Four metal–organic frameworks constructed with hydroxylphenyl imidazole dicarboxylate: Syntheses, crystal structures and properties

Solvothermal reactions of 2-(3-hydroxylphenyl)-1H-imidazole-4,5-dicarboxylic acid (m-OHPhH3IDC) with Sr(II), Ba(II) and Zn(II) metals, respectively, lead to four metal–organic frameworks, namely, [Sr(m-OHPhH2IDC)2(H2O)2]n (1), {[Sr(m-OHPhH2IDC)2(H2O)2]·H2O}n (2), {[Zn2(m-OHPhHIDC)2(phen)2]·H2O}n (phen = 1,10-phenanthroline) (3) and [Ba(m-OHPhH2IDC)2(H2O)2]n (4). According to the single-crystal X-ray structural analyses, in these polymers, the m-OHPhH3IDC ligand can be singly deprotonated or doubly deprotonated, and coordinates to metal ions by diverse modes. Complexes 1, 2 and 4 exhibit 2D layered structures with rhombic grids. Complex 3 generates a wave-like architecture by π–π interactions from a zigzag chain. The thermal and solid-state photoluminescence properties of the complexes have been investigated and discussed in detail.

Graphical abstractFour novel Ba(II), Zn(II) and Sr(II) imidazole dicarboxylate-based coordination polymers have been prepared and characterized by single-crystal X-ray crystallography. The thermal and solid-state photoluminescence properties of the four complexes have been determined as well.Figure optionsDownload full-size imageDownload as PowerPoint slide