Shchyrba, Aneliia. Physics and chemistry at surfaces : exploring molecular architectures and their properties. 2014, PhD Thesis, University of Basel, Faculty of Science.
Official URL: http://edoc.unibas.ch/diss/DissB_11048
investigated on selected substrates, namely Au(111), Ag(111), Cu(111), Cu(100) or Bi reconstructed Cu(100).
A number of model cases for controlling on-surface architectures and their properties has been found and is reported about in this thesis:
1) Architecture control of a coordination polymer, comprised from chiral and flexible
molecular building blocks, by tuning of the intermolecular bonding motif;
2) Chirality transfer in a 1D coordination polymer formed from chiral molecules;
3) Dimensionality (0D, 1D, 2D) control via selection of the transition metal adatom,
which modifies a ligand and participates in an on-surface coordination complex;
4) Demonstration of a 2D molecular ‘sponge’, created on the basis of a borylene derived
covalent link with angular flexibility;
5) Investigation of confined 2D electron states in quantum boxes of different size and
6) Self -sorting of bi-molecular system in a 2D array by the coulomb interaction of the
surface dipole which depends on band-alignment, charge transfer and the screening in
Specifically, we show that chiral and flexible helicene molecules with cyano-groups, covalently attached in symmetric positions, give rise to a 1D arrangement. The intrinsically chiral species imprints its chirality onto the weakly H-bonded assembly, which occurs if molecules are deposited on samples held at low (~90 K) temperatures. This imprint vanishes under the influence of stronger metal-coordination bonds formed after providing metal coordination centers to the H-bonded assembly. The flexibility of the helicene as well as the competition between intermolecular and molecule-surface interactions allow the coordinated chains to assemble in structures with the mirror symmetry apparently being reduced.
The next important issue, addressed in this thesis, is the on-surface modification of the ligand as an approach to control the dimensionality of the resulting on-surface polymer. We present a novel metal-specific reaction of amino- /imino- functionalized perylene derivatives. This precursor is modified upon addition of Co, Fe or Ni at room-temperature into an endo-ligand.
In contrast, the presence of Cu adatoms in conjunction with thermal activation leads to the formation of an exo-ligand. Thus the type of metal ligand defines whether a 1D or 2D coordinated polymer can be formed.
We show that borylene-functionalized molecules react upon thermal activation with trimesic acid in a novel on-surface reaction. Moreover, the covalent connection, formed in this reaction, exhibits a high degree of flexibility and allows for the formation of the differently sized pores. The resulting molecular ‘sponge’, created this way, serves as a template confining the surface state electrons. We investigate the effect of size and shape of the pores on this quantum phenomenon.
Furthermore, we present a new way of creating highly-ordered bimolecular self-sorted chessboard arrays. The bi-component mixture of Mn-phthalocyanine (MnPc) and Cu-phthalocyanine (CuPc) on Bi/Cu(100) self-assembles without participation of any chemical
bonding or molecular functionalization but only on the basis of the lateral 2D Coulomb interactions. We resolve charge-transfer channels of two types, directing the supramolecular self-assembly: one oriented perpendicular to the substrate surface, the other oriented in-plane.
These investigations are performed in ultra-high vacuum conditions (UHV) with the use of variable temperature Scanning Tunneling Microscopy / Spectroscopy (STM/STS), X-Ray Photoelectron Spectroscopy (XPS) and synchrotron-based Near Edge X-ray Absorption Fine
Structure (NEXAFS) spectroscopy. The experimental results are supported by Density Functional Theory (DFT) calculations, performed by research partners.
|Advisors:||Jung, Thomas Andreas|
|Committee Members:||Housecroft, Catherine E.|
|Faculties and Departments:||05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||93 S.|
|Last Modified:||30 Jun 2016 10:56|
|Deposited On:||01 Dec 2014 15:58|
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