ISMSC 2007 - Università degli Studi di Pavia

PSB 71
Synthesis and preliminary molecular recognition studies of novel protonionizable
crown ethers containing a diarylphosphinic acid moiety
Péter Huszthy a,b , Tünde Tóth b , György Székely a , Viktor Farkas c , Miklós Hollósi c
a Department of Organic Chemistry and Technology, Budapest University of Technology and
Economics, H-1111 Budapest, Szent Gellért tér 4, Hungary
b Research Group for Alkaloid Chemistry of Hungarian Academy of Sciences, H-1111
Budapest, Szent Gellért tér 4, Hungary
c Department of Organic Chemistry, Eötvös Lóránd University, H-1117 Budapest, Pázmány
Péter sétány I/A, Hungary
Proton-ionizable crown ethers having a pH switching mechanism have attracted the attantion of
many researchers, because at pH values higher than their pKa, they are mostly ionized to ligand
anions, which increase the cation-ligand complex stability with enhancement of selectivity, and
avoid the need for a counter anion is in transport through various membrane systems or in
solvent extraction [1, 2].
R
* O O
O
P
OH
O O
O
R = H, alkyl group
Figure
*
R
Starting from commercially available and
relatively cheap starting materials novel
enantiopure proton-ionizable crown ethers
(Figure, R=alkyl) and their achiral parent
compound (Figure, R=H) containing the
diarylphosphinic moiety were synthetized by
multistep reactions.
The molecular recognition studies on these
novel proton-ionizable ligands including
enantioselective complexation with the
enantiomers of chiral primary amines using CD
spectroscopy are in progress.
Financial support of the National Scientific Research Fund of Hungary (OTKA: K 62654) is
greatfully acknowledged.
[1] C. W. McDaniel, J. S. Bradshaw and R. M. Izatt, Heterocycles, 1990, 30, 665-706.
[2] R. A. Bartsch, ACS Sympos. Series, 1999, 716, 146-155. (Chem. Abstr. 1999, 130, 201386.)
Cyclen based dimers as tridimentional receptors for polyphosphate
recognition.
Raphaël Tripier, Stephanie Develay, Michel Le Baccon, Guy Serratrice and Henri Handel
PSB 72
UMR CNRS 6521, “Chimie, Electrochimie Moléculaire et Analytique”, Université de Bretagne
Occidentale, C. S. 93837, 6 avenue Victor Le Gorgeu, 29238 Brest Cedex 3, France. Tel: 33 2
98017927; Fax: 33 2 98017001; E-Mail: Raphael.tripier@univ-brest.fr
There is a growing interest in the molecular recognition of anionic species because of their
potential applications in environmental, industrial and health-related areas. Phosphate type
anions are ubiquitous as well in human activity effluents as in biological structures.
Polyprotonated macrocycles behave as efficient receptors for polycharged anions in aqueous
solutions; they strongly associate to nucleotides via electrostatic interactions between the
cationic binding sites (ammonium groups) of the receptor and the negatively charged
polyphosphate chain.
We recently reported a facile synthesis of
cyclen based dimers (bis-macrocycles and
macrotricycles) using the efficient bisaminal
tool that allowed us to get
tetraazacycloalkanes dimers in high
overall yields. These ligands which include
eight amino groups and rigid phenyl or
pyridinyl spacer(s) are potentially good
receptors for inorganic anions or
nucleotides.
The host-guest interaction between orthophosphate, pyrophosphate and triphosphate anions
and these tridimentional ligands possessing ortho-, meta-, para-xylenyl or 2,6-pyridinyl linkers
was investigated by potentiometric measurements and NMR spectroscopy. 1 Each ligand gave in
aqueous solution protonated species that further formed ternary complexes after binding with
anions; the structure of these complexes were analyzed as a result of hydrogen bond formation
and coulombic attraction between the organic host and the inorganic guest.
The results unambiguously showed the importance of the protonation degree, the rigidity of the
ligand and underlined, especially for the triphosphate species, the contribution of the nitrogen
atom of the pyridinyl spacer as supplementary anchoring point in acidic medium. The
equilibrium constants found for all the detected species will be reported and the selectivity will
be discussed.
[1] S. Develay, R. Tripier, M. Le Baccon , V. Patinec, G. Serratrice, H. Handel, Dalton Trans.
2005, 3016; S. Develay, R. Tripier, M. Le Baccon , V. Patinec, G. Serratrice, H. Handel,
Dalton Trans. 2006, 3418; S. Develay, R. Tripier, N. Bernier, M. Le Baccon, V. Patinec, G.
Serratrice, H. Handel, Dalton Trans. 2007, 1038-1046.