Crystal Structure Diversities Based on 4,4′-(2,3,6,7-Tetramethoxyanthracene-9,10-diyl)dibenzoic Acid: From 2D Layer to 3D Net Framework

Five metal–organic coordination complexes with the formulas of {Mn­(L)­(H2O)2}n (1), {[Cd1.5L1.5(DEF)2]·2DEF}n (2), [Co1.5(L)1.5(H2O)]n (3), {[Co­(L)­(H2O)2]·4H2O}n (4), and {[Ni­(L)­(H2O)2]·4H2O}n (5), (H2LOMe = 4,4′-(2,3,6,7-tetramethoxyanthracene-9,10-diyl)­dibenzoic acid) based on a new rigid dicarboxylate ligand were synthesized and structurally characterized. Structural analysis reveals that H2LOMe acts as multibidentate bridging linker to connect metal ions and possesses similar coordination modes with terephthalic acid. Complex 1 is a (44)-sql layer incorporating bidentate-bridging H2LOMe and infinite Mn­(CO2)2 SBUs. Complexes 2 and 3 have similar 2D (36)-hxl layer topology structure based on bidentate-chelating/bridging H2LOMe ligand and trinuclear hourglass SBUs. Complexes 4 and 5 are isostructural and possess 3D open frameworks based on infinite M-(μ2-H2O) chain. From the viewpoint of crystal structure diversity and comparison, our results further demonstrate that the coordination mode of metal ions and ligand are the vital elements in determining the final crystal structure. Moreover, thermal stabilities of 1–5 and temperature-dependent photoluminescence behaviors of 1 and 2 are discussed.