1 Azocalixarene Chemistry Department of Chemistry Pamukkale University, Denizli/Turkey A Presentation by Dr. HASALETTİN DELİGÖZ PAKİSTAN, Feb 2010 2 nd.

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Azocalixarene ChemistryAzocalixarene Chemistry

Department of ChemistryPamukkale University, Denizli/Turkey

A Presentationby

Dr. HASALETTİN DELİGÖZ

PAKİSTAN, Feb 2010

2nd Pak-Turk Seminar on Chemical Science (2nd PTSCS )

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Where is Where is Denizli?Denizli?

ANKARA Capital

ISTANBUL 2010 European

Cultural Capital

DENİZLİ

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PAMUKKALE UNIVERSITY FacultiesMedicine, Sciences-Arts, Economic-Administrative, Education, Engineering,Physical Cure

InstitutesSciencesSocialHealth

Number of Staffs : 2,200 (academic staff, teaching and research assistants)

Number of Students:31,500

Scientific research performance of Pamukkale University Turkey TUBITAK 3.

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LLABORATORIES, LIBRARIESABORATORIES, LIBRARIESAND COMPUTING SERVICESAND COMPUTING SERVICES

M. Sc : 7 (finished)

Ph D : 1 (Continued)

Articles : 45 Cited : 570

Projects :Tübitak:6 Üniversity:10

CALİX LABORATORY

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CalixareneCalixarene Calix = Basket/Vaze, Arene = Aromatic

The name comprises, macrocyclic compounds made from phenolic aromatic rings linked by methylene

sub-units.

OHOH OH

OH

OHOH OHOH

OHOH

OHOH

Calix[4]arene

* Gutsche, C. D.; Muthukrishnan, R., J. Org. Chem., 43, 4905 (1978)

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OH OH

OH

OH

OHOH

OH

OH

OH

OH

OH OH

OHOH

OH

OH OH

OH

calix[4]arene

calix[8]arene

calix[6]arene

CALIX[n]ARENESCALIX[n]ARENESThe chemistry of calixnarenes n = 4 - 8 is well represented in the literature due to the easieness of their synthesis.

*C.D. Gutsche, Calixarenes; J.F. Stoddart (Ed.), Royal Society of Chemistry, Cambridge, (1989)

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OHOH

OHOH

R

OH

NaOH

O

C

H H

R = te rt-butyl

RR

R

R

+

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.

*C.D. Gutsche, Prog. Macrocyclic Chem., 3, 93, (1987).

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History of the Calixarenes

He synthesized a solid and resin-like product

from phenol-formaldehyde reactions.

Adolph von Baeyer 1872 (Germany, University of Munich)

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Leo Hendrick Baekeland 1907 (Belgium)

He obtained a phenol-formaldehyde resin, which is called as bakelite.

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Alois Zinke 1940’s (Austria, University of Graz)

He obtained first cyclic compounds by reducing the chain-

extenting of phenol-formaldehyde resins.

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Nothing has been remarkably made for 30 years.

? ? ?

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Finally he developed methods for synthesis each of

the three major cyclic oligomers.

David Gutsche 1970’s (USA, University of Washington)

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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)

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OH

R

4

OH

Bu

4

OH

CH2R

4OH

R

4

OH

CH2Nu

4OH

H

4

OR

Bu

4

Bu

4OR

p-Claisen Rearrangement

R=R=R=R=

CH2CH2NH2

CH2CH2CNCHOCH=NOH

t

Upper rim

Lower rim

t

t

p-ChloromethylationElectrophilic Substitution

Dealkylation

Williamson Ether Synthesis

p-Quinone-methide Method

R=

R=

R=

H

CH3

C6H5

CNOCH3N3H

CH2COR

CH2COOR

CH2COONH2

Nu =Nu =Nu =Nu =

R=

R=

R=

R= Me

Esterification

R= COCH3

R= COC6H5

R = SO3HR = NO2

*Z. Asfari, V. Böhmer, J. Harrowfield and J. Vicens (Eds.), Calixarenes 2001, Kluwer Academic Publishers, Dortrecht, The Netherlands, (2001)

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Formation of azocalixarene structuresAzocalixarenes, 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.

OHOH

OHOH

NN

NNN

NNN

R

R R

R CH3 CH2 CH2 CH2

N N

CH3 C

O

NH

S

NNH S

O

O

N

SN

S

NSNS

OHOH

OHOH

NN

NNN

NN

N

a) R =

b) R =

c) R =

d) R =

2 3

*H. Deligöz and E. Erdem, Sol. Extr. Ion Exch., 15, 811, (1997)

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OH HO

N

N

N

N

OHOHOH HOOH NH2

NaNO2, conc. HCl

MeOH-DMF

R

R R

N

N

R

N

N

R

Azocalixarenes were synthesized in “one-pot” procedures in satisfactory yields.

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.

In order to introduce functional groups into each azo group one must choose a reaction with a quantitatively high yield, because the isolation of a fully-substituted product from lower-substituted by products is fairly difficult.

OHOH

OH

OH

OHOH

OH

OH

OROH

OR

OR

N=N

ORRO

OR

OH

N=NR'

R'=

NO2

O2N

OR

OROR

OH

ii

iii

C

O

R'= R'=

R=

i

18 19 20

Scheme The synthetic route for three novel bisazocalix [4]arene derivatives i) AlCl3/Toluene, ii) PhCOCl, Pyridine, iii) NaNO2/conc.HCl, NH2-R’-NH2

*T. Tilki, İ. Şener, F. Karcı, A. Gülce and H. Deligöz, Tetrahedron, 61, 9624, (2005)

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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 electron-withdrawing 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.

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*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.

Het Het

Het Het

OHOH

OHOH

NN

NN N

NN

N

N

S Cl

NH

N

N

SCH3

ON

CH3

NN

S

NN

S SH

N

NH

Het =

Het =

Het =

Het =

Het =

a)

b)

c)

d)

e)

f)

Het =

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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.

Het

OH

N

N

N

S

N

S Cl

NH

N

N

SCH3

ON

CH3

NN

S

NN

S SH

N

NH

6

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Het =

Het =

Het =

Het =

Het =

Het =

a)

b)

c)

e)

f)

g) Het =

d)

*I. Şener, F. Karcı, E. Kılıç and H. Deligöz, Dyes and Pigments, 62, 149, (2004).

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- In comparison of UV spectra, it is found that all of the spectra show a strong absorption maximum in the 285-298 nm range with high extinction coefficients. It can be seen that azocalix4arene gives two absorption bands (π – π* and n – π* transitions).- In the IR spectra, the streching vibrations of the azocalix4arenes 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 azocalixnarene, approximately.

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- The 1H NMR data showed that all azocalix4arenes (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 azocalix4arenes resonate at ca. 9.0-11.0 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.

OHOH

OHOH

NN

NN N

NN

N

N

N

O

O

N

O

N

O

N

N N

NH

H H

H

(A)(B)

azo-enol 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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Four azocalix4arenes (30a-d) have been synthesized from p-tert-butylphenol, p-nitrophenol, p-aminobenzoic acid and 1-amino-2-hydroxy-4-napthalenesulphonic acid by diazocoupling reactions with p-aminocalix4arene.

Complexation of azocalixarenes with metals

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*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 azocalix4arene derivatives were obtained and characterized.

R :

O

OS

N--NH--S--

O

N=NR

MO

N=N R

. x H2O

Figure : 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.

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The electronic spectra of the complexes exhibits intense charge-transfer 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.

Figure : Absorption spectra of azocalix4arene 30b and their complexes in CHCl3.

(i) Cu2+, (ii) Ni2+ and (iii) Co2+

OHOH HOOH

N

N

N

NN N

N N

OH HO OH

HOO2N

NO2 NO2

NO2

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Consequently, both a square-planar structure for the Cu(II) and Ni(II) complexes of azocalix4arenes and an octahedral structure with water molecules as axial ligands for the Co(II) complexes of azocalix4arenes is proposed as shown in Figure.

M: Cu, Ni

Figure : Structures of azocalix[4]arene-metal complexes.

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Ligands

Picrate salt extracted (%)

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 - - - - - - - -

Table 1. Extractions of metal picrates with ligandsa

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.

Extraction of metals with azocalixarenes Liquid-liquid extraction of various transition metal cations with azocalix4arenes 30a-d from the aqueous phase into the organic phase was carried out.

*M.S. Ak and H. Deligöz, J. Incl. Phenom., 59, 115, (2007)

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Extraction efficiencies of the azocalix4arenes 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.

0

20

40

60

80

100

Zn2+ Cu2+ Ni2+ Co2+ Hg2+ Hg+ Ag+

Ex

tra

cti

on

(%

)

30d

30c

30b

30a

Figure : Extraction percentage of the metal picrates with azocalix4arenes.

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The above phenomena can be explained by the hard - soft acid – base (HSAB) principle as follows; the azocalix4arenes 30a,b contain electron-donating and electron-withdrawing groups, respectively. Azocalix4arene 30a containing electron-donating groups (tert-butyl) is a harder base and prefers the Hg2+ cation (91.0%). Azocalix4arene 30b containing electron-withdrawing groups (–NO2) is a softer base and prefers the Hg+ cation (69%).

30

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Compound 2c is a harder base and prefers Hg2+ cation, compound 2d is a softer base and prefers Hg+ cation.

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.

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Absorption properties of azocalixarenesStrong 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.

1

2

3

1 :D M S O2:D M F3:A ceton itrile4 :M e th an o l 5 :6 :C h lo ro fo rm

A cetic ac id

30 0 40 0 50 0 60 0 70 0

2 .00 0

1 .50 0

1 .00 0

0 .50 0

0 .00 0

A b

s o

r b

a n

c e 6

4

5

W av elen g th /nm

Figure : Absorption spectra of azocalixarene 21j in various solvents.

21j

*F. Karcı, I. Şener and H. Deligöz, Dyes and Pigments, 59, 53, (2003).

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Thermal behaviours of azocalixarenesThermal 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).

*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.

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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

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- 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.

- Conventional calix[4]arenes cannot extract them at all, substantiating that the bridging azo plays some important roles in the recognition of metal ions.

- Solvent extraction study has shown that azocalix[4]arenes can extract transition metal ions.

CONCLUSION

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- 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 feasible of extractants based on chromogenic azocalix[4]arene molecules for heavy metal ion detection was shown.

- 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 azocalixarenes are rather selective for Ag+, Hg+, Hg2+, but these compounds are an excellent extractant for all metals.

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THANKSTHANKSProf. 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