Mercury coordination polymers with flexible ethane-1,2-diyl-bis-(pyridyl-3-carboxylate): Synthesis, structures, thermal and luminescent properties

The reaction of the flexible ligand, ethane-1,2-diyl-bis-(pyridyl-3-carboxylate), (L) with HgI₂ and HgBr₂ salts under the same experimental conditions leads to the formation of two coordination polymers with different motifs: ([Hg(L)(Br₂)])_n(1) and ([Hg(L)(I₂)])_n(2). In both compounds, the ligand, (L) acts in a μ2-N:N′-bidentate fashion to link HgBr₂ and HgI₂ units to form a linear and helical chain motif, along [1 0 0] for (1) and [0 0 1] for (2). The ethylene moiety of (L) has gauche and trans conformation in compounds (1) and (2), respectively. The flexible conformation of L produces differences in the optical and crystal properties of the two compounds. - Graphical abstract: This work demonstrates how the HgX₂ units are coordinates by bi-dentate ligand forming polymeric coordination complexes by self-assembly of both chemical units.- Highlights: • News 1-D d¹⁰ transition metal coordination polymers. • The photoluminescent properties have been measured. • The thermal properties have been measured