ISMSC 2007 - Università degli Studi di Pavia

Complexity from Simple Parts via Subcomponent Self-Assembly
Jonathan R. Nitschke * , Marie Hutin, David Schultz, Rupam Sarma and Victoria E. Campbell
Organic Chemistry Department, University of Geneva, 30 quai Ernest-Ansermet, CH-1211
Genève 4
Highlights of some of our work in progress, as well as a few of the topics of the first four years of
our research program, will be presented. 1 Starting with the use of the template effect to create
stable structures linked together by both covalent (C=N) and coordinative (NM) bonds 2, 3 from
mixtures of amines, aldehydes, and copper(I) ions, we have generated a variety of structures,
including a tetrametallic grid held together by the hydrophobic effect, 4 helicates, 5, 6 macrocycles
and catenates. 7 Four of these constructions are shown below.
R
N
N Cu
N
N
N
N Cu N
N
N
CuN
N
N
R
R
N
NCu
N
N
R
O
O
N N
N Cu N
N Cu N
N N
O O
O
O
H
N
N
H
N N
N Cu N
N Cu N
N N
H
N
H
N
O
O
N N
Cu
N N
N N
Cu
N N
N N
Cu
N N
The covalent imine (C=N) bonds that knit these structures together are thermodynamically
stable, but capable of exchange with free
amines. Differentials between the pKa’s
of aliphatic and aromatic amines may be
used as a driving force to effect selective
imine exchange. As shown at right,
protonated sulfanilic acid can displace
the more basic aliphatic diamine a,
which allows the deprotonated
sulfanilate to incorporate itself in place of
the diamine. If the pH of the reaction
solution is raised, however, the reaction
reverses: Deprotonated diamine a is
2 O
4 H 2N SO 3 -
N N
N Cu N
N Cu
N N
N
H3N NH3 a
N N
N Cu N
N Cu N
N N
- O3S SO 3 -
more nucleophilic than sulfanilate. Changes in pH may thus be used to switch between a closed
macrocycle and open helicate.
Current directions of our research program include the selection of specific structures from
dynamic libraries, 3, 6, 8, 9 the preparation of conducting, metal-containing polymers, and the
linking together of foldamers (in collaboration with Ivan Huc and Sijbren Otto) into assemblies
having molecular weights and levels of structural definition comparable to those of proteins.
1. J.R. Nitschke Acc. Chem. Res. 2007, 40, 103
2. J.R. Nitschke Angew. Chem. Int. Ed. 2004, 43, 3073
3. D. Schultz, J.R. Nitschke Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 11191
4. J.R. Nitschke, M. Hutin, G. Bernardinelli Angew. Chem. Int. Ed. 2004, 43, 6724
5. J.R. Nitschke, D. Schultz, G. Bernardinelli, D. Gérard J. Am. Chem. Soc. 2004, 126, 16538
6. M. Hutin, R. Franz, J.R. Nitschke Chem. Eur. J. 2006, 12, 4077
7. M. Hutin, C.A. Schalley, G. Bernardinelli, J.R. Nitschke Chem. Eur. J. 2006, 12, 4069
8. D. Schultz, J.R. Nitschke Angew. Chem. Int. Ed. 2006, 45, 2453
9. M. Hutin, G. Bernardenelli, J.R. Nitschke Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 17655
O
H2N NH2 a
O
N
Cu
N
I
O
O O
O
O
H +
2 O
+
+
O
- O3S
OH -
IL 5
SO 3 -
IL 6