Three-foot Research And Dibromo 4-pyridyl Urea Synthesis And Properties Of Bis-urea Xylene Bridge Linking The Receptors

Two oligourea anion ligandsL1, L2and their anion complexes are reported in this thesis. First, the4-pyridyl-functionalized tripodal tris(urea) ligand L1was synthesized and its coordination to oxyanions and spherical anions were studied. Second, a dibromoxylene bridged bisurea ligand L2has been designed and synthesized, which is expected to assemble to helical complexes with the PO43-anion. There are four chapters.The first chapter overviews the development of anion coordination chemistry, the significance of anions, and the design and synthesis of anion receptors. The second chapter describes the synthesis of the4-pyridyl-functionalized tripodal tris(urea) ligand L1and its complexes with oxyanions. The ligand readily forms the2:1(host/guest) complex that encapsulates the tetrahedral oxoanions with the "full capsule" structure. The third chapter presents a series of complexes of the tripodal tris(4-pyridylurea) ligand L1with halide ions, which feature the1:1(host/guest) binding mode ("half capsule" structure). The fourth chapter describes the synthesis of the di-bromoxylene bridged bis-urea ligand L2.The tripodal structure has proven to be a promising scaffold for anion binding and has been widely used. In methanol and water systems, we got the complexes of L and SO42-, CO32-, Cl-, and F-anions (complexes1-10) with the composition [Mg(H2O)6][SO4(?)L2](1), M2(H2O)4[CO3cL2](M=Na,2; K,3), M(H2O)3[ClcL](M=Na,4; K,5), K(H2O)3[F(?)L](6), M(H2O)6[Cl(?)L]2(M=Mg,7; Ca,8; Mn,9A), M[ClcL]2,(M=Mn,9B; Co,10), respectively. For the oxyanion sulfate, two ligand molecules form a "full capsule" and the anion is encapsulated within the capsule through multiple hydrogen bonds. In the case of the spherical halide ions, we obtained three types of complexes and studied the anion binding both in solid state and solution. In complexes1-3, the host-guest ratio is2:1in solid state but is1:1in solution. For complexes4-10, the binding mode is1:1in both solid state and solution, wherein the anion forms the1:1"half capsule" by six hydrogen bonds. The countercation has minimum effects on the chloride-encapsulating but greatly alters the whole structure of the complexes. In addition, in complexes9B and10, the transition metal ions are directly coordinated by the pyridyl groups of the ligand, while in other complexes (1-9A) the cation exists as the hydrated form and interacts with the ligand in the second coordination sphere. These anion complexes have been characterized in detail and the solution anion coordination properties of L were studied.