Microwave synthesis, crystal structure, antioxidant, and antimicrobial study of new 6-heptyl-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline compound

BACKGROUND: Although the development of antibiotic and antioxidant manufacturing, the problem of bacterial resistance and food and/or cosmetics oxidation still needs more efforts to design new derivatives which can help to minimize these troubles. Benzimidazo[1,2-c]quinazolines are nitrogen-rich heterocyclic compounds that possess many pharmaceutical properties such as antimicrobial, anticonvulsant, immunoenhancer, and anticancer. RESULTS: A comparative study between two methods, (microwave-assisted and conventional heating approaches), was performed to synthesise a new quinazoline derivative from 2-(2-aminophenyl)-1H-benzimidazole and octanal to produce 6-heptyl-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline (OCT). The compound was characterised using FTIR, (1)H and (13)C NMR, DIMS, as well as X-ray crystallography. The most significant peak in the (13)C NMR spectrum is C-7 at 65.5 ppm which confirms the cyclisation process. Crystal structure analysis revealed that the molecule grows in the monoclinic crystal system P2(1)/n space group and stabilised by an intermolecular hydrogen bond between the N1–H1A…N3 atoms. The crystal packing analysis showed that the molecule adopts zig-zag one dimensional chains. Fluorescence study of OCT revealed that it produces blue light when expose to UV-light and its’ quantum yield equal to 26%. Antioxidant activity, which included DPPH(·) and ABTS(·+) assays was also performed and statistical analysis was achieved via a paired T-test using Minitab 16 software with P < 0.05. Also, the antimicrobial assay against two Gram-positive, two Gram-negative, and one fungus was screened for these derivatives. CONCLUSIONS: Using microwave to synthesise OCT have drastically reduced reaction time, and increased yield. OCT show good antioxidant activity in one of the tests and moderate antimicrobial activity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13065-018-0509-z) contains supplementary material, which is available to authorized users.