Modulating Outer‐Sphere Electron Transfer in Cobalt(III) Metallo‐Surfactants Using Ionic Liquids and Lipid Vesicles

ABSTRACT This research examines the impact of the ionic liquid 1‐butyl‐3‐methylimidazolium bromide ([Bmim]Br) and DPPC (1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine) vesicles on the kinetics of outer‐sphere electron transfer (OSET) inside cobalt(III) metallo‐surfactant systems. The systems studied were 1 cis ‐[Co(A1) 2 (A) 2 ](ClO 4 ) 3 , 2 cis ‐[Co(A2) 2 (A) 2 ](ClO 4 ) 3 , and 3 cis ‐[Co(A3) 2 (A) 2 ](ClO 4 ) 3 , (where A1 = imidazo[4,5‐f][1,10]phenanthroline, A2 = dipyrido[3,2‐d:2′‐3′‐f]quinoxaline, A3 = dipyrido[3,2‐a:2′,4′‐c]phenazine, and A = Dodecylamine) alongside [Fe(CN) 6 ] 4− ions. Kinetic data conducted across various concentrations of DPPC and [Bmim]Br, as well as different temperatures, validate a second‐order OSET mechanism. The electron‐transfer rate constants rise in direct correlation with [Bmim]Br concentration, indicating the influence of ionic liquid‐induced microenvironmental effects. Conversely, DPPC vesicles impede the reaction below their phase transition temperature due to limited reactant mobility, whereas they accelerate the rate beyond the transition due to enhanced membrane fluidity and advantageous reactant arrangement. Activation parameters obtained from OSET theory indicate negative ΔS ‡ values, signifying a more ordered transition state. The results illustrate how ionic liquids (ILs) and lipid assemblies can affect electron‐transfer kinetics via regulated self‐aggregation, hydrophobic interactions, and reactant placement. The results provide insights for the rational design of metallo‐surfactant systems in catalysis, biomimetic redox processes, and soft‐matter electrochemistry, supporting SDG goals through advances in sustainable electron‐transfer control.