Syntheses, Structures, Photoluminescence, and Theoretical Studies of a Class of Beryllium(II) Compounds of Aromatic N,O-Chelate Ligands

Three members of a new class of luminescent, neutral, and monomeric Be(II) complexes of aromatic N,O-chelate ligands, namely [Be(pbm)2] (1), [Be(pbx)2] (2), and [Be(pbt)2] (3) [Hpbm = 2-(2ʹ-hydroxylphenyl)benzimidazole, Hpbx = 2-(2ʹ-hydroxylphenyl)benzoxazole, and Hpbt = 2-(2ʹ-hydroxylphenyl)benzothiazole], have been prepared and characterized by X-ray crystallography and photoluminescence studies. All the complexes are neutral, mononuclear molecules and display strong photoluminescence in the blue/green region, and thus, they may serve as candidates for electroluminescence materials. The electronic transitions in the photoluminescent process have also been investigated by means of time-dependent density functional theory (TDDFT) energy level and molecular-orbital analyses, showing that their absorption and luminescent properties are ligand-based and ligand-tunable.