Measurement of Through-Space Dipole-Dipole Coupling from Shifts in VibrationalFrequencies for a Stilbazolium Derivative Embedded in a Self-Assembled Monolayer

摘要

Self assembled monolayers (SAM's) were produced from the spontaneous adsorptionof a thiol bearing stilbazoliam derivative and dodecanethiol. A range of mole fractions in the solutions from which these SAM's were produced used to give monolayers with varying amounts of the stilbazolium derivative and the n-alkyl thiol. The relatively large dipole moment of the stilbazolium derivative leads to dipole dipole coupling between these derivatives, as demonstrated from shifts in the vibrational frequencies of certain normal modes of this compound. The magnitude and surface coverage dependence of these shifts indicate that this dipole dipole coupling is due to a through space, electrostatic interaction between the immobilized dipoles. This study comprises the first experimental demonstration of this phenomenon in monolayers supported on solid substrates.