Metastable Liquid Crystal as Time-Responsive Reaction Medium: Aging-Induced Dual Enantioselective Control

Yasuhiro Ishida *†‡, Yuki Matsuoka ‡, Yukiko Kai §, Kuniyo Yamada †, Kenta Nakagawa , Toru Asahi , and Kazuhiko Saigo #

A metastable liquid crystal (LC) was found to serve as a time-responsive reaction medium, in which the enantioselectivity of a photoreaction was perfectly switched through isothermal annealing of the reaction system. When the LC salt of an enantiopure amine with a photoreactive acid was irradiated with UV/vis light, in situ photodimerization of the acid moiety proceeded smoothly to afford the (+)-isomer of the photodimer with high enantioselectivity (+86% ee). In contrast, photoirradiation of an aged sample, isothermally annealed for 20 h, gave predominantly the (−)-isomer (−94% ee). Systematic studies revealed that the reversal in selectivity originated from metastability of the LC system, which gradually transformed into a crystalline phase during annealing. This finding demonstrates the potential use of metastable aggregates as dynamic time-responsive media, reminiscent of biological systems.

Defined Polymer–Peptide Conjugates to Form Cell-Instructive starPEG–Heparin Matrices In Situ

Mikhail V. Tsurkan^†, Karolina Chwalek^†, Silvana Prokoph, Andrea Zieris, Kandice R. Levental^‡*, Uwe Freudenberg^*, Carsten Werner

 Poly(ethylene glycol)-peptide- and glycosaminoglycan-peptide conjugates obtained by a regio-selective amino acid protection strategy are converted into cell-instructive hydrogel matrices capable of inducing morphogenesis in embedded human vascular endothelial cells and dorsal root ganglia.

A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics

Bong-Gi Kim,Eun Jeong Jeong,Jong Won Chung,Sungbaek Seo,Bonwon Koo & Jinsang Kim

Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur–fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.