Unraveling weak interactions in aniline-pyrrole dimer clusters

Abstract

Weak intermolecular interactions in aniline-pyrrole dimer clusters have been studied by the dispersion-corrected density functional theory (DFT) calculations. Two distinct types of hydrogen bonds are demonstrated with optimized geometric structures and largest interaction energy moduli. Comprehensive spectroscopic analysis is also addressed revealing the orientation-dependent interactions by noting the altered red-shifts of the infrared and Raman activities. Then we employ natural bond orbital (NBO) analysis and atom in molecules (AIM) theory to have determined the origin and relative energetic contributions of the weak interactions in these systems. NBO and AIM calculations confirm the V-shaped dimer cluster is dominated by N−H···N and C−H···π hydrogen bonds, while the J-aggregated isomer is stabilized by N−H···π, n→π* and weak π···π* stacking interactions. The noncovalent interactions are also demonstrated via energy decomposition analysis associated with electrostatic and dispersion contributions.