Intramolecular hydrogen bonding, π-π stacking interactions, and substituent effects of 8-hydroxyquinoline derivative supermolecular structures: a theoretical study.

Quantum chemical calculations have been performed to gauge intramolecular hydrogen bonding and π-π stacking interactions of 8-hydroxyquinoline (8-HQ) derivatives (substituents X = OH, CH3, H, F, Cl, CF3, CN, NO2) supermolecular structures. The effects of substituents on 8-HQ derivatives have also been studied with the M06-2X method and 6-311++G** basis set. The basis set superposition error (BSSE)-corrected binding energies (ΔE), hydrogen bonding distances (rH···N), and intermolecular distance (d┻) were calculated with corresponding Hammett electronic parameters (σ). The topological parameters (ρ, ∇ρ2) and energy of intramolecular hydrogen bonding interaction (EH···N) of these π-π stacking 8-HQ derivatives have been studied by using atoms in molecules (AIM) theory. The electrostatic potential (ESP) analysis has been applied to gain the most negative and the most positive electrostatic potential V(r) values (Vs,min and Vs,max). It can be found that there are good relationships between the Hammett constants and the Vs,min values.