Molecular modifications on β-nitro-styrene derivatives increase their antioxidant capacities

Abstract

• Theoretical and experimental studies using molecular calculation and DPPH evaluation were performed on β-nitro-styrene derivatives. • Four molecular modifications were proposed on benzene or alkene moieties using electron donating groups (EDGs) or electron withdrawing groups (EWGs). • Their antioxidant capacity can be increased by using EDGs substituted on β or para positions. • New derivatives can be proposed. β-Nitro-styrenes among other nitroderivatives are known due to their high electrophilicity and low electron donation capacities. A preferential molecular modification on 1-nitro-2-phenylethene was analyzed by DFT method in B3LYP/6-311++G(2d,2p) level of theory on gas phase seeking to increase its electron donating capacity. For this, four molecular modifications were proposed showing the impact of alkene moiety, substitutions on β or para positions using electron donating groups (EDGs) or electron withdrawing groups (EWGs). The para is the preferential position for methylation when compared to ortho or meta positions. Our results show that EDGs increase the redox capacity in β and para positions and decrease the electrophilicity when compared to EWGs. The increase on electron donation capacity is in accordance with DPPH evaluation and β-nitro-phenylethene derivatives still are poor antioxidants. Therefore, the antioxidant capacity on β-nitro-phenylethene can be increased by using EDGs substituted on β or para positions.