ISMSC 2007 - Università degli Studi di Pavia

PSA 1
Efficient synthesis of pseudopeptidic macrocycles through anion templation
Ignacio Alfonso, Miriam Bru, M. Isabel Burguete, Santiago V. Luis, Jennifer Rubio
Departamento de Química Inorgánica y Orgánica, UAMOA, Universidad Jaume I, Campus del
Riu Sec, Avenida Sos Bainat, s/n, E-12071, Castellón (Spain).
The development of synthetic methods for macrocyclization reactions allows the preparation of
new receptors and biologically interesting molecules.[1] Usually, these processes are hampered
by low yields and tedious purification steps, as mixtures of compounds are often obtained.
Templated synthesis is an attractive alternative for controlling the selectivity and efficiency of
those processes.[2] In spite of the increasing interest on anion coordination chemistry, anion
templation approach to this problem is still in its infancy.[3] Taking advantage of the experience
gained, we designed an anion templated procedure for the selective preparation of a family of
pseudopeptidic macrocycles which would be difficult to obtain by more conventional
methodologies. Besides, the anion templation effect has been thoroughly studied using different
experimental (NMR, ESI-MS, CD, UV) and theoretical (molecular modeling) approaches.[4]
O O
NH HN
R R
NH2 H2N
+
CHO
CHO
O
O
N
H
NH
R
NH 2
R
O
N
NH
NH
N
O
R
N
R
CHO
O
R
O
N
HN
HN
N
O
R
R
N
H
NH
N
O
N
R
R
NH HN
O O
N
N N
R R
O
N
H
HN
N
R
O
O
O
NH
R
N
H
NH HN
R
O O
N N
R
N
H H
N
R
R
N
H H
N
R
N N
O O
[1] (a) B. Dietrich, P. Viout, J.-M. Lehn, Macrocyclic Chemistry, VCH, New York, 1993. (b) D.
Parker, Macrocycle Synthesis: A Practical Approach, Oxford University Press, New York, 1996.
(c) F. Vögtle, Cyclophane Chemistry, Wiley, Chichester, 1993.
[2] Z. R. Laughrey, B. C. Giba, Top. Curr. Chem. 2005, 249, 67-125.
[3] R. Vilar, Angew. Chem. Int. Ed. 2003, 42, 1460-1477.
[4] M. Bru, I. Alfonso, M. I. Burguete, S. V. Luis, Angew. Chem. Int. Ed. 2006, 45, 6155-6159.
N
H
H
N
R
R
HN
HN
O
O
PSA 2
Synthesis and Solid State Structure of a Double Calix[6]arene Nanotube
Arturo Arduini a , Giovanni Faimani a , Andrea Pochini a , Andrea Secchi a , Franco Ugozzoli b , Chiara
Massera b
a Dipartimento di Chimica Organica e Industriale dell’Università, Viale G. P. Usberti 17/a, I-
43100, Parma, Italy
b Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica
dell’Università, Viale G. P. Usberti 17/a, I-43100, Parma, Italy
The functioning of new molecular devices, able to perform programmed tasks, derive from the
chemical properties and the spatial orientation of the fragments or components that constitute
their skeleton. In the phase of the design of these systems, very convenient guidelines are
provided by the principles of supramolecular chemistry, especially in those cases where these
devices originate from self-assembly processes, should respond to external stimuli and function
as molecular machines. [1]
With the aim to synthesize new molecular devices, designed to perform specific functions, we
have showed that the three-phenylureido calix[6]arene (I) can act as three-dimensional
heteropolytopic receptor. It can be threaded selectively from the upper rim by suitable axles
derived from the 4,4’bipyridyl and yields oriented pseudorotaxanes endowed with high
thermodynamic stability. These supramolecular complexes can be reversibly decomposed
through electrochemical stimuli and can be stoppered to yield oriented rotaxanes that differ for
the orientation of the two calixarene rims with respect to the different stoppers. [2]
1.65 nm
NH
HN
O
NH
HN
O
O MeO
MeO O OMe O
O
O
O
I
HN
HN
O
O N 2 NO2 NO2
O MeO
MeO O OMe O
O
NH
HN
NH
O
NH
HN
O
NH
O MeO
MeO O OMe O
O
O
O
II
These findings prompted us to explore the possibility to exploit the calix[6]arene platform for the
construction of tubular molecules in view of their use as oriented molecular pores or channels.
Herewith we describe the synthesis of a double calix[6]arene derivative (II) obtained from the
head to tail linkage of two calix[6]arene sub-units together with the solid state structure of its
pseudorotaxene with dioctylbipyridinium tosylate.
(1) V. Balzani, M. Venturi, A. Credi Molecular Devices and Machines, A Journey into the
Nanoworld Wiley-VCH, Weinheim (2003).
(2) a) A. Arduini, F. Ciesa, M. Fragassi, A. Pochini, A. Secchi Angew. Chem. Int. Ed. 2005 44,
278. b) A. Credi, S. Dumas, S. Silvi, M. Venturi, A. Arduini, A. Pochini, A. Secchi J. Org.
Chem. 2004, 69, 5881.
2.30 nm