Ri 2031 detector

A JASCO P1020 NK digital polarimeter was used to measure the optical rotations. The diffuse reflectance method was used to record IR spectra on a JASCO FT/IR-410 spectrophotometer. UV spectra were obtained on a JASCO V-560 UV/Vis spectrophotometer. ECD spectra were measured on a JASCO J-725N spectrophotometer. ¹H and ¹³C NMR spectra were recorded on a JEOL JNM-AL 400 (¹H: 400 MHz) or Varian Unity plus 500 (¹H: 500 MHz, ¹³C: 126 MHz, respectively) spectrometer using CDCl₃. Chemical shift values are given in δ (ppm), using the solvent peak signals (CDCl₃: TMS) as references, and coupling constants (J) are reported in Hz. A JEOL JMS-700 MStation was used to record mass spectra, including high-resolution spectra. Column chromatography was performed on Silica gel 60 (100–210 mesh, Kanto Chemical Co., Inc., Tokyo, Japan). Preparative HPLC was performed on a JASCO chromatograph (n-hexane–EtOAc, CHCl₃–EtOAc) equipped with a JASCO PU-2086 pump, a JASCO UV-970 detector, a JASCO RI-2031 detector, and various columns: COSMOSIL 5SL-II (10 × 250 mm, Nacalai Tesque Inc., Kyoto, Japan), COSMOSIL 5SL-II (4.6 × 250 mm, Nacalai Tesque Inc., Kyoto, Japan), YMC-Pack Diol-120-NP (4.6 × 250 mm, YMC Co., Ltd., Kyoto, Japan), and Inertsil CN-3 (4.6 × 250 mm, GL Sciences, Tokyo, Japan).

¹H NMR spectra were recorded on a JEOL ECS-400 spectrometer (JEOL, Tokyo, Japan) operated at 400 MHz. The number-average molecular weights (M_n) and molecular weight distributions (M_w/M_n) of the product polymers were determined via size-exclusion chromatography (SEC) in DMF containing 100 mM LiCl at 40 °C on two hydrophilic polymer gel columns [Tosoh α-M + α-3000 (7.8 mm i.d. × 30 cm) (Tosoh Corporation, Tokyo, Japan); flow rate of 1.0 mL/min] (for poly(4VG)) connected to a JASCO PU-2080 precision pump and a JASCO RI-2031 detector (JASCO, Tokyo, Japan). The columns were calibrated against standard polystyrene samples (Agilent Technologies, Santa Clara, CA, USA; M_p = 580–3,053,000, M_w/M_n = 1.02–1.23). The glass transition temperature (T_g) of the polymers was recorded on a Q200 differential-scanning calorimeter (TA Instruments, Inc., New Castle, DE, USA), and the T_g values were obtained from the second scan after removing the thermal history. The samples were first heated to 210 °C at 10 °C/min, equilibrated at this temperature for 10 min, and cooled to −60 °C at 5 °C/min. After holding at this temperature for 5 min, the samples were then reheated to 210 or 260 °C at 10 °C/min. The thermogravimetric analyses (TGA) were performed on a Q500 system (TA Instruments Inc.) at 5 °C/min under a N₂ gas flow.

The phytocompound, yatein, was isolated from C. formosana leaves extracts. In brief, C. formosana leaves were extracted using methanol at room temperature (RT) for one week (twice) to obtain a methanolic extract. The dried samples were further divided to n-hexane, ethyl acetate (EtOAc), n-butanol, and H₂O fractions using liquid–liquid partition. The n-hexane fraction was further fractionated into ten subfractions using normal phase column chromatography (Geduran Si-60, Merck, Darmstadt, Germany). Yatein was isolated and purified from the subfraction 4 by semipreparative high-performance liquid chromatography using a PU-2080 pump (Jasco, Tokyo, Japan) equipped with an RI-2031 detector (Jasco) and a 5 μm Luna silica column (250 mm × 10.0 mm internal diameter; Phenomenex, Torrance, CA, USA). The mobile phase consisted of 30% of EtOAc and 70% of n-hexane (v/v), and the flow rate was 4 mL/min. The retention time of yatein in HPLC analysis was 18.0 min. The purity and the structure elucidation of yatein was conducted by ¹H and ¹³C NMR, and all spectrum data were consistent with literature [34 (link)].