Surprisingly high quantum yield of emission in a fluorescent coordination polymer with paramagnetic Mn(II) ions

A two-dimensional coordination polymer, [Mn₃(HEBTC)₂(DMSO)₆] (1), has been achieved by a solvothermal reaction of Mn²⁺ with 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylic acid (H₄EBTC). The layer of a coordination polymer is composed of trinuclear Mn²⁺ clusters linked by HEBTC^3- ligands to form a (3,6)-connected topological net. CP 1 with paramagnetic Mn²⁺ ions shows dual emissions centered at 397 and 468 nm in the solid state under ambient conditions with respectable quantum yields of 15.3% (397 nm) and 12.3% (468 nm). The dual emissions arise from n ← π∗ transition in HEBTC^3- and MLCT between HEBTC^3- and Mn²⁺ centers.