Four Metal Complexes Based on Bulky Imidazole Ligands: Solvothermal Syntheses, Crystal Structures, and Fluorescence Properties

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) 2015-09, Vol.641 (11), p.1874-1880
• Main Authors: Zhang, Xue, Li, Sai, He, Yue-Jiao, Han, Tong, Wang, Xiao-Ling, Chen, Bang, Zou, Kang-Yu, Li, Zuo-Xi
• Format: Article
• Language: English
• Subjects: Bulky imidazole ligand; Crystal structure; Fluorescence; Ligand-related compound; Solvothermal synthesis
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.201500230

In order to explore the influences of (de‐)protonation of the imidazole ring on the structural diversity of the resulting complexes, the imidazole‐based ligands 4, 5‐diphenylimidazole (Hdpi) and 1H‐phenanthro[9, 10‐d]imidazole (Hpi) were utilized as bulky building blocks to construct four complexes by solvothermal reactions, i.e. [Ag(Hdpi)2](NO3)·(H2O) (1), [Cu(dpi)]∞ (2), [Cu(Hpi)(NO3)]∞ (3), and [(H2pi)(NO3)]·H2O (4). In complex 1, two Hdpi ligands adopt a monodentate pattern and coordinate with one AgI ion to form a mononuclear unit, which is further connected by hydrogen bonds into a 1D supramolecular helix. The deprotonated dpi ligand of 2 acts in bidentate mode, and bridges CuI ions to afford a 1D chain. In 3, the NO3– ion, acts as a monodentate bridging ligand and joins CuI ions to generate a 1D chain. The Hpi ligand employs a monodentate mode to bond with CuI ions of the 1D chain. 4 is protonated and two H2pi nitrogen atoms are free of coordination. Interestingly, hydrogen bonds among the NO3– ion, the H2pi ligand, and the water molecule yield a macro ring R44(14). The resulting structural diversity reveals that the (de‐)protonation of imidazole ring directly steers the coordination number of ligand, and thus causes a significant effect on the structure, especially the dimensionality. Furthermore, the solid‐state fluorescence properties of the free ligands and compounds 1–4 were studied at room temperature.