Selective fructose transport through supported liquid membranes containing diboronic acid or conjugated monoboronic acid-quaternary ammonium carriers.

The design and preparation of two new classes of boronic acid carriers is described along with an evaluation of their abilities to extract and transport the commercially important sugars, fructose, glucose, and sucrose through polymer supported liquid membranes. Transport fluxes with diboronic acid carriers are lower than those observed with monoboronic acids. However, fructose selectivity is improved when the diboronic linker group allows the formation of a 1:1 macrocyclic complex. A conjugated monoboronic acid-quaternary ammonium carrier facilitates fructose transport about twenty times better than an analogous monoboronic acid/quaternary ammonium mixture. The rate-determining step for the transport is diffusion through the membrane. (C) 1999 Elsevier Science Ltd. All rights reserved.