Selective detection of saccharides by fluorescent boronic acid sensors has been the object of active research over the last two decades with numerous experimental reports published. A theoretical study is presented here on pyrene- and anthracene-boronic acid systems and their fluorescent sensing of D-glucose, employing Density Functional Theory and Time-Dependent Density Functional Theory. The difficulties encountered by straight-forward computational approaches are described while it is shown that it is possible to obtain a physically correct description of the photoinduced electron transfer in these systems from diagrams of the molecular orbital energies of the separate donor and acceptor moieties. (C) 2013 Elsevier B.V. All rights reserved.