Studies On Synthesis, Molecular Recognition And Coordination Chemistry Of Pyridine-2-ylurea Compounds

Four substituted ureas, N-Benxyl-N′-pyridin-2-ylurea (H1), Bis(N-pyridin-2-ylurea)ethane (H2), Bis(N-pyridin-2-ylurea)hexane (H3), Bis(N-pyridin-2-ylurea)-2, 6-dimethylbenzene (H4) have been synthesized with the simple method. These compounds bear one or two pyridine-2ylurea moieties. Their structures were confirmed by IR and 1H NMR. The self-assembly action involved in compound H1 was studied by the analysis of its crystal structure.The four substituted ureas contain the ADD pattern, while cytosine has the DAA pattern. We studied their molecular recognition action using the four substituted ureas as hosts and cytosine as guest. We determined the association constants with the UV-Vis spectra titration, analyzed the influence of the structure of hosts on the association constants. The 1H NMR spectra were used to elucidate further the recognition abilities. The results showed that there is a strong recognition action between the four substituted ureas and cytosine.One Co(II) and Cu(II) complexes obtained by the reactions of N-Benxyl-N′-pyridin-2-ylurea ligand with CoCl2 and CuCl2 have been prepared and characterized. Single-crystal structure analysis revealed that the two complexes formed two dimensional netwoks by the N–H···Cl hydrogen bonding interactions. In addition, the properties on IR spectra of the ligand and the complexes have been studied.