Irtracer 100 ftir spectrometer

Fourier transform infrared spectra were recorded using an IRTracer-100 FT-IR spectrometer (Shimadzu) with a Deuterated Lanthanum α-Alanine doped TriGlycine Sulphate (DLaTGS) detector. These peptide-based building block self-assembly solutions were deposited on a CaF₂ window and dried under vacuum. The peptide deposits were resuspended with D₂O and subsequently dried to form thin films. The re-suspension procedure was repeated twice to ensure maximal hydrogen-to-deuterium exchange. The measurements were taken using 4 cm⁻¹ resolutions and an average of 1000 scans. The transmittance minimal values were determined using the Lab solutions IR analysis program (IR Tracer).

Melting points (uncorrected) were measured on a WRX-4 microscopic melting point apparatus (Shanghai Yi Ce Instrument Factory). All ¹H and ¹³C NMR spectra were obtained on a Bruker DPX 300 spectrometer with CDCl₃ and CD₃OD as solvents and TMS as an internal standard. HR-ESI-MS spectra were analyzed on a Bruker Apex II mass spectrometer. IR spectra were recorded with a Shimadzu IRTracer 100 FT-IR spectrometer (KBr plate). Optical rotation values were measured with a JASCO P-2000 Polarimeter. The crystal structure was analyzed with a Thermo Fisher ESCALAB 250 four-circle X-ray diffractometer (Xcalibur, Eos, Gemini). Unless otherwise stated, all reagents were purchased from commercial suppliers and used without further purification. Organic solutions were concentrated under reduced pressure using a rotary evaporator or oil pump. Flash column chromatography was performed using Qingdao Haiyang silica gel (200–300 mesh). HPLC analyses were performed on an Agilent 1100 instruments, UV detection was monitored at 254 and 220 nm, an IB N-5 column (5 μm, 4.6 × 250 mm) was used as the chiral stationary phase, and hexane/i-PrOH (90 : 10) was used as the mobile phase at a flow rate of 1.0 mL min⁻¹.