2D→3D Polycatenated and 3D→3D Interpenetrated Metal-Organic Frameworks Constructed From Thiophene-2,5 and Rigid Bis(Imidazole) Ligands

Abstract

Hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2,5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H<inf>2</inf>tdc) in the presence of Zn(II) and Cd(II) salts in H<inf>2</inf>O produced three new metal-organic frameworks, namely, [Zn(μ-tdc)(H<inf>2</inf>O)(μ-dib)]<inf>n</inf> (1), [Cd(μ-tdc)(H<inf>2</inf>O)(μ-dib)]<inf>n</inf> (2), and {[Cd <inf>2</inf>(μ<inf>3</inf>-tdc)<inf>2</inf>(μ-dimb)<inf>2</inf>] ·(H<inf>2</inf>O)}<inf>n</inf> (3). These MOFs were characterized by FT-IR spectroscopy, elemental, thermal (TG, DTA, DTG and DSC), and single-crystal X-ray diffraction analyses. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D→3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 66. Molecular simulations were used to assess the potentials of the complexes for H<inf>2</inf> storage application. Moreover, these coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature. © 2013 Elsevier Inc.