Synthesis, crystal structure and thermal investigation of molecular salts of ( R )-1-phenylethanamine combined with quantum chemical studies

Molecular salts (R)-1-phenylethanaminium oxalate ( 1 ), (R)-1-phenylethanaminium 2-carboxy-4,6-dinitrophenolate ( 2 ) and (R)-1-phenylethanaminium 4-methylbenzenesulfonate ( 3 ) were synthesized and characterized by1H, 13C{1H} NMR and FT-IR spectra. The structures of [C8NH12]2 +[C2O4]2-( 1 ), [C8NH12] +[C7H3N2O7]- (2)and [C8NH12] +[C7H7SO3]- ( 3 ) were confirmed by single crystal X-ray diffrac-tion which belonging to monoclinic, triclinic and orthorhombic crystal systems with the Flack parameter (x)-0.3(8), 0.9(6) and 0.05(10) respectively. The salt 1 forms a three dimensional structure comprising N-H middotmiddotmiddotO hydrogen bonds and C-H middotmiddotmiddot pi interactions, while, in 2 , strong O-H middotmiddotmiddotO and N-H middotmiddotmiddotO hydrogen bonds along with C-H middotmiddotmiddotO and pi middotmiddotmiddot pi interactions lead to a three-dimensional architecture, and in 3 , the N-H middotmiddotmiddotO hydrogen bonds generate one-dimensional ribbon framework. The qualitative and quantitative confirma-tion of the presence of various interactions in 1, 2 and 3 were made by Hirshfeld surface analyses. Ther-mogravimetric analysis was performed to know their thermal stability. Density functional theory was performed to outline the optimized structure, the frontier molecular orbitals, reactive parameters, and molecular electrostatic potential. Natural bonding orbitals (NBO) analysis was carried out to study the donor-acceptor atom interactions contributing to the stabilization of the crystal structure. The topology analysis (QTAIM and NCI) gave further insights into understanding the attractive and repulsive types of interactions exhibited by the molecule.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Molecular salts were synthesized and characterized using NMR and spectroscopy. The crystal structures of the salts were determined by X-ray diffraction, and the intermolecular interactions were confirmed by Hirshfeld surface analysis. The thermal stability of the salts was investigated by thermogravimetric analysis, and the optimized structures and molecular properties were studied using density functional theory.