Solvent effect on adsorption of benzylidene oxindole to C20 nanocage: A DFT approach

Abstract

AbstractIn this paper, one of the selective and potent inhibitors named (E)‐3‐benzylidene‐indoline‐2‐one (I), as against different receptor tyrosine kinase in metastasis, angiogenesis, and tumor growth, is inspected in the gas phase and in solution, at B3LYP/6‐311++G** and B3LYP/AUG‐cc‐pVTZ level of theory. A stimulating issue for this biologically active species is the effect of different media on its stability, structure, and energy gap in intermolecular [4 + 2] adsorption of I (as diene) to C20 (as dienophile) to yield (E)‐3‐benzylidene‐indoline‐2‐one[20]fullerene: Ia complex. In going from gas phase to C6H6, C2H4Cl2, EtOH, MeNO2, DMSO, and H2O solvents, individually, the optimization of complex (Ia) leads to the following: (1) The thermodynamic stability; the adsorption energy difference between liquid and gas phase (∆El–g) and dipole moment (μ) seem proportional to the dielectric constant (ε) of the scrutinized media. (2) The kinetic stability; energy difference (∆EL–H) between the frontier molecular orbitals; FMO in different media is altered in the opposite direction of ε. (3) Despite of popular belief that the endo isomer emerges thermodynamically more stable than its corresponding exo isomer, we suggest formation of kinetically more stable exo isomer because of π–π stacking among the benzyl ring and C20 nanocage. (4) The possibility of hetero [4 + 2] cycloaddition is anticipated by the lowest energy barrier of 3.8 kcal/mol probed for exo transition state (TS) in gas phase, while the highest energy barrier of 7.9 kcal/mol corresponds to the endo TS in water. (5) Due to lack of the repulsion type interaction, the exo [4 + 2] cycloaddition of unstable C20 fullerene with the scrutinized oxindole can be carried out thermally at r.t. and currently hold responsible for the origin of stereoselectivity.