Synthesis, π‐Face‐Selective Aggregation,and π‐Face Chiral Recognition of Configurationally Stable C3‐Symmetric Propeller‐Chiral Molecules with a π‐Core

The C₃‐symmetric propeller‐chiral compounds (P,P,P)‐ 1 and (M,M,M)‐ 1 with planar π‐cores perpendicular to the C₃‐axis were synthesized in optically pure states. (P,P,P)‐ 1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the (P/L)‐face and (P/H)‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. (P,P,P)‐ 1 formed dimeric aggregates in organic solutions as indicated by the results of ¹H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of ¹H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)‐ 1 /(M,M,M)‐ 1 interactions were much weaker than the homochiral (P,P,P)‐ 1 /(P,P,P)‐ 1 interactions. The results indicated that the propeller‐chiral (P/L)‐face interacts with the (P/L)‐face more strongly than with the (P/H)‐face, (M/L)‐face, and (M/H)‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.     

Development of a certified reference material for the determination of perfluorooctanoic acid

A certified reference material (CRM) for the determination of perfluorooctanoic acid (PFOA) has been issued as NMIJ CRM 4056-a by the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). Purity (kg kg^?1) based on a titration method was determined by subtracting the mass fractions of impurities measured using liquid chromatography/mass spectrometry (LC/MS) from those of acids expressed as PFOA measured by a neutralization potentiometric titration. To validate an obtained result, purity based on a mass balance method was determined by subtracting the mass fractions of impurities, measured using LC/MS, Karl-Fischer titration (KFT), and vacuum evaporation, from 1 kg kg^?1. Results from both titration and mass balance methods were in agreement within the accepted limits of uncertainty. The certified purity of NMIJ CRM 4056-a was determined to be 0.959 kg kg^?1, calculated as the mean of the results obtained with the two methods. The standard uncertainty of the certified purity was evaluated from purity evaluations as well as from sample homogeneity and stability obtained from LC/MS and KFT analyses. Consequently, the expanded uncertainty was estimated to be 0.005 kg kg^?1 with a coverage factor of k = 2.     

A Dual-Ligand Porous Coordination Polymer Chemiresistor with Modulated Conductivity and Porosity

Single-ligand-based electronically conductive porous coordination polymers/metal–organic frameworks (EC-PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their limited tunability in terms of both conductivity and topology. In this study, a new 2D π-conjugated EC-MOF containing copper units with mixed trigonal ligands was developed: Cu₃(HHTP)(THQ) (HHTP=2,3,6,7,10,11-hexahydrotriphenylene, THQ=tetrahydroxy-1,4-quinone). The modulated conductivity (σ≈2.53×10⁻⁵ S cm⁻¹ with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m² g⁻¹) of the Cu₃(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor.     

A Dual‐Ligand Porous Coordination Polymer Chemiresistor with Modulated Conductivity and Porosity

Single‐ligand‐based electronically conductive porous coordination polymers/metal–organic frameworks (EC‐PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their limited tunability in terms of both conductivity and topology. In this study, a new 2D π‐conjugated EC‐MOF containing copper units with mixed trigonal ligands was developed: Cu₃(HHTP)(THQ) (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene, THQ=tetrahydroxy‐1,4‐quinone). The modulated conductivity (σ≈2.53×10^?5 S cm^?1 with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m² g^?1) of the Cu₃(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor.     

Alternating copolymerizations of 9,10–dicarbonyl–9,10–dihydroanthracene with 1,4–benzoquinones and 1,4–benzoquinone diimines: A novel preparative route to polyarylate and polyaramide

The anthracene–9, 10–bisketene compound 9, 10-dicarbonyl-9, 10–dihydroanthracene (1) was found to react spontaneously with a variety of benzoquinones and benzoquinone diimines to give aromatic polyesters and polyamides, respectively. These addition reactions are regarded as a novel preparative route to polyarylate and polyaramide.     

Amphoteric poly(vinyl alcohol) gel as a force generator: Observation of microporous gel formation with cryo-SEM

Amphoteric PVA hydrogels were made from mixed aqueous solutions of poly(acrylic acid), poly(allylamine) hydrochloride and poly(vinyl alcohol) by repetitive freezing and thawing. The hydrogen bond induced gelation produced an elastic and tough microporous hydrogel which generated tension as high as 0.3MPa corresponding to the solvent exchange from water to acetone. In this paper we show the microscopic structure of hydrogels determined by means of cryo-SEM technique and X-ray analysis.     

Synthesis of novel glycopeptide-polyoxazoline block copolymers by direct coupling between living anionic and cationic polymerization systems

A novel glycopeptide-containing block copolymer, poly[O-(tetra-O-acetyl-β-D -glucopyranosyl)-L -serine]-block-poly(2-methyl-2-oxazoline) ( 5 ), was synthesized by mutual termination of living polymerizations of a sugar-substituted α-amino acid N-carboxyanhydride (NCA) ( 1 ) and 2-methyl-2-oxazoline ( 3 ). 5 was deacetylated to provide the glycopeptide-polyoxazoline block copolymer, poly[O-(β-D -glucopyranosyl)-L -serine]-block-poly(2-methyl-2-oxazoline) ( 6 ).