Enhanced optical activity by achiral rod-like molecules nanosegregated in the B4 structure of achiral bent-core molecules

Taketo Otani; Fumito Araoka; Ken Ishikawa; Hideo Takezoe

doi:10.1021/ja904447b

Enhanced optical activity by achiral rod-like molecules nanosegregated in the B4 structure of achiral bent-core molecules

J Am Chem Soc. 2009 Sep 2;131(34):12368-72. doi: 10.1021/ja904447b.

Authors

Taketo Otani¹, Fumito Araoka, Ken Ishikawa, Hideo Takezoe

Affiliation

¹ Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-42, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.

PMID: 19642676
DOI: 10.1021/ja904447b

Abstract

Chirality in a mixture system consisting of bent-core 1,3-phenylene bis[4-(4-8-alkoxyphenyliminomethyl)benzoates] (P8-O-PIMB) and rod-like n-pentyl-cyanobiphenyl (5CB) molecules has been studied. Precise circular dichroism (CD) spectra using thin sample cells indicate mainly two characteristics: (1) the origin of CD signals is due to chiral-segregated bent-core molecules in the B(4) phase, where 5CB is in the isotropic phase; (2) the enhanced CD signal is detected in the B(X) phase, where 5CB is in the nematic phase. These results suggest that 5CB molecules are embedded in the network of helical nanofilaments formed by P8-O-PIMB and form helical superstructure with the same handedness as the helical nanofilaments in the B(X) phase, resulting in the giant CD signals.