Linear and star-shaped molecules based on p-conjugated chromophores containing a polycyclic aromatic core, with the adequate HOMO LUMO energy orbitals, have generated significant interest for use in optoelectronic devies due to their properties of isotropic absorption and strong tendency to stack into quasi-1D columns, thus generating a preferred charge transporting pathway.[1]

The majority of organic semiconductors display hole-transporting properties (p-type), with the phthalocyanines (Pcs)[2] as one of the most representative families. Donor-acceptor systems formed by electron-rich groups conjugated with electron-poor moieties that can organize themselves into columns are good candidates to show ambipolar behavior. For this reason, the fussion of p-type phthalocyanines with some other n-transporting materials might give rise to different grade of conjugation between both systems affording potential candidates for ambipolar character. The synthesis of this type of systems has been scarcely described to date due to the difficulties to synthetize phthalocyanines with the adequate substituents for the condensation with acceptor moieties.

Herein, we will emphasize the progress in the chemistry of donor-acceptor conjugated Pcs-acceptor arrays (Figure 1)[3] with particular attention being focused on systems that exhibit attractive electronic, optical and electrochemical properties, thus allowing them to be considered as promising candidates for future applications such as NIR dyes, photovoltaic dyes, nonlinear optical materials and nano-electronic devices.

Acknowledgements. This work has been supported by the Spanish Ministerio de Economía y Competitividad, Generalitat Valenciana and the European FEDER funds (grants CTQ2011-26455, CTQ2014-55798-R, PROMETEO 2012/010 and ISIC/2012/008)

References:

(1)    (a) Forrest, S. R. Nature, 2004, 428, 911. (b) Shirota, Y.; Kageyama. H. Chem. Rev. 2007, 107, 953.

(2)    (a) de la Torre, G.; Claessens, C. G.; Torres, T. Chem. Commun. 2007, 2000. (b) Martin-Gomis, L.; Fernández-Lázaro, F.; Sastre-Santos, A. J. Mater. Chem. A 2014, 2 15672.

(3)    (a) Blas-Ferrando, V. M.; Ortiz, J.; Campos, V.M.; Mas-Torrent, M.; Fernandez-Lázaro, F.; Sastre-Santos, Á.; submitted. (b) Follana-Berná, J, Inan, D.; Blas-Ferrando, V. M.; Gorczak, N.; Fernández-Lázaro, F.; Grozema, F.; Sastre-Santos, Á. in preparation.

Figure 1. Chemical structure of different conjugated phthalocyanine-acceptors arrays