Blake Alexander J, Bencini Andrea, Caltagirone Claudia, De Filippo Greta, Dolci Luisa Stella, Garau Alessandra, Isaia Francesco, Lippolis Vito, Mariani Palma, Prodi Luca, Montalti Marco, Zaccheroni Nelsi, Wilson Claire
School of Chemistry, The University of Nottingham, University Park, UK.
Dalton Trans. 2004 Sep 7(17):2771-9. doi: 10.1039/B407037B. Epub 2004 Aug 6.
The coordination chemistry of the new pyridine-based, N2S2-donating 12-membered macrocycle 2,8-dithia-5-aza-2,6-pyridinophane (L1) towards Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) has been investigated both in aqueous solution and in the solid state. The protonation constants for L1 and stability constants with the aforementioned metal ions have been determined potentiometrically and compared with those of ligand L2, which contains a N-aminopropyl side arm. The measured values show that Hg(II) in water has the highest affinity for both ligands followed by Cu(II), Cd(II), Pb(II), and Zn(II). For each metal ion considered, 1:1 complexes with L1 have also been isolated in the solid state, those of Cu(II) and Zn(II) having also been characterised by X-ray crystallography. In both complexes L1 adopts a folded conformation and the coordination environments around the two metal centres are very similar: four positions of a distorted octahedral coordination sphere are occupied by the donor atoms of the macrocyclic ligand, and the two mutually cis-positions unoccupied by L1 accommodate monodentate NO3- ligands. The macrocycle L1 has then been functionalised with different fluorogenic subunits. In particular, the N-dansylamidopropyl (L3), N-(9-anthracenyl)methyl (L4), and N-(8-hydroxy-2-quinolinyl)methyl (L5) pendant arm derivatives of L1 have been synthesised and their optical response to the above mentioned metal ions investigated in MeCN/H2O (4:1 v/v) solutions.
新型基于吡啶的、具有N₂S₂供体的12元大环化合物2,8-二硫杂-5-氮杂-2,6-吡啶并环（L1）与Cu(II)、Zn(II)、Cd(II)、Hg(II)和Pb(II)在水溶液和固态中的配位化学已被研究。通过电位滴定法测定了L1的质子化常数以及与上述金属离子的稳定常数，并与含有N-氨丙基侧链的配体L2的相应常数进行了比较。测量值表明，水中的Hg(II)对这两种配体的亲和力最高，其次是Cu(II)、Cd(II)、Pb(II)和Zn(II)。对于所考虑的每种金属离子，还在固态中分离出了与L1形成的1:1配合物，其中Cu(II)和Zn(II)的配合物也通过X射线晶体学进行了表征。在这两种配合物中，L1均采用折叠构象，两个金属中心周围的配位环境非常相似：大环配体的供体原子占据了扭曲八面体配位球的四个位置，L1未占据的两个相互顺式位置容纳单齿NO₃⁻配体。然后，大环L1已用不同的荧光亚基进行了功能化。特别是，合成了L1的N-丹磺酰胺丙基（L3）、N-(9-蒽基)甲基（L4）和N-(8-羟基-2-喹啉基)甲基（L5）侧链衍生物，并在MeCN/H₂O（4:1 v/v）溶液中研究了它们对上述金属离子的光学响应。
