STM Study of Au(111) Surface-Grafted Paramagnetic Macrocyclic Complexes [Ni2L(Hmba)]+ via Ambidentate Coligands

详细信息    查看全文

• 作者：Christian Salazar ; Jochen Lach ; Florian Rückerl ; Danny Baumann ; Sebastian Schimmel ; Martin Knupfer ; Berthold Kersting ; Bernd Büchner ; Christian Hess
• 刊名：Langmuir
• 出版年：2016
• 出版时间：May 10, 2016
• 年：2016
• 卷：32
• 期：18
• 页码：4464-4471
• 全文大小：550K
• 年卷期：0
• ISSN：1520-5827

文摘

Molecular anchoring and electronic properties of macrocyclic complexes fixed on gold surfaces have been investigated mainly by using scanning tunnelling microscopy (STM) and complemented with X-ray photoelectron spectroscopy (XPS). Exchange-coupled macrocyclic complexes [Ni₂L(Hmba)]⁺ were deposited via 4-mercaptobenzoate ligands on the surface of a Au(111) single crystal from a mM solution of the perchlorate salt [Ni₂L(Hmba)]ClO₄ in dichloromethane. The combined results from STM and XPS show the formation of large monolayers anchored via Au–S bonds with a height of about 1.5 nm. Two apparent granular structures are visible: one related to the dinickel molecular complexes (cationic structures) and a second one related to the counterions ClO₄^– which stabilize the monolayer. No type of short and long-range order is observed. STM tip-interaction with the monolayer reveals higher degradation after 8 h of measurement. Spectroscopy measurements suggest a gap of about 2.5 eV between HOMO and LUMO of the cationic structures and smaller gap in the areas related to the anionic structures.