Effect of substituents on complex stability aimed at designing new iron(III) and aluminum(III) chelators
详细信息 查看全文
- 作者：Valeria Marina Nurchi ; Tiziana Pivetta ; Joanna Izabela Lachowicz ; Guido Crisponi
- 关键词：Fe(III) complexes ; Al(III) complexes ; Chelating agents ; Potentiometry ; Spectrophotometry ; pM ; Conditional constants
- 刊名：Journal of Inorganic Biochemistry
- 出版年：2009
- 出版时间：February 2009
- 年：2009
- 卷：103
- 期：2
- 页码：227-236
- 全文大小：490 K
文摘
The solution equilibria of iron(III) and aluminum(III) with two classes of hard ligands (catechol, salicylic acid and their nitro-derivatives) have been reliably studied by potentiometric, spectrophotometric and NMR spectroscopy. The effect of the nitro substituent on the binding properties of catechol and salicylic acid has been examined thoroughly. The inductive and resonance properties of the substituent that, as expected, lower the basicity of the phenolic and carboxylic groups, lead to a general decrease in both protonation and complex formation constants. This decrease causes an increase in pM of between 0.2 and 1.1 pM units for the nitro-substituted salicylates and of about 4 units for 4-nitrocatechol, with a significantly higher chelating efficacy. The influence of the substituent on catechol and salicylic acid is discussed in detail on the basis of conditional constants at pH 7.4.