Liquid crystalline metal-free phthalocyanines designed for charge and exciton transport.
A joint theoretical and experimental study of the electronic and structural properties of liquid crystalline metal-free phthalocyanines bearing a strong potential for charge and exciton transport has been performed. The synthesis of such compounds has been triggered by quantum chemical calculations showing that: (i) hole transport is favored in metal-free phthalocyanines by their extremely low reorganization energy (0.045 eV) and large electronic splittings; and (ii) the efficiency of energy transfer along the one-dimensional discotic stacks is weakly affected by rotational disorder due to the two-dimensional character of the molecules. We have synthesized two metal-free phthalocyanines with different branched aliphatic chains on the gram scale to allow for a full characterization of their solid-state properties. The two compounds self-organize in liquid crystalline mesophases, as evidenced by optical microscopy, differential scanning calorimetry, X-ray powder diffraction, and molecular dynamics simulations. They exhibit a columnar rectangular mesophase at room temperature and a columnar hexagonal mesophase at elevated temperature.
Tant
Julien
J
Laboratoire de Chimie des Polymères, Université Libre de Bruxelles, CP 206/1 Boulevard du Triomphe, B-1050 Brussels, Belgium.
Geerts
Yves Henri
YH
Lehmann
Matthias
M
De Cupere
Vinciane
V
Zucchi
Gaël
G
Laursen
Bo Wegge
BW
Bjørnholm
Thomas
T
Lemaur
Vincent
V
Marcq
Valérie
V
Burquel
Anick
A
Hennebicq
Emmanuelle
E
Gardebien
Fabrice
F
Viville
Pascal
P
Beljonne
David
D
Lazzaroni
Roberto
R
Cornil
Jérôme
J