Integration of Experimental Techniques and Computational Modeling to Elucidate Charge Stabilization Mechanisms of Ferrocene Encapsulated in β-Cyclodextrin

The origin of the redox stabilization of ferrocene (Fc) within β-cyclodextrin (β-CD) remain unclear. In this study, a combination of experimental techniques and computational modeling using Density Functional Theory (DFT) was employed to investigate the β-CD/Fc complex. Both structural and entropic factors play key roles in stabilizing the complex, with the structural confinement within β-CD limiting Fc's chemical reactivity, as evidenced by a lowered formal potential and enhanced redox reversibility accompanied by reduced Fukui index values of cyclopentadienyl rings. When Fc enters the hydrophobic cavity of β-CD, a dynamic stabilization mechanism is initiated. The hydrophobic forces drive Fc into the cavity, displacing water molecules, which increases the system’s entropy and results in a favorable energy change. Once encapsulated, the structural confinement within β-CD restricts Fc's mobility, particularly shielding its reactive iron center. The interaction between Fc's cyclopentadienyl rings and the β-CD cavity, along with the exclusion of solvent, enhances redox stability and reversibility, resulting in a well-stabilized host-guest complex driven by both confinement and entropic gains.