Paragon 1000 spectrophotometer

All reagents and solvents were of commercial quality, purchased from Sigma-Aldrich (Madrid, Spain) and were used as received. Reactions were monitored by thin layer chromatography on aluminium plates coated with silica gel and fluorescent indicator. Separation by flash chromatography were performed on SDS 60 ACC, 230–400 mesh or Scharlau Ge 048 silica gel. Melting points were measured with Reichert 723 hot stage microscope (Vienna, Austria), or in open capillary tubes using a Büchi immersion instrument, and are uncorrected. Infrared spectra were recorded on a Perkin–Elmer Paragon 1000 spectrophotometer (Tres Cantos, Spain), with solid compounds compressed into KBr pellets and liquid compounds placed between two NaCl disks. NMR spectra data were obtained using Bruker spectrometers (Rivas-Vaciamadrid, Spain) maintained by the CAI de Resonancia Magnética, UCM, operating at 250 and 300 MHz for ¹H NMR and, 63 and 75 MHz for ¹³C NMR; chemical shifts (δ) are given in parts per million and coupling constants (J) in Hertz. Elemental analyses were determined by the CAI de Microanálisis, Universidad Complutense, using a Leco CHNS-932 combustion microanalyzer (Tres Cantos, Spain). The enantiomeric excess of compounds 6ai and 6aj was assessed by ¹H-NMR in the presence of 1.5 equivalents of (+) tris(3-heptafluoropropylhydroxymethylene) europium camphorate.

Melting points were determined in centigrade scale in one end open capillaries on a Büchi 570 melting point apparatus and are uncorrected. IR spectra were recorded on a Perkin-Elmer Paragon-1000 spectrophotometer or an Esquire 3000 spectrometer. ¹H and ¹³C NMR spectra were recorded by a Bruker 500 and 125 MHz instrument using TMS as internal standard and CDCl₃ as solvent. High-resolution mass spectra were recorded on a Bruker 400 mass spectrometer. Column chromatography was carried out with Merk silica gel (60–120 mesh). Optical rotation was measured on a Perkin-Elmer polarimeter.

The scanning electron microscopy (SEM) was recorded on a field emission SEM (Nova NanoSEM 450, FEI Company, USA). Fourier transform infrared (FTIR) spectra was measured by a Paragon 1000 spectrophotometer (PerkinElmer, Inc US). Raman spectrometry was performed using a Raman spectrometer (DXR, Thermo Fisher Scientific Inc., USA) with a laser wavelength of 532 nm at room temperature. The structure of the composite was tested by powder X-ray diffraction (D8 Advance, Bruker Corp., Germany, XRD) using Cu-Kα radiation at 40 kV. Electrical conductivity was done by the method of four-point probe (DP-SB100A/20, Beijing Ya'ou De Peng Technology Co. Ltd., China). Specific surface area and aperture distribution of the composites was performed by specific surface analyzer (ASAP 2010M + C, Micromeritics, USA).