Adenine-Based Coordination Polymers: Synthesis, Structure, and Properties

A solvothermal reaction of metal nitrate (M = Zn, Cd), cyclohexanedicarboxylic acid, and adenine resulted in the isolation of three new coordination polymers, [Zn-4(1,4-CHDA)(2.5)(ad)(3)2H(2)O] 7H(2)O 2DMA (CHDA = cyclohexane dicarboxylic acid, ad = adenine, DMA = dimethylacetamide), I, [Cd-3(1,4-CHDA)(2)(ad)(2)H2O], II, [Cd(1,2-CHDA)(9-HEA)H2O] 4H(2)O [9-HEA = 9-(2-hydroxyethyl)adenine], III. Single-crystal structural studies show that compounds I and II have three-dimensional structures whereas III has a two-dimensional one. The formation of a Cd-8 macrocycle in II, based on a polyhedral arrangement, appears to be new. In all the compounds, the amino group of the adenine appears to be free and can be utilized for the detection of explosives such as nitrophenol, dinitrophenol, and trinitrophenols. The hydroxyl nitro aromatics appears to have a much stronger influence on the luminescence behavior of the compounds with very low detection limits. This, in fact, provides a new opportunity for exploring these compounds for the detection of harmful nitro aromatics in solution. The present compounds also exhibit considerable sensitivity towards metal ion detection, especially Fe2+/Fe3+, Cr3+, Ag+, and Hg2+ ions in solution. Base-catalyzed Knoevenagel condensation studies exhibit good conversion and selectivity.