Chem.
Soc. 127, 8270–8271 (2005)
35. Kang, S.O., Linares, J.M., Powell, D., VanderVelde, D., Bow-
man-James, K.: New polyamide cryptand for anion binding.
J. Am. Chem. Soc. 125, 10152–10153 (2003)
36. Xie, H., Yi, S., Wu, S.: Study on host-guest complexation of
anions based on tri-podal naphthylthiourea derivatives. J. Chem.
Soc. Perkin Trans. 2, 2751–2754 (1999)
53. Zhu, S.S., Staats, H., Brandhorst, K., Grunenberg, J., Gruppi, F.,
Alcanale, E., Lutzen, A., Rissanen, K., Schalley, C.A.: Anion
binding to resorcinarene-based cavitands: the importance of C–H—
anion interactions. Angew. Chem. Int. Ed. 47, 788–792 (2008)
54. Yoon, J., Kim, S.K., Singh, N.J., Kim, K.S.: Imidazolium receptors
for the recognition of anions. Chem. Soc. Rev. 35, 355–360 (2006)
55. Metzger, S., Lippert, B.: A metalated guaning, cytosine base
quartet with a novel GC pairing pattern involving H(5) of C.
J. Am. Chem. Soc. 118, 12467–12468 (1996)
37. Park, J.J., Kim, Y.-H., Kim, C., Kang, J.: Fine tuning of receptors
polarity for the development of selective naked eye anion
receptor. Tetrahedron Lett. 52, 3361–3366 (2011)
38. Park, J.J., Kim, Y.-H., Kim, C., Kang, J.: Naked eye detection of
fluoride and pyrophosphate with an anion receptor utilizing
anthracene and nitrophenyl group as signaling group. Tetrahe-
dron Lett. 52, 2759–2763 (2011)
39. Kang, J., Lee, J.H., Kim, Y.H., Lee, S.K., Kim, E.Y., Lee, H.G.,
Kim, C.: Simple urea/thiourea sensors for the biologically
important ions. J. Incl. Phenom. Macrocycl. Chem. 70, 29–35
(2011)
40. Park, J.J., Kang, J.: A new colorimetric anion sensor which have
both a fat brown RR dye and a nitrophenyl group as signaling
group. Incl. Phenom. Macrocycl. Chem. 69, 57–61 (2011)
41. Dang, N.T., Park, J.J., Jang, S., Kang, J.: A naked eye detection
of fluoride with urea receptors which have both an azo group and
a nitrophenyl group as a signaling group. Bull. Korean Chem.
Soc. 31(5), 1204–1208 (2010)
56. Auffinger, P., Louise-May, S., Westof, E.: Molecular dynamics
simulations of the anticodon hairpin of tRNAAsp : structuring
effects of C–HꢀꢀꢀO hydrogen bonds and of Long-Range hydration
forces. J. Am. Chem. Soc. 118, 1181–1189 (1996)
57. Chaney, J.D., Goss, C.R., Folting, K., Santarsiero, B.D., Hol-
lingworth, M.D.: Formyl C–HꢀꢀꢀO hydrogen bonding in crystal-
line bis-formamides? J. Am. Chem. Soc. 118, 9432–9433 (1996)
58. Sharma, C.V.K., Desiraju, G.R.: C–HꢀꢀꢀO hydrogen bond patterns
in crystalline nitro compounds: studies in solid-state molecular
recognition. J. Chem. Soc. Perkin Trans. 2, 2345–2352 (1994)
59. Steiner, T., Saenger, W.: Geometry of carbon–hydrogen–oxygen
hydrogen bonds in carbohydrate crystal structures. Analysis of neu-
tron diffraction data. J. Am. Chem. Soc. 114, 10146–10154 (1992)
60. Desiraju, G.R.: The C–HꢀꢀꢀO hydrogen bond in crystals. What is
it? Acc. Chem. Res. 24, 290–296 (1991)
61. Benesi, H., Hildebrand, H.J.: A spectrophotometric investigation
of the interaction of iodine with aromatic hydrocarbons. Am.
Chem. Soc. 71, 2703–2707 (1949)
42. Kang, J., Lee, Y.J., Lee, S.K., Lee, J.H., Park, J.J., Kim, Y., Kim,
S.-J., Kim, C.: A naked-eye detection of fluoride with urea/
thiourea receptors which have both a benzophenone group and a
62. Hynes, M.J.: EQNMR: a computer program for the calculation of
stability constants from nuclear magnetic resonance chemical
shift data. J. Chem. Soc. Dalton Trans. 311–312 (1993)
123