ISMSC 2007 - Università degli Studi di Pavia

PSB 81
Tripodal polyamines as anion receptors: Extraction and structural studies
Marco Wenzel 1,2 , Bianca Antonioli 1 , Kerstin Gloe 1 , Karsten Gloe 1 , Maria G. Sanchez 1 , Gert
Bernhard 2 , David J. Bray 3 , Jack K. Clegg 3 , Leonard F. Lindoy 3
1 Department of Chemistry, TU Dresden,01062 Dresden, Germany
2 Institute of Radiochemistry, Research Centre Dresden-Rossendorf, 01314 Dresden, Germany
3 School of Chemistry, University of Sydney, NSW 2006, Australia
Tripodal polyamines based on the tris(2-aminoethyl)amine (tren) platform are useful complexing
agents for cations or anions depending on the pH of the solution.[1,2] The binding properties of
such compounds can be tuned by the addition of aromatic binding groups to the molecule.
A series of different substituted tren (1-4) derivatives were synthesised and characterised. Here
we present some recent solvent extraction and liquid membrane transport results that show a
gradation in anion binding behaviour along I - , Cl - , Br - , CrO4 2- , SO4 2- and PO4 3- . Finally, structural
aspects of the anion complexes formed will be discussed, with the X-ray structure of the
bromide complex of ligand 3 being presented.
R
1
2
3
4
NH
R =
R =
R =
R =
N
NH
NH
R
R
OCH 3
OC 10H 21
X-ray structure of [H33][Br3]·Br -
[1] A.G. Blackman, Polyhedron, 2005, 24, 1-39
[2] K. Wichmann, B. Antonioli, T. Söhnel, M. Wenzel, K. Gloe, K. Gloe, J.R. Price, L. F. Lindoy,
A.J. Blake, M. Schröder, Coord. Chem. Rev., 2006, 250, 2987-3003
Carbohydrate Dynamic Combinatorial Libraries for Quadruplex DNA
Recognition
Jean-Luc Wietor, Anthony Bugaut, Katja Jantos, Shankar Balasubramanian, Jeremy K. M.
Sanders
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK CB2 1EW.
E-mail: jlw48@cam.ac.uk
A Dynamic Combinatorial Library (DCL) [1] made from small building blocks can change its
composition upon introduction of a template molecule, with increases in the concentration of
successful template-binding library members. Disulfides, obtained from the oxidation of thiols,
are often used to provide a stable yet exchangeable bond between building blocks.
We use this concept to probe the affinity of carbohydrates to quadruplex-DNA [2], a biomolecule
that plays central roles in cell ageing processes, expression of oncogenes and cancer. The
selective binding of quadruplex DNA over duplex DNA or of one particular quadruplex
conformation or sequence remains a major goal in this area.
We present a system based on a quadruplex-binding macrocycle [3], several simple
carbohydrate building blocks and glutathione, a thiol-containing tripeptide which acts as a
disulfide exchange mediator. Upon addition of the quadruplex template, we observed an
increase of macrocycle-carbohydrate species at the expense of other library members (Figure
1).
O
Quadruplex
O
O
G
G Template
G
G
O
Building blocks:
O
O
DCL
G
O
G
O
Amplification
carbohydrate macrocycle G glutathione
Figure 1: Schematic of a DCL and amplification of successful quadruplex binders.
This system allowed us (a) to demonstrate the specific attractive interactions between
quadruplex DNA and neutral carbohydrates and (b) to probe effects of carbohydrate size and
anomeric isomerism on binding strength.
[1] P. T. Corbett, J. Leclaire, L. Vial, K. R. West, J.-L. Wietor, J. K. M. Sanders and S. Otto,
Chem. Rev., 2006, 106, 3652-3711
[2] S. Burge, G. N. Parkinson, P. Hazel, A. K. Todd and S. Neidle, Nucleic Acids Res., 2006, 34,
5402-5415
[3] K. Jantos, R. Rodriguez, S. Ladame, P. S. Shirude and S. Balasubramanian, J. Am. Chem.
Soc., 2006, 128, 13662-13663
O
G
G
PSB 82