Novel redox receptors for ion-pair and α-amino acid: Synthesis and complexation properties of calix[4]arene derivatives bearing large conjugated ferrocene groups

Article abstract of DOI:10.1007/s10847-011-9959-9

By reacting calix[4]arene 1,3-bi-hydrazide derivative (2) with formacylferrocene in " 1 + 2" condensation mode, novel calix[4]arene derivative bearing two conjugated ferrocene groups (3) was obtained in yield of 88%. By reacting 1,3-bi-substituted [2-(p-f

Full text of DOI:10.1007/s10847-011-9959-9

J Incl Phenom Macrocycl Chem (2012) 72:183–188
DOI 10.1007/s10847-011-9959-9
ORIGINAL ARTICLE
Novel redox receptors for ion-pair and a-amino acid: synthesis
and complexation properties of calix[4]arene derivatives bearing
large conjugated ferrocene groups
Fafu Yang
Hongyu Guo
•
Zhiqiang Liu
•
Biqiong Hong
•
Received: 4 September 2010 / Accepted: 5 April 2011 / Published online: 24 April 2011
Ó Springer Science+Business Media B.V. 2011
Abstract By reacting calix[4]arene 1,3-bi-hydrazide
derivative (2) with formacylferrocene in ‘‘1 ? 2’’ condensa-
tion mode, novel calix[4]arene derivative bearing two con-
jugated ferrocene groups (3) was obtained in yield of 88%.
By reacting 1,3-bi-substituted [2-(p-formylphenyloxy)ethyl-
chemistry and electrochemistry [1–3]. In recent years,
some researches focused on using calixarenes as building
block to construct the redox-active calixarene derivatives
[4–8]. To reach this aim, some ferrocene-functioned
calixarenes were synthesized and their electrochemical
recognitions for guests were studied. For examples, Beer
et al. reported series of ferrocene-functioned calixarenes [9,
10]. Tomapatanaget and Tuntulani [11, 12] synthesized a
ferrocene-amide calixarenes with recognition for carbox-
ylic anions. Guo et al. [13] found a ferrocene-based thi-
acalix[4]arene ditopic receptor for europium(III) and
dihydrogenphosphate ion. Cheng and coworkers [14] dis-
covered redox anion receptors based on calix[4]pyrrole
bearing ferrocene amide. Moon and Kaifer [15] prepared a
dimmer of calix[4]arene bearing four ferrocene-urea
groups. Lately, Shaabani and Shaghaghi [16] observed a
ferrocene amine-substituted calix[4]arene derivative with
electrochemical response to lanthanides lately. In most
cases, ferrocenes were introduced into calixarene platform
by amide bond, ester bond, urea bond, carbonyl bond, and
the redox-active response for guests was greatly influenced
by the characteristic and structure of the linking groups.
Recently, the ion pairs and amino acids recognition were
attracted much attention due to their potential application in
ion probe, ion controlled sensor, biological systemic mimic,
etc. The receptors containing two recognition sites, one for
cation and one for anion, possess complexation abilities for
ion pairs or zwitterionic amino acids. For examples, Vicens
and coworkers [17] found a tripodal aza crown ether
calix[4]arenes with binding abilities for ion pairs. Haino and
coworkers [18] studied the energetics of ion pairs binding to
calix[4]arene molecular containers. Sirit and coworkers [19]
reported a chiral calix[4]azacrowns with recognition for
amino acid derivatives. Jaffrezic-Renault and coworkers
[20] investigated calix[4]arene based molecules for amino
0
oxy]-p-tert-butylcalix[4]arene (5) with 1,1 -diacetylferro-
cene hydrazone (4) in ‘‘1 ? 1’’ condensation mode, novel
calix[4]arene derivative with 1,3-substituted large conjugated
ferrocene bridge (6) was synthesized in yield of 83%. The
structures and conformations of new compounds were con-
1
firmed by elemental analyses, IR spectra, ESI-MS, H NMR,
etc. The electrochemical cyclic voltammetry experiments
revealed that compounds 3 and 6 possessed excellent revers-
1
ible electrochemical properties. The H NMR titration study
showed that compound 6 possessed excellent complexation
abilities for NaH PO and glycine in 1:1 host–guest complex
2
4
-
1
with the association constants of 3,850 and 2,460 M
respectively.
,
Keywords Calix[4]arene ꢀ Ferrocene ꢀ Complexation ꢀ
Redox ꢀ Ion pair ꢀ Amino acid
Introduction
Supramolecular electrochemical recognition plays impor-
tant role in the research field of both supramolecular
F. Yang (&) ꢀ Z. Liu ꢀ B. Hong ꢀ H. Guo
College of Chemistry and Materials, Fujian Normal University,
Fuzhou 350007, People’s Republic of China
e-mail: yangfafu@fjnu.edu.cn
F. Yang
Fujian Key Laboratory of Polymer Materials, Fuzhou
3
50007, People’s Republic of China
123

1
84
J Incl Phenom Macrocycl Chem (2012) 72:183–188
acid detection. Lately, Ohto and coworkers [21] reported the
adsorption of amino acid derivatives on calixarene impreg-
nated resins. However, to the best of our knowledge, no
redox calixarene receptor for ion-pair or zwitterionic
a-amino acid was studied up to now, although some calixa-
rene derivatives with binding abilities for ion pairs or amino
acids were reported.
(s, 4H, ArH), 7.13 (s, 4H, ArH), 7.55 (s, 2H, CH), 8.20 (s,
?
2H, OH), 11.26 (s, 2H, NH); MS m/z (%): 1207.8 (MNa ,
100). Anal. calcd for C H O N Fe : C 70.92, H 6.80; N
7
0
80
6
4
2
4.72; found C 70.81, H 6.94; N 4.56.
Synthesis of calix[4]arene derivative with 1,3-
substituted large conjugated ferrocene bridge (6)
In this present work, two novel calix[4]arene derivatives
bearing large conjugated ferrocene groups has been
designed and synthesized. The electrochemical investiga-
tion revealed that they are excellent redox receptors with
reversible cyclic voltammetry curves, which were reported
for the first time in calixarene-ferrocene chemistry. The
calix[4]arene derivative bearing bridging-large conjugated
ferrocene group (6) possessed excellent complexation
abilities to NaH PO and glycine, which were confirmed by
The mixture of compound 4 (0.5 mmol) and 5 (0.5 mol) in
80 mL of CHCl /methanol (V:V = 1:1) was stirred and
3
refluxed. TLC detection indicated the disappearance of
materials in 10 h. The solvent was evaporated. Then
10 mL methanol was added and stored in refrigerator
overnight. The precipitation was formed and separated.
After vacuum drying, compound 3 was obtained as red
-
2
4
1
1
powder in 83% yield. m.p. 238–240 °C; IR (KBr, cm ):
the method of H NMR titration study.
1
1
606 (C=N); H NMR (400 MHz, CDCl ) dppm: 1.08 [s,
3
1
8H, C(CH ) ], 1.30 [s, 18H, C(CH ) ], 2.52 (bs, 6H,
3
3
3 3
CH ), 3.39 (d, 4H, J = 12.8 Hz, ArCH Ar), 4.39 (d, 4H,
3
2
Experimental
J = 12.8 Hz, ArCH Ar), 4.36–5.01 (m, 16H, OCH and
2
2
FeH), 6.89 (d, 4H, J = 8.0 Hz, ArH), 6.96 (s, 4H, ArH),
7.03 (bs, 4H, ArH), 7.54 (d, 4H, J = 8.0 Hz, ArH), 7.87 (s,
1
H NMR spectra were recorded in CDCl on a Bruker-
3
?
H, CH), 8.55 (s, 2H, OH); MS m/z (%): 1229.4 (MNa ,
ARX 400 instrument, using TMS as reference. ESI-MS
spectra were obtained from DECAX-30000 LCQ Deca XP
mass spectrometer. The electrochemical experiments were
carried out using a CHI 600A electrochemical apparatus.
Elemental analyses were performed at Vario EL III Ele-
mental Analyzer. IR spectra were recorded on a Thermo
Nicollet AVATAR 5700 FTIR spectrometer using KBr
2
1
4
00). Anal. calcd for C H O N Fe: C 75.64, H 7.18; N
76 86 6 4
.64; found C 75.57, H 7.25; N 4.48.
Electrochemical studies
-
1
0
The electrochemical experiments were carried out using a
CHI 600A electrochemical apparatus in in dry CH Cl /
pellets in spectral range 4,000–400 cm . 1,1 -Diacetyl-
2
2
ferrocene hydrazone (4) were prepared by condensation of
0
MeCN (V:V = 1:4) with n-Bu NPF (0.1 mol/L) as the
4 6
1
,1 -diacetylferrocene with hydrazine hydrate according to
supporting electrolyte at room temperature. A standard
three-electrode cell consists of platinum electrode as
working electrode, a platinum wire as counter electrode,
the published procedures. Calix[4]arene bi-hydrazide
derivative (2) and calix[4]arene bi-aldehyde derivative (5)
were synthesized by our published procedure [22, 23]. All
solvents were purified by standard procedures.
?
and 0.01 mol/L Ag /Ag as reference electrode. The scan-
ning speed was 0.1 V/s. The ferrocenium/ferrocene redox
couple was taken as the internal standard. All sample
-
solutions were 1 9 10 mol/L.
3
Synthesis of calix[4]arene derivative bearing two
conjugated ferrocene groups (3)
1
The mixture of compound 2 (0.5 mmol) and formacylfer-
rocene (1.0 mol) in 20 mL of CHCl /methanol (V:V = 1:1)
H NMR titration experiments
3
was stirred and refluxed. TLC detection indicated the dis-
appearance of materials in 4 h. The solvent was evapo-
rated. Then 10 mL methanol was added and stored in
refrigerator overnight. The precipitation was formed and
separated. After vacuum drying, compound 6 was obtained
as amaranthine powder in 88% yield. m.p. 253–256 °C; IR
Solutions of compound 6 (0.01 M) and guests (0.01 M)
, NaH
including n-Bu
were prepared in DMSO-d
NH
PO
, NaPF
PO and glycine
2 4
4
2
4
6
solutions. Typically, to
6
0.20 mL of solution of compound 6 in NMR tube was
added corresponding equiv. of guest. In each NMR tube,
the amount of DMSO-d was then adjusted to the same
6
-
1
1
(
KBr, cm ): 1691 (C=O), 1606 (C=N); H NMR
quantity. The chemical shift of the OH and CH on the
receptor was monitored at 30 °C. The program EQNMR
was then used to analyze the resulting titration curves and
(
400 MHz, CDCl ) dppm: 1.01 [s, 18H, C(CH ) ], 1.26
3
3 3
[
s, 18H, C(CH ) ], 3.51 (bd, 4H, J = 12.8 Hz, ArCH Ar),
3 3 2
-
1
4
.01–5.01 (m, 26H, OCH , ArCH Ar and FeH), 6.92
2
to calculate stability constant values in M [24].
2
1
23

J Incl Phenom Macrocycl Chem (2012) 72:183–188
Results and discussion
185
calixarene derivatives were synthesized by introducing fer-
rocene unit on calixarene platform with amide bond, ester
bond, urea bond, carbonyl bond, however, compounds 3 and
Syntheses, structures and conformations
6
were the first examples of ferrocene-substituted calix[4]-
0
The synthetic routes were showed in Scheme 1. 1,1 -
arene derivatives with Schiff-base bond and possessed a
large p-electron conjugated system, which were favorable
for conducting new electronic effect for redox-active.
Moreover, the binding cavities of compounds 3 and 6 could
be regarded as two binding sites. One site was composed of
ethoxy groups and another site was composed of conjugated
Schiff-base groups, which were similar to the structures of a
calix[4]crown with ion-pair sites [14]. Thus, it was possible
that compounds 3 and 6 could bind cations and anions con-
currently, such as for ion-pairs and zwitterionic a-amino
acids.
Diacetylferrocene hydrazone (4) were prepared by conden-
0
sation of 1,1 -diacetylferrocene with hydrazine hydrate
according to the published procedures. Calix[4]arene bi-
hydrazide derivative (2) and calix[4]arene bi-aldehyde
derivative (5) were synthesized by our published procedure
[
22, 23]. By condensation of calix[4]arene bi-hydrazide
derivative (2) and formacylferrocene in CHCl /MeOH (1:1,
3
V/V) system, novel 1,3-substituted ferroceneacylhydrazone
calix[4]arene derivative (3) was prepared in yield of 88%. On
the other hand, by refluxing compound 4 with 5 in CHCl3/
MeOH (1:1, V/V) for 10 h under diluted condition, the
novel ferrocene-substituted calix[4]arene derivative 6 was
obtained in ‘‘1 ? 1’’ condensation mode after recrystalli-
All new compounds were characterized by elemental
1
analyses, IR spectra, ESI-MS spectra and H NMR spectra.
In the IR spectra, the disappearance of absorption peaks at
-
1,694 cm (aldehyde groups) and the emergence of strong
1
zation with CHCl /MeOH in yield of 83%. Both compounds
3
-
1
3 and 6 were obtained conveniently by precipitation in
methanol in high yields. It was pity that we failed to
peaks at 1,606 cm (C=N groups) indicated the complete
accomplish of condensation reaction. The ESI-MS spectra
of compounds 3 and 6 showed clearly molecular ion peak
0
accomplish the condensation of compound 2 with 1,1 -
diacetylferrocene in all kinds of system or using acetic acid
?
?
at 1207.8 (MNa ) and 1229.4(MNa ), respectively. In the
1
H NMR spectra, compounds 3 and 6 showed two singlets
etc. as catalyst. Although some ferrocene-substituted
t-Bu
t
-Bu Bu-
t
Bu-t
t-Bu
t
-Bu Bu-
t
Bu-
t
t-Bu
t
-Bu Bu-
t
Bu-t
Fe
HO OH O
NH -NH
O
2
2
CHO
HO OH
O
O
HO OH
O
O
HN
N
O
NH
N
O
HN
O
NH
O
EtO
O
OEt
O
NH2
NH2
HC
HC
1
Fe
Fe
2
3
t
-Bu Bu-
t
Bu-t
Fe
Fe
t-Bu
AlCl3
NH NH
2
2
Fe
CH COCl
3
CH3
H C
3
CH3
H C
3
N
N
O
O
NH2
NH2
4
O
HO OH
O
O
CH OH
3
t
-Bu
t
-Bu Bu-
t
Bu-
t
O
CHCl3
Bu-
t
OHC
O
OTs
HO OH
O
O
HC
HC
N
O
O
N
N
K CO / CH CN
2
3
3
4
CH3
H C
3
N
OH
6
Fe
CHO
5
CHO
Scheme 1
123

1
86
J Incl Phenom Macrocycl Chem (2012) 72:183–188
(
1:1) for the tert-butyl groups, one pair of doublets (1:1) for
0.000006
the methylene bridges of the calix[4]arene skeleton. All the
spectral data were in accordance with the assigned struc-
tures and certainly indicated that the calix[4]arene units
adopt the cone conformation as showed in Scheme 1 [22,
0.000004
0
0
.000002
.000000
2
3].
Electrochemical studies
-0.000002
-
-
0.000004
0.000006
The electrochemical properties of receptors 3 and 6 were
investigated by method of cyclic voltammetry (CV) at
room temperature. Cyclic voltammetry (CV) was per-
-
3
formed using solutions of 3 and 6 (1 9 10 mol/L) pre-
pared in dry CH Cl /MeCN (V:V = 1:4) with n-Bu NPF
6
-0.000008
-0.2
0.0
0.2
0.4
0.6
2
2
4
potential/V
(
0.1 mol/L) as the supporting electrolyte. A standard three-
electrode cell consists of platinum electrode as working
2 2
Fig. 2 Cyclic voltammogram of compound 6 (1 mM) in CH Cl /
electrode, a platinum wire as counter electrode, and
?
.01 mol/L Ag /Ag as reference electrode. Cyclic vol-
MeCN (V:V = 1:4) containing n-Bu
electrolyte; scan rate = 100 mV/s
4 6
NPF (0.1 M) as supporting
0
tammograms of 3 and 6 showed reversible redox couples of
ferrocene/ferrocenium at E1/2 = 215 and 286 mV, respec-
tively, as shown in Figs. 1 and 2. The observation of only
one redox wave for iron centers in compound 3 indicated
no interaction between the ferrocene units.
1
H NMR titration study
1
The H NMR titrations were employed to study the com-
1
plexation properties in DMSO-d at 30 °C. The H NMR
6
titration of host 6 for NaH PO and glycine were carried
2
4
out as representative complexation experiments. Figure 3
showed that, in the solution of host 6 with 1.0 equiv.
n-BuN H PO , the shifts of OH and CH moved from 8.55
4
2
4
and 7.87 to 9.12 and 8.03, respectively. Moreover, the
shifts of OH and CH moved further to 9.50 and 8.11 in the
0
0
0
.00002
.00001
.00000
1
Fig. 3 H NMR spectra of compound 6 in DMSO-d
6
solution on
PO ? 1.0
addition of 1.0 equiv. n-BuN
equiv. NaPF and 1.0 equiv. glycine, respectively
4 2
H PO
4
, 1.0 equiv. n-BuN
4
H
2
4
6
-
-
-
0.00001
0.00002
0.00003
solution of host 6 with 1.0 equiv. n-BuN H PO and 1.0
4
4
2
equiv. NaPF . These results indicated that the presence of
6
?
Na increased the binding ability of receptor 6 towards
-
H PO . On the other hand, the shifts of OH and CH
2
4
-
0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
moved to 9.21 and 8.10 in the solution of host 6 with 1.0
equiv. glycine, which indicated the host 6 also exhibited
excellent complexation ability for zwitterionic a-amino
V
Fig. 1 Cyclic voltammogram of compound 3 (1 mM) in CH
MeCN (V:V = 1:4) containing n-Bu
electrolyte; scan rate = 100 mV/s
2
Cl
2
/
acid. The plots between the mole ratios of NaH PO or
2
4
NPF
6
(0.1 M) as supporting
4
glycine: 6 and the OH chemical shift of host 6 were
1
23

J Incl Phenom Macrocycl Chem (2012) 72:183–188
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9
9
9
9
8
8
8
.6
.4
.2
.0
.8
.6
.4
4
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2
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7
8
9
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-
1
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1
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-
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1
1
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1
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2
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