The positron‐emitting radionuclide, fluorine‐18, is used to radiolabel molecules to develop tracers for diagnostic imaging with positron‐emission tomography. There is growing interest in the potential of using strong coordinate bonds between electropositive Ga(III) and electronegative fluoride (≈ 557 kJ/mol) to provide new methods of incorporating fluorine‐18 into molecules. The potential of gallium(III) complexes with acyclic pentadentate bispicolinic acid containing ligands (H₂L^1–3) to form ternary complexes with fluoride, [GaL^1–3F] was investigated with a view to developing new methods for fluorine‐18 radiolabelling. A solid‐phase peptide synthesis approach was used to produce a bispicolinic acid chelator with a lysine residue. Characterisation of [GaL¹X] (X = OH, Cl, F) by X‐ray crystallography revealed that L¹ acted as dianionic N₂O₂ donor to the Ga(III) with the fifth site occupied by a monodentate anion (OH^–, Cl^– or F^–). Despite its high stability in aqueous mixture and [D₆]DMSO and the straightforward synthesis of [GaL¹F], it was only possible to form the radioactive analogue [¹⁸F][GaL¹F] in low radiochemical yields.

中文翻译：

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带有非环状双picolinolin配体的氟化镓配合物作为潜在的新型Fluine‐18标记成像剂

发射正电子的放射性核素氟18用于放射性标记分子，以开发示踪剂，以进行正电子发射断层扫描进行诊断成像。人们越来越关注在正电的Ga（III）和负电的氟化物（≈557 kJ / mol）之间使用强配位键来提供将氟18引入分子的新方法的潜力。镓（III）与含无环五齿双吡啶甲酸的配体（H ₂ L ^{1 – 3}）形成与氟化物[Ga L ^{1 – 3}为了开发氟18放射性标记的新方法，对F]进行了研究。固相肽合成方法用于生产带有赖氨酸残基的双吡啶甲酸螯合剂。通过X射线晶体学表征[Ga L ¹ X]（X = OH，Cl，F）显示，L ¹充当Ga（III）的双阴离子N ₂ O ₂供体，第五个位点被单齿阴离子占据（ OH ^–，Cl ^–或F ^–）。尽管它在含水混合物和[D ₆ ] DMSO中具有很高的稳定性，并且可以直接合成[Ga L ¹ F]，但仅可能形成放射性类似物[¹⁸ F] [Ga L ¹ F]处于低放射化学收率。