The conductance and current-induced fluorescence of a single distyryl-benzene and a single distyryl-paracyclophane molecule in a tunneling junction is simulated. Our approach is formulated in terms of the electronic states of the neutral and charged molecular bridge and is applied to calculate the effective tunneling rates. We find that an orbital picture is adequate for describing the conductance of distyryl-benzene; however, a many-electron picture is needed for the paracyclophane linked complex. A strategy for maximizing electroluminescence by controlling the voltage drop across the junction through chemical modification of the molecular bridge is suggested. (C) 2007 Elsevier B.V. All rights reserved.