Two- and three-dimensional coordination polymers based on zinc(II) and furan-2,5-dicarboxylic acid: structure variation due to metal-to-linker ratio.

Two Zn-based coordination polymers (CPs) were synthesized by the hydrothermal method, using Zn(NO)·6HO and furan-2,5-dicarboxylic acid (FDCA) in dimethylformamide (DMF) solvent, at 95 °C. Poly[tetrakis(dimethylazanium) [tetrakis(μ-furan-2,5-dicarboxylato-κO:O)dizinc(II)]], {(CHN)[Zn(CHO)]} or {[DMA][Zn(FDC)]} (DMA = dimethylazanium and FDC = furan-2,5-dicarboxylate), (1), was obtained with a 1:1 molar ratio of Zn and FDCA. It crystallized in the monoclinic space group C2/c. Coordinated by Zn ions, FDC ligands form 2 double-stranded helices propagating along the b axis. The helices are interconnected and extend laterally in the a direction, forming a two-dimensional (2D) sheet-like network. The 2D sheets are stacked along the c direction without interconnections. DMA cations are cocrystallized in (1) and are hydrogen bonded with carboxylate O atoms of the FDC ligands. The hydrogen-bonding pattern consists of R(4) and R(10) motifs alternating in a chain. Poly[bis(dimethylazanium) [bis(μ-furan-2,5-dicarboxylato-κO:κO:κO:κO)bis(μ-furan-2,5-dicarboxylato-κO:κO:κO)dizinc(II)] dimethylformamide 3.08-solvate], {(CHN)[Zn(CHO)]·3.08CHNO} or {[DMA][Zn(FDC)]·3.08DMF}, (2), was obtained with a 1:2 molar ratio of Zn and FDCA. It crystallized in the monoclinic space group P2/c, forming a three-dimensional network. The pores are filled with DMA cations and DMF solvent molecules.