ISMSC 2007 - Università degli Studi di Pavia

PSB 89
Direct C-C coupling of 1,2,4-Triazin-5(2H)-ones with Benzoannelated Crown
Ethers in the Synthesis of Amino Acid's Receptors.
Nadezhda A. Itsikson , Mikhail I. Kodess , Anatoly I. Matern b , Yuri Yu. Morzherin b Oleg N.
Chupakhin a
a I. Postovsky Institute of Organic Synthesis of RAS, S.Kovalevskaya/Akademicheskaya, 22/20,
620219, Ekaterinburg,
b Urals State Technical University, Chemical Technology Faculty, Mira, 28, 620002,
Ekaterinburg, Russia
Molecular recognition of bipolar organic molecules such as amino acids is a rapidly growing
area of research due to their potential application as sensors for monitoring of biological
systems and as selective extractants.
A convenient method for one-step modification of hetarenes by different macrocyclic compound
based on the methodology of nucleophilic addition to unsubstituted carbon atom in azines has
been elaborated.1-3
For example reaction of benzocrown ether 1 with 3-Ph-1,2,4-triazin-5(2H)-one 2 results in the
coupling of two different complexating centres in the one molecule, so can be effectively applied
for design of heteroditopic receptors.
The complexating properties of obtained compounds toward amino acids have been studied by
used various methods. The results of extraction of amino acids by obtained compounds are
shown in the figure
3
This work was financially supported by the grants Russian Foundation of Basic Researches 05-
03-32094, 05-03-32085.
[1] V.N. Charushin, O.N. Chupakhin. Pure and Applied Chem., 2004, 9, 1621.
[2] G.L. Rusinov, D.G. Beresnev, N.A. Itsikson, and O.N. Chupakhin, Heterocycles, 2001, 2349.
[3] D.G. Beresnev, N. A. Itsikson, O.N. Chupakhin, V.N. Charushin, M.I. Kodess, A.I. Butakov,
G.L. Rusinov, Yu.Yu. Morzherin, A.I. Konovalov, and I.S. Antipin, J.Org.Chem., 2006; 71, 21,
8272.
PSB 90
Synthesis, Spectroscopic, Potentiometric Studies and Molecular Modeling
of a New Biomemitic Siderophore Analogue
Suban K. Sahoo, Minati Baral and B. K. Kanungo
Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal
148106, India
Siderophores are low molecular weight molecules produced by bacteria and fungi for iron
uptake, which contain either hydroxamate or catechol binding units and the complexes have six
oxygens in an octahedral sphere about the Fe(III). Among all siderophores, the catechol based
enterobactin is known to form very strong chelate with highest formation constant and its
efficiency as Fe(III) ion scavenger and carrier has stimulated the synthesis of many analogues
containing three catechol units in tripod with respect to their use in iron overload treatment and
to elucidate biological process [1]. Keeping these facts in view, two novel enterobactin
analogues: cis,cis-1,3,5-tris[(2,3-dihydroxybenzylidene)aminomethyl]cyclohexane (L 1 ) and
cis,cis-1,3,5-tris[(2,3-dihydroxybenzyl amine) aminomethyl]cyclohexane (L 2 ) (Figure 1)
containing one catechol unit in each arm of a tripodal amine, cis,cis-1,3,5tris(aminomethyl)cyclohexane
have been investigated as a chelators for iron(III) through pH
potentiometric and spectrophotometric methods in an aqueous medium of 0.1N ionic strength
and 298 K.
HO
OH
N
H
H
N
OH
OH
N
HO
HO
OH H
N
NH
OH
OH
N
H
HO
L HO
H H
H
H
1 L2 HO
N
O
OH
N
Fe
O
HO
N
O
HO
N
H
O
O
N
H
O
Fe
O
N
H
O
O
FeL1 FeL2 Figure 1. L 1 , L 2 , FeL 1 and FeL 2 .
Both the ligands form monomeric complexes of the types FeLH3, FeLH2, FeLH and FeL. Ligand
L 2 (log KML = 27.1) forms stable complex as compared to L 1 (log KML = 20.4). The step-wise
formation of complexes was explained through the results obtained from potentiometric titration
and spectrophotometric measurements, and using molecular modeling calculations. Ligand L 1
showed the potential to coordinate iron(III) through imine nitrogens and catecholic oxygens at
ortho to form a tris(iminophenolate) type complex whereas L 2 formed a tris(catecholate) type
complex (Figure 1). Molecular modeling calculations suggested that, ligand L 1 undergoes ringflipping
from most stable equatorial conformation to axial conformation during complexation
whereas no such conformational changes were depicted in L 2 .
[1] J. Neilands, J. Biol. Chem., 1997, 270, 26723.