Transcript CALIX[n]ARENES

2nd Pak-Turk Seminar on
Chemical Science (2nd PTSCS )
Azocalixarene Chemistry
A Presentation
by
Dr. HASALETTİN DELİGÖZ
Department of Chemistry
Pamukkale University, Denizli/Turkey
PAKİSTAN, Feb 2010
1
Where is Denizli?
ANKARA
Capital
ISTANBUL
2010 European
Cultural Capital
DENİZLİ
2
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Calixarene
Calix = Basket/Vaze, Arene = Aromatic
The name comprises, macrocyclic compounds made from
phenolic aromatic rings linked by methylene sub-units.
OH
OH HO
OH
HO
OH
OH
OH
OH OH
HO
OH
Calix[4]arene
* Gutsche, C. D.; Muthukrishnan, R., J. Org. Chem., 43, 4905 (1978)
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CALIX[n]ARENES
The chemistry of calixnarenes n = 4 - 8 is well represented
in the literature due to the easieness of their synthesis.
OH
OH
OH HO
OH
OH
OH
HO
HO
OH
calix[6]arene
calix[4]arene
OHHO
OH
HO
OH
HO
OHHO
calix[8]arene
*C.D. Gutsche, Calixarenes; J.F. Stoddart (Ed.), Royal Society of Chemistry, Cambridge, 7(1989)
Calixarenes, which are accessible by the base-catalyzed
condensation
of
para-substituted
phenols
with
formaldehyde, are ideal frameworks for the development
of chromogenic ionophores in the molecular recognition
of ionic species of chemical and biological interest since
the incorporation of a suitable sensory group into the
calixarene result in a tailored chromogenic receptor.
OH
O
H
HO
OH OH
NaOH
C
+
R
OH
H
R
R
R = tert-butyl
*C.D. Gutsche, Prog. Macrocyclic Chem., 3, 93, (1987).
R
R
8
History of the Calixarenes
Adolph von Baeyer 1872 (Germany, University of Munich)
He synthesized a solid and resin-like product from
phenol-formaldehyde reactions.
9
Leo Hendrick Baekeland 1907 (Belgium)
He obtained a phenol-formaldehyde resin, which is
called as bakelite.
10
Alois Zinke 1940’s (Austria, University of Graz)
He obtained first cyclic compounds by reducing the chainextenting of phenol-formaldehyde resins.
11
?
?
?
Nothing has been remarkably made for 30 years.
12
David Gutsche 1970’s (USA, University of Washington)
Finally he developed methods for synthesis each of
the three major cyclic oligomers.
13
Calix[n]arenes are readily converted into a wide
range of derivatives by the alkylation of the phenolic
groups at the lower rim.
This type of chemical modification is first
introduced by Gutsche as part of conformational studies in
calix[n]arenes, since then this has been widely used by
several research groups to produce pendant ether,
carboxylate, ester, amide, phosphine,
vic-dioxime and ketone derivatives.
*C.D. Gutsche, Calixarenes Revisited, Royal Society of Chem., Cambridge, UK, (1998)
14
R
R
R = SO3H
R = NO2
OH
4
OH
R= CH2CH2NH2
R=CH2CH2CN
R= CHO
4 R= CH=NOH
R= CH3
p-Claisen Rearrangement
Electrophilic Substitution
R= H
CH2R
4
OH
p-Chloromethylation
H
CH2Nu
Upper rim
4
t
OH
R= C6H5
Nu = CN
Nu =OCH3
Nu = N3
4 Nu = H
OH
Bu
Dealkylation
p-Quinone-methide Method
4
OH
Lower rim
R= CH2COR
But
R= CH2COOR
But
4
4
OR
R= COCH3
R= COC6H5
OR
R= CH2COONH2
R= Me
Williamson Ether Synthesis
Esterification
*Z. Asfari, V. Böhmer, J. Harrowfield and J. Vicens (Eds.), Calixarenes 2001, Kluwer
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Academic Publishers, Dortrecht, The Netherlands, (2001)
Formation of azocalixarene structures
Azocalixarenes, which are generated by the insertion of a
conjugated chromophore azo (-N=N-) group into the p- position
unit of the calixarene structure, have several isomers based
on the position of the nitrogen atoms and the ring size.
R
R
R
R
N
N
N N
N N
N
N
OH OH
HO
OH
CH3 CH2 CH2 CH2
b) R =
N
N
a) R =
d) R =
N
CH3 C NH
N
N
N N
N
N
N
O
NH S
S
S
N
N
S
O
c) R =
N
N
N S
S
OH
OH OH
HO
O
2
*H. Deligöz and E. Erdem, Sol. Extr. Ion Exch., 15, 811, (1997)
3
16
Azocalixarenes were synthesized in “one-pot” procedures in
satisfactory yields.
R
R
R
R
R
N
N
N
N
N
N
N
N
NaNO2, conc. HCl
OH OH OH HO
MeOH-DMF
NH2
OH OH
HO
As a general procedure, p- substituted azocalix[n]arenes are
obtained by the diazo-coupling reaction in the following
manner. At first, the calix[n]arene is prepared by the
debutylation of p-tert-butylcalix[n]arene.
*H. Deligöz and N. Ercan, Tetrahedron, 58, 2881, (2002)
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Another recent work
in this field, the
synthetic
route
to
bisazocalix[4]arenes is
illustrated in Scheme.
i
OH
OH
OH
HO
OH
OH
HO
OH
ii
R=
In order to introduce
O
functional groups into
iii
each azo group one
must choose a reaction
N=N
N=N
R'
with a quantitatively
high yield, because the
isolation of a fullyR'=
R'=
R'=
substituted
product
from lower-substituted
18
19
20
by products is fairly Scheme The synthetic route for three novel bisazocalix
difficult.
[4]arene derivatives i) AlCl3/Toluene, ii) PhCOCl,
C
OR
OR
OH
OR
OR
OR
OR
OR
HO
OR
RO
OH
NO2
O2N
Pyridine, iii) NaNO2/conc.HCl, NH2-R’-NH2
*T. Tilki, İ. Şener, F. Karcı, A. Gülce and H. Deligöz, Tetrahedron, 61, 9624, (2005) 18
Synthesis, structures, and characterization
We have tried the development of a new class of
chromoionophore dyes. Designed calix[4]arenes contain both
an aniline moiety as an electron-donating or electronwithdrawing group and an azophenol moiety to provide color.
Another study the calixarene is
composed of a ring of six
phenolic
units
used
as
molecular substructures, such
as the six azo groups in C6
symmetry are assembled to
provide the required structure.
R
a) R= o-Cl
b) R= m-Cl
c) R= p-Cl
d) R= o-NO2
e) R= m-NO2
f) R= p-NO2
N
N
OH
g) R= o-CH3
h) R= m-CH3
i) R= p-CH3
j) R= m-OCH3
k) R= p-OCH3
l) R= H
6
22
*F. Karcı, I. Şener and H. Deligöz, Dyes and Pigments, 62, 131, (2004)
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Azocalix[n]arenes based on heterocyclic amines have been
developed, and the resultant azocalixarene have been
higher tinctorial strength and give brighter dyeing than
those derived from aniline-based diazo components.
N
N
Het
N
N
d)
=
CH3
Het
N
N
N
N
N
b)
N
e)
Het =
Het =
N
H
HO
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c)
NH
Het =
N
N
S
N
OH OH
OH
O
Het =
Cl
S
N
N
Het
a) Het
Het
SCH3
N
f)
Het =
S
N
SH
Azocalixarenes containing calix[n]aren as coupling
components have also been described as having from
blue to violet various publications.
*I. Şener, F. Karcı, E. Kılıç and H. Deligöz, Dyes and Pigments, 62, 141, (2004)
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Recently, our previous experience has been forwarded us to
synthesize azocalix[6]arenes (24a-g) and their hetarylazo
derivatives by substituting different rings on lower rim and
to investigated both the effect of varying pH and solvent
upon the absorption ability of hetarylazocalix[6]arenes.
N
N
e)
a) Het =
Het
S
N
N
N
CH3
N
f)
b) Het =
S
N
OH
24
6
N
g) Het =
Het =
N
H
N
Het =
Cl
S
c)
O
Het =
S
N
SH
N
d)
NH
Het =
N
SCH3
*I. Şener, F. Karcı, E. Kılıç and H. Deligöz, Dyes and Pigments, 62, 149, (2004).
21
- In comparison of UV spectra, it is found that all of
the spectra show a strong absorption maximum in the 285298 nm range with high extinction coefficients. It can be
seen that azocalix4arene gives two absorption bands
(π – π* and n – π* transitions).
- In the IR spectra, the streching vibrations of the
azocalix4arenes appear at 3300-3200 cm-1 (–OH),
3100-3000 cm-1 (arom. –C–C–),
2950-2900 cm-1 (aliph. –C–H),
1700-1650 cm-1 (arom. –C=C–)
and 1600-1500 cm-1 (–N=N–)
for azocalixnarene, approximately.
22
- The 1H NMR data showed that all azocalix4arenes (23a) exist
in a cone conformation due to the appearence of ArCH2Ar as a
typical AB protons signal at 3.2-4.8 ppm. The lower field signals
of the hydroxyl group of the azocalix4arenes resonate at ca. 9.011.0 ppm, approximately and these are typical for intramolecular
hydrogen bonding protons.
Figure: 1H NMR spectrum of 6-(chlorobenzothiazolylazo)calix[4]arene (23a)
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The azocalix[4]arenes (21) may exist in two possible
tautomeric forms, azo-enol and keto-hydrazo.
N
N
H
N
N
N
HO
(A)
azo-enol
N
N
H
N
N
H
N
N
N
H
O
OH OH
OH
N
N
N
N
O
O
O
(B)
keto-hydrazo
Figure: The tautomeric forms of 4-(phenylazo)calix[4]arene (21)
*F. Karcı, I. Şener and H. Deligöz, Dyes and Pigments, 59, 53, (2003)
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Complexation of azocalixarenes with metals
Four azocalix4arenes (30a-d) have been synthesized from
p-tert-butylphenol, p-nitrophenol, p-aminobenzoic acid and
1-amino-2-hydroxy-4-napthalenesulphonic acid by diazo
coupling reactions with p-aminocalix4arene.
R
R
R
N
N
N
R
N
N
NH2
OH
c)
a)
N
N
N
COOH
OH
b)
OH
OH
OH
HO
NH2
d)
NO2
HO
SO3H
30
*M.S. Ak and H. Deligöz, J. Incl. Phenom., 59, 115, (2007)
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The resulting ligands are treated as three transition metal
salts (e.g., CuCl2.2H2O, NiCl2.6H2O or CoCl2.6H2O). Cu(II), Ni(II) and
Co(II) complexes of the azocalix4arene derivatives were
obtained and characterized.
N=N
O
R
M
O
R
. x H2O
N=N
R :
Figure :
N
O
--NH--S-S
O
Square-planar Cu(II) and Ni(II) Complexes of 29b.
For M = Cu, x = 2; for M = Ni, x = 1.
All the complexes have a metal:ligand ratio of 1:2.
26
The electronic spectra of the complexes exhibits intense chargetransfer bands around 314-394 nm, but weak d-d transitions are
observed only for the Cu(II), Ni(II) and Co(II) complexes
with 30a at 538, 527, 529 nm,
with 30b at 550, 417, 407 nm,
with 30c at 438, 606, 608 nm and
with 30d at 450, 517, 603 nm, respectively.
NO2
NO2
NO2
O2N
OH
HO
OH
N
N
N
HO
N
N
N
OH
OH
N
OH
N
HO
Figure : Absorption spectra of azocalix4arene 30b and their complexes in CHCl3.
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(i) Cu2+, (ii) Ni2+ and (iii) Co2+
Consequently, both a square-planar structure for the
Cu(II) and Ni(II) complexes of azocalix4arenes and an
octahedral structure with water molecules as axial ligands
for the Co(II) complexes of azocalix4arenes is proposed
as shown in Figure.
M: Cu, Ni
Figure : Structures of azocalix[4]arene-metal complexes.
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Extraction of metals with azocalixarenes
Liquid-liquid extraction of various transition metal cations
with azocalix4arenes 30a-d from the aqueous phase into
the organic phase was carried out.
Table 1. Extractions of metal picrates with ligandsa
Picrate salt extracted (%)
Ligands
Ag+
Hg+
Hg2+
Co2+
Ni2+
Cu2+
Cd2+
Zn2+
Al3+
Cr3+
La3+
30a
66.7
79.0
91.0
11.7
10.9
6.5
9.0
6.0
4.0
11.2
6.0
30b
67.0
69.0
57.1
7.7
10.1
5.7
6.9
2.6
1.2
17.8
5.3
30c
73.0
81.2
65.7
23.4
16.7
8.9
11.4
38.7
3.2
21.8
7.9
30d
-
8.6
9.3
-
-
-
-
-
-
-
-
a: H2O/CHCl3 = 10/10 (v/v) : Aqueous phase, [metal nitrate]=10-2 M; [picric acid]=2x10-5 M;
organic phase, chloroform [ligand] = 1x10-3 M; 25 ºC for 1 h.
*M.S. Ak and H. Deligöz, J. Incl. Phenom., 59, 115, (2007)
29
Extraction efficiencies of the azocalix4arenes 30a-d have
been carried out by the two phase solvent extraction of
transition metal picrates (Ag+, Hg+, Hg2+, Co2+, Ni2+, Cu2+, Cd2+, Zn2+,
Al3+, Cr3+ and La3+) into chloroform under neutral conditions.
The results are summarized in Figure.
Extraction (%)
100
80
30d
60
30c
30b
30a
40
20
0
Zn2+
Cu2+
Ni2+
Co2+
Hg2+
Hg+
Ag+
Figure : Extraction percentage of the metal picrates with azocalix4arenes.
30
The above phenomena can be explained by the hard - soft
acid – base (HSAB) principle as follows; the azocalix4arenes
30a,b contain electron-donating and electron-withdrawing
groups, respectively. Azocalix4arene 30a containing
electron-donating groups (tert-butyl) is a harder base and
prefers the Hg2+ cation (91.0%). Azocalix4arene 30b
containing electron-withdrawing groups (–NO2) is a softer
base and prefers the Hg+ cation (69%).
R
R
R
N
N
N
R
N
N
NH2
OH
c)
a)
N
N
N
COOH
OH
d)
b)
OH
OH
OH
HO
NH2
NO2
HO
SO3H
30
31
Compound 2c is a harder
base and prefers Hg2+
cation, compound 2d is a
softer base and prefers Hg+
cation.
R
R
R
R
N
N
N N
OH OH
HO
N N
N
N
OH
CH3 CH2 CH2 CH2
b) R =
N
N
a) R =
S
O
c) R =
d) R =
N
N
CH3 C NH
N
O
NH S
S
O
2
Compound 16a containing
electron-donating group is a
harder base and prefers the
Hg2+ cation. Compound 16b
containing
electron-with
drawing group is a softer base
and prefers the Hg+ cation.
32
N
Absorption properties of azocalixarenes
Strong evidence for the existence of these compounds in an
equilibrium is provided by the isosbestic points in the visible
spectra of compound 21j in different solvents (Figure). This
equilibrium may exist between tautomeric forms. The
equilibrium depends on the basicity of the solvents used.
2.000
1:DMSO
2:DMF
3:Acetonitrile
4:Methanol
5:Acetic acid
6:Chloroform
5
4
1.500
Ab s o r b an ce
3
1
6
OMe
OMe
1.000
MeO
OMe
2
N
0.500
N
N
N
N N
0.000
N N
OH
300
400
500
Wavelength/nm
600
700
OH OH
HO
21j
Figure : Absorption spectra of azocalixarene 21j in various solvents.
*F. Karcı, I. Şener and H. Deligöz, Dyes and Pigments, 59, 53, (2003).
33
Thermal behaviours of azocalixarenes
Thermal behaviours of two parents calix[4]arene (1, 2) and
three azocalix[4]arene derivatives (3,4,5) containing upper rim
functionalized groups such as n-butyl, phenylazo and heterocyclic
thiazol are investigated by means of thermogravimetry (TG) and
differential thermal analysis (DTA).
34
*H. Deligöz, Ö. Özen, G. Koyundereli and H. Çetişli, Thermochimica Acta, 426, 33, 2005
Decomposition of azocalixarenes have three steps.
Firstly, H2O was released from the lattice compounds. The
first peak was occurred endothermic.
Secondly, DMF was released from the lattice compounds
and this step was occurred endothermic, too.
Lastly, the biggest decomposition were occurred. For
complexes residues products are Fe2O3 but ligands did
not any residue product, all of them decomposed.
In another work, in order to extend the calixarene
complexing reactions to Fe3+, we concentrate on complexation
between calix[n]arenes (n= 4, 6, 8) and Fe3+ , in an attempt to
understand the important properties of calix[n]arene-Fe3+
complexes.
The TG and DTA curves of parent calix[4]arenes and their complexes 1, 2 in nitrogen atmosphere.
* H.Deligöz, Ö. Özen and G.K. Çılgı, J. Coord. Chem., 60, 73, 2007
36
CONCLUSION
- In summary, we can say that in these phase transfer
experiments the effectiveness of azocalixarenes for transfering the
metal cations is reflected by the soft –donor systems and intra
cavity complexation.
- The important features of azo functions are related to the
electronic structures of possesing lone pair electrons and vacant 3d
electrons, suggesting the binding ability of azocalix[n]arenes to
metal ions.
- Solvent extraction study has shown that azocalix[4]arenes can
extract transition metal ions.
- Conventional calix[4]arenes cannot extract them at all,
substantiating that the bridging azo plays some important roles in
37
the recognition of metal ions.
- The chemistry of azocalix[4]arene has just been started, its
ready availability in substantial quantities and the presence of
azo moiety instead of methylene would surely give this new
member of the calix family azo unlimited applications in quite
near future.
- The goal of these work is to condition a new chromogenic
azocalix[n]arene molecule to elaborate an ion selective electrode
(ISE) able to detect to this type of pollutant.
- The feasible of extractants based on chromogenic
azocalix[4]arene molecules for heavy metal ion detection was
shown.
- The azocalixarenes are rather selective for Ag+, Hg+, Hg2+,
but these compounds are an excellent extractant for all metals.
38
THANKS
Prof. Mustafa Yılmaz (Superviser)
Prof. Halil Çetişli
(Collaboration)
Assit.Prof. İzzet Şener (Collaborations)
Research Assit. Özlem Özen Karakuş (PhD Students)
And
Prof. Muhammed Iqbal Bahangen (Chief Org)
Prof. Shahabuddin Memon (My brother)
…. And your audience
39