Abstract
The development of new types of emissive organic dyes is an exciting area of research due to
the applicability of these compounds in a wide range of disciplines. Cationic triangulenium
salts are highly stable carbenium ions with a planar conformation. The convenient and
versatile synthetic procedures developed by Laursen and Krebs, which go through a series of
selective subsequent nucleophilic aromatic substitutions (SNAr), both intermolecular and
intramolecular, starting from different propeller shaped triphenylmethylium cations have
permitted the preparation of triangulenium moieties bearing various substituents Indeed, a
variety of triangulenium derivatives possessing different optical properties have already been
reported in literature.
The main focus of this research project was to investigate the reactivity and selectivity of various propeller shaped systems upon nucleophilic aromatic substitution with different types of nucleophiles either in ortho and para position in order to obtain novel interesting triangulenium salts. The reactivity of the triangulenium compounds towards nucleophilic addition upon the central carbon with alkynyl or aryllithium reagents was also explored. Firstly, I focused on the synthesis of thioether para substituted dyes, where the reactivity of various para-methoxy substituted propeller shaped cations towards different alkyl thiols was examined. Furthermore, ringclosure reactions of these thioether bearing propellers in order to obtain trioxa- and azaoxatriangulenium salts were investigated. Additionally, the influence of the thioethers upon the optical properties of the new resulting dyes was investigated in solution studies.
Subsequently, the synthesis and optical properties of a novel class of dyes, structurally similar to rhodamines and acridinium dyes was undertaken. Taking advantage of the regioselectivity of the intramolecular ringclosure reaction with either nitrogen or oxygen centered nucleophiles starting from asymmetric electron rich propeller shaped cations, it was possible to obtain a series of dyes with tetramethoxy rhodamine and acridinium structures. These dyes possess excellent emissive properties with possible applications as cell staining agents or as fluorescent probes.
Lastly, I focused on the use of triangulenes as binding group for molecular electronics. It has been shown that TATA can form self-assembled monolayers (SAMs) on a gold surface. This characteristic makes this motif a very attractive binding group for molecular electronic measurements and devices. For this reason triazatriangulenium (TATA+) moiety was functionalized through the central carbon by nucleophilic attack and a variety of platforms were prepared and conductance studies were performed and showed that TATA can act as suitable binding group for molecular electronics. Due to the aurophilic properties of sulfur, triangulenium containing silyl protected thiol substituents in para position were synthesized with the aim of getting a stronger adhesion of the binding group on the gold substrate.
The main focus of this research project was to investigate the reactivity and selectivity of various propeller shaped systems upon nucleophilic aromatic substitution with different types of nucleophiles either in ortho and para position in order to obtain novel interesting triangulenium salts. The reactivity of the triangulenium compounds towards nucleophilic addition upon the central carbon with alkynyl or aryllithium reagents was also explored. Firstly, I focused on the synthesis of thioether para substituted dyes, where the reactivity of various para-methoxy substituted propeller shaped cations towards different alkyl thiols was examined. Furthermore, ringclosure reactions of these thioether bearing propellers in order to obtain trioxa- and azaoxatriangulenium salts were investigated. Additionally, the influence of the thioethers upon the optical properties of the new resulting dyes was investigated in solution studies.
Subsequently, the synthesis and optical properties of a novel class of dyes, structurally similar to rhodamines and acridinium dyes was undertaken. Taking advantage of the regioselectivity of the intramolecular ringclosure reaction with either nitrogen or oxygen centered nucleophiles starting from asymmetric electron rich propeller shaped cations, it was possible to obtain a series of dyes with tetramethoxy rhodamine and acridinium structures. These dyes possess excellent emissive properties with possible applications as cell staining agents or as fluorescent probes.
Lastly, I focused on the use of triangulenes as binding group for molecular electronics. It has been shown that TATA can form self-assembled monolayers (SAMs) on a gold surface. This characteristic makes this motif a very attractive binding group for molecular electronic measurements and devices. For this reason triazatriangulenium (TATA+) moiety was functionalized through the central carbon by nucleophilic attack and a variety of platforms were prepared and conductance studies were performed and showed that TATA can act as suitable binding group for molecular electronics. Due to the aurophilic properties of sulfur, triangulenium containing silyl protected thiol substituents in para position were synthesized with the aim of getting a stronger adhesion of the binding group on the gold substrate.
| Original language | English |
|---|
| Publisher | Department of Chemistry, Faculty of Science, University of Copenhagen |
|---|---|
| Publication status | Published - 2014 |