Design, Synthesis, and Multiscale Computational Evaluation of Ferrocenyl Acetylaniline Derivatives Targeting Oxidative Stress-Related Enzymes

Abstract

This thesis reports the synthesis, physicochemical characterisation and in silico evaluation of a series of ferrocenyl acetylaniline derivatives (FcMe2Ac, FcMe3Ac and FcMe4Ac), with the objective of elucidating the relationship between molecular structure, electronic properties and interaction behaviour. The target compounds were successfully synthesised via a nucleophilic substitution approach and isolated in good yields ranging from 48% to 80%. Structural confirmation was achieved using FT-IR, UV–Visible spectroscopy and nuclear magnetic resonance (¹H, ¹³C and 2D NMR). The FT-IR spectra revealed characteristic absorption bands corresponding to N–H stretching (~3290–3445 cm⁻¹) and carbonyl groups (~1647–1651 cm⁻¹), while UV–Visible analysis showed absorption maxima in the range of 259–432 nm, associated with π→π* and d–d transitions. NMR analysis confirmed the expected structural features, including signals for the ferrocenyl unit (~4.1–4.3 ppm) and aromatic protons (~6.6–7.8 ppm). Electrochemical investigations using cyclic voltammetry demonstrated a quasi-reversible Fe(II)/Fe(III) redox process, with formal potentials of 43.9, 51.0 and 57.5 mV for FcMe2Ac, FcMe3Ac and FcMe4Ac, respectively. Peak-to-peak separations (ΔEp = 87.8–115 mV) and current ratios close to unity confirmed quasi-reversible behaviour. Diffusion coefficients ranged from 1.11 × 10⁻⁷ to 5.74 × 10⁻⁷ cm²·s⁻¹, while heterogeneous electron-transfer rate constants (kₛ) varied from 0.14 × 10⁻³ to 0.62 × 10⁻³ cm·s⁻¹, reflecting the influence of substitution on transport and kinetic properties. Density functional theory calculations revealed HOMO energies between −5.83 and −5.68 eV and HOMO–LUMO gaps ranging from 3.99 to 4.29 eV, indicating moderate chemical stability and reactivity. Global reactivity descriptors showed hardness values between 1.995 and 2.143 eV and electrophilicity indices up to 3.519 eV, while dipole moments increased from 3.82 to 5.12 D, reflecting enhanced molecular polarity. Molecular docking studies indicated favourable binding affinities, with binding energies ranging from −7.05 to −8.36 kcal·mol⁻¹, where FcMe4Ac exhibited the strongest interaction. Molecular dynamics simulations (100 ns) confirmed the stability of the FcMe4Ac–protein complexes, with RMSD values stabilising around 0.10–0.25 nm and reduced residue fluctuations, indicating a stable binding mode. ADMET predictions demonstrated favourable pharmacokinetic profiles, including high gastrointestinal absorption, LogP values between 3.12 and 3.45, and no predicted mutagenic or hepatotoxic effects. Overall, the results demonstrate that structural modification of ferrocenyl derivatives significantly influences their electronic properties, electrochemical behaviour and interaction profiles. Among the studied compounds, FcMe4Ac emerged as the most promising candidate, combining favourable redox properties, strong binding affinity, high dynamic stability and suitable pharmacokinetic characteristics.