Subtle conformational-based distinctions in the supramolecular structure of self-assembled monolayers (SAMs) of ω-ferrocenylalkanethiolates on gold (FcC n SAu) have been shown to significantly impact their electrical and redox properties. We investigate the effect of differences in the intermolecular van der Waals interactions and molecular packing energy of FcC n SAu SAMs comprised of an odd (SAM odd ) versus even (SAM even ) number of methylenes on the electrochemical behavior for n = 6−16. Redox-induced thickness changes are investigated by electrochemical surface plasmon resonance (ESPR). Electrochemical impedance spectroscopy (EIS) under non-Faradaic conditions is used to evaluate the dielectric properties of the reduced (neutral) state of the FcC n SAu SAMs. Oxidation of the SAM-bound ferrocenes yields an effective film thickness change of 0.19 ± 0.01 nm, which is attributed to untilting of the alkyl chains. The SAMs manifest odd−even differences in the apparent redox potential, and hence in the thermodynamics of the redox reaction, across the chain lengths n = 6−16 investigated. By contrast, odd−even alternations in the oxidation-induced resonance angle change measured by ESPR and SAM double-layer capacitance determined by EIS are only observed beginning at n = 9 or 10. We show that the odd−even effects in the resonance angle and SAM capacitance are related to a difference in the dielectric constants of SAM odd and SAM even . The chain length dependencies of the measured parameters are discussed in the context of the SAM structure.

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