Theoretical studies on the bond strength and electron density characteristics in multiple hydrogen bonded arrays

Multipoint hydrogen bonded motifs with intermolecular N-H⋯N hydrogen bonds have been theoretically studied at the PBE0-D3/ma-def2-TZVP level. The properties of electron density at the bond critical points of hydrogen bonds have been analyzed through "atoms in molecule" (AIM) theory and "electron localization function" (ELF) method. The results imply that the secondary electrostatic interactions have a significant effect to the strength of multipoint hydrogen bonds. Good relationships are found between ρ, ELF parameters and CVB indices. Moreover, they also show good relationships with hydrogen bond distances. These parameters may be treated as universal indicators of the hydrogen bond strength. The investigations would be useful in understanding comprehensively the multipoint hydrogen bonded motifs and helpful in designing the supramolecular systems through multipoint hydrogen bonds.