Novel photo- and/or thermochromic MOFs derived from bipyridinium carboxylate ligands

Two new Zn-MOFs based on 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium bromide have been synthesized. Compound 1 has a 3D interpenetrated cationic framework with photo- and thermochromism, while compound 2 possesses a 2D layered cationic network with only photochromism.

Anion Effect on the Structural Diversity of 1-D and 2-D Zinc(II) Coordination Polymers with a Flexible Fluorinated Bis(imidazole) Ligand

Reactions of a flexible fluorinated ligand, 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-ylmethyl) benzene (Fbix), with ZnX2 (X =OAc- or NO3-) lead to the formation of the two new ZnII coordination polymers [Zn(Fbix)(OAc)2]n (1) and {[Zn2(Fbix)3(NO3)2](NO3)2(H2O)3}n (2), which have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Although the ZnII centers of both 1 and 2 are in a similar tetrahedral coordination geometry, each ZnII ion in 1 is surrounded by two Fbix spacers and two terminal OAc- anions to form a highly undulated chain, whereas each ZnII ion in 2 is embraced by three Fbix ligands and one NO3- anion to result in a two-dimensional cationic network. Since 1 and 2 are synthesized under the same conditions, the structural differences between them are attributable to the difference of the counterions. The solid-state properties such as thermal stability and luminescence of 1 and 2 have also been studied briefly.