Experimental and Theoretical Studies of Substituent Effects in Hydrogen Bond Based Molecular Recognition of a Zwitterion by Substituted Arylureas

Article abstract of DOI:10.1016/0040-4020(94)00921-G

Electron withdrawing groups have a strong effect on hydrogen bonding to aryl ureas.The effect of para substituents modestly exceeds the effect of meta substituents.Among common substituent parameters, ?^- (ρ = 1.77, r² = 0.988) is found to be the best predictor for the observed effects of para substituents in aryl ureas.Semi-empirical and ab initio methods are used to calculate charge distributions in substituted benzene derivatives and in these ureas.A comparison of experimental and predicted (AM1, STO3G, 321-G*, 631-G**) dipole moments of benzene derivatives is presented.It is shown that calculated surface electric potentials for these thioureas succesfully predict the relative hydrogen bonded association energies.