Macroscopic ordering of helical pores for arraying guest molecules noncentrosymmetrically

Abstract

Helical nanostructures have attracted continuous attention, not only as media for chiral recognition and synthesis, but also as motifs for studying intriguing physical phenomena that never occur in centrosymmetric systems. To improve the quality of signals from these phenomena, which is a key issue for their further exploration, the most straightforward is the macroscopic orientation of helices. Here as a versatile scaffold to rationally construct this hardly accessible structure, we report a polymer framework with helical pores that unidirectionally orient over a large area (∼10 cm2). The framework, prepared by crosslinking a supramolecular liquid crystal preorganized in a magnetic field, is chemically robust, functionalized with carboxyl groups and capable of incorporating various basic or cationic guest molecules. When a nonlinear optical chromophore is incorporated in the framework, the resultant complex displays a markedly efficient nonlinear optical output, owing to the coherence of signals ensured by the macroscopically oriented helical structure.

An Ising transition of chessboard tilings in a honeycomb liquid crystal

“…The bold trace at Tc = 88°C marks the phase transition between two square columnar phases. In both phases reflections indexed as (10), (11), (20) etc. are seen, their q 2 ratio being 1:2:4:5 ….…”

“…Among numerous well established or developing applications of liquid crystals (LC) is nanoscale patterning on the sub-10 nm length scale. 1 , 2 Such patterning may be used in organic electronics and photovoltaics, 3 , 4 , 5 , 6 , 7 , 8 in selective membranes, 9,10,11 for ion conducting arrays 12, , 13 , cubosomes 14 and hexosomes 15 for drug delivery etc. For use in soft nanolithography highly ordered arrays are required, preferably with a square or rectangular lattice and high dimensional stability, ideally with zero thermal expansion.…”

Macroscopically Oriented Porous Materials with Periodic Ordered Structures: From Zeolites and Metal–Organic Frameworks to Liquid‐Crystal‐Templated Mesoporous Materials

“…Detailed structure of the crosslinked polymer based on these data is given in (b‐i). Reproduced with permission . Copyright 2015, Nature Publishing Group.…”

“…As described in Section , one notable advantage of porous crosslinked polymers, compared with other conventional porous materials, is the ease with which chiral structures can be introduced. In 2015, Ishida and co‐workers demonstrated that chiral pores can be rationally constructed by using chiral template units in this synthetic scheme, and they reported on a macroscopically oriented version (Figure b). In their studies, an enantiopure amine [(1 R ,2 S )‐norephedrine; (–)‐(1 R ,2 S )‐2‐amino‐1‐phenyl‐propan‐1‐ol] was used as a template unit, whereas the same frame unit as described in Section and , the wedge‐shaped benzoic acid with three acryloyl groups (Figure bi, left), was used as its counterpart.…”

“…This progress report presents an overview of recent studies on the synthesis, properties, and applications of porous materials with macroscopically oriented structures ( Table 1 ). The scope of this report is limited to porous materials with nano‐ or mesoscale periodic channels constructed by supramolecular self‐assembly of atomic and/or molecular components, such as zeolites (Section ), MOFs (Section ), mesoporous oxides (Section ), and polymers based on liquid crystals (LCs) (Section ) . In other words, porous materials produced by physical processes, such as anodic aluminum oxides or porous silicones, are beyond the scope of this report.…”