“Wurster-Type” Ureas as Redox-Active Receptors for Anions
摘要:
Four redox-active receptors, 1-4, based on the incorporation of p-phenylenediamine(s) within a urea framework, were synthesized, and the affinities of two for a series of anions were quantified through UV-vis and NMR spectroscopic studies. The structure of 1 was confirmed by X-ray crystallography. For the oxoanions studied, complex stabilities approached 10(6) M-1 in acetonitrile and decreased with the decreasing basicity of the anion (CH3COO- > C6H5COO- > H2PO4- > NO2- > NO3-). The presence of the urea functionality caused an increase in the oxidation potential of the p-phenylenediamine subunit compared to that of free p-phenylenediamine. Electrochemical studies of the anion complexes revealed two-wave behavior with the appearance of a second oxidation wave cathodic to that in the free receptors and characteristic of the bound anion, Ab initio DFT studies of a representative acetate complex revealed the consequences of host oxidation state on complex structure.
“Wurster-Type” Ureas as Redox-Active Receptors for Anions
作者:John P. Clare、Anna Statnikov、Vincent Lynch、Andrew L. Sargent、John W. Sibert
DOI:10.1021/jo9011392
日期:2009.9.4
Four redox-active receptors, 1-4, based on the incorporation of p-phenylenediamine(s) within a urea framework, were synthesized, and the affinities of two for a series of anions were quantified through UV-vis and NMR spectroscopic studies. The structure of 1 was confirmed by X-ray crystallography. For the oxoanions studied, complex stabilities approached 10(6) M-1 in acetonitrile and decreased with the decreasing basicity of the anion (CH3COO- > C6H5COO- > H2PO4- > NO2- > NO3-). The presence of the urea functionality caused an increase in the oxidation potential of the p-phenylenediamine subunit compared to that of free p-phenylenediamine. Electrochemical studies of the anion complexes revealed two-wave behavior with the appearance of a second oxidation wave cathodic to that in the free receptors and characteristic of the bound anion, Ab initio DFT studies of a representative acetate complex revealed the consequences of host oxidation state on complex structure.