Li Zhenyu, Kosov Daniel S
Department of Chemistry and Biochemistry, University of Maryland, College Park, 20742, USA.
J Phys Chem B. 2006 May 25;110(20):9893-8. doi: 10.1021/jp0610665.
Recent experimental realization [J. Am. Chem. Soc., 127 (2005) 7328] of various dithiocarbamate self-assembly on gold surface opens the possibility for use of dithiocarbamate linkers to anchor molecular wires to gold electrodes. In this paper, we explore this hypothesis computationally. We computed the electron transport properties of 4,4'-bipyridine (BP), 4,4'-bipyridinium-1,1'-bis(carbodithioate) (BPBC), 4-(4'-pyridyl)-peridium-1-carbodithioate (BPC) molecule junctions based on the density functional theory and nonequilibrium Green's functions. We demonstrated that the stronger molecule-electrode coupling associated with the conjugated dithiocarbamate linker broadens transmission resonances near the Fermi energy. The broadening effect along with the extension of the pi conjugation from the molecule to the gold electrodes lead to enhanced electrical conductance for BPBC molecule. The conductance enhancement factor is as large as 25 at applied voltage bias 1.0 V. Rectification behavior is predicted for BPC molecular wire junction, which has the asymmetric anchoring groups.
最近在金表面上各种二硫代氨基甲酸盐自组装的实验实现[《美国化学会志》，127 (2005) 7328]为使用二硫代氨基甲酸盐连接体将分子线锚定到金电极上开辟了可能性。在本文中，我们通过计算探索了这一假设。我们基于密度泛函理论和非平衡格林函数计算了4,4'-联吡啶（BP）、4,4'-联吡啶鎓-1,1'-双（碳二硫代酸酯）（BPBC）、4-(4'-吡啶基)-哌啶-1-碳二硫代酸酯（BPC）分子结的电子传输性质。我们证明，与共轭二硫代氨基甲酸盐连接体相关的更强的分子-电极耦合拓宽了费米能级附近的传输共振。这种拓宽效应以及从分子到金电极的π共轭的延伸导致BPBC分子的电导增强。在施加电压偏置1.0 V时，电导增强因子高达25。对于具有不对称锚定基团的BPC分子线结，预测了整流行为。
