2018 Fiscal Year Research-status Report
STM-Induced Light Emission Investigation of Individual Self-Decoupled Molecules
| Project/Area Number |
18K14076
|
|---|
| Research Institution | Institute of Physical and Chemical Research |
|---|
Principal Investigator |
C Songpol 国立研究開発法人理化学研究所, 開拓研究本部, 特別研究員 (90802984)
|
|---|
| Project Period (FY) |
2018-04-01 – 2020-03-31
|
| Keywords | self-assembly / tripod / thiol / triptycene / STM |
|---|
| Outline of Annual Research Achievements |
The most stable design of molecular 'tripods' has been selected by comparing high-resolution STM images with theoretical simulations, and the upright chemisorption and the structural composition of the self-assembled monolayer of molecular tripods has been elucidated. It was found that the chemical binding group and metallic substrate material, as well as the flexibility of the tripod 'leg' to account for lattice mismatches have all been shown to be key components for maintaining upright adsorption orientation. The most reliable binding group was found to be thiolates, which provide upright orientation on both Au(111) and Ag(111) surfaces. The chirality of each triptycene unit results in both racemic and enantiopure domains. The electronic structure also shows the molecules to have a wide bandgap, indicative of insulating properties. Triptycenes with carboxylic binding groups were also found to form long-range self-assembled structures on Ag(111), but not on Au(111). The carboxilyc triptycenes form a one-dimensional self-assembly with 50% upright orientation. It is assumed that the carboxylic groups are bound together by hydrogen bonds which do not break easily on the surface. Preliminary luminescence investigations show that both thiolate and carboxylate triptycenes have insulating properties.
|
| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
The three dimensional chemical structure of the molecular tripods complicates the interpretation of STM images. Straightforward interpretation can be misleading and must thus be compared with theoretical simulations, the latter requiring rather high computational costs. Statistical data was obtained over the combination of five different molecules and two different metallic surfaces in order to confirm the reliability of the results. Ultimately, the results have been clearly elucidated and are progressing according to plan.
|
| Strategy for Future Research Activity |
The self-assembly of the selected tripod molecules will be investigated for their electronic and optical isolation properties. This will reveal how the self-assembled structure symmetry and thickness affects the pristine properties of molecules adsorbed upon them. A double-deckered self-decoupling molecule, comprised of a chromophore chemically attached onto the tripod, will then be investigated for its structural, electronic, and optical properties.
|
| Causes of Carryover |
Most of the first year's work involves fundamental investigation without much need for modification of experimental systems. Most of the budget in the first fiscal year was spent on vacuum components for maintaining high vacuum environment and other consumables to aid the analysis of results. In the next fiscal year, there will be the need for optics components for optical characterization. Also, a high-performance PC and specialized software will be needed in order to carry out density functional theory simulations, for comparison with the observed experimental results.
|
Research Products
(2 results)
