...
首页> 外文期刊>Journal of Inorganic Biochemistry: An Interdisciplinary Journal >~(31)P NMR, potentiometric and spectrophotometric studies of phytic acid ionization and complexation properties toward Co~(2+), Ni~(2+), Cu~(2+), Zn~(2+) and Cd~(2+)
【24h】

~(31)P NMR, potentiometric and spectrophotometric studies of phytic acid ionization and complexation properties toward Co~(2+), Ni~(2+), Cu~(2+), Zn~(2+) and Cd~(2+)

机译:〜(31)P NMR,植酸对Co〜(2 +),Ni〜(2 +),Cu〜(2 +),Zn〜(2+)和Cd〜( 2+)

获取原文
获取原文并翻译 | 示例
           

摘要

Acido-basic properties of phytic acid as well as its binding properties toward five bivalent metal ions (Co~(2+), Ni~(2+), Cu~(2+), Zn~(2+) and Cd~(2+)) were investigated. Potentiometric titration curves refined with the program PROTAF allowed the determination of acidity constants of the ligand as well as complexation constants with the considered metal ions for systems containing ligand-to-metal ratios over unity. The chelating ability of phytic acid varies with the metal according to the sequence: Cu~(2+) > Zn~(2+) > Cd~(2+) > Ni~(2+) approx= Co~(2+). ~31P NMR titrations of the Zn~(2+)- phytic acid system suggest that the metal is bound to P2 or P5 in several monocoordinated species for low pH values. On the other hand, near pH = 9, bicoordinated species probably occur which mainly involve P2 with P1 or P3 as the chelating phosphate groups. Electronic spectra of Co~(2+) -phytic acid complexes lead to similar conclusions: an octahedral geometry for a monocoordinated species in the pH range 2-7 and tetrahedral complexes above pH = 9, which are probably bicoordinated. For metal-to-ligand ratios over unity, a solid compound Co_5L centre dot nH_2O (n approx 20) was isolated.
机译:植酸的酸碱性及其对5种二价金属离子(Co〜(2 +),Ni〜(2 +),Cu〜(2 +),Zn〜(2+)和Cd〜( 2+))。用程序PROTAF改进的电位滴定曲线可以确定配体的酸度常数,以及对于所含配体与金属之比超过1的系统,与考虑的金属离子的络合常数。植酸的螯合能力随金属的不同而变化,依次为:Cu〜(2+)> Zn〜(2+)> Cd〜(2+)> Ni〜(2+)近似= Co〜(2+) 。 Zn〜(2 +)-植酸体系的〜31P NMR滴定表明,在低pH值下,金属在几种单配位物种中与P2或P5结合。另一方面,在pH = 9附近,可能会出现双配位物质,其中主要涉及具有P1或P3作为螯合磷酸基团的P2。 Co〜(2 +)-植酸配合物的电子光谱得出相似的结论:pH范围为2-7的单配位物种的八面体几何形状和pH = 9以上的四面体配位的八面体几何结构可能是双配位的。对于金属与配体的比值大于1的情况,分离出了固态化合物Co_5L中心点nH_2O(n约为20)。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号