Synthesis and structural characterization of 1D and 2D coordination polymers based on flexible 1, 3-adamantanediacetic acid andexo-bidentate organic linkers

Abstract

Five mixed‐linkers based coordination polymers, namely {M(1, 3‐Hadc)(bpy)(H₂O)₂}_n [M = Ni^II (1), Co^II (2)], {Zn(1, 3‐adc)(bpy)_0.5}_n (3), {Cd(1, 3‐Hadc)₂(bpy)}_n (4), and {Cu(1, 3‐Hadc)₂(bpp)}_n (5) [1, 3‐H2adc = 1, 3‐adamantanediacetic acid, bpy = 4, 4′‐bipyridine, bpp = 1, 3‐bis(4‐pyridyl)propane] were synthesized by solvent diffusion reactions. Their structures were determined by single‐crystal X‐ray diffraction analyses. Compounds 1 and 2 are isostructural and they have 1D linear coordination polymer structure that are further interdigitated via hydrogen bonding resulting in 2D extended networks. The dehydrated 1 shows type‐I profile for H₂O vapor suggesting hydrophilic nature of the framework. In compound 3, a paddle‐wheel type secondary building unit (SBU) directs the overall structure to form a 2D square grid type structure. The 2D sheets further stack along the c axis in a AB fashion and leaves no void space. Compound 4 has a hexacoordinate CdII and forms a zigzag coordination polymer chain‐like structure and these chains form a 2D structure by hydrogen bonding interactions. Compound 5 contains a longer linker bpp compared to bpy and forms a 2D structure similar to that of 4. These results demonstrate that by changing the metal ions coordination mode versatile structures with different dimensionalities and network topologies can be realized in a same mixed linkers system.