A series of variable coordination polymers based on flexible aromatic carboxylates

Abstract

Six coordination polymers (CPs), namely, [Ag(tmb)]n (1), [Cu(tmb)2(H2O)]n (2), [Eu(HCOO)(tmb)2]n (3), [Ag(bimb)(Hbimb)]n (4), [Cu(bimb)2]n (5) and [Eu(bimb)3]n (6) (Htmb = 4-((1H-1,2,4-triazol-1-yl)methyl)benzoic acid), Hbimb = 4-((1H-benzo[d]imidazol-1-yl)methyl)benzoic acid), have been successfully synthesized under similar solvothermal conditions and characterized by elemental analysis, IR, thermogravimetric analysis and single-crystal X-ray diffraction. 3-D complex 1 presents a binodal (3,6)-connected rutile topology with the Schlafli symbol (42·610·83) (4·62)2. Previously reported complex 2 shows a 3-D framework of pcu topology, in which the inorganic ⋯Cu–O–Cu–O⋯ chains are connected to each other through the tmb− ligands. In 3, Eu(III) atoms are connected by carboxylate groups to form a double-helical chain, which further expands to a 3-D framework of tsi topology with the Schlafli symbol (36·416·56). Complex 4 exhibits a 1-D chain structures which are further connected by O–H⋯O hydrogen bonding and π⋯π interactions to form a 3-D supramolecular framework. Complex 5 features a two-dimensional 44 layer. In 6, Eu3+ ions are bridged by bimb− ligands to form a 1-D three-strand double-helical chain which is further connected by ligands to produce a 2-D layer with a 4·82 topology. The different structural dimensions of the six complexes (1–6) are closely related to the steric effect of the triazole ring or benzimidazole ring in the ligands. Furthermore, the fluorescence properties of 1, 3, 4, and 6 are studied in the solid state at room temperature.