scholarly journals First π-linker featuring mercapto and isocyano anchoring groups within the same molecule: synthesis, heterobimetallic complexation and self-assembly on Au(111)

2016 ◽  
Vol 7 (2) ◽  
pp. 1422-1429 ◽  
Author(s):  
Jason C. Applegate ◽  
Monisola K. Okeowo ◽  
Nathan R. Erickson ◽  
Brad M. Neal ◽  
Cindy L. Berrie ◽  
...  
Keyword(s):  
Self Assembly ◽  
Self Assembled Monolayers ◽  
Heterobimetallic Complexes ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Anchoring Groups

Azulene is a convenient platform for accessing heterobimetallic complexes and self-assembled monolayers of a π-linker with asymmetric junctions.

Formation and stability of porphyrin and phthalocyanine self-assembled monolayers on ZnO surfaces

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1264-1271 ◽  
Author(s):  
Hanna Hakola ◽  
Essi Sariola-Leikas ◽  
Paavo Jäntti ◽  
Thomas Mokus ◽  
Kati Stranius ◽  
...  
Keyword(s):  
Thin Films ◽  
Zno Nanorods ◽  
Self Assembled Monolayers ◽  
Layer Formation ◽  
Zno Film ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Anchoring Groups ◽  
The Stability ◽  
Phosphate Groups

Formation of self-assembled monolayers (SAMs) of three porphyrin and one phthalocyanine derivatives on thin ZnO film was studied by monitoring absorption spectra of the samples. The compounds were equipped with carboxylic or phosphate groups to bind to the surface. The SAM formation was found to be fast. The layer was formed in less than 15 min for all studied porphyrins, and 30 min was sufficient to form phthalocyanine layer. For porphyrins with different anchor groups the SAM formation was too fast to see any difference between the anchoring groups. The stability of SAMs was tested then by immersing the samples into neat solvents. Upon immersion the SAMs were gradually losing the absorbance for all the compounds with degradation trends being in line with p[Formula: see text] values of the binding groups of the same type. However, even for the weakest binding group the SAM was relatively stable after a few tens of minutes of washing, which was sufficient to remove physisorbed compounds but the SAM was essentially not destroyed. Comparison of SAMs on thin films with SAMs on ZnO nanorods and TiO2 nanoparticle films indicated the same fast layer formation but relatively weaker SAMs stability, showing 20–40% faster absorption losses during the washing.

Self-Assembled Patterning of Ultrathin Silicides by Local Oxidation

MRS Bulletin ◽  
1999 ◽  
Vol 24 (8) ◽  
pp. 31-35 ◽  
Author(s):  
S. Mantl ◽  
Q.T. Zhao ◽  
B. Kabius
Keyword(s):  
Self Assembly ◽  
Vertical Direction ◽  
Self Assembled Monolayers ◽  
X Rays ◽  
Precise Control ◽  
Spacer Layer ◽  
Local Oxidation ◽  
Assembled Monolayers ◽  
Alternative Approaches ◽  
Self Assembled

Most microfabrication techniques employ masks to transfer the desired microstructure onto a wafer using ultraviolet light, x-rays, electrons, or ions for the projection of the structures. Generally, photoresist processing and etching follow to form the final structures. In all cases, the facilities necessary to perform these processes grow increasingly more complex as the feature size of the structures diminishes, and these processes face their practical or economic limits at dimensions of about 50 nm. Thus alternative approaches are under investigation, including different self-assembly techniques. They require no costly facilities and no masks with nanometer structures, and they promise high throughput, since the patterning is directly achieved by a physical or chemical process. Self-assembled monolayers of long-chain organic molecules are the most widely studied examples, where chemisorption and spontaneous self-ordering of the molecules are observed on appropriate substrates. Another interesting example is island-ordering, laterally or in a vertical direction, during epitaxial growth. The lattice-mismatched islands tend to nucleate preferentially on top of each other when separated by a thin spacer layer, due to the associated strain field. Another approach is the use of specific stressor layers on the surface to obtain alignment of buried precipitates along the stressor lines. However, the main challenges of all self-assembly techniques are precise control of the dimensions of the structures and reproducibility.

scholarly journals STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

2011 ◽  
Vol 2 ◽  
pp. 674-680 ◽  
Author(s):  
Tibor Kudernac ◽  
Natalia Shabelina ◽  
Wael Mamdouh ◽  
Sigurd Höger ◽  
Steven De Feyter
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Self Assembled Monolayers ◽  
Assembly Process ◽  
Organic Monolayers ◽  
Preferential Adsorption ◽  
Scanning Tunnelling ◽  
Assembled Monolayers ◽  
Tunnelling Microscopy ◽  
Self Assembled

Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM). The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid–solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

scholarly journals Molecular self-assembly of substituted terephthalic acids at the liquid/solid interface: investigating the effect of solvent

2017 ◽  
Vol 204 ◽  
pp. 191-213 ◽  
Author(s):  
A. Della Pia ◽  
D. Luo ◽  
R. Blackwell ◽  
G. Costantini ◽  
N. Martsinovich
Keyword(s):  
Molecular Dynamics ◽  
Molecular Mechanics ◽  
Self Assembly ◽  
Terephthalic Acid ◽  
Self Assembled Monolayers ◽  
Heptanoic Acid ◽  
Molecular Dynamics Calculations ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Key Aspects

Self-assembly of three related molecules – terephthalic acid and its hydroxylated analogues – at liquid/solid interfaces (graphite/heptanoic acid and graphite/1-phenyloctane) has been studied using a combination of scanning tunnelling microscopy and molecular mechanics and molecular dynamics calculations. Brickwork-like patterns typical for terephthalic acid self-assembly have been observed for all three molecules. However, several differences became apparent: (i) formation or lack of adsorbed monolayers (self-assembled monolayers formed in all systems, with one notable exception of terephthalic acid at the graphite/1-phenyloctane interface where no adsorption was observed), (ii) the size of adsorbate islands (large islands at the interface with heptanoic acid and smaller ones at the interface with 1-phenyloctane), and (iii) polymorphism of the hydroxylated terephthalic acids’ monolayers, dependent on the molecular structure and/or solvent. To rationalise this behaviour, molecular mechanics and molecular dynamics calculations have been performed, to analyse the three key aspects of the energetics of self-assembly: intermolecular, substrate–adsorbate and solvent–solute interactions. These energetic characteristics of self-assembly were brought together in a Born–Haber cycle, to obtain the overall energy effects of formation of self-assembled monolayers at these liquid/solid interfaces.

Self-assembly of trithia-9-crown-3 and octathia-24-crown-8 on Au(111) surfaces

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 81726-81730
Author(s):  
Xiao-Ping Liu ◽  
Ke Deng ◽  
Qian Wei ◽  
Ming-hui Liang ◽  
Zhan-Jun Zhang ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Self Assembly ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Microscopy Images

Scanning tunneling microscopy images of trithia-9-crown-3 and octathia-24-crown-8 self-assembled monolayers (SAMs) reveal completely different SAM structures for the two kinds of thiacrown molecules at liquid n-tetradecane/Au(111) interface.

Low Temperature Direct Metal Bonding by Self Assembled Monolayers

2007 ◽  
Vol 990 ◽  
Author(s):  
Xiaofang Ang ◽  
Li Cheong Chin ◽  
Guo Ge Zhang ◽  
Jun Wei ◽  
Zhong Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Surface Passivation ◽  
Bonding Temperature ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Thermocompression Bonding ◽  
Self Assembled

ABSTRACTElevated bonding temperature for interconnection deteriorates the reliability of both the device and the interconnect; hence the imperative for developing low temperature bonding methods. This study investigates the feasibility of using self-assembled monolayers (SAMs) to assist direct gold-gold bonding. This involves a simple molecular self-assembly process whereby a monolayer of alkyl chains with a sulfur end group is attached to the gold surface prior to thermocompression bonding. Using this method, we have achieved gold to gold bonding at a bonding temperature below 100°C, a significant reduction compared to the conventional bonding temperatures of above 150 °C. We attribute this temperature reduction to two properties of SAMs - (1) surface passivation of the Au surface that precludes adsorption of surface contaminants, and (2) The easy displacement of SAMs through thermal desorption just before bonding occurs. This SAMs-assisted bonding mechanism is supported by X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR) results.

Tribology of PFPE Overcoated Self-Assembled Monolayers Deposited on Silicon Surface: Effect of Thermal Treatment

2005 ◽  
Author(s):  
N. Satyanarayana ◽  
S. K. Sinha
Keyword(s):  
Thermal Treatment ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Surface Effect ◽  
Chemical Properties ◽  
Dip Coating ◽  
Self Assembled Monolayers ◽  
Wear Life ◽  
Assembled Monolayers ◽  
Self Assembled

Effect of thermal treatment on the friction and wear of monomolecular layers of SAMs (Self-assembled monolayers) overcoated with PFPE was studied using ball-on-disk tribometer. Two SAMs, Octadecyltrichlorosilane (OTS) and 3-aminopropyltrimethoxysilane (APTMS) were formed on the Si substrate by self-assembly followed by dip-coating with perfluoropolyether (PFPE). Modified Si samples are thermally treated at 150 °C under vacuum for 2h. The physical and chemical properties of modified samples, before and after thermal treatment, are analyzed using contact angle measurements, X-ray photoelectron spectroscopy (XPS). Tribological properties are evaluated using Universal Micro Tribometer (UMT). A Si3N4 ball of 4mm diameter is used as the counterface. Thermal treatment of the PFPE coated SAMs and Si surface reduced the coefficient of friction to slightly lower values in all cases. Thermal treatment has shown slight increase in wear life in the case of PFPE coated APTMS SAM surfaces whereas it decreased the wear life in the case of PFPE coated OTS SAM and Si surfaces. The exact reasons for this behavior are not clear at present, but it is being speculated that thermal treatment effects the extent of bonding between the surface groups of PFPE and SAMs and mobile characteristics of the PFPE, which finally influence the wear durability characteristics. Therefore, the differences in the wear durability characteristics are analyzed using changes in the surface energies and the amount of strongly adsorbed PFPE, as a result of thermal treatment.

scholarly journals Self-Assembled Monolayers of Redox-Active 4d–4f Heterobimetallic Complexes

Langmuir ◽  
2019 ◽  
Vol 35 (42) ◽  
pp. 13711-13717
Author(s):  
Andrea Mulas ◽  
Galina V. Dubacheva ◽  
Hassan Al Sabea ◽  
Fabien Miomandre ◽  
Jean-Frédéric Audibert ◽  
...  
Keyword(s):  
Self Assembled Monolayers ◽  
Heterobimetallic Complexes ◽  
Redox Active ◽  
Assembled Monolayers ◽  
Self Assembled
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