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Journal of Chemical Technology and Applications | Volume 2
Annual Spring Conference and Expo on
April 04-05, 2018 | Miami, USA
Chemical Engineering: From
Materials Engineering to Nanotechnology
allied
academies
T
his studypresents photoresponsivedynamic pseudorotaxane
crystals comprising of azobenzene and ferrocenyl groups in
an axle component threaded through dibenzo [24] crown-8
ether rings. These pseudorotaxanes are synthesized by mixing
dialkylammonium axle molecule tethered with azobenzene
with/without methyl-substituent and the ring molecule with/
without bromo-substituents in dichloromethane. Single
crystals of the pseudorotaxane exhibit bending motions caused
by cis-trans photoisomerization of the azobenzene group
using alternating 360 nm and 445 nm lasers. These bending
motions are reversible and repeated more than 200 times.
The bending motions of the crystals are significantly varied
by the substituents. Single-crystal X-ray crystallography of the
pseudorotaxanes reveals the details of the initial molecular
structures. A crystal of pseudorotaxane without substituents
exhibits small degree of bending within 0.3 second by 360 nm
irradiation, because of multiple π-π interactions in azobenzene
groups. Contrary, the crystals of pseudorotaxanes with bulky
substituents show large displacement in bending within
7-30 seconds induced by 360 nm irradiation. Distorted π-π
interactions of the azobenzene groups facilitate twisting of the
axle molecule. In addition, all crystals exhibited very fast cis-to-
trans backward process within 0.3 second, which is much faster
than typical azobenzene crystals.
Speaker Biography
Shao-Chi Cheng joined Dr. Horie’s materials synthesis group in 2013 when he was an
undergraduate student at Department of Chemical Engineering, National Tsing-Hua
University, Taiwan. He is now a PhD student and his research interest is synthesis of
azobenzene-containing supramolecular pseudorotaxane crystals for potential use in
microscale molecular machines.
e:
angusn124@hotmail.comPhotoinduced bending of azobenzene-based [2] pseudorotaxane crystals
Shao-Chi Cheng
National Tsing-Hua University, Taiwan