Observation of Different Molecular Alignments of [Ni(salphen)] Substituted by a Different Number of Octyl Groups at HOPG Surface
作者:Yoshinori Tamaki、Kazuaki Tomono、Yuki Hata、Nanami Saita、Takashi Yamamoto、Kazuo Miyamura
DOI:10.1246/bcsj.20110314
日期:2012.5.15
The surface adsorption structures of two Schiff-base metal complexes, [N,N′-bis(5-octylsalicylidene)-o-phenylenediaminato]nickel(II) (1) and [N,N′-bis(3,5-dioctylsalicylidene)-o-phenylenediaminato]nickel(II) (2), are imaged using scanning tunneling microscopy (STM), and compared with the dimeric structure predicted by single-crystal X-ray diffraction and NMR analyses. STM images of 1 and 2 obtained at an o-dichlorobenzene/HOPG interface showed that 1 was adsorbed in the form of dimers, while 2 was adsorbed as monomers at HOPG surface. The surface structure of 1 was similar to that of the reported salen complex analogue. 1H NMR measurement revealed that the equilibrium constants of dimer formation for 1 and 2 in chloroform-d were determined to be K (= [dimer]/[monomer]2) = 14.5 and 1.9 mol−1 dm3, respectively. This decreased tendency of 2 to form dimer is concluded to be the reason why 2 did not form dimers at HOPG surface. The crystal structure of 1 in which 1 is found to form dimers is also presented.
利用扫描隧道显微镜(STM)对[N,N′-双(5-辛基水杨酰)-邻苯二胺]镍(II)(1)和[N,N′-双(3,5-二辛基水杨酰)-邻苯二胺]镍(II)(2)这两种希夫碱金属配合物的表面吸附结构进行了成像,并与单晶 X 射线衍射和核磁共振分析预测的二聚结构进行了比较、的扫描隧道显微镜(STM)成像,并与单晶 X 射线衍射和核磁共振分析预测的二聚结构进行了比较。在邻二氯苯/HOPG 界面获得的 1 和 2 的 STM 图像显示,1 以二聚体形式吸附,而 2 则以单体形式吸附在 HOPG 表面。1 的表面结构与已报道的沙林络合物类似物相似。1H NMR 测量显示,1 和 2 在氯仿-d 中形成二聚体的平衡常数分别为 K(=[二聚体]/[单体]2)= 14.5 和 1.9 mol-1 dm3。由此推断,2 形成二聚体的趋势减弱是 2 在 HOPG 表面没有形成二聚体的原因。此外,还展示了 1 的晶体结构,其中发现 1 能形成二聚体。