A series of four related phenol derivatives, with 2,2′-dipicolylamine substituents at the ortho positions, were prepared and their Zn2+ coordination complexes studied by spectroscopic methods. X-ray crystal diffraction analysis of a dinuclear zinc complex with two bridging acetate anions showed a ternary structure with highly charged interior and lipophilic exterior, which helps explain why this class of water-soluble complexes can effectively diffuse through cell membranes. The stability of the dinuclear zinc complexes in aqueous solution was found to be strongly anion dependent; that is, bridging oxyanions, such as acetate and pyrophosphate, lock the two Zn2+ cations to the surrounding ligand and greatly enhance ligand/zinc affinity. Overall, the results provide new insight into the structural and mechanistic factors that control the recognition and chemosensing performance of phenoxide bridged dipicolylamine molecular probes.

中文翻译：

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桥联阴离子对酚盐桥联二吡啶甲胺锌配位配合物结构和稳定性的影响

制备了一系列在邻位具有 2,2'-二吡啶甲胺取代基的四种相关苯酚衍生物，并通过光谱方法研究了它们的 Zn2+ 配位配合物。具有两个桥接乙酸根阴离子的双核锌配合物的 X 射线晶体衍射分析显示出内部带高电荷和亲脂外部的三元结构，这有助于解释为什么这类水溶性配合物可以有效地通过细胞膜扩散。发现双核锌配合物在水溶液中的稳定性强烈依赖于阴离子；也就是说，桥接氧阴离子，如乙酸盐和焦磷酸盐，将两个 Zn2+ 阳离子锁定到周围的配体上，大大增强了配体/锌的亲和力。总体，