ISMSC 2007 - Università degli Studi di Pavia

Design, synthesis and study of the first “excimer helicates”
Miguel Vázquez, a M. Eugenio Vázquez, b Clara Gómez-Reino, b Maurizio Licchelli, c Manuel R.
Bermejo a
a Departamento de Química Inorgánica, Facultad de Química, Universidad de Santiago de
Compostela, 15782 Santiago de Compostela, Spain
b Departamento de Química Orgánica, Facultad de Química, Universidad de Santiago de
Compostela, 15782 Santiago de Compostela, Spain
c Dipartimento di Chimica Generale, Università di Pavia, 27100 Pavia, Italy
There has been an increased interest in the study of metallic helicates since the discovery of
their DNA binding properties, but the nature and details of such interaction are still poorly
understood.[1] Therefore, it is of great importance the development of new analytical tools for
studying their assembly and recognition properties with DNA. Excimers are particularly useful
for the development of sensors, since their emission is sensitive to changes in the molecular
geometry and environment. This property has been extensively exploited to monitor numerous
biologically relevant recognition processes and, in our opinion, is remarkably suited to the study
of helicates and their interactions.[2]
Herein we present the first two examples of “excimer helicates”, using the bis-naphtalene
tetraamine L1 as ligand. We have found that the interaction of either M II (Zn II or Cd II ) with ligand
L1 follows 2:2 stoichiometry, with a three dimensional arrangement that brings the naphtalene
fluorophores face-to-face on each end of the ligand, promoting the formation of intramolecular
excimer species that can be applied to monitor the self-assembly process.
We strongly believe that that this new family of supramolecular architectures opens new
important perspectives for studying the interactions of helicates with DNA.
E.T.
H
N
H
N
base
H 2
N
H 2
N
acid
L 1
H
N
H2
N
H 4L 1 4+
290 nm 290 nm 475 nm
E.T.
H N
290 nm
H 2
N
NH NH
HN NH HN NH
2 M HN NH
II II M MII
310 - 360 nm
[M 2(L 1) 2] 4+
PSB 75
[1] M. J. Hannon, Chem. Soc. Rev., 2007, 36, 280.
[2] C. Guarnaccia, B. Raman, S. Zahariev, A. Simoncsits, S. Pongo, Nucleic Acids Res. 2004,
32, 4992
Synthesis and characterisation of a liquid-crystalline 2catenane and its
copper(I) complex
Etienne D. Baranoff a , Julie Voignier b , Takuma Yasuda a , Valérie Heitz b , Jean-Pierre Sauvage b ,
Takashi Kato a
a Department of Chemistry and Biotechnology School of Engineering, University of Tokyo,
Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
b Laboratoire de Chimie Organo-Minérale, Institut de Chimie de Strasbourg, Université Louis
Pasteur, 4 rue Blaise Pascal 67070 Strasbourg Cedex, France
The combination of 2catenanes and liquid crystals (LC), which are mobile and ordered
condensed states, is a new promising approach towards practical devices and molecular
machines. Indeed 2catenanes could control self-assembled behaviour of LC molecules,
whereas the LC molecular order of these mobile systems will provide them with an organized
dynamic environment. Free 2catenane 1 was obtained by double esterification of 3 with 4
mediated by EDC in 75% yield. Subsequent reaction of 1 with copper(I) led quantitatively to 2.
As expected, formation of layered self-assembled structures of smectic LC phases induced by
the incorporation of forklike dendrons 4 1
into the 2catenane 3 2 was observed. The LC
2catenane 1 and its copper(I) complex 2 form organized structures in their bulk state over
wide temperature ranges. 3
3 4
free [2]catenane 1
Copper(I) [2]catenane 2
PSB 76
[1] K. Kishimoto, M. Yoshio, T. Mukai, M. Yoshizawa, H. Ohno, T. Kato, J. Am. Chem. Soc.,
2003, 3196-3197
2 for related compounds see: J.-L. Weidmann, J.-M. Kern, J.-P. Sauvage, D. Muscat, S.
Mullins, W. Köhler, C. Rosenauer, H. J. Räder, K. Martin, Y. Geerts, Chem. Eur. J., 1999, 5,
1841-1851
3 E.D. Baranoff, J. Voignier, T. Yasuda, V. Heitz, J.-P. Sauvage, T. Kato, Angew. Chem. Int.
Ed., 2007, in press.