Photomodulation of Transport Rates in Liquid Membranes Containing Photoactive Carriers

Abstract

A steady-state model describing photofacilitated transport in liquid membranes is used to consider photoactive carriers with a wide range of thermodynamic and kinetic properties in order to calculate photoinduced modulation in the transport rates of solutes, a phenomenon known as photomodulation. Most experimental and theoretical studies have focused on systems in which strongly binding forms of the carrier and carrier−solute complex absorb light to convert to weakly binding forms. For such systems, absorption of light can cause photomodulation increases up to a factor of 3. However, the maximum photoefficiencies are only a few percent, where photoefficiency is defined as the difference between the flux under illumination and in the dark divided by the incident photon flux. Conversely, if the weakly binding forms of the carrier and complex are photoactive, photomodulation increases of a factor of 20 can be achieved, along with photoefficiencies well over 10%. This study provides guidelines for the selecti...