Bregier-Jarzebowska Romualda
Faculty of Chemistry, A. Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland.
J Solution Chem. 2014;43(12):2144-2162. doi: 10.1007/s10953-014-0269-x. Epub 2014 Nov 26.
Binary and ternary complexes of copper(II) with l-glutamic acid (Glu) and diamines 1,3-diaminopropane and 1,4-diaminobutane, putrescine (tn, Put), as well as adducts formed in the metal-free systems, have been investigated in aqueous solutions. The types of complexes formed and their overall stability constants were established on the basis of computer analysis of potentiometric results. The reaction centers and the modes of interaction were identified on the basis of spectroscopic studies (NMR, Vis and EPR). In the ligands studied the interaction centers are the oxygen atoms from carboxyl groups, nitrogen atom from the amine group of glutamic acid and the nitrogen atoms from amine groups of the diamines. The centers of noncovalent interaction in the adducts that formed in the metal-free systems are also potential sites of metal ion coordination, which is important in biological systems. In the Glu-diamine systems, molecular complexes of the (Glu)H(diamine) type are formed. In the (Glu)H(tn) adduct, in contrast to the corresponding complex with Put, an inversion effect was observed in which the first deprotonated amine group of tn became a negative reaction center and interacted with the protonated amine groups from Glu. Depending on the pH, the amine groups from the diamine can be either a positive or a negative center of interaction. In the Cu(Glu) species the first molecule of Glu takes part in metallation through all functional groups, whereas the second molecule makes a "glycine-like" coordination with the Cu(II) ions that is only through two functional groups. According to the results, introduction of Cu(II) ions into metal-free systems (Glu-diamine) changes the character of interactions between the bioligands in the complexes that form in Cu(II)-Glu-diamine systems and no ML…L' type complexes are formed. However, in the ternary systems only the heteroligand complexes Cu(Glu)(diamine) and Cu(Glu)(diamine)(OH) are observed.
研究了铜（II）与L-谷氨酸（Glu）和二胺1,3-二氨基丙烷、1,4-二氨基丁烷、腐胺（tn，Put）形成的二元和三元配合物，以及在无金属体系中形成的加合物在水溶液中的情况。根据电位滴定结果的计算机分析确定了形成的配合物类型及其总稳定常数。基于光谱研究（NMR、可见光谱和电子顺磁共振）确定了反应中心和相互作用模式。在所研究的配体中，相互作用中心是羧基的氧原子、谷氨酸胺基的氮原子和二胺胺基的氮原子。在无金属体系中形成的加合物中的非共价相互作用中心也是金属离子配位的潜在位点，这在生物体系中很重要。在Glu-二胺体系中，形成了（Glu）H（二胺）型分子配合物。在（Glu）H（tn）加合物中，与相应的Put配合物相比，观察到一种反转效应，其中tn的第一个去质子化胺基成为负反应中心，并与Glu的质子化胺基相互作用。根据pH值，二胺的胺基可以是正的或负的相互作用中心。在Cu（Glu）物种中，第一个Glu分子通过所有官能团参与金属化，而第二个分子仅通过两个官能团与Cu（II）离子进行“甘氨酸样”配位。根据结果，将Cu（II）离子引入无金属体系（Glu-二胺）会改变在Cu（II）-Glu-二胺体系中形成的配合物中生物配体之间的相互作用性质，并且不会形成ML…L'型配合物。然而，在三元体系中仅观察到异配体配合物Cu（Glu）（二胺）和Cu（Glu）（二胺）（OH）。
