Oxoanion complexation of nitroisophthalamide receptors: Insights from the DFT calculations

Amide derivative receptors have been designed to investigate the oxoanion complexation ability via hydrogen and halogen bond interactions. Structural, energetic and electronic properties of nitroisophthalamide receptors, i.e., di(benzyl)- (R1), di(hexafluoro)- (R2), di(chloro-,tetrafluoro)- (R3), di(hexachloro)-(R4), di(fluoro-,tetrachloro)-nitroisophthalamide (R5), and their complexes with C₂H₃O₂^-, C₇H₅O₂^-, NO₃^-, H₂PO₄^-, and ClO₄^- oxoanions were computed and obtained using the density functional theory calculations at the B3LYP/6-31G(d,p) theoretical level in gas phase. According to the computed results, all of oxoanions can form the stable complexes with amide receptors R1-R5 via exothermic process in which receptor R1 is found to interact with oxoanions through hydrogen bonds whereas the receptors R2-R5 are found to interact with oxoanion through both of hydrogen and halogen bonds. It is clearly seen that acetate ion displays the strongest complexation interaction with all receptors compared to the other oxoanions. In addition, electronic properties of receptors R1-R5 in both gas and DMSO phases are modified after complexation with oxoanions. Therefore, the designed amide receptors may be potentially used for oxoanion sensing application.