TlI benzene multicarboxylic acid coordination polymers: Structural, thermal and fluorescence studies

[Tl3(μ-1,2,3-btc)]n (1,2,3-H3btc = 1,2,3-benzenetricarboxylic acid) (1), [Tl2(μ-1,3,5-Hbtc)(H2O)]n (1,3,5-H3btc = 1,3,5-benzenetricarboxylic acid) (2) and [Tl4(μ-1,2,4,5-btc)]n (1,2,4,5-H4btc = 1,2,4,5-benzenetetracarboxylic acid) (3), three new TlI coordination polymers have been synthesized, characterized by elemental analysis and IR spectroscopy and their structures determined by single-crystal X-ray diffraction. The thermal stability of compounds 1–3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single-crystal X-ray analysis of compounds 1–3 shows that the compounds are structurally diverse showing three-dimensional coordination polymers. The carboxylic groups of the ligands 1,2,3-btc3−, 1,3,5-Hbtc2− and 1,2,4,5-btc4− in the new TlI coordination polymers are not chelated and only act as bridging groups. In compounds 1–3, the lone pair of Tl(I) atoms is ‘active’ in the solid state and the coordination spheres are hemisphere type. Solution state luminescent spectra of compound 2 indicate intense fluorescent emissions at ca. 400 nm.