Otsuki Joe, Ohya Chiaki, Komatsu Yuji, Morisaki Takuya
Department of Applied and Materials Chemistry, College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan.
J Nanosci Nanotechnol. 2012 Jan;12(1):159-66. doi: 10.1166/jnn.2012.5137.
We have prepared a novel sandwich-type double-decker porphyrin complex with cerium, in which one of the porphyrins has long alkyl chains and the other has a pendant free-base porphyrin unit. The preparation of the complex was achieved with a Sonogashira coupling reaction between a preformed double-decker complex bearing an ethynyl moiety and an iodophenyl porphyrin. This complex forms moderately ordered self-assembled monolayers at the interface of 1-phenyloctane and highly oriented pyrolytic graphite. STM images with submolecular resolution revealed that the double-decker complexes form monolayers through adsorption of the alkyl-substituted porphyrin unit, presenting the other porphyrin having the additional porphyrin unit to the solution. All molecules are oriented in the same direction within single ordered domains. The double-decker complex and the corresponding free-base porphyrin form mixed monolayers due to their common adsorbing group and the matching unit cell parameters. The high spots for the double-decker cores are accompanied by lower spots, which can be assigned as the pendant free-base porphyrin units, revealing that the double-decker complexes predominantly take perpendicular orientation, in which the additional porphyrin unit orients perpendicular to the molecular row. Both the double-decker complex and the free-base porphyrin adsorb on the surface initially after the mixture was deposited, but the double-decker complex is gradually replaced by free-base porphyrin toward the thermodynamically stable assembly, in which the free-base porphyrin predominates. This behavior is unique to this particular complex among some analogous complexes with the same adsorbing group, which implies that groups not directly involved in adsorption may have profound effects on the adsorption and assembling properties of the molecule.
我们制备了一种新型的含铈夹心型双层卟啉配合物，其中一个卟啉带有长烷基链，另一个带有一个游离碱卟啉侧基单元。该配合物的制备是通过一个预先形成的带有乙炔基部分的双层配合物与一个碘苯基卟啉之间的Sonogashira偶联反应实现的。这种配合物在1-苯基辛烷与高度取向热解石墨的界面处形成中等有序的自组装单分子层。具有亚分子分辨率的STM图像显示，双层配合物通过烷基取代卟啉单元的吸附形成单分子层，使另一个带有额外卟啉单元的卟啉朝向溶液。在单个有序区域内，所有分子都沿相同方向取向。由于其共同的吸附基团和匹配的晶胞参数，双层配合物和相应的游离碱卟啉形成混合单分子层。双层核心的高亮点伴随着较低的亮点，可将其归属于游离碱卟啉侧基单元，这表明双层配合物主要采取垂直取向，其中额外的卟啉单元垂直于分子行取向。在混合物沉积后，双层配合物和游离碱卟啉最初都吸附在表面，但双层配合物逐渐被游离碱卟啉取代，朝着热力学稳定的组装体转变，其中游离碱卟啉占主导。在一些具有相同吸附基团的类似配合物中，这种行为是这种特定配合物所独有的，这意味着不直接参与吸附的基团可能对分子的吸附和组装性质有深远影响。
