Auxiliary ligand-directed structural variation of the Zn(II)–1,4-bis(imidazol-1-yl)benzene net: synthesis, characterization, and luminescence

Abstract

In this article, two different anionic ligands, 3,4-oxybis(benzoate) (bopH₂) and sulfate, have been employed as co-ligands to perform a comparison on the structures of coordination polymers based on the Zn(II)–rigid 1,4-bis(imidazol-1-yl)benzene (bib) net. Two new coordination polymers, {Zn(bib)(bop)}_∞ (1) and {Zn(bib)(SO₄)}_∞ (2), were synthesized from hydrothermal reactions and characterized by elemental analyses, IR and single-crystal X-ray diffraction. Complex 1 contains two unique 2-D layers, which are further interpenetrated to form a two-fold 2-D → 2-D framework. However, 2 consists of a 3-D structure with pcu topology constructed by sulfates as pillars. The structural difference of 1 and 2 indicates that size of the ancillary ligands play important roles in formation of such coordination architectures. Thermal and fluorescence properties of 1 and 2 are also investigated in the solid state.

Keywords:

• Metal–organic framework
• Rigid ligand
• Ancillary ligand
• Crystal structure
• Fluorescence

Acknowledgments

The authors acknowledge the financial support and grant from the Natural Science Foundation of Guangxi Province (Grant nos. 2010GXNSFD013017, 2010GXNSFA013062, 200 911MS241, and 2011GXNSFB018023). The grant from Qinzhou University (Grant no. 2011XJKY-14B) is also acknowledged.