ISMSC 2007 - Università degli Studi di Pavia

Hierarchical self-assembly of dimeric coordination cages
Francesca Gruppi a , Marco Busi a , Enrico Dalcanale a
a Dipartimento di Chimica Organica ed Industriale, Università di Parma, Viale G.P. Usberti 17/a,
43100 Parma, Italy
Metal-directed self-assembly is a powerful tool for the construction of nanosize architectures
performing specific functions. In previous works we have studied the quantitative self-assembly
of stable organopalladium and organoplatinum coordination cages. [1, 2] The aim of the present
work is the definition of hierarchical self-assembly protocols leading to assembly of coordination
cages networks. As a first step in this direction, we have designed and synthesized tetradentate
cavitand ligand 1, presenting three cyanophenyl and one ethynylpyridine ligands. The different
affinity of cavitand 1 ligands toward Pt(II) and Pd(II) complexes has been investigated. Among
the several possibilities, the hierarchical self-assembly protocol of scheme 1 has been selected
as the most valid approach to quantitative formation of a dimeric coordination cage in solution.
4
4
N N N
O O
O O O O O O
R R R R
6 Pd(dppp)OTf 2
N
O O
Ph Ph Ph Ph
NN N N
P P
N N
NN
PdL PdL
PdL Pt
Pt PdL PdLPdL
NN N N
O O
Pt(tppb)OTf 2
R R R R
OOO
O
OOO O OO
R R R R
OO
Ph
P
O O
O O
Ph
R R R R
O OO O
N N N N
O OO O OO
R R R R
Ph
P
Ph
OO
N N N N
R
O O O OOO O O
N N
OO O OOO OO
R
Pt
Ph
Ph
P
P
R R
R R
Ph
Ph
R
NN
R
Ph
Ph
P
P
Ph
16
Pt
Ph
R
O O O OO O O O
N N
N N
OO O OO O
OO
[1] R. Pinalli, V. Cristini, V.Sottili, S. Geremia, M. Campagnolo, A. Caneschi, E. Dalcanale,
J.Am. Chem.Soc., 2004, 126, 6516 – 6517
[2] F. Fochi, P. Jacopozzi, E. Wegelius, K. Rissanen, P. Cozzini, E. Marastoni, E. Fisicaro, P.
Manini, R. Fokkens, E. Dalcanale, J. Am. Chem. Soc., 2001,123, 7539 – 7552
1
R
R R
R R
PSA 67
R
N
N
N N
R
PSA 68
Circular Polarization of Fluorescence Emitted from a Supramolecular
Complex of Achiral Conjugated Polymers and Neutral Polysaccharides
S. Haraguchi 1 , M. Numata 1 , C. Li 1 , M. Fujiki 2 , K. Sakurai 3 and S. Shinkai 1
1
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu
University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
2
Graduate School of Materials Science, Nara Institute of Science and Technology, Takayama,
Ikoma, Nara 630-0101, Japan
3
Department of Chemical Processes and Environments, Faculty of Environmental Engineering,
The University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0135,
Japan -Conjugated polymers are nowadays used as the active layer in polymer light-emitting
diodes (PLEDs). Several research groups have tried to control the linear polarization of the light
output from the device by orienting the polymer chains in the film that are acting as the active
layer. Hight degrees of linear polarization can be obtained in this way. As well as linearly
polarized light sources, circularly polarized sources also find many applications in modern
display technologies. In principle, it may be possible to construct a PLED that directly emits
circularly polarized light by introducing molecular chirality into the conjugated polymer. Due to
the break in the mirror-image symmetry, left or right circularly polarized light is then emitted and
absorbed with different probabilities. For example, by substituting poly(p-phenylene vinylene)
with chiral side chains, PLEDs were indeed found to emit circularly polarized light. However, in
such cases, dichroism (CD) and circularly polarized luminescence (CPL) in the -* transition
region has generally been observed only when the polymer is in aggregated and solid film
states, due to chiral supramacromolecular ordering resulting from intermolecular - stacking.
For this reason the emission of the aggregated phase is weaker by 1 order of magnitude than
that of the free chains. Therefore, the backbone helix structure, which does not depend on the
aggregated phase, is believed to achieve a high quantum yield of circularly polarized
luminescence. Recently, we demonstrated that supramolecular chiral insulated molecular wire
can be formed between achiral water-soluble conjugated polymers and neutral polysaccharides
(schizophyllan; SPG)(1). In the present work, we have focused on the use of this
supramolecular chiral complex as a PLED that directly emits circularly polarized light.
[1] C. Li, M. Numata, A. -H. Bae, K. Sakurai, S. Shinkai, J. Am. Chem. Soc., 127, 4548 (2005).