Solvent-induced conformational isomerism of a flexible fluorinated bis(imidazole) ligand on the self-assembly of 1-D and 2-D CuII coordination polymers

Two distinct coordination polymers [Cu(Fbix)2(NO3)2]n (1) and {[Cu(Fbix)2(NO3)2]·6H2O}n (2) have been prepared from the reactions of CuII nitrate with a flexible fluorinated ligand 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-yl-methyl)benzene (Fbix) under different solvents. Single crystal X-ray diffraction reveals that 1 displays a 1-D double-chain structure containing the Fbix with gauche conformation whereas 2 has a 2-D rhombic grid network containing the Fbix with anti conformation. Their spectroscopic, thermal, and fluorescence properties have also been investigated.

Graphical abstractTwo new CuII coordination polymers [Cu(Fbix)2(NO3)2]n (1) and {[Cu(Fbix)2(NO3)2]·6H2O}n (2) have been obtained through the solvent-regulated assembly of CuII nitrate and a flexible fluorinated ligand 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-yl-methyl)benzene (Fbix). Their significant structural discrepancy of the 1-D (for 1) and 2-D (for 2) networks results from the conformational isomerism of the Fbix ligands.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel flexible fluorinated bis(imidazole) building block is used to creat two CuII coordination polymers. ► Structural discrepancy of the 1-D and 2-D networks results from the varied conformations of the ligands. ► Thermal behavior and solid-state fluorescent emissions are available.