Homo- and heterobinuclear Cu2+ and Zn2+ complexes of abiotic cyclic hexaazapyridinocyclophanes as SOD mimics
作者:Raquel Belda、Salvador Blasco、Begoña Verdejo、Hermas R. Jiménez、Antonio Doménech-Carbó、Conxa Soriano、Julio Latorre、Carmen Terencio、Enrique García-España
DOI:10.1039/c3dt51012c
日期:——
The new receptor 3,7,11,15,19,23-hexaaza-1(2,6)-pyridinacyclotetracosaphane (L1) containing a complete sequence of propylenic chains has been synthesised. The acid–base behaviour and Cu2+ and Zn2+ coordination have been analysed by potentiometric measurements in 0.15 M NaClO4 for L1 and for the related compounds 3,7,11,14,18,22-hexaaza-1(2,6)-pyridinacyclotricosaphane (L2), 3,7,10,13,16,20-hexaaza-1(2,6)-pyridinacycloheneicosaphane (L3) and 3,7,10,12,15,19-hexaaza-1(2,6)-pyridinacycloicosaphane (L4). The crystal structure of [(CuH4L2)(H2O)(ClO4)](ClO4)5·3H2O shows an interesting combination of a metal ion coordinated by the pyridine nitrogen atom and the adjacent amine groups of the chain, and a perchlorate anion sitting at the middle of the site defined by the remaining four protonated ammonium groups of L1. Paramagnetic NMR data suggest that imidazole coordinates to the Cu2+ ions as a bridging ligand in a wide pH range. SOD activity for Cu2+–Cu2+ and Cu2+–Zn2+ complexes with L1–L4 have been measured by NBT assays at pH 7.4, obtaining some of the lowest values so far reported for SOD mimics. SOD activity has also been checked by chemiluminescence assays using polymorphonuclear leukocytes (PMNLs).
合成了一种新的受体3,7,11,15,19,23-六氮-1(2,6)-吡啶环四嵌烯(L1),包含完整的丙烯链序列。通过在0.15 M NaClO4中进行电位测量,分析了L1及相关化合物3,7,11,14,18,22-六氮-1(2,6)-吡啶环三嵌烯(L2)、3,7,10,13,16,20-六氮-1(2,6)-吡啶环二十嵌烯(L3)和3,7,10,12,15,19-六氮-1(2,6)-吡啶环二十烷(L4)的酸碱行为及Cu2+和Zn2+的配位。[(CuH4L2)(H2O)(ClO4)](ClO4)5·3H2O的晶体结构显示了金属离子通过吡啶氮原子和链的相邻氨基团协调的有趣组合,并且一个高氯酸根阴离子位于L1剩余的四个质子化铵离子定义的位置中间。参数磁性核磁共振数据表明咪唑在宽pH范围内作为桥连配体配位于Cu2+离子。通过NBT测定法在pH 7.4下测量了L1–L4与Cu2+–Cu2+和Cu2+–Zn2+复合物的超氧化物歧化酶(SOD)活性,获得了迄今为止报告的SOD模拟物中最低的值之一。SOD活性还通过使用多形核白细胞(PMNLs)的化学发光测定法进行了检查。