Neutral Luminescent Bis(bipyridyl) Osmium(II) Complexes
with Improved Phosphorescent Properties
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Abstract
A new
class of neutral bis(isocyanoborato) bis(bipyridyl)
Os(II) complexes with the general formula of [Os(N–N)<sub>2</sub>(CNBR<sub>3</sub>)<sub>2</sub>] (N–N = bpy, 4,4′-Me<sub>2</sub>bpy; R = C<sub>6</sub>F<sub>5</sub>, C<sub>6</sub>H<sub>5</sub>) were prepared with simple synthetic methodologies. One of these
complexes was structurally characterized by X-ray crystallography.
Unlike most of the neutral bis(bipyridyl) Os(II) complexes, which
are very weakly emissive or nonemissive, these isocyanoborato complexes
displayed intense orange to red phosphorescence with a luminescent
quantum yield up to 0.09 in CH<sub>2</sub>Cl<sub>2</sub> solution
at room temperature. The photophysical and electrochemical properties
of these complexes were also investigated. Detailed photophysical
study showed that these complexes exhibited significantly enhanced
emission properties over other reported neutral bis(bipyridyl) Os(II)
complexes. In addition, it also revealed that the photophysics, electrochemistry,
and excited state properties can be fine-tuned or modified through
the functionalization of isocyanoborate ligands
