Synthesis, crystal structures, Hirshfeld surface analysis, and quantum chemistry calculations of two novel hydrous long-chain dibasic ammonium salts CnH2(n+4)N2O6 (n = 31 and 33)

Abstract

The synthesis of long-chain single-crystal compounds is a gordian knot. Through the salification reaction of carboxylic acid, long-chain n-alkanoic acid was successfully connected at both ends of 1,3-propylene diamine, and the carbon chain of long-chain n-alkanoic acid was doubled. Hydrous 1, 3-propanediamine ditetradecanoate (abbreviated as 3C14) and 1, 3-propanediamine dipentadecanoate (abbreviated as 3C15) were successfully synthesized. The crystal structures of the two compounds were characterized by X-ray single-crystal diffraction. The molecular structure and crystal structure of the two compounds were analyzed, and their composition, spatial structure, and coordination mode were determined. Hirshfeld surface analysis revealed the intermolecular interaction of the two title compounds. The 3D energy framework enabled the intermolecular interaction to be presented more intuitively and digitally, in which dispersion energy can play a leading role. The energy values of HOMO and LUMO of the two title compounds were calculated, and their energy gaps were 0.2947 eV and 1.6286 eV, respectively. The charge distributions in the compounds were visualized using a molecular electrostatic potential (ESP) surface. ESP maps indicated that the electrophilic sites are localized around the oxygen atom. The crystallographic data and parameters of quantum chemical calculation in this paper will provide data and theoretical support for the development and application of such materials.