Rhenium(<scp>v</scp>) oxocomplexes with novel pyrazolyl-based N<sub>4</sub>- and N<sub>3</sub>S-donor chelators
作者:Carolina Moura、Rute F. Vítor、Leonor Maria、António Paulo、Isabel C. Santos、Isabel Santos
DOI:10.1039/b611034g
日期:——
The novel pyrazolyl-based ligands 3,5-Me2pz(CH2)2NH(CH2)2NH(CH2)2NH2 (1) and pz*(CH2)2NH-Gly-CH2STrit (pz* = pz (8), 3,5-Me2pz (9), 4-(EtOOC)CH2-3,5-Me2pz (10)) were synthesized, and their suitability to stabilize Re(V) oxocomplexes was evaluated using different starting materials, namely (NBu4)[ReOCl4], [ReOCl3(PPh3)2] and trans-[ReO2(py)4]Cl. Compound 1 reacts with trans-[ReO2(py)4]Cl yielding the cationic compound [ReO(OMe)3,5-Me2pz(CH2)2N(CH2)2NH(CH2)2NH2}](BPh4) (11) in a low isolated yield. In contrast, the neutral complexes [ReOpz*(CH2)2NH-Gly-CH2S}] (pz* = pz (12), 3,5-Me2pz (13), 4-(EtOOCCH2)-3,5-Me2pz (14)) were synthesized almost quantitatively by reacting [ReOCl3(PPh3)2] or (NBu4)[ReOCl4] with the trityl-protected chelators 8–10. The X-ray diffraction analysis of 11 and 13 confirmed the tetradentate coordination mode of the respective ancillary ligands. In 11 the monoanionic chelator coordinates to the metal through four nitrogen atoms, while in 13 the chelator is trianionic, coordinating to the metal through three nitrogens and one sulfur atom. Solution NMR studies of 12–14, including two-dimensional NMR techniques (1H COSY and 1H/13C HSQC), confirmed that the N3S coordination mode of the chelators is retained in solution. Unlike 11, complexes 12–14 may be considered relevant in the development of radiopharmaceuticals, as further corroborated by the synthesis of the congener [99mTcOpz(CH2)2-NH-Gly-CH2S}] (12a). This radioactive compound was obtained from 99mTcO4− in aqueous medium, in almost quantitative yield and with high specific activity and radiochemical purity.
合成了新型的以吡唑基为基础的配体3,5-Me2pz(CH2)2NH(CH2)2NH(CH2)2NH2 (1)和pz*(CH2)2NH-Gly-CH2STrit(pz* = pz (8),3,5-Me2pz (9),4-(EtOOC)CH2-3,5-Me2pz (10)),并评估了它们稳定Re(V)氧化络合物的适用性,使用的起始材料分别为(NBu4)[ReOCl4]、[ReOCl3(PPh3)2] 和 trans-[ReO2(py)4]Cl。化合物1与trans-[ReO2(py)4]Cl反应,生成阳离子化合物[ReO(OMe)3,5-Me2pz(CH2)2N(CH2)2NH(CH2)2NH2}](BPh4) (11),其孤立产率较低。相比之下,几乎定量合成了中性复合物[ReOpz*(CH2)2NH-Gly-CH2S}] (pz* = pz (12),3,5-Me2pz (13),4-(EtOOCCH2)-3,5-Me2pz (14)),通过将[ReOCl3(PPh3)2]或(NBu4)[ReOCl4]与三苯基保护的螯合剂8–10反应。对11和13的X射线衍射分析确认了各自辅助配体的四齿配位模式。在11中,单阴离子螯合剂通过四个氮原子与金属配位,而在13中,螯合剂是三阴离子,通过三个氮和一个硫原子与金属配位。对12–14的溶液NMR研究,包括二维NMR技术(1H COSY和1H/13C HSQC),确认了螯合剂的N3S配位模式在溶液中的保留。与11不同,复合物12–14被认为在放射药物开发中具有相关性,进一步通过合成同类物[99mTcOpz(CH2)2-NH-Gly-CH2S}] (12a)得到了印证。该放射性化合物在水相中从99mTcO4−获得,几乎定量收率,并具有高特异活性和放射化学纯度。