2-Chloro-5-nitrobenzoato complexes of Eu(III) and Tb(III) – A 1D coordination polymer and enhanced solution luminescence

A luminescent 2-chloro-5-nitrobenzoic acid derivative of Eu(III) with a columnar structure has been isolated and characterized. This compound shows red emission in the solid state. Solutions of the ligand and Eu(III) in 1:1 stoichiometry are also luminescent with an excited state lifetime of 307.0 ± 4.4 μs and a quantum yield of emission of 1.0%. This is to date the highest reported value of quantum yield of luminescence of Eu(III) sensitized by a nitrobenzoic acid derivative. The analogous solution for Tb(III) displays bright green luminescence with an excited state lifetime of 1.040 ± 0.026 ms and a quantum yield of 3.7%.