Polymeric fibers and microporous films by photo‐crosslinking of triphenylene‐derived liquid crystals

Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one ( TPC1 _n ) or two ( TPC2 _n ) n‐alkoxy groups (C _nH_2n+1O; n = 10–14), respectively, as peripheral groups are synthesized. Both of them are polymerized into fibers up to 2 mm long by UV irradiation in liquid paraffin in the columnar LC temperature ranges. The fiber structures seem to be preconstructed in liquid paraffin. In addition, TPC2 _n are shown to form microporous films up to 15 μm in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the films in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1 _n and the hydrogenated derivative of TPC2 ₁₂ , the porous film‐forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 605–612     

Liquid chromatography-mass spectrometry for simultaneous analyses of iminodipeptides containing an N-terminal or a C-terminal proline

Simultaneous analyses of synthetic iminodipeptides containing an N-terminal proline or a C-terminal proline have been demonstrated using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system. The separation of iminodipeptides was carried out on a reversed-phase high-performance liquid chromatographic column using 0.1% aqueous trifluoroacetic acid-methanol (75:25, v/v, pH 2.0) as mobile phase. Very intense protonated molecular ions [M + H]+ of various synthetic iminodipeptides, Pro-Gly, Gly-Pro, Pro-Ala, Ala-Pro, Pro-Val, Val-Pro, Pro-Leu and Leu-Pro, were observed. Pro-Gly (Pro-X) and Gly-Pro (X-Pro) have the same protonated molecular ion (m/z 173), but the peaks of these compounds on the mass chromatograms were clearly distinguished by the differences of the retention times and mass spectra. The synthetic iminodipeptides containing an N-terminal proline added to urine samples from a patient with prolidase deficiency were also distinguished from iminodipeptides containing a C-terminal proline in urine samples from a patient with prolidase deficiency by scanning the [M + H]+ ion of each iminodipeptide. We established the method to measure simultaneously the various iminodipeptides containing an N-terminal or a C-terminal proline in biological samples.     

Influence of carbon contamination on etched GaSb substrate on the quality of MBE-GaSb film and electrical transport through the film and the substrate

Undoped MBE-GaSb films were grown on undoped GaSb (100) substrates and the influence of carbon contamination on the etched GaSb substrate on the grown film were investigated. It was found that carbon contamination of the etched GaSb substrate was dependent on the chemical treatment method and produced stacking faults in the subsequent MBE growth of the GaSb film. Carbon contamination on the etched GaSb substrate degraded the quality of the GaSb film and affected ohmic characteristics between the film and the substrate. Substrate surface free of carbon contamination and thereby exhibitting no influence on the electrical transport through the film and the substrate could be reproducibly obtained by performing an oxide etch-off chemical treatment on the GaSb substrate.