scholarly journals Syntheses and properties of thienyl-substituted dithienophenazines

2010 ◽  
Vol 6 ◽  
pp. 1180-1187 ◽  
Author(s):  
Annemarie Meyer ◽  
Eva Sigmund ◽  
Friedhelm Luppertz ◽  
Gregor Schnakenburg ◽  
Immanuel Gadaczek ◽  
...  
Keyword(s):  
Density Functional ◽  
Pyrolytic Graphite ◽  
Electron Donors ◽  
Time Dependent ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
Highly Ordered Pyrolytic Graphite ◽  
Assembled Monolayers

A series of dithienophenazines with different lengths of the oligomeric thiophene units (quaterthiophenes and sexithiophenes) was synthesized. The thiophene and phenazine units act as electron donors and acceptors, respectively, resulting in characteristic absorption spectra. The optical spectra were calculated using time-dependent density functional theory at the B3LYP/TZVP level and verify the experimental data. Adsorption of the dithienophenazines on highly ordered pyrolytic graphite (HOPG) was investigated by scanning tunneling microscopy, showing that one of the compounds forms highly organized self-assembled monolayers.

scholarly journals Mono- and multilayers of molecular spoked carbazole wheels on graphite

2014 ◽  
Vol 10 ◽  
pp. 2783-2788 ◽  
Author(s):  
Stefan-S Jester ◽  
A Vikas Aggarwal ◽  
Daniel Kalle ◽  
Sigurd Höger
Keyword(s):  
Octanoic Acid ◽  
Pyrolytic Graphite ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Chemical Structures ◽  
Rigid Objects ◽  
Assembled Monolayers ◽  
Stm Images ◽  
Insight Into

Self-assembled monolayers of a molecular spoked wheel (a shape-persistent macrocycle with an intraannular spoke/hub system) and its synthetic precursor are investigated by scanning tunneling microscopy (STM) at the liquid/solid interface of 1-octanoic acid and highly oriented pyrolytic graphite. The submolecularly resolved STM images reveal that the molecules indeed behave as more or less rigid objects of certain sizes and shapes – depending on their chemical structures. In addition, the images provide insight into the multilayer growth of the molecular spoked wheels (MSWs), where the first adlayer acts as a template for the commensurate adsorption of molecules in the second layer.

scholarly journals Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

2014 ◽  
Vol 10 ◽  
pp. 2774-2782 ◽  
Author(s):  
Joscha Vollmeyer ◽  
Friederike Eberhagen ◽  
Sigurd Höger ◽  
Stefan-S Jester
Keyword(s):  
Interior Design ◽  
Pyrolytic Graphite ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Conformational Polymorphism ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Solid Liquid Interface ◽  
Solid Liquid

Three shape-persistent naphthylene–phenylene–acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar) nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D) crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

scholarly journals Self-assembly of N-heterocyclic carbenes on Au(111)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alex Inayeh ◽  
Ryan R. K. Groome ◽  
Ishwar Singh ◽  
Alex J. Veinot ◽  
Felipe Crasto de Lima ◽  
...  
Keyword(s):  
Self Assembly ◽  
Density Functional ◽  
Surface Coverage ◽  
High Mobility ◽  
Heterocyclic Carbenes ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Surface Geometry ◽  
Functional Theory ◽  
Interesting Alternative

AbstractAlthough the self-assembly of organic ligands on gold has been dominated by sulfur-based ligands for decades, a new ligand class, N-heterocyclic carbenes (NHCs), has appeared as an interesting alternative. However, fundamental questions surrounding self-assembly of this new ligand remain unanswered. Herein, we describe the effect of NHC structure, surface coverage, and substrate temperature on mobility, thermal stability, NHC surface geometry, and self-assembly. Analysis of NHC adsorption and self-assembly by scanning tunneling microscopy and density functional theory have revealed the importance of NHC-surface interactions and attractive NHC-NHC interactions on NHC monolayer structures. A remarkable way these interactions manifest is the need for a threshold NHC surface coverage to produce upright, adatom-mediated adsorption motifs with low surface diffusion. NHC wingtip structure is also critical, with primary substituents leading to the formation of flat-lying NHC2Au complexes, which have high mobility when isolated, but self-assemble into stable ordered lattices at higher surface concentrations. These and other studies of NHC surface chemistry will be crucial for the success of these next-generation monolayers.

scholarly journals Density Functional Theory with Modified Dispersion Correction for Metals Applied to Self-Assembled Monolayers of Thiols on Au(111)

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
M. P. Andersson
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dimethyl Disulfide ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Dispersion Correction ◽  
Dissociative Chemisorption ◽  
Functional Theory ◽  
Assembled Monolayers ◽  
Self Assembled

Using sound physical principles we modify the DFT-D2 atom pairwise semiempirical dispersion correction to density functional theory to work for metallic systems and in particular self-assembled monolayers of thiols on gold surfaces. We test our approximation for two functionals PBE-D and revPBE-D for lattice parameters and cohesive energies for Ni, Pd, Pt, Cu, Ag, and Au, adsorption energies of CO on (111) surfaces of Pd, Pt, Cu, Ag, and Au, and adsorption energy of benzene on Ag(111) and Au(111). Agreement with experimental data is substantially improved. We apply the method to self-assembled monolayers of alkanethiols on Au(111) and find reasonable agreement for PBE-D and revPBE-D for both physisorption of n-alkanethiols as well as dissociative chemisorption of dimethyl disulfide as an Au-adatom-dithiolate complex. By modifying the C6 coefficient for Au, we obtain quantitative agreement for physisorption and chemisorption for both PBE-D and revPBE-D using the same set of parameters. Our results confirm that inclusion of dispersion forces is crucial for any quantitative analysis of the thiol and thiolate bonds to the gold surface using quantum chemical calculations.

scholarly journals Lithium incorporation into a silica thin film: Scanning tunneling microscopy and density functional theory

2009 ◽  
Vol 80 (24) ◽  
Author(s):  
Jan Frederik Jerratsch ◽  
Niklas Nilius ◽  
Hans-Joachim Freund ◽  
Umberto Martinez ◽  
Livia Giordano ◽  
...  
Keyword(s):  
Thin Film ◽  
Density Functional Theory ◽  
Scanning Tunneling Microscopy ◽  
Density Functional ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
Silica Thin Film ◽  
Lithium Incorporation

scholarly journals Exact location of dopants below the Si(001):H surface from scanning tunneling microscopy and density functional theory

2017 ◽  
Vol 95 (7) ◽  
Author(s):  
Veronika Brázdová ◽  
David R. Bowler ◽  
Kitiphat Sinthiptharakoon ◽  
Philipp Studer ◽  
Adam Rahnejat ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Scanning Tunneling Microscopy ◽  
Density Functional ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
Exact Location

Specific Immobilization of Streptavidin on Mixed Self-Assembled Monolayers as Mixing Ratio

2007 ◽  
Vol 121-123 ◽  
pp. 495-498 ◽  
Author(s):  
Jun Hyung Park ◽  
Buyng Su Park ◽  
Gu Huh ◽  
Seung Hyun Lee ◽  
Hyun Sook Lee ◽  
...  
Keyword(s):  
Colorimetric Detection ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Local Domain ◽  
Mixing Ratio ◽  
Tunneling Microscopy ◽  
Self Assembled Monolayer ◽  
Assembled Monolayers ◽  
Self Assembled

We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

Scanning Tunneling Microscopy of Template-Stripped Au Surfaces and Highly Ordered Self-Assembled Monolayers

Langmuir ◽  
2008 ◽  
Vol 24 (12) ◽  
pp. 5984-5987 ◽  
Author(s):  
Sangyeob Lee ◽  
Sung-Soo Bae ◽  
Gilberto Medeiros-Ribeiro ◽  
Jason J. Blackstock ◽  
Sehun Kim ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Assembled Monolayers ◽  
Self Assembled
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