scholarly journals Advanced opto-electronics materials by fullerene and acetylene scaffolding

2005 ◽  
Vol 77 (11) ◽  
pp. 1851-1863 ◽  
Author(s):  
François Diederich
Keyword(s):  
Electronic Properties ◽  
Self Assembly ◽  
Weak Interactions ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Conjugated Systems ◽  
New Class ◽  
Polydisperse Polymer ◽  
Fundamental Research ◽  
Storage Properties

Functional π-systems with unusual opto-electronic properties are intensively investigated from both fundamental research and technological application viewpoints. This article reports on novel π-conjugated systems obtained by acetylenic and fullerene scaffolding. Linearly conjugated acetylenic nanorods, consisting of monodisperse poly(triacetylene) (PTA) oligomers and extending up to 18 nm length, were prepared to investigate the limits of effective conjugation and to explore at which length a monodisperse oligomer reaches the properties of an infinite polydisperse polymer. With the cyanoethynylethenes (CEEs), a powerful new class of electron acceptors is introduced that undergo intense intramolecular charge-transfer (CT) interactions with appended donors. Macrocyclic scaffolds with unusual opto-electronic properties are perethynylated dehydroannulenes, expanded radialenes, and radiaannulenes bearing peripheral dialkylanilino donor groups. Extended porphyrin-fullerene conjugates are investigated for their novel photophysical and efficient multicharge storage properties. Self-assembly of fullerenes and porphyrins, governed by weak interactions between the two components, leads to unprecedented nanopatterned surfaces that are investigated by scanning tunneling microscopy (STM).

scholarly journals Septipyridines as conformationally controlled substitutes for inaccessible bis(terpyridine)-derived oligopyridines in two-dimensional self-assembly

2011 ◽  
Vol 2 ◽  
pp. 405-415 ◽  
Author(s):  
Daniel Caterbow ◽  
Daniela Künzel ◽  
Michael G Mavros ◽  
Axel Groß ◽  
Katharina Landfester ◽  
...  
Keyword(s):  
Self Assembly ◽  
Pyrolytic Graphite ◽  
Scanning Tunneling ◽  
Strong Impact ◽  
Tunneling Microscopy ◽  
New Class ◽  
Self Assembling ◽  
Assembly Behavior ◽  
Structure Calculations ◽  
Transoid Conformation

The position of the peripheral nitrogen atoms in bis(terpyridine)-derived oligopyridines (BTPs) has a strong impact on their self-assembly behavior at the liquid/HOPG (highly oriented pyrolytic graphite) interface. The intermolecular hydrogen bonding interactions in these peripheral pyridine units show specific 2D structures for each BTP isomer. From nine possible constitutional isomers only four have been described in the literature. The synthesis and self-assembling behavior of an additional isomer is presented here, but the remaining four members of the series are synthetically inaccessible. The self-assembling properties of three of the missing four BTP isomers can be mimicked by making use of the energetically preferred N–C–C–N transoid conformation between 2,2'-bipyridine subunits in a new class of so-called septipyridines. The structures are investigated by scanning tunneling microscopy (STM) and a combination of force-field and first-principles electronic structure calculations.

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

scholarly journals Au(100) as a Template for Pentacene Monolayer

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2393
Author(s):  
Artur Trembułowicz ◽  
Agata Sabik ◽  
Miłosz Grodzicki
Keyword(s):  
Self Assembly ◽  
Molecular Layer ◽  
High Vacuum ◽  
Gold Surface ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Height Difference ◽  
Characteristic Features ◽  
Reconstructed Surface

The surface of quasi-hexagonal reconstructed Au(100) is used as the template for monolayer pentacene (PEN) self-assembly. The system is characterized by means of scanning tunneling microscopy at room temperature and under an ultra-high vacuum. A new modulated pattern of molecules with long molecular axes (MA) arranged along hex stripes is found. The characteristic features of the hex reconstruction are preserved herein. The assembly with MA across the hex rows leads to an unmodulated structure, where the molecular layer does not recreate the buckled hex phase. The presence of the molecules partly lifts the reconstruction—i.e., the gold hex phase is transformed into a (1×1) phase. The arrangement of PEN on the gold (1×1) structure is the same as that of the surrounding molecular domain on the reconstructed surface. The apparent height difference between phases allows for the distinction of the state of the underlying gold surface.

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.

Chiral Molecular Cavities of Calix[4]Crown on Au(111)

2008 ◽  
Vol 8 (11) ◽  
pp. 5702-5707 ◽  
Author(s):  
Ge-Bo Pan ◽  
Jun Luo ◽  
Qi-Yu Zheng ◽  
Li-Jun Wan
Keyword(s):  
Self Assembly ◽  
Chiral Recognition ◽  
Scanning Tunneling ◽  
Racemic Mixture ◽  
Tunneling Microscopy ◽  
Geometrical Structures ◽  
Simple Method ◽  
Ordered Structures ◽  
Ordered Arrays ◽  
Stm Images

Well-ordered arrays of chiral molecular cavities have been constructed by self-assembly of inherently chiral calix[4]crown on Au(111) in 0.1 M HClO4 solution and investigated by scanning tunneling microscopy (STM). The chiral features are clearly observed in high resolution STM images. It is found that the adsorption of the two enantiomers results in the same ordered structures with upright orientation on Au(111). Moreover, only phase separation has been observed for the racemic mixture of the two enantiomers in the experiment. This is mainly due to the weak molecule-substrate interaction as well as asymmetric geometrical structures of the two enantiomers. The present study provides a simple method for construction of ordered arrays of chiral molecular cavities, which are of potential in chemical sensors, chiral recognition, and nonlinear optics.

scholarly journals STM study on the self-assembly of oligothiophene-based organic semiconductors

2011 ◽  
Vol 2 ◽  
pp. 802-808 ◽  
Author(s):  
Elena Mena-Osteritz ◽  
Marta Urdanpilleta ◽  
Erwaa El-Hosseiny ◽  
Berndt Koslowski ◽  
Paul Ziemann ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Self Assembly ◽  
Theoretical Calculations ◽  
The Self ◽  
Scanning Tunneling ◽  
Ambient Conditions ◽  
Tunneling Microscopy ◽  
Substitution Pattern ◽  
Electronic Density ◽  
The Individual

The self-assembly properties of a series of functionalized regioregular oligo(3-alkylthiophenes) were investigated by using scanning tunneling microscopy (STM) at the liquid–solid interface under ambient conditions. The characteristics of the 2-D crystals formed on the (0001) plane of highly ordered pyrolitic graphite (HOPG) strongly depend on the length of the π-conjugated oligomer backbone, on the functional groups attached to it, and on the alkyl substitution pattern on the individual thiophene units. Theoretical calculations were performed to analyze the geometry and electronic density of the molecular orbitals as well as to analyze the intermolecular interactions, in order to obtain models of the 2-D molecular ordering on the substrate.

Understanding molecular self-assembly of a diol compound by considering competitive interactions

2016 ◽  
Vol 18 (39) ◽  
pp. 27390-27395 ◽  
Author(s):  
Oscar Díaz Arado ◽  
Maike Luft ◽  
Harry Mönig ◽  
Philipp Alexander Held ◽  
Armido Studer ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Scanning Tunneling Microscopy ◽  
Self Assembly ◽  
Density Functional ◽  
Competitive Interactions ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
Chemical Groups

With a combination of scanning tunneling microscopy and density functional theory, effects on molecular self-assembly involving two distinct chemical groups were investigated.

scholarly journals On-surface synthesis of singly and doubly porphyrin-capped graphene nanoribbon segments

2021 ◽  
Vol 12 (1) ◽  
pp. 247-252
Author(s):  
Luis M. Mateo ◽  
Qiang Sun ◽  
Kristjan Eimre ◽  
Carlo A. Pignedoli ◽  
Tomas Torres ◽  
...  
Keyword(s):  
High Resolution ◽  
Dft Calculations ◽  
Scanning Tunneling Microscopy ◽  
Electronic Properties ◽  
Graphene Nanoribbon ◽  
Scanning Tunneling ◽  
Tunneling Microscopy

Singly and doubly porphyrin-capped graphene nanoribbon segments are reported and their electronic properties are studied by high-resolution scanning tunneling microscopy and spectroscopy, and DFT calculations.

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