Dib ligand effects on ZnII coordination polymers built from a semirigid tricarboxylate ligand: Topological structures and luminescence properties

Four complexes based on H3L, namely, [Zn2(L)(dib)1.5(μ2-O)]n (1), {[Zn(HL)(dib)]·H2O}n (2), [Zn(HL)(dib)]n (3), [Zn3(L)2(dib)3]n (4) [4-[(3-carboxynaphthalen-2-yl)oxy]phthalic acid (H3L) and 1,4-di(1H-imidazol-1-yl) benzene (dib)] have been synthesized by solvothermal reactions. Complex 1 displays (3,5)-connected gra-type topology with a Schläfli symbol of (63)(69.8), the two-dimensional (2D) structure was extended to a three-dimensional (3D) framework by dib ligand, showing an enhanced luminescence intensity. Complex 2 possesses a 2D 4-connected sql-type topology with a Schläfli symbol of (44.62), which are further stacked with each other by C–H⋯π and C–H⋯O interactions to form a 3D supramolecular framework. Complex 3 features a novel 4-connected topology with a Schläfli symbol of (33.42.5), the driving forces in 3D supramolecular​ frameworks are C–H⋯O, C–H⋯π, and π⋯π stacking interactions in 3. Complex 4 has a 3D (3,4,4)-connected net with a Schläfli symbol of (63.8.102)2(63)2(64.8.10), representing a new topological prototype. In addition, complexes 1–4 exhibit non-interpenetrated structures owing to the steric hindrance of the naphthalene ring. It is also noteworthy that dib Ligand may not only affect the coordination mode of polycarboxylate acid but also subtly adjust the pH value of reaction solvent as well as N,N′-dimethylformamide (DMF). Additionally, the luminescent properties were investigated in the solid state at room temperature for 1–4.

Four coordination polymers based on a semirigid tricarboxylic acid together with dib ligand have been synthesized by solvothermal reactions. Their syntheses, 3D supramolecular​ frameworks, topological structures, and luminescent properties are discussed in detail.Figure optionsDownload as PowerPoint slide