ISMSC 2007 - Università degli Studi di Pavia

Some analytical applications of modified cyclodextrins
PSB 19
Lidia Kim a , Cristian Baltariu a , Ana Delia Stancu a , Radu-Cristian Mutihac c , Elena Diacu b , Hans-
Jürgen Buschmann c , Lucia Mutihac a
a
University of Bucharest, Department of Analytical Chemistry, 4-12 Regina Elisabeta, 030018,
Bucharest, Romania
b
University Politehnica, Faculty of Applied Chemistry and Materials Science, Polizu 1, 011061,
Bucharest, Romania,
c
Deutsches Textilforschungszentrum Nord-West, e.V., Institut an der Universität Duisburg-
Essen, Adlerstrasse 1, D-47798 Krefeld, Germany
There are studies dedicated to the molecular inclusion of biological substrates, like biogenic
amines, amino acids, and peptides by cyclodextrins [1-3]. The interactions involved in
cyclodextrin complexes (hydrogen bonding, van der Waals forces, release of conformational
strain, change–transfer, electrostatic and hydrophobic interactions) are known to play an
important role in pharmaceutical science, biochemistry, immunochemistry and also in analytical
chemistry. Thus, cyclodextrins and their derivatives form inclusion complexes with aromatic
amino acids or their oligopeptides, being well known that the aromatic amino acid residues are
responsible for interaction of proteins/peptides.
The analytical applications in extraction and transport processes of biological compounds such
as amino acids by using modified cyclodextrins are presented. In order to outline the possibility
of modified cyclodextrins acting as carriers through membrane, we have investigated some
aspects of the solvent extraction and the transport through chloroform liquid membrane of some
amino acid methylesters in the presence of picric acid or tropaeolin 00. The effects of
physicochemical parameters involved in extraction and transport processes such as the
structure of cyclodextrin, the nature of the anion used as counterion, and the structure of amino
acid have been studied. Moreover the influence of the composition and the structure of the
compounds under study upon the partition processes occurring in triphasic systems have been
reported.
[1] J.-M. Lehn, Supramolecular Chemistry, Concepts and Perspectives, VCH, Weinheim, 1995.
[2]. J. Szejtli, T. Osa, Comprehensive Supramolecular Chemistry, Elsevier, Oxford, Vol. 3,
Cyclodextrins, 1996.
[3]. H.-J. Buschmann, L. Mutihac, E. Schollmeyer, Supramol. Chem. 2005, 17, 447- 451.
PSB 20
4-(3-(Phtalhydrazide) azo)N-phenylaza-15-crown-5. Synthesis and properties
Rodica D. Baratoiu a , Radu Socoteanu a , Lucia Mutihac b , Titus Constantinescu a
a
Roumanian Academy, “Ilie G. Murgulescu” Institute of Physical Chemistry, Laboratory of
Supramolecular Chemistry and Interphase Processes, Splaiul Independentei 202, 060021,
Romania; e-mail: titelconstantinescu@yahoo.com
b
University of Bucharest, Departament of Analytical Chemistry, 4-12, Regina Elisabeta, Blvd.,
030018, Bucharest, Romania
A new compound 1 with hydrophobic properties, low acidity, and important chromogenic and
ionophoric properties due to the molecular design, has been synthesized [1].
25 24 23 22
O
21
26 O 20
27
19
O
N
28 O 29
30 31 32 33
15 14
16 13
17 18
1
12
11
9
10
N
7
N
5 4
O 6 3 O
1
N
2
N
H H
The relative hydrophobic character due to the azo-N-phenylaza-15-crown-5 moiety (compared
with N-phenylaza-15-crown-5 and 5-amino-2,3-dihydro-1,4-phtalazine-dione), has been
estimated, by determination of molecular hydrophobicity (RM0) using reverse phase thin-layer
chromatography (RP-TLC). On attempting to calculate log P values using fragmental constants
(Hansch and Leo), a relatively good correlation (R 2 =0.858) with experimental data for R M0 was
obtained. Compound 1 is a weak acid (pKa = 6.7 in water) and exhibits positive solvatochromy,
depending on the solvent polarity (ET(30), Dimroth-Reichardt’s parameters). The chromogenic
properties as function of pH were established by spectral measurements, meaning (NMR and
UV-vis), which indicate : i) in acidic medium, the quaternization by protonation of macrocyclic
nitrogen (N 19 ) atom took place (this process was put in evidence by recording the 1 H- and 13 C-
NMR spectra at different temperatures, in the presence of trifluoroacetic acid; the free energy
of the rotation barier around the double bond N 19 =C 16 that was formed, G * = 15.2 kcal mol -1 ),
respectively a significant batochromatic shift (23 nm) in UV-vis spectrum was observed; ii) in
alkaline medium, a significant hipsochromatic shift (85 nm) took place (due to the acidity of the
2,3-dihydro-1,4-phtalazine-dione moiety). The ionophoric properties of compound 1 (due to the
N-phenylaza-15-crown-5 moiety) towards Li + , Na + , K + , Rb + and Cs + ions, were investigated by
UV-vis measurements in acetonitrile and chloroform as solvents.
[1] R. D. Baratoiu, A. E. Barbu, L. Mutihac, M. T. Caproiu, C. Draghici, R. Socoteanu, T.
Constantinescu, Rev. Roum. Chim., 2006, 51, 261-267.
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