Conductance Behavior of Tetraphenyl-Aza-BODIPYs
Andrei Markin, Ali Ismael, Ross J. Davidson, David C. Milán, Richard J. Nichols, Simon J. Higgins, Colin J. Lambert, Yu‐Ting Hsu, Dmitry S. Yufit, Andrew Beeby
Abstract
We studied the electrical conductance of single-molecule junctions formed from molecular wires with four anchor groups. Three tetraphenyl-aza-BODIPYs with four or two thiomethyl anchor groups were synthesized, and their single-molecule conductance was measured using break-junction-STM. Using DFT based calculations these compounds were shown to display a combination of a high and low conductance, depending on the molecule’s connectivity in the junction. A scissor correction is employed to obtain the corrected HOMO–LUMO gaps and a tight binding model (TBM) is used to highlight the role of transport through the pi system of the tetraphenyl-aza-BODIPY central unit. The three higher-conductance geometries follow the sequence 3 > 4 > 2, which demonstrates that their conductances are correlated with the number of anchors.