Ng Zhaoyue, Loh Kian Ping, Li Liqian, Ho Peter, Bai Ping, Yip John H K
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
ACS Nano. 2009 Aug 25;3(8):2103-14. doi: 10.1021/nn900570v.
Organometallic wires are interesting alternatives to conventional molecular wires based on a pure organic system because of the presence of d orbitals in the transition metal complex. However, synthetic problems, such as decreased stability of the compounds when labile metal complexes are present, often impede their isolation in a pure state and preclude a rapid development of such hybrid molecular wires. In this work, we show that preassembled self-assembled monolayers (SAM) based on pyridine-terminated 1-((4-acetylthiophenyl)ethynyl)-4-((4-pyridyl)ethynyl)benzene can act as a template for the architectural build up of a second layer of transition metal complexes to form an array of organometallic molecular wires on gold. Ru(II)(terpy)(bipy)(2+) (terpy = 2,2':6',2''-terpyridine and bipy = 2,2'-bipyridine) or cyclometalated Pt(II)(pbipy) (pbipy = 6-phenyl-2,2'-bipyridine) were axially coordinated onto the organic SAM via its terminal pyridinium moieties. Current-voltage studies show that the electronic coupling between the transition metal and organic wire produces a molecular wire that exhibits higher conductance than the original organic chain. The presence of the transition metal complexes in the hybrid molecular wire introduces distinctive negative differential resistance (NDR) effects.
由于过渡金属配合物中存在d轨道，有机金属线是基于纯有机体系的传统分子线的有趣替代物。然而，合成问题，例如当存在不稳定金属配合物时化合物稳定性降低，常常阻碍它们以纯态分离，并妨碍这种杂化分子线的快速发展。在这项工作中，我们表明基于吡啶封端的1-((4-乙酰基硫代苯基)乙炔基)-4-((4-吡啶基)乙炔基)苯的预组装自组装单分子层（SAM）可以作为过渡金属配合物第二层结构构建的模板，以在金上形成有机金属分子线阵列。Ru(II)(terpy)(bipy)(2+)（terpy = 2,2':6',2''-三联吡啶，bipy = 2,2'-联吡啶）或环金属化的Pt(II)(pbipy)（pbipy = 6-苯基-2,2'-联吡啶）通过其末端吡啶鎓部分轴向配位到有机SAM上。电流-电压研究表明，过渡金属与有机线之间的电子耦合产生了一种分子线，其表现出比原始有机链更高的电导率。杂化分子线中过渡金属配合物的存在引入了独特的负微分电阻（NDR）效应。
