Department of Chemistry, State University of New York, University at Buffalo, Amherst, New York 14260, USA.
Inorg Chem. 2012 Jul 16;51(14):7448-50. doi: 10.1021/ic301001u. Epub 2012 Jul 3.
Iron(II) complexes of the macrocyclic ligands 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (TCMC) and (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane (STHP) contain a highly stabilized Fe(II) center in the high-spin state, which is encapsulated by an octadentate macrocycle. The complexes are resistant to acid, metal cations, phosphate, carbonate, and oxygen in aqueous solution. Fe(TCMC) contains exchangeable amide protons, and Fe(STHP) contains exchangeable protons attributed to alcohol OH donors, which give chemical exchange saturation transfer (CEST) peaks at physiological pH and 37 °C at 50 and 54 ppm from bulk water, respectively. The distinct pH dependence of the CEST peak of the two complexes over the range of pH 6-8 shows that these two groups may be useful in the development of ratiometric pH sensors based on iron(II).
大环配体 1,4,7,10-四(氨甲酰甲基)-1,4,7,10-四氮杂环十二烷（TCMC）和（1S,4S,7S,10S）-1,4,7,10-四(2-羟丙基)-1,4,7,10-四氮杂环十二烷（STHP）的二价铁（II）配合物在高自旋态下含有一个高度稳定的 Fe(II)中心，该中心被一个八齿大环包裹。这些配合物在水溶液中对酸、金属阳离子、磷酸盐、碳酸盐和氧气具有抗性。[Fe(TCMC)]²⁺含有可交换的酰胺质子，[Fe(STHP)]²⁺含有归因于醇 OH 供体的可交换质子，它们在生理 pH 和 37°C 下分别在 50 和 54 ppm 处产生来自体相水的化学交换饱和转移（CEST）峰。两种配合物的 CEST 峰在 pH 6-8 范围内的明显 pH 依赖性表明，这两种基团可能在基于铁(II)的比率型 pH 传感器的开发中有用。
