Samuel Guieu

Luminescent bi-metallic fluoroborate derivatives of bulky salen ligands

A family of hemisalen fluoroborate complexes has been prepared and characterized. These new fluorophores exhibit an intense blue emission upon irradiation with UV light. Interestingly, the introduction of bulky aromatic substituents enhanced the quantum yield considerably, up to 44%. Upon studying various solvents, it appeared that the effect of the phenyl substituents is more of electron donating nature than of restricting the intramolecular motion of the dyes.

Aggregation-induced emission enhancement in halochalcones

A family of push–pull fluorophores, consisting of a chalcone core decorated with electron-donating substituents and halogen atoms, was designed and synthesized. Luminescence studies were performed in solution, aggregate form and in the solid state. Although some compounds are only weakly fluorescent in solution, all are emissive in the solid state showing aggregation-induced emission enhancement. In the crystalline state, the halogen atoms are not involved in halogen bonds but their presence strongly influences the aggregation-induced emission properties of the fluorophores.

Porphyrin–boron diketonate dyads

Porphyrins and boron diketonates represent two well studied classes of compounds, and whose photophysical properties make them suitable for application in bioimaging, as photosensitizer agents, or as pH or ion sensors. Compounds that combine the optical properties of these two chromophores in a single molecule are not known. Herein, we report the synthesis and characterization of two porphyrin–boron diketonate dyads and their zinc complexes. Overall, the absorption and emission spectra of these dyads are dominated by the porphyrin core. The nature of the diketonate or the boron diketonate has little effect on the absorption and fluorescence profiles of the dyads, inducing small bathochromic shifts and a slight increase in the fluorescence quantum yield.

Aggregation-induced emission enhancement of chiral boranils

New boranils based on chiral benzylamines have been synthesized and their photophysical properties studied. These BF2-complexes exhibit a bright blue fluorescence in solution and in the solid state, and exhibit aggregation-induced emission enhancement. The chirality of the ligand, even if it is not directly located at the boron center, has consequences on the circular dichroism of the complexes.

Tunable Color of Aggregation Induced Emission Enhancement in a Family of Hydrogen-Bonded Azines and Schiff Bases

A simple synthesis strategy afforded a family of hydrogen-bonded azines and Schiff-bases. Although in dilute solution these dyes are faint light emitters, all exhibit bright luminescence upon aggregation. Changing the peripheral substituents from electron donating to electron withdrawing allows emission fine-tuning in a range from bluish-green to orange-red. The crystal structures of the materials reveal that the restriction of intramolecular rotations is the main mechanism for the aggregation-induced emission enhancement properties.

Halogen-bonded dimers and ribbons from the self-assembly of 3-halobenzophenones

A series of similar synthons highlights the difficulty in predicting the crystal packing of small molecules, and the formation of halogen bonds in the solid state. Small modifications, such as in peripheral groups or in the nature of halogen substituents, may dramatically change the supramolecular interactions, driving the organization of the molecules in the crystals.

Synthesis and Characterization of Linear and Macrocyclic Ligands with Multiple Hemisalen Pockets

Abstract Procedures for the convenient preparation of new ligands possessing multiple metal binding sites are presented. Among those, a Schiff base macrocycle exhibiting three outward hemisalen pockets was synthesized using a one-pot reduction/condensation reaction. These ligands are promising building blocks for supramolecular architectures such as metal–organic frameworks or polyhedra. GRAPHICAL ABSTRACT

Dimethyl 5,5′-methyl­enebis(2-hy­droxy­benzoate)

In the title compound, C17H16O6, the two methyl salicylate moieties are related by crystallographic twofold rotational symmetry with the two benzene rings close to being perpendicular [inter-ring dihedral angle = 86.6 (8)°]. Intramolecular phenolic O—H⋯O hydrogen bonds with carboxyl O-atom acceptors are present, with these groups also involved in centrosymmetric cyclic intermolecular O—H⋯O hydrogen-bonding associations [graph set R 2 2(4)], giving infinite chains extending across (101).