Synthesis of Designed Conductive One-Dimensional Coordination Polymers of Ni(II) with 6-Mercaptopurine and 6-Thioguanine

Calculations performed with the goal of designing suitable electrical conductive [M(6-MP)2]n (M = transition metal, 6-MP = 6-mercaptopurinato) one-dimensional coordination polymers suggested that metal ions such as Ni(II) could provide suitable materials. In this work, direct hydrothermal reactions between 6-mercaptopurine (6-MPH) and the analogous 6-thioguanine (6-ThioGH) with NiSO4·6H2O yield the compounds [Ni(6-MP)2]n·2nH2O [1] and [Ni(6-ThioG)2]n·2nH2O [2]. The X-ray structures confirm that both compounds present similar structures based on one-dimensional chains in which the deprotonated nucleobases act as the bridging ligands connecting the metal ions by short distances. Electrical measurements at room temperature confirm the conductor character of both coordination polymers. The small differences found in these measurements have been rationalized with the help of density functional theory calculations. Preliminary adsorption studies on surfaces for 1 have allowed characterization of single chains on mica and graphite. The results obtained suggest the potential use of coordination polymers on nanomaterials for molecular electronics.