A racemic monomer‐based optically inactive polyacetylene folds into a one‐handed helix assisted by a nonracemic alcohol, which can separate various enantiomers as a chiral stationary phase in chromatography. The chiral‐resolving power is virtually identical to that of the enantiopure monomer‐based one‐handed helical polyacetylene. Because of its unique static memory of the induced helicity, the original racemic polyacetylene expresses an auto‐evolution of its helical handedness over time, and at the same time, chirality of the nonracemic alcohol is discriminated accompanied by successive enhancement of its optical purity enantioselectively adsorbed on the helical polyacetylene owing to the chiral filter effect as directly monitored by NMR, which contributes to further enhancing the helix‐sense‐excess of the helical polyacetylene.

Two novel poly(biphenylylacetylene)s (PBPAs) bearing achiral alkylphenyl groups at the 4′‐position of the biphenyl pendant through ester linkers with different sequences were synthesized by the rhodium‐catalyzed polymerization of the corresponding monomers. The influence of the alkylphenyl pendants and the ester sequences on the macromolecular helicity induction and subsequent static helicity memory was investigated. In addition, the chiral recognition ability as chiral stationary phases for high‐performance liquid chromatography of the helicity‐memorized PBPAs was also examined. Both polymers formed almost perfect right‐ and left‐handed helical conformations through noncovalent chiral interactions with enantiomeric alcohols, and their induced macromolecular helicities were completely retained (“memorized”) after removal of the helix inducer. A PBPA bearing a 4‐n‐butylphenoxycarbonyl pendant group with a static helicity memory showed a remarkably high chiral recognition ability toward a wide variety of chiral aromatics, including simple point chiral compounds, axially chiral biaryls, a chiral spiro compound, helicenes, and planar chiral cyclophanes, particularly under the reversed‐phase conditions.

We report unique coordination-driven supramolecular helical assemblies of a series of dirhodium(II) tetracarboxylate paddlewheels bearing chiral phenyl-or methyl-substituted amidebound m-terphenyl residues with triethylene glycol monomethyl ether (TEG) or n-dodecyl tails through a 1:1 complexation with 1,4-diazabicyclo[2.2.2]octane (DABCO). The chiral dirhodium complexes with DABCO in CHCl 3 /n-hexane (1:1) form onehanded helical coordination polymers with a controlled propeller chirality at the m-terphenyl groups, which are stabilized by intermolecular hydrogen-bonding networks between the adjacent amide groups at the periphery mainly via a cooperative nucleation−elongation mechanism as supported by circular dichroism (CD), vibrational CD, and variable-temperature (VT) absorption and CD analyses. The VT visible-absorption titrations revealed the temperature-dependent changes in the degree of polymerization. The columnar supramolecular helical structures were elucidated by X-ray diffraction and atomic force microscopy. The helix sense of the homopolymer carrying the bulky phenyl and n-dodecyl substituents is opposite those of other chiral homopolymers despite having the same absolute configuration at the pendants. A remarkably strong "sergeants and soldiers" (S&S) effect was observed in most of the chiral/achiral copolymers, while the copolymers of the bulky chiral phenyl-substituted dirhodium complexes with n-dodecyl chains displayed an "abnormal" S&S effect accompanied by an inversion of the helix sense, which could be switched to a "normal" S&S effect by changing the solvent composition. A nonracemic dirhodium complex of 20% enantiomeric excess bearing the less bulky chiral methyl substituents with n-dodecyl chains assembled with DABCO to form an almost onehanded helix (the "majority rule" (MR) effect), whereas the three other nonracemic copolymers showed a weak MR effect.

Enhancement of root hair development in response to phosphate (Pi) deficit has been reported extensively. Root hairs are involved in major root functions such as the absorption of water, acquisition of nutrients and secretion of organic acids and enzymes. Individual root hair cells maintain these functions and appropriate structure under various physiological conditions. We carried out a study to identify protein(s) which maintain the structure and function of root hairs, and identified a protein (SEED AND ROOT HAIR PROTECTIVE PROTEIN, SRPP) that was induced in root hairs under Pi-deficient conditions. Promoter assay and mRNA quantification revealed that SRPP was expressed in root hairs and seeds. A knockout mutant, srpp-1, consistently displayed defects in root hairs and seeds. Root hairs in srpp-1 were short and the phenotypes observed under Pi-deficient conditions were also detected in ethylene-treated srpp-1 plants. Propidium iodide stained most root hairs of srpp-1 grown under Pi-deficient conditions, suggesting cell death. In addition to root hairs, most srpp-1 seeds were withered and their embryos were dead. SRPP tagged with green fluorescent protein was detected in the cell wall. Electron microscopy showed abnormal morphology of the cell wall. Wild-type phenotypes were restored when the SRPP gene was expressed in srpp-1. These data strongly suggest that SRPP contributes to the construction of robust cell walls, whereby it plays a key role in the development of root hairs and seeds.

A series of cis-poly(biphenylylacetylene) (PBPA) derivatives bearing chiral and achiral pendant groups at the 4′-position of the biphenyl units through an amide (−NHCO−) or carbamate (−NHCOO−) linker were synthesized by polymerization of the corresponding biphenylylacetylene (BPA) monomers that can be readily prepared in one step from a novel aminofunctionalized BPA. An excess one-handed helix induction in the PBPAs through covalent and noncovalent chiral interactions and their chiral recognition abilities when used as chiral stationary phases for high-performance liquid chromatography were investigated. PBPAs bearing optically pure L-amino acid residues showed unique two-state helical conformational changes between the extended and contracted helices regulated by the solvent-mediated on/off switching of the intramolecular hydrogen-bonding formations between the pendants or at each pendant. The chiral recognition abilities of the helical PBPAs were significantly influenced by the kinds of the pendant L-amino acid residues. The preferred-handed contracted helical PBPA carrying an L-leucine-derived pendant showed an excellent chiral resolving power toward various racemic compounds including axially and point chiral compounds and chiral metal complexes. The elution orders of some racemates were completely reversed when its helical conformation was changed to the extended helix. On the other hand, the trans-enriched nonhelical L-leucine-bound PBPA derived from its preferred-handed cis-helical PBPA and achiral pendant-bound cishelical PBPAs induced by noncovalent chiral interactions and subsequent static memory of the helicity showed a poor and no chiral recognition, respectively.