Shaporenko A, Heister K, Ulman A, Grunze M, Zharnikov M
Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
J Phys Chem B. 2005 Mar 10;109(9):4096-103. doi: 10.1021/jp040667y.
Self-assembled monolayers (SAMs) formed from 4'-substituted 4-mercaptobiphenyls X-(C6H4)2SH (X-BPT, with X = I, Cl, and F) on polycrystalline (111) gold and silver substrates have been characterized by synchrotron-based high-resolution X-ray photoelectron spectroscopy and angle-resolved near-edge X-ray absorption fine structure spectroscopy. The X-BPT molecules were found to form highly oriented and densely packed SAMs on both substrates, with a smaller molecular inclination in the case of Ag. The experimental data show clear evidence for the charge transfer between the 4'-substituent and biphenyl moieties with the direction and extent of the transfer depending on the electronegativity of the halogen substituent. At the same time, no direct evidence of the charge transfer between the 4'-substituent and the thiolate group was observed. However, the substitution of the 4'-hydrogen by a halogen atom seems to affect the detailed packing arrangements of the SAM constituents.
由4'-取代的4-巯基联苯X-(C6H4)2SH（X-BPT，其中X = I、Cl和F）在多晶（111）金和银基底上形成的自组装单分子层（SAMs），已通过基于同步加速器的高分辨率X射线光电子能谱和角分辨近边X射线吸收精细结构光谱进行了表征。发现X-BPT分子在两种基底上均形成高度取向且紧密堆积的SAMs，在银的情况下分子倾斜度较小。实验数据清楚地证明了4'-取代基与联苯部分之间的电荷转移，转移的方向和程度取决于卤素取代基的电负性。同时，未观察到4'-取代基与硫醇盐基团之间电荷转移的直接证据。然而，用卤原子取代4'-氢似乎会影响SAM成分的详细堆积排列。
