一种新型四齿1,2-HOPO螯合剂的合成、金属配位研究

以6-羟基-2-吡啶羧酸为原料,经5步反应合成得到一种新型四齿β-二酮1,2-羟基吡啶酮衍生物。通过红外、核磁、质谱对其结构进行了表征。采用电位-光谱结合的方法,测定了四齿β-二酮1,2-羟基吡啶酮衍生物与UO2+2、Cu~(2+)、Zn~(2+)和Fe~(3+)的络合能力。结果表明,四齿β-二酮1,2-羟基吡啶酮衍生物对UO2+2和Fe3+有明显的络合能力,有望成为一种新型铀酰离子促排剂(p UO2=15.4)和铁螯合剂(p Fe=21.22)。

Synthesis and metal-complexation of a new tetradentate derivative as a potential therapeutic chelating agent

The article is to present the sysnthesis result of a new sort of tetradentate ligand based on 1-hydroxy-2 (1 H)-pyridinone as a uranyl chelating agent.The target product has been synthesized as a reuslt of 5 steps of the experimental reaction,that is,the hydroxylation,the hydroxyl protection,the amidation,the acyl chloridation and that of deprotection.Beginning with the commercially available 6-hydroxy-picolinic acid,the first step is to synthesize the carboxylate-derivatized 1,2-HOPO,which is followed by the second step,a step on how to protect the hydroxyl of pyridone ring.In the due step,the said 1,2-HOPOBn carboxylic acid can be directly condensed with the ethanolamine so as to work out N-(hydroxyethyl)-1-benzyloxy-2 (1H)-pyridinone-6-amide,which has to contain the reactive hydroxyl group and should be prone to be made to react with the malonyl dichloride to form the N,N-bis (N-(hydroxyethyl)-1-benzyloxy-2 (1H)-pyridinone-6-amido) malonate.And,finally,it has to deprotect the benzyl groups again to get the desirable renovated tetradentate chelator through a process of hydrogenation at the presence of Pd/C.And,next,the prepared ligands should be examined and characterized via the 1H NMR spectroscopy,the 13C NMR spectroscopy,the FTIR spectroscopy as well as the mass spectrometry.The final analysis and evaluation results should prove to be well in accord with the structure of the actual products,so as to verify its capacity well qualified as a metal sequestering agent,both with the protonation constant and pM for the oriented uranyl ion,ferric (Ⅲ),copper (Ⅱ) and zinc identified and determined in accordance with the standardized potentiometrie-speetrophotometric measurements.More exactly speaking,in its neutral form,the ligand should have two dissociable protons,well in accord with the pyridinone hydroxy groups.Whereas the first 2 protonation constants (lgKH1 =9.22,lgKH2 =9.07) has to tend to be easily attributed to the hydroxypyridinone hydroxy groups,the other 2 remaining protonation constants(lgKH3 =5.83,lgKH4 =3.77) should be doubtlessly attributed to the pyridinium protons.Therefore,the final testing results prove that the ligand should demonstrate high chelating capacity towards the uranyl ion than the tetradentate ligand Bis-Me3,2-HOPO.In addition,on the basis of pFe3+ values,it is also of great necessity that the ligand should be made better qualified efficient iron chelator (pFe3+ =21.22) than the clinically-used DFP(19.3),so that the novel tetradentate ligands based on 1-hydroxy-2(1H)-pyridinone has amuch greater potential chelating for the uranyl ions.