Photoalignment and Surface-Relief-Grating Formation are Efficiently Combined in Low-Molecular-Weight Halogen-Bonded Complexes
Advanced Materials, 2012, 24, OP345?OP352
A. Priimagi, M. Saccone, G. Cavallo, A. Shishido, T. Pilati, P. Metrangolo, G. Resnati
Halogen bonding drives the self-assembly of the azobenzene 1 and the stilbazole 2 into the dimeric supramolecular complex 3. A weak hydrogen bond involving the methoxyl oxygen atom and a methyl hydrogen of the dimethylanilino group promotes the self-assembly of these dimers into highly undulating infinite polar chains. The colors are as follows: C, gray; H, light gray; N, sky blue; O, red; F, yellowish green; I, magenta.
Halogen bonding drives the self-assembly of the azobenzene 1 and the stilbazole 2 into the dimeric supramolecular complex 3. A weak hydrogen bond involving the methoxyl oxygen atom and a methyl hydrogen of the dimethylanilino group promotes the self-assembly of these dimers into highly undulating infinite polar chains. The colors are as follows: C, gray; H, light gray; N, sky blue; O, red; F, yellowish green; I, magenta.
ABSTRACT
It is demonstrated that halogen bonding can be used to construct low-molecular-weight supramolecular complexes with unique light-responsive properties. In particular, halogen bonding drives the formation of a photoresponsive liquid-crystalline complex between a non-mesogenic halogen bond-donor molecule incorporating an azo group, and a non-mesogenic alkoxystilbazole moiety, acting as a halogen bond-acceptor. Upon irradiation with polarized light, the complex exhibits a high degree of photoinduced anisotropy (order parameter of molecular alignment > 0.5). Moreover, efficient photoinduced surface-relief-grating (SRG) formation occurs upon irradiation with a light interference pattern, with a surface-modulation depth 2.4 times the initial film thickness. This is the first report on a halogen-bonded photoresponsive low-molecular-weight complex, which furthermore combines a high degree of photoalignment and extremely efficient SRG formation in a unique way. This study highlights the potential of halogen bonding as a new tool for the rational design of high-performance photoresponsive suprastructures.