A DFT Insight into Structure, NBO, NCI, QTAIM, Vibrational, and NLO Properties of Cationic Amino Acid Ionic Liquid [Pro-H] + BF 4 −

The structure, bonding, and nature of interactions present in monomeric and dimeric ionic liquid [Pro-H] + BF 4 − have been investigated. The electrochemical stability of [Pro-H] + BF 4 − was studied. The results of the NBO analysis show the significant delocalization and hyperconjugation interactions. The dimeric ionic liquid (IL) exists in a strongly associated structure with a number of hydrogen bonds. The results of RDG analysis of monomeric and dimeric ionic liquid show the presence of hydrogen bond interactions, repulsive interactions, and Van der Waals interactions between cation and anion. The AIM analysis of monomeric and dimeric ionic liquid was performed to understand the nature of non-covalent interactions and their strength. The FMO analysis indicates better charge transfer in dimeric ionic liquid. Vibrational analysis was performed to understand the structure of monomeric ionic liquid. NLO properties were also investigated, and results show that ionic liquid can act as potential NLO material. The molar refractivity of ionic liquid was also calculated.