Role of aromatic π-bridge on electron transport property in a donor-bridge-acceptor system: A computational study on frontier molecular orbitals

Density functional calculations are performed to analyze the conduction process through various aromatic bridges in a donor-bridge-acceptor molecular wire through frontier molecular orbital analysis. The systematic study on the molecular orbital populations shows that when five-membered hetero-aromatic rings (electron-rich aromatic rings) are inserted in the conduction path between the donor-acceptor complex, a large decrease in the potential barrier (PB) is observed as compared to the six-membered hetero-aromatic ring (electron-deficient aromatic ring) inserted molecular systems. In addition, the systematic variation of the PB with various donor/acceptor substitution and increasing the number of intervening bridging aromatic rings in these molecular systems clearly points out to a structure-property correlation which will be further helpful in designing new polymeric/oligomeric molecular wires.