DFT studies of NH---Cl hydrogen bond of amino acid hydrochloride salts in ion channels.

Abstract

Quantum chemical calculations were made, to study NH---Cl hydrogen bonds of two amino acid hydrochloride salts called alanine and threonine. The Nuclear Magnetic Resonance and Nuclear Quadrupole Resonance parameters for nitrogen and chlorine were calculated via four functionals such as, B3LYP, M062X, M06L, and CAM-B3LYP and by applying the 6-311++G(d,p) basis set. One of the functionals produced more accurate results. Geometry optimization was performed using the M062X/6-31++G(d,p) method, and Natural Bond Orbitals analysis was performed by applying the M062X/6-311++G(d,p) level. This study examined Nuclear Magnetic Resonance and Nuclear Quadrupole Resonance parameters with changes in structure from monomer to pentamer and investigated correlations between Natural Bond Orbitals parameters and Nuclear Magnetic Resonance or Nuclear Quadrupole Resonance parameters. The Natural Bond Orbitals parameters were used to investigate changes in structural parameters along with crystal development.