Density Functional Theoretical Study on Redox-Dependent Hydrogen Bonding between Amide and Arylurea

摘要

The responses of chemical systems to changes in external stimuli such as pressure, temperature, electrons, photons, and chemicals are important aspects of supramolecular chemistry, which has found applications in the sensor, molecular electronics, and molecular machine fields, to name a few. Furthermore, hydrogen bonding is one of the most important molecular interactions in terms of these applications. Generally, the reduction of a receptor leads to the formation of a radical anion, which binds more strongly to substrates than the neutral parent molecule. We previously reported the results of a theoretical study on nitrobenzene/urea hydrogen bonding, in which it was found that a computational model based on density functional theory (DFT) produced an excellent correlation with experimental data. Recently, Woods et al. described redox-switched hydrogen bonding between amide and diaryl-urea. Unlike other studies on redox-dependent hydrogen bonding, their system is based on oxidation rather than reduction. 1,4-dimethylpiperizine-2,3-dione (PZD), which has two pre-organized hydrogen acceptor atoms, can form intermole-cular hydrogen bonds with both urea NH's. In the context of redox-switching, the dependence of strength of bonding upon changes in external stimuli is of great importance. We performed DFT calculations on these hydrogen bonding pairs and correlated the results with the experimental data.