Evidences of noncovalent interactions between indole and dichloromethane under different solvent conditions

Context Theoretical investigation of indole (IND) and its binary combination with dichloromethane (DC) in various solvents were computed to track the impact of molecular interactions on spectral characteristics. When transitioning from plain drug to complexes, different modes of IND display a substantial shift in peak location. The 3561.26 cm(-1) band shows (similar to 15.58 cm(-1)) red shift upon dilution. The geometry in various solvents was calculated using quantum chemical calculation utilizing density functional theory (DFT). The highest ALIE values are located at the indole skeleton and on complexation with DC, and the ring atoms become more electron rich. The atom-centered density matrix propagation (ADMP) molecular dynamic (MD) calculation shows that the geometries optimized through the DFT calculation match the global minima effectively. MD simulations indicate that indole is more stable in water and methanol. Methods DFT studies have been employed to study the interaction between indole and dichloromethane. CAM-B3LYP/6-311++ G(d)(6D,7F) level of theory was employed using Gaussian 16 W suite. Quantum topological descriptors were discussed using quantum theory of atoms in molecules (QTAIM) with the help of Multiwfn software. Reduced density gradient (RDG) plot describes the nature of the interaction, while average local ionization energy (ALIE) explained the variation in local ionization energy of the molecular surface before and after complexation.

Automated summary

The theoretical investigation reveals that the molecular interactions between indole and dichloromethane in different solvents have a significant impact on the spectral characteristics. The peak locations of indole undergo substantial shifts upon complexation, with the 3561.26 cm(-1) band showing a red shift of approximately 15.58 cm(-1). Quantum chemical calculations based on density functional theory (DFT) were used to determine the geometry in various solvents. Molecular dynamic simulations indicate that indole is more stable in water and methanol.