300 mhz instrument

The 1-D ¹H and ¹³C NMR spectra and 2-D ¹H-¹H correlations spectroscopy (COSY), ¹H-¹³C heteronuclear single quantum correlation (HSQC), and heteronuclear multiple bond correlation (HMBC) spectra were recorded in DMSO-d₆ using a Bruker 300 MHz instrument (Rheinstetten, Germany) at College of Natural Sciences, University of Rzeszów.

The chemicals used for experimental work were commercially procured from various chemical units, namely, E. Merck India Ltd., CDH and S.D. Fine chem. and Qualigens. These solvent and reagents were of LR grade and were purified before use. The silica gel G (160-120 mesh) used for analytical chromatography (TLC) was obtained from E. Merck India Ltd. The solvent system used was benzene : acetone (9 : 1) and (8 : 2) and toluene : ethyl acetate : formic acid (5 : 4 : 1). Ashless Whattman number 1 filter paper was used for vacuum filtration. Melting points were determined in open glass capillary using melting point apparatus and are uncorrected. The proton nuclear magnetic resonance (¹HNMR) spectra were recorded on Bruker 300 MHz instrument in DMSO-d₆/CDCl₃ using tetramethylsilane [(CH₃)₄Si] as internal standard. The infrared spectra of the compound were recorded in KBr on Perkin-Elmer FTIR Spectrometer, and the iodine chamber and U.V.-lamp were used for visualisation of TLC spots. Mass spectra were recorded on API 2000 LC/MS/MS system and elemental analyses were performed on Perkin-Elmer 2400. The commercially available grades of solvents and reagents were found to be of adequate purity. However, the presence of undesirable impurities and others was likely to be used for experimental work for purification.

IR spectra were recorded with ALPHA FT-IR Bruker instrument in ATR mode or in KBr pellets. The NMR spectra were recorded with Bruker 300 MHz instrument (Rheinstetten, Germany). Spectral assignments were performed based on 2-D ¹H-¹H COSY and ¹H-¹³C HSQC and HMBC experiments.

The ¹H and ¹³C NMR spectra were measured by a 300 MHz instrument (Bruker, Rivas-Vaciamadrid, Spain), and CDCl₃ was used as the solvent for all the spectra. The solvent signal was taken as the reference using a chemical shift (δ) of ca. 7.26 ppm and 77.16 ppm for ¹H and ¹³C NMR, respectively. Coupling constants (J) were given in Hz. The exact mass values were determined by using a Waters ACQUITY™ XevoQToF spectrometer (Waters Corp., Cerdanyola del Vallès, Spain) connected to the UPLC system via an electrospray ionization (ESI) interface. The ESI source was operated in positive ionization mode with the capillary voltage at 3.0 kV (Waters Corp., Cerdanyola del Vallès, Spain). The temperature of the source and desolvation was set at 120 °C and 500 °C, respectively. The cone and desolvation gas flows were 10 L h⁻¹ and 450 L h⁻¹, respectively. All data collected in centroid mode were acquired using Masslynx™ software (Waters Corp., Cerdanyola del Vallès, Spain). Leucine-enkephalin was used as the lock mass, generating an [M + H]⁺ ion (m/z 556.2771) at a concentration of 250 pg/mL and a flow rate of 20 μL/min to ensure accuracy during the mass analysis.

All chemicals and solvents were purchased from Aldrich (Bucharest, Romania) or Chimopar (Bucharest, Romania). ¹H- and ¹³C-NMR spectra were recorded on a Bruker 300 MHz instrument (Rheinstetten, Germany), using deuterated chloroform as the solvent and tetramethylsilane (TMS) as the internal standard. Infrared (IR) spectra were recorded on a Bruker FT-IR apparatus (Bremen, Germany). UV-Vis spectra were recorded in water at room temperature using an UVD-3500 double beam spectrophotometer (Labomed, LA, USA). Dinamic light scattering (DLS) analysis was performed in water on a Beckman Coulter particle size analyzer (Brea, CA, USA) using the Delsa Nano software (Beckman Coulter, Brea, CA, USA). Transmission electron microscopy (TEM) pictures were obtained using a Jeol 200 CX microscope (Jeol, Tokyo, Japan); a drop of diluted Au NPs was added on a 3 mm carbon copper grid and left to dry.