Infrared spectroscopy of three-dimensional self-assembled monolayers: N-alkanethiolate monolayers on gold cluster compounds
Infrared spectroscopy of three-dimensional self-assembled monolayers: N-alkanethiolate monolayers on gold cluster compounds
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DOI：
10.1021/la960249n
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发表时间：
1996-07-24
期刊：
影响因子：
3.9
通讯作者：
Murray, RW
中科院分区：
文献类型：
--
作者：
Hostetler, MJ;Stokes, JJ;Murray, RW
利用透射红外光谱研究了纳米金团簇吸附的烷硫酸酯单层膜的结构。丙硫醚和四硫醚之间的烷基链长不同；特别是C3、C4、C5、C6、C7、C8、C10、C12、C16、C20和C24烷硫酸酯作为固体悬浮液在KBr颗粒中进行了研究。研究发现，较小的链长（C3、C4和C5）相对无序，存在大量的间扭式缺陷，因此最像液态的游离烷烃。长度较长的烷硫酸酯主要呈全反式之字形构象。可检测到的近表面间扭式缺陷数量随链长增加而减少，端间扭式缺陷比例相当高，其相对数量随链长增加而增加。无法检测到内部间扭性缺陷。提出了一个模型来解释这些观察结果，并将数据与自组装到更传统的二维系统上的烷硫代酸酯收集的数据进行了比较。
Transmission infrared spectroscopy has been used to probe the structure of alkanethiolate monolayers adsorbed onto nanometer-sized gold clusters. The alkyl chain lengths vary between propanethiolate and tetracosanethiolate; specifically the C3, C4, C5, C6, C7, C8, C10, C12, C16, C20, and C24 alkanethiolates have been examined as solid suspensions in KBr pellets. It has been found that the smaller chain lengths (C3, C4, and C5) are relatively disordered, with large amounts of gauche defects present, and thus most resemble the free alkanes in the liquid state. The longer length alkanethiolates are predominantly in the all trans zigzag conformation. There are detectable amounts of near surface gauche defects, the amount of which decreases with increasing chain length, and a reasonably high percentage of end-gauche defects, the relative amount of which increases with increasing chain length. Interanl gauche defects cannot be detected. A model is proposed to explain these observations, and the data are compared with that collected for alkanethiolates self-assembled onto the more traditional two-dimensional systems.