Page 30 - ILLS Annual Report 2018

SOFT MATTER
Yuuya Nagata. Japanese
Kyoto University, Japan
‘I am an assistant professor working in Kyoto University, Japan. My research interests are in the development of new chiral materials based on the helical polymers. In order to reveal the intriguing nature of the helical
polymers, I am so interested in the use of the neutron beam scattering techniques, including SANS and QENS.’
Elucidating the solvent effect on the switch of
the helical chirality of poly(quinoxaline-2,3-diyl)s
Small-angle diffractometer D22
Reversible control of macromolecular helical chirality has attracted increasing attention because of its potential application for new functional materials. In this report, the mechanism of determining helical chirality by chiral side chains was successfully revealed through small-angle neutron scattering (SANS) experiments in conjunction
with theoretical calculations.
AUTHORS
Y. Nagata, T. Nishikawa and M. Suginome (Graduate School of Engineering, Kyoto University, Japan)
S. Sato (University of Tokyo, Japan)
M. Sugiyama, R. Inoue and N. Sato (Kyoto University Institute for Integrated Radiation and Nuclear Science, Japan)
L. Porcar and A. Martel (ILL) ARTICLE FROM
JACS (2018)—doi: 10.1021/jacs.7b11626
REFERENCES
[1] E. Yashima, K. Maeda, H. Iida, Y. Furusho and K. Nagai, Chem. Rev. 109 (2009) 6102
[2] E. Yashima, N. Ousaka, D. Taura, K. Shimomura, T. Ikai and K. Maeda, Chem. Rev. 116 (2016) 13752
[3] Y. Nagata, T. Yamada, T. Adachi, Y. Akai, T. Yamamoto and M. Suginome, J. Am. Chem. Soc. 135 (2013) 10104
The helix is the most essential and fundamental structural motif of the macromolecule [1, 2]. For over half a century, control of the screw sense of helical macromolecules has attracted considerable attention, owing to the development of unprecedented functional materials. Here, a side-chain-based induction of helicity is advantageous
not only because it allows the independent design of the main-chain and side-chain structures, but also because it enables the reversible formation of P- (right-handed) and
M- (left-handed) helical main-chain structures upon varying external conditions. However, although the side-chain-based induction of helicity has been reported, to date no attempts have been made to elucidate the underlying mechanism.
In our recent paper, we revealed the mechanism of the reversible formation of single-handed P- and M- helical main chains of a poly(quinoxaline-2,3-diyl) that bear (R)-2-octyloxymethyl chiral side chains (2oct) in two different solvents, i.e. tetrahydrofuran (THF) and a mixed solvent
of 1,1,2-trichloroethane (1,1,2-TCE) and THF (8/2) (figure 1) [3]. The proposed mechanism was supported by a detailed analysis of the high-scattering vector
(q) region from small-angle neutron scattering (SANS) experiments, in conjunction with theoretical calculations for the structural models obtained thus.
Figure 1
a) Chemical structure of 2oct, which is a poly(quinoxaline-2,3-diyl) with 100 repeating units, bearing (R)-2-octyloxymethyl side chains.
b) Structure of the backbone of 2oct together with the absolute helix inversion, which depends on the solvents THF and the mixed solvent 1,1,2-TCE/THF (8/2).
ANNUAL REPORT 2018