Aromatic aldehydes

Sulfamic acid, methyl acetoacetate, ammonium acetate and aromatic aldehydes were purchased from Sigma-Aldrich Chemical Co. and used without purification. All organic solvents used for the synthesis were of analytical grade. Column chromatography was performed using silica gel 60 Å (ACROS Organics, 0.035–0.070 mesh). The reactions were monitored by thin-layer chromatography (TLC) performed on glass plates coated with silica gel (Merck 60GF245); a mixture of hexane : ethyl acetate was used as the eluent, and the products were visualized using iodine vapor. The melting points were obtained using a Fisatom 430D apparatus and were reported as uncorrected values. ¹H NMR and ¹³C NMR spectra were recorded on Bruker Ascend 400 MHz operating at 400 MHz and 100 MHz, respectively, in deuterated chloroform (CDCl₃) as the solvent. The chemical shift data were reported in units of δ (ppm) downfield from tetramethylsilane (TMS), which was used as an internal standard. Infrared spectra were obtained using potassium bromide (KBr) pellets or sodium chloride (NaCl) disks on a Shimadzu-IR Prestige-21 spectrometer.

Solvents and all materials were purchased from commercial resources and utilized as received without any further purification. Histamine dihydrochloride (Sigma-Aldrich, >99%), aromatic aldehydes (Merck, Fluka and Sigma-Aldrich, 98–99%), dimedone (Sigma-Aldrich, >97%), 4-hydroxycoumarin (Fluka, purum), and acetonitrile (Sigma-Aldrich, 99.8%) were used as received. The performed LEDs were commercial and no cutoff filter was used. Fourier transform infrared (FT-IR) spectra were recorded on a Shimadzu 8700 Fourier transform spectrophotometer in the range 400 to 4000 cm⁻¹ with KBr pellets. UV-visible spectra were recorded on a Photonix UV-visible array spectrophotometer. X-ray diffraction (XRD) patterns were acquired on a PHILIPS PW 1730 diffractometer with Cu K_α at 30 mA, 40 keV and a scanning rate of 3° min⁻¹ in the 2θ domain from 5 to 80°. Energy dispersive X-ray spectroscopy (EDS) was performed with an Electron Probe Microanalyser JEOL JXA-8230 equipped with an energy dispersive spectrometer Bruker QUANTAX 200. A Mira 3-MU field emission scanning electron microscope (FESEM) was used to investigate the morphology of the synthesized nanomaterials. Particle size and further morphology studies were performed on a TEM (Philips CM-200 and Titan Krios). NMR experiments were carried out on a Bruker Avance DMX600 instrument operating at 400 MHz for proton.