π-conjugated structures have been at the center of a growing interest regarding their applications in material science, for OLED, for solar cells and for information storage. In order to extend their applications field, the electronic properties of these molecules can be tuned by substituting the π-conjugated backbone with electron donating or withdrawing groups. An alternative strategy is to tune these properties by replacing the carbon atoms of a compound by heteroatoms. This leads to compounds presenting large arrays of tuned properties. For example, replacing a carbon-carbon pair, in a π-conjugated compound, by a boron-nitrogen pair can lead to bathochromically or hypsochromically shifted fluorescence, which can be exploited for emitting materials in OLED. The objective of the present thesis is to gain a detailed understanding of both the properties and the molecular and supramolecular structures of such compounds. The present thesis describes the synthetic strategies for the obtainment of π-conjugated structure where carbon-carbon pairs have been replaced by boron-nitrogen pairs. Upon substitution of the central phenyl ring, of hexasubstituted derivative, by a borazine ring, as a slight hypsochromic shift of the fluorescence in the UV region has well as an increase of quantum yield was noticed. The adsorption behavior on metallic surface was later probed, followed by the incorporation of the compound inside the emissive layer of OLED devices. In a second part, the self-assembly of phenylboronic acid with hydrogen bond acceptors was probed in the solid state by X-ray crystallography and in solution by ITC analysis. The equilibrium between these derivatives and their anhydride form was studied, with parameters such as the temperature and the position of the substitution by electron withdrawing/donating groups.
|la date de réponse||18 janv. 2013|
|Superviseur||Davide BONIFAZI (Promoteur), Stephane Vincent (Jury), Johan Wouters (Président), Ivan Jabin (Jury) & Franco Cacialli (Jury)|
- Supramolecular chemistry
- Boronic acid