First blue luminescent diborate compound: B2(μ-O)Et2(7-azain)2 (7-azain = 7-azaindole anion)

A novel blue luminescent diborate compound B2(µ-O)Et2(7-azain)2 (7-azain = 7-azaindole anion) is synthesized and characterized structurally; it emits a blue color at λmax = 422 nm in the solid and at λmax = 419 nm in solution and is stable under air as a solid.