Protonation Behavior and Intramolecular Interactions of<i>α</i>,<i>ω</i>-Alkanediaminepolymethylenepolyphosphonates
作者:Tomohide Ichikawa、Kiyoshi Sawada
DOI:10.1246/bcsj.70.829
日期:1997.4
The protonation equilibria of two types of aminopolyphosphonates ((CH3)2−p(CH2PO3)pN(CH2)mN(CH2PO3)p′(CH3)2−p′) in aqueous solution were investigated by means of potentiometry and 31P NMR spectroscopy. The protonation behavior of diaminotetramethylenetetraphosphonate (p = p′ = 2) is significantly altered by a change in the number of methylene chains (m = 2, 3, 6). The protonations of the imino fragments of hdtmp, which is connected with a six methylene chain (m = 6), are essentially independent of each other, whereas edtmp, which is connected with a two methylene chain (m = 2), forms a hydrogen bond between both nitrogen atoms (NH+···N) in the mono protonated species. The ethylenediaminepolyphosphonates (m = 2), having an iminodiphosphonate group (p = 2, p′ = 0—2), show a peculiar 31P NMR behavior in which the signal shows a downfield shift at higher protonated species. However, eddmp (N,N′), having one methylenephosphonate group at each imino fragment (p = p′ = 1), does not show such an anomaly. These results indicate the existence of an intramolecular interaction between both fragments, such as a hydrogen bond of a protonated nitrogen atom with unprotonated phosphonates of another imino fragment, where two methylenephosphonate groups in one imino fragment are required to operate such an interaction.
通过电位测定法和 31P NMR 光谱法研究了水溶液中两种氨基多膦酸盐((CH3)2-p(CH2PO3)pN(CH2)mN(CH2PO3)p′(CH3)2-p′)的质子化平衡。四亚甲基四膦酸二胺(p = p′ = 2)的质子化行为随着亚甲基链数量(m = 2、3、6)的变化而发生显著改变。连接有 6 个亚甲基链(m = 6)的 hdtmp 的亚氨基片段的质子化基本上是相互独立的,而连接有 2 个亚甲基链(m = 2)的 edtmp 则在单质子化物种的两个氮原子(NH+--N)之间形成氢键。具有亚氨基二膦酸基团(p = 2,p′ = 0-2)的乙二胺多膦酸盐(m = 2)显示出一种奇特的 31P NMR 行为,在质子化程度较高的种类中,信号会出现下移。然而,eddmp (N,N′)的每个亚氨基片段上都有一个亚甲基膦酸基(p = p′ = 1),却没有出现这种异常现象。这些结果表明这两个片段之间存在分子内相互作用,如质子化氮原子与另一个亚氨基片段的非质子化膦酸盐之间的氢键,其中一个亚氨基片段中的两个亚甲基膦酸盐基团是产生这种相互作用的必要条件。