Nicolet is5 ir spectrometer

Optical rotations were measured with a P-2000 digital polarimeter (JASCO, Hachioji, Japan). UV spectra were obtained with a NADE Evolution 201 spectrophotometer (ThermoFisher, Waltham, MA, USA). IR spectra were recorded on a Nicolet iS5 IR spectrometer (ThermoFisher, Waltham, MA, USA).¹H-NMR (600 MHz) and ¹³C (150 MHz) spectra were measured with a Varian 600 MHz (Palo Alto, CA, USA) spectrometer. Chemical shifts were reported in ppm, while using the signals of the residual solvent as internal reference (δ_H 3.31 and δ_C 49.0 for CD₃OD, δ_H 7.26 and δ_C 77.1 for CDCl₃). HRESIMS data were recorded on an Agilent Technologies 6520 Accurate Mass Q-TOF LC/MS spectrometer (Agilent Technologies, Santa Clara, CA, USA). Medium-pressure liquid chromatography (MPLC) was performed on a FLEXA Purification System (Agela Technologies, Tianjin, China) using a ODS column. Column chromatography (CC) was carried out with silica gel (200–300 mesh, Qingdao Marine Chemical Inc. Qingdao, PR China) and Sephadex LH20 (Amersham Biosciences, Piscataway, NJ, USA). CC fractions were analyzed by TLC (silica gel GF254, Qingdao Marine Chemical Factory, Qingdao, China). Semi-preparative HPLC (Waters 600, Milford, MA, USA) equipped with a Waters 2996 detector and a C₁₈ column (250 mm × 20 mm ID, 5 µm; YMC Co. Ltd., Tokyo, Japan).

The morphology and size of N,S-CDs were analyzed by transmission electron microscope (HT-7700, Japan) operated at 100 kV. Fourier transform infrared (FT-IR) spectra were obtained on a Thermo Scientific Nicolet iS5 IR spectrometer (USA) ranging from 400 to 4000 cm⁻¹ using attenuated total reflection (ATR) accessory. XPS analysis was measured by Thermo Scientific ESCALAB Xi⁺ X-ray photoelectron spectrometer (USA) using Al Kα as the excitation source (1486.6 eV).

All reagents were purchased from Merck (Sigma-Aldrich, St. Louis, MO, USA) and Alfa (Alfa-Aesar, Ward Hill, MA, USA). Reactions were performed using an Anton-Paar Monowave 50 microwave reactor (Graz, Austria). The melting points were determined on a Kofler hot-plate apparatus HMK (Franz Kustner Nacht KG, Dresden, Germany) and are uncorrected. Infrared (IR) spectra were recorded on Nicolet iS5 IR spectrometer (Thermo Scientific, West Palm Beach, FL, USA). The spectra were obtained by the accumulation of 256 scans with 2 cm⁻¹ resolution in the region of 4000–450 cm⁻¹. All ¹H- and ¹³C-NMR spectra were recorded on a JEOL JNM-ECA 600II device (600 MHz for ¹H and 150 MHz for ¹³C, JEOL, Tokyo, Japan) in dimethyl sulfoxide-d₆ (DMSO-d₆). ¹H and ¹³C chemical shifts (δ) are reported in ppm. High-resolution mass spectra were measured using a high-performance liquid chromatograph Dionex UltiMate^® 3000 (Thermo Scientific, West Palm Beach, FL, USA) coupled with an LTQ Orbitrap XL^TM Hybrid Ion Trap-Orbitrap Fourier Transform Mass Spectrometer (Thermo Scientific) equipped with a HESI II (heated electrospray ionization) source in the positive and negative mode.