Paper
Journal of Materials Chemistry C
exhibited liquid crystalline behaviour. M-XX presented hexag-
onal columnar mesomorphism whereas rectangular columnar
mesophases were observed for M-XA complexes. In any case, the
mesomorphic organization remains at room temperature and is
frozen below the glass transition in the M-XX complexes.
All of the complexes bearing chiral tails derived from citro-
nellol showed optical activity in the mesophase. For azobenzene
containing complexes, the possibility of switching reversibly the
supramolecular chirality of the material was demonstrated
when the chiral tail was located in the oxadiazole arm of the
V-shaped acid. Indeed, the optical activity of thin lms can be
amplied and switched between opposite signs for the complex
with only a single chiral tail in the oxadiazole moiety. For the
complex with chiral tails in both the oxadiazole and azobenzene
arms amplication was not observed but switching between two
opposite CD signals could be achieved. In contrast, none of
these effects was visible for complexes bearing the chiral tail in
the azobenzene moiety. More interestingly, supramolecular
chirality is induced in thin lms of the achiral complex
M-X12A12.
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Acknowledgements
We thank the following institutions for nancial support:
CAPES, CNPq/PRONEX, MINECO (projects MAT38538-CO2-01,
MAT2011-27978-CO2-01 and CTQ2012-35692), Gobierno de
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Aragon (project E04) and the EU (FEDER and FSE founding).
Thanks are due to: Nuclear Magnetic Resonance, Mass Spec-
trometry, Elemental Analysis and Thermal Analysis Services of
the CEQMA, Universidad de Zaragoza-CSIC (Spain).
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