Ponente
Descripción
Three 2-aryl-benzimidazole derivatives (2-phenyl-1H-benzimidazole, 2-(2’-nitrophenyl)-1H-benzimidazole and 2-(4’-nitrophenyl)-1H-benzimidazole) were obtained from the reaction between benzaldehyde derivative and o-phenylenediamine. The purification was carried out by using a purge of N2 (g) at 180oC during 10 hours. The crystalline structure of the synthesized benzimidazole derivatives was determined from laboratory X-ray powder diffraction data using direct space global optimization strategy (simulated annealing) followed by the Rietveld refinement. 2-phenyl-1H-benzimidazole crystallize in the monoclinic system, space group C2/c and 2-(2’-nitrophenyl)-1H-benzimidazole, 2-(4’-nitrophenyl)-1H-benzimidazole crystallizes in the orthorhombic system, space group Pbca respectively. The conformational structure that these molecules acquired in the three-dimensional network exhibited intermolecular hydrogen bonding interactions. Infrared (FT-IR) and Raman spectrum of the 2-aryl-benzimidazole derivatives were compared with vibrational modes of the free molecule and crystal structure, which were calculated by DFT in order to determinate the inter and intramolecular hydrogen bonding interactions. Using also DFT calculation, in combination to IR and Raman spectroscopy, the presence of characteristic vibrational modes of benzimidazole derivatives and the influence exerted by the position of the nitro group in both spectra were confirmed. The antioxidant effect of 2-aryl-benzimidazoles derivatives showed depending on the concentration, with enhancement for 2-(2’-nitrophenyl)-1H-benzimidazole and 2-(4’-nitrophenyl)-1H-benzimidazole.
Acknowledgments: We would like to thank the support of PREI-DGAPA for the invited professor to MPHS and the generous allocation of computer time at the CCC-UAM. This work was partially supported MICINN (Spanish Ministry of Science and Innovation) project PID2019-1 and project PN223LH010-011 of the National Program of the Basic and Naturals Science (PNCByN).
