Self-assembled monolayers of tetrathiafulvalene derivatives on Au(111): Organization and electrical properties
Self-assembled monolayers of tetrathiafulvalene derivatives on Au(111): Organization and electrical properties
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DOI：
10.1021/jp0495949
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发表时间：
2004-06-03
影响因子：
3.3
通讯作者：
Lindsay, SM
中科院分区：
文献类型：
--
作者：
Gomar-Nadal, E;Ramachandran, GK;Lindsay, SM
制备了不对称四硫富瓦烯（TTF）衍生物在金（111）表面形成的自组装单分子膜（SAMs），并对其结构和电学性质进行了研究。TTF通过两个S-Au键与金属结合，而另一个“末端”带有两个长烷基链。基于组合的表面表征技术，包括椭偏仪，FTIR，接触角，STM和AFM的观察表明，这些单分子层是无序的或至少松散地堆积在横向尺寸。通过这些分子SAM的传导是非常高的，因为连接到TTF单元的“绝缘”烷基链的长度为15-20埃的量级，这种情况部分地由分子相对于表面的倾斜取向和烷基链的松散堆积结构引起。电流媲美共轭候选人的“分子线”，如胡萝卜素二硫醇和低聚亚苯基乙炔观察。SAM中单个分子的电阻，使用c-AFM在双末端几何结构中确定，估计为25.7 +/- 0.3 GOmega。
Self-assembled monolayers (SAMs) formed by dissymmetric tetrathiafulvalene (TTF) derivatives on gold (111) are prepared, and the structural and electrical properties have been studied. The TTFs are united to the metal through two S-Au bonds while the other "end" bears two long alkyl chains. Observations based on a combination of surface characterization techniques including ellipsometry, FTIR, contact angle, STM, and AFM suggest that these monolayers are disordered or at least loosely packed in the lateral dimensions. Conduction through these molecular SAMs is remarkably high given that the length of the "insulating" alkyl chains attached to the TTF unit is on the order of 15-20 Angstrom, a situation that arises in part from the tilted orientation of the molecules with respect to the surface and the loosely packed structure of the alkyl chains. Currents rivaling those in conjugated candidate "molecular wires" such as carotene dithiols and oligo-phenylene-ethynylenes are observed. The resistance of a single molecule in a SAM, determined in a two-terminal geometry using c-AFM, is estimated to be 25.7 +/- 0.3 GOmega.