Synthesis, structural characterization, and luminescence properties of heteroleptic bismuth-organic compounds

Abstract

Four heteroleptic bismuth-organic phases bearing 2,2′;6′,2′′-terpyridine (terpy) and 2-thenoyltrifluoroacetone (TTA) of the general formula [BiX_y(TTA)_3−y(terpy)], where X = NO₃ (2), Cl (3), Br (4), Br₂ (5), were synthesized at room temperature. A minor phase, [Bi₂(terpy)₂(MeO)₂(NO₃)₄] (1), formed in the same reaction as 2, and was manually separated to afford a phase pure sample of 2. The structures were determined through single crystal X-ray diffraction, and further characterized via powder X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The structures of 2–5 are built from discrete monomeric units, whereas 1 contains dimeric complexes. Significant π–π stacking and halide–π interactions are observed in the solid-state structures. Europium-doped phases of 2–5 were synthesized through addition of an aliquot of a europium nitrate or europium chloride solution to the initial reaction solution. For comparison, [EuNO₃(TTA)₂(terpy)]·0.3MeOH (6), which is isostructural to 2, was synthesized. Photophysical measurements were carried out for each of the lanthanide containing phases, and quantum yield and lifetime values were determined for the visible-light emitters. The synthesis, structural chemistry, and spectroscopic properties of the phases are presented.