Ghassan Elias Bechara

Associate professor
Chemistry - Biochemistry department - Section III - Tripoli
Speciality: Chemistry
Specific Speciality: Chimie Biologie

Publications 3 publications
Isabelle Nassoa,b, Neri Geumc, Ghassan Becharaa,b, Béatrice Mestre-Voegtléa,b, Chantal Galaupa,b,∗, Claude Picarda Highly luminescent Tb(III) macrocyclic complex based on a DO3A hosting unit and an appended carboxylated N,C-pyrazolylpyridine antenna ELSEVIER 2014

The synthesis of a new ligand based on a DO3A moiety (DO3A = 1,4,7,10 tetraaza cyclododecane - 1,4,7-triacetic acid) as a hosting agent for the lanthanide ions and an appended chromophoric unit N,C-pyrazolylpyridine core functionalized by a carboxylic acid in the 3-position of the pyrazole ring was reported. The luminescence properties of the 1/1 Eu(III) and Tb(III) corresponding complexes were investigated in air-equilibrated water and deuterated water (Tris buffer, pH 7.4) at 298 and 77 K. High luminescence lifetime ( = 2.30 ms), quantum yield (˚ = 45%) and efficiency for the sensitized emission (sens = 60%) were observed for the terbium complex. A detailed study of the steps originating from light absorption at the chromophore unit and leading to lanthanide-centred emission was reported.

Ghassan Bechara a,b, Nadine Leygue a,b, Chantal Galaup a,b, Béatrice Mestre-Voegtlé a,b, Claude Picard a,b Polyazamacrocycles based on a tetraaminoacetate moiety and a (poly)pyridine intracyclic unit: direct synthesis and application to the photosensitization of Eu(III) and Tb(III) ions in aqueous solutions ELSEVIER 2010

A series of five new 15-, 18- or 21-membered polyazamacrocycles (L1eL5) based on a pyridine, bipyridine or terpyridine unit and a triethylenetetraminetetraacetic acid (TTTA) skeleton is described. In ligands L4 and L5 the azaheterocycle contains an additional extracyclic functionality (ester group) suitable for covalently attachment to bioactive molecules. The synthetic procedure is based on the use of a linear tetra- N-alkylated tetramine synthon incorporating masked acetate arms and an efficient metal template ion effect, which controls the crucial macrocyclization step. In the case of L1eL3, the formation of lanthanide complexes with europium(III) and terbium(III) was investigated and the fluorescence characteristics of the complexes were established. In this series, the terbium(III) complex derived from the bipyridine ligand exhibits the highest lifetime and quantum yield values (s¼2.18 ms, F¼26%).

Ghassan Bechara, Nadine Leygue, Chantal Galaup, Béatrice Mestre, Claude Picard An efficient route to pyridine and 2,20-bipyridine macrocycles incorporating a triethylenetetraminetetraacetic acid core as ligand for lanthanide ions ELSEVIER 2009

Two novel macrocyclic chelators L1 and L2 incorporating an intracyclic pyridine or 2,20-bipyridine unit and a triethylenetetraminetetraacetic acid core (TTTA) were synthesized with the aim of forming lanthanide complexes suitable as efficient long-lived luminophores. For this goal, an efficient methodology for the preparation of TTTA derivatives using prealkylated precursors is described. Starting from commercially available compounds, the target ligands were obtained in seven (L1) and nine (L2) steps in 40% and 20% overall yields, respectively. Stable Tb(III) complexes were prepared and displayed interesting luminescence properties.