Synthesis, characterization and properties of four dimeric ZnII–BMP coordination polymers modulated by a series of aromatic polycarboxylate acid

To systematically explore the influence of aromatic polycarboxylate ligands on building ZnII–BMP (1,5-bis(2-methylbenzimidazol) pentane) coordination polymers, four coordination polymers, namely {[Zn2(BMP)(PHSA)2]·H2O}n (1), [Zn4(BMP)2(BTEC)2(H2O)]n (2), [Zn2(BMP)(BTRC)(OH)]n (3), {[Zn3(BMP)(TCI)2(H2O)]·H2O}n (4) (H2PHSA = 2-phenylsuccinic acid, H4BTEC = benzene-1,2,4,5-tetracarboxylic acid, H3BTRC = benzene-1,3,5-tricarboxylic acid, H3TCI = Tris (2-carboxyethyl) isocyanurate) are synthesized by varying aromatic polycarboxylate ligands. Systematic structure analysis shows that 1–4 are comprised by one or more ZnII dimer in which carboxylate ligands bridge two metal ions forming dinuclear cores, and BMP links these cores. In 1, PHSA2− bridges ZnII ions to generate paddle-wheel dimer [Zn2(η1-COO)4] and these dimers are further linked by BMP to form 2D structure. 2 exhibits a layer with two different dimers: [Zn2(η1-BTEC4−)2] and [Zn2(η1-BTEC4−)(μ2-H2O)] indicating that bridge water have subtle influences on the coordination geometry. [Zn2(η1-BTRC3−)(μ2-OH)] dimers in 3 are further linked by two kind of wavelike layers constructing the 2-fold interpenetrated 3D architecture. 4 shows a 2-fold interpenetrated 3D architecture with dimeric centre. Notably, besides ZnII dimer [Zn2(η1-TCI3−)3], a monuclear ZnII ion exists as a terminal of ligand BMP enhancing photoluminescence intensity of 4 subtlely.

Graphical abstractTo systematically explore the influence of aromatic polycarboxylate ligands on building ZnII–bmp (1,5-bis(2-methylbenzimidazol) pentane) coordination polymers, four coordination polymers with various dimeric centers have been hydrothermally synthesized.Figure optionsDownload full-size imageDownload as PowerPoint slide