Bonastre-Sabater Irene, Lopera Alberto, Martínez-Camarena Álvaro, Blasco Salvador, Doménech-Carbó Antonio, Jiménez Hermas R, Verdejo Begoña, García-España Enrique, Clares M Paz
Departamento de Química Inorgánica, Instituto de Ciencia Molecular. Universidad de Valencia, Calle Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain.
Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, avda. Complutense s/n, 28040 Madrid, Spain.
Dalton Trans. 2024 Oct 15;53(40):16480-16494. doi: 10.1039/d4dt01236d.
The Cu complexes of three [1 + 1] azacyclophane macrocycles having the 1-pyrazole ring as the spacer and the pentaamine 1,5,8,11,15-pentaazadecane (L1) or hexaamines 1,5,8,12,15,19-hexaazanonadecane (L2) and 1,5,9,13,17,21-hexaazaheneicosane (L3) as bridges show endo- coordination of the pyrazolate bridge giving rise to discrete monomeric species. Previously reported pyrazolacyclophanes evidenced, however, exo-coordination with the formation of dimeric species of 2 : 2, 3 : 2 or even 4 : 2 Cu : L stoichiometry. The complexes have been characterized in solution using potentiometric studies, UV-Vis spectroscopy, paramagnetic NMR, cyclic voltammetry and mass spectrometry. The measurements show that all three ligands have as many protonation steps in water as secondary amines are in the bridge, while they are able to form both mono- and binuclear Cu species. The crystal structures of the complexes [Cu(HL1)Br]Br(ClO)·HO (1) and Cu(HL2)Cl(ClO)·HO·CHOH (2) have been solved by X-ray diffraction studies. In 1 the metal ion lies at one side of the macrocyclic cavity being coordinated by one nitrogen of the pyrazolate moiety and the three consecutive nitrogen atoms of the polyamine bridge. The other nitrogen of the pyrazole ring is hydrogen-bonded to an amine group. In 2 the two metal ions are interconnected by a pyrazolate bis(monodentate) moiety and complete their coordination spheres with three amines and either a bromide or a perchlorate anion, which occupy the axial positions of distorted square pyramid geometries. Paramagnetic NMR studies of the binuclear complexes confirm the coordination pattern observed in the crystal structures. Cyclic voltamperommetry data show potentials within the adequate range to exhibit superoxide dismutase (SOD) activity. The IC values calculated by McCord-Fridovich enzymatic assays show that the binuclear Cu complexes of L2 and L3 have SOD activities that rank amongst the highest ones reported so far.
三种[1 + 1]氮杂环番大环化合物的铜配合物，以1-吡唑环作为间隔基，以五胺1,5,8,11,15-五氮杂十六烷（L1）或六胺1,5,8,12,15,19-六氮杂十九烷（L2）以及1,5,9,13,17,21-六氮杂二十一烷（L3）作为桥联基团，显示出吡唑酸酯桥的内配位，形成离散的单体物种。然而，先前报道的吡唑环番证明存在外配位，形成化学计量比为2∶2、3∶2甚至4∶2的铜∶配体的二聚体物种。已使用电位滴定研究、紫外-可见光谱、顺磁核磁共振、循环伏安法和质谱对这些配合物在溶液中进行了表征。测量结果表明，所有三种配体在水中的质子化步骤数量与桥联基团中的仲胺数量相同，同时它们能够形成单核和双核铜物种。通过X射线衍射研究解析了配合物[Cu(HL1)Br]Br(ClO)·H₂O（1）和[Cu(HL2)Cl(ClO)]₂(ClO)₄·H₂O·CH₃OH（2）的晶体结构。在配合物1中，金属离子位于大环腔的一侧，由吡唑酸酯部分的一个氮原子和多胺桥联基团的三个连续氮原子配位。吡唑环的另一个氮原子与一个胺基形成氢键。在配合物2中，两个金属离子通过一个吡唑酸酯双（单齿）部分相互连接，并通过三个胺基以及一个溴离子或一个高氯酸根阴离子完成其配位球，这些离子占据扭曲的四方锥几何结构的轴向位置。双核配合物的顺磁核磁共振研究证实了在晶体结构中观察到的配位模式。循环伏安法数据显示电位在适当范围内，以表现出超氧化物歧化酶（SOD）活性。通过麦考德-弗里多维奇酶促测定法计算的IC₅₀值表明，L2和L3的双核铜配合物具有的SOD活性位列迄今报道的最高活性之中。
