Synthesis, Physical Properties and Supramolecular Organization of B-doped Molecular Material

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thesis describes the synthetic strategies for the obtainment of π-conjugated structure where carbon-carbon pairs have been replaced by boron-nitrogen pairs.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.(DOCSC02) -- FUNDP, 201

Self-assembly of decoupled borazines on metal surfaces : the role of the peripheral groups

Two borazine derivatives have been synthesised to investigate their self-assembly behaviour on Au(111) and Cu(111) surfaces by scanning tunnelling microscopy (STM) and theoretical simulations. Both borazines form extended 2D networks upon adsorption on both substrates at room temperature. Whereas the more compact triphenyl borazine 1 arranges into close-packed ordered molecular islands with an extremely low density of defects on both substrates, the tris(phenyl-4-phenylethynyl) derivative 2 assembles into porous molecular networks due to its longer lateral substituents. For both species, the steric hindrance between the phenyl and mesityl substituents results in an effective decoupling of the central borazine core from the surface. For borazine 1, this is enough to weaken the molecule–substrate interaction, so that the assemblies are only driven by attractive van der Waals intermolecular forces. For the longer and more flexible borazine 2, a stronger molecule–substrate interaction becomes possible through its peripheral substituents on the more reactive copper surface

Versatile self-adapting boronic acids for H-bond recognition: from discrete to polymeric supramolecules

By taking advantage of the peculiar dynamic covalent reactivity of boronic acids to form tetraboronate derivatives, interest has risen to use the aryl derivatives in materials science and supramolecular chemistry, nevertheless their ability to form H-bonded complexes has been only marginally touched. Herein we report the first solution and solid-state binding studies of first double H-bonded DD•AA-type complexes of a series of aromatic boronic acids that adopt a synsyn conformation with suitable complementary H-bonding acceptor partners. The first determination of the Ka in solution of ortho substituted boronic acids showed that 1:1 association is in the range between 300 and 6900 M-1. Crystallization of dimeric 1:1, trimeric 1:2 and 2:1 complexes enabled in depth examination of these complexes in the solid state, proving the selection of the –B(OH)2 syn-syn conformer through a pair of frontal H-bonds with the relevant AA partner. Non-ortho substituted boronic acids result in “flat” complexes. On the other hand, sterically demanding analogues bearing ortho-substituents strive to retain their recognition properties rotating the ArB(OH)2 moiety forming “T-shaped” complexes. Solid-state studies of a diboronic acid and a tetraazanaphthacene provided for the first time the formation of a supramolecular H-bonded polymeric ribbon. Given the conformational dynamicity of the –B(OH)2 functional group, it is expected that these findings will also open new possibilities in metal-free catalysis or organic crystal engineering, where double H-bonding donor boronic acids could act as suitable organocatalysts or templates developing functional materials with tailored organizational properties.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Nanostructured cocrystals of a borazine with [60]fullerene

In this paper, the preparation and photophysical characterization of nanostructured cocrystals composed of B-trimesityl-Ntriphenylborazine (1) and C 60 are reported. Preliminary results in the solid state show that the borazine-centered fluorescence is quenched in the cocrystal, displaying strong interchromophoric interaction in the solid state, as also shown by photoconductivity measurements. \ua9 2012 The Chemical Society of Japan

CCDC 1037669: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 1063177: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 1037393: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures