Self-assembly of two fluorescent supramolecular frameworks constructed from unsymmetrical benzene tricarboxylate and bipyridine

Two new supramolecular compounds, [Ag(4,4′-bipy)]n [Ag(HBTC)]n (1) and [Cu(H2BTC)(2,2′-bipy)] (2) (HBTC/H2BTC = 1,2,4-benzenetricarboxylate, 4,4′-bipy/2,2′-bipy = 4,4′/2,2′-bipyridine), have been synthesized and characterized by elemental analyses, IR spectra, ultraviolet–visible diffuse reflection integral spectra (UV–Vis DRIS), fluorescent spectra, thermogravimetric analysis and single crystal X-ray diffraction analysis. It is noteworthy that there were two kinds of one-dimensional stairs-chain including cationic [Ag(4,4′-bipy)]n chain and anionic [Ag(HBTC)]n chain in 1. Furthermore, a two-dimensional double layer supramolecular framework was constructed through coordination bonds, hydrogen bonds, π–π stacking interactions and Ag⋯O weak coordinative interactions. The one-dimensional supramolecular chain of 2 was built from combining mononuclear [Cu(H2BTC)(2,2′-bipy)] by inter- and intra-molecular hydrogen bonding interactions. Additionally, the two complexes exhibit intense blue or olivine luminescence at room temperature.

Graphical abstractTwo new supramolecular compounds have been synthesized by hydrothermal method. The compound 1 consists of two kinds of independent chain including cationic [Ag(4,4′-bipy)]n chain and anionic [Ag(HBTC)]n chain. As for 2, the Cu(I) centers adopt a trigonal planner environment and a 1-D infinite supramolecular chain structure formed by hydrogen bonding interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide