Structure-sensitive bend elastic constants between piconewton and subnanonewton in diphenylacetylene-core-based liquid crystals.
Elastic constants in liquid crystals are known to be in the range of pico- and several-tens piconewton (pN). We report herein that a bend elastic constant, K33, remarkably varies depending on a slight modification of the chemical structure in an analogous series of calamitic liquid crystals. In contrast to the record-high bend elastic constants (hundreds pN or sub-nN) reported previously in a compound with an azo linkage, analogous compounds with tolan and ester linkages show several-tens pN and pN, respectively. X-ray diffraction studies of these compounds reveal that smectic-like layer structures (cybotacticclusters) are formed in the nematic phase of only the homologous compounds with an azo linkage, certifying the idea that the existence of cybotactic clusters strongly enhances K33. Two theoretical considerations were made: (1) Based on molecular conformation calculation, flat molecules that have high torsional potential energy, such as the one with an azo linkage, easily pack to form cybotactic clusters. (2) Theoretical estimation was made of how much cluster volume ratio is necessary to give about 100-times-larger K33s.
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Satoshi
S
Aya
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan.
Shohei
S
Ogino
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Yoshihiro
Y
Hayashi
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan and Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8522, Japan.
Kunihiko
K
Okano
University of Warsaw, Department of Chemistry, ul. Zwirki i Wigury 101, Warsaw, 02-089, Poland.
Damian
D
Pociecha
RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Khoa V
KV
Le
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan and RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Fumito
F
Araoka
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Susumu
S
Kawauchi
University of Warsaw, Department of Chemistry, ul. Zwirki i Wigury 101, Warsaw, 02-089, Poland.
Ewa
E
Gorecka
Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, Maribor, Slovenia and Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
Nataša
N
Vaupotič
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Hideo
H
Takezoe
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Ken
K
Ishikawa