Computational study of charge transfer iso-surface in first three excited states, electron-hole transition effects, chemical nature and bond order analysis investigations of chrysogine

Abstract

This work presents the theoretical DFT (Density Functional Theory) studies and the biological application of chrysogine, a marine alkaloid. Energy minimisation and additional DFT evaluations were performed for vacuum and solvent media. It has been observed that solvation with polar solvents has resulted in a slight variation in the molecule’s properties. The Multiwfn software was employed to carry out various topological analyses. Among these, the charge transfer studies show that the second and third excited states are the most significant. From the reactivity analysis, the least energy gap (4.9624 eV) is obtained in water, indicating that chrysogine is most reactive in aqueous media. Theoretical UV studies show that the trends in λmax values correspond to n -->π* and n -->σ* electronic transitions within the molecule. An increase in medium polarity has demonstrated in the MEP (Molecular Electrostatic Potential) maps an increase in the potential range from −6.619 × 10−2 a.u. to 6.619 × 10−2 a.u. in the gas phase, to a sharp rise to −8.036 × 10−2 a.u. to 8.036 × 10−2 a.u. in ethanol, −8.098 × 10−2 a.u. to 8.098 × 10−2 a.u. in methanol, −8.130 × 10−2 a.u. to 8.130 × 10−2 a.u. in DMSO, and −8.127 × 10-2 a.u. to 8.127 × 10−2 a.u. in water. The most significant transition contributing to molecular stability from NBO (Natural Bond Orbital) analysis is: (O2-C9) π* → π* (C7-C8) with the energy of 258.13 kcal mol−1. The ADMET profile for the molecule was assimilated with the help of online servers. The molecule was docked against lung cancer target proteins (PDB ID: 1NTK, 3QFB) using software such as AutoDock Tools and PyMOL. The respective illustrations and data were visualised using Discovery Studio Visualizer. Good binding affinities (−5.69 kcal mol−1 for 1NTK and −6.64 kcal mol−1 for 3QFB proteins) and interactions were achieved with the selected targets.