Bazzicalupi Carla, Bencini Andrea, Bianchi Antonio, Borsari Lucia, Danesi Andrea, Giorgi Claudia, Lodeiro Carlos, Mariani Palma, Pina Fernando, Santarelli Samuele, Tamayo Abel, Valtancoli Barbara
Dipartimento di Chimica, Polo Scientifico, Università di Firenze, Via della Lastruccia 3, 50019, Sesto Fiorentino, Firenze, Italy.
Dalton Trans. 2006 Sep 7(33):4000-10. doi: 10.1039/b603505a. Epub 2006 May 12.
The synthesis and characterisation of the new macrocyclic ligand 6-methyl-2,6,10-triaza-[11]-12,25-phenathrolinophane (L1), which contains a triamine aliphatic chain linking the 2,9 positions of 1,10-phenanthroline and of its derivative L2, composed by two L1 moieties connected by an ethylenic bridge, are reported. Their basicity and coordination properties toward Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II) have been studied by means of potentiometric and spectroscopic (UV-Vis, fluorescence emission) measurements in aqueous solutions. L1 forms 1:1 metal complexes in aqueous solutions, while L2 can give both mono- and dinuclear complexes. In the mononuclear L2 complexes the metal is sandwiched between the two cyclic moieties. The metal complexes with L1 and L2 do not display fluorescence emission, due to the presence of amine groups not involved in metal coordination. These amine groups can quench the excited fluorophore through an electron transfer process. The ability of the Zn(II) complexes with L1 and L2 to cleave the phosphate ester bond in the presence has been investigated by using bis(p-nitrophenyl)phosphate (BNPP) as substrate. The dinuclear complex with L2 shows a remarkable hydrolytic activity, due to the simultaneous presence within this complex of two metals and two hydrophobic units. In fact, the two Zn(II) act cooperatively in substrate binding, probably through a bridging interaction of the phosphate ester; the interaction is further reinforced by pi-stacking pairing and hydrophobic interactions between the phenanthroline unit(s) and the p-nitrophenyl groups of BNPP.
报道了新型大环配体6-甲基-2,6,10-三氮杂-[11]-12,25-菲咯啉环烷（L1）的合成与表征，该配体含有连接1,10-菲咯啉2,9位的三胺脂肪链及其衍生物L2，L2由通过烯桥连接的两个L1部分组成。通过在水溶液中的电位滴定和光谱（紫外可见、荧光发射）测量研究了它们对Cu(II)、Zn(II)、Cd(II)、Pb(II)和Hg(II)的碱性和配位性质。L1在水溶液中形成1:1的金属配合物，而L2可以给出单核和双核配合物。在单核L2配合物中，金属夹在两个环状部分之间。由于存在未参与金属配位的胺基，L1和L2的金属配合物不显示荧光发射。这些胺基可以通过电子转移过程淬灭激发的荧光团。以双（对硝基苯基）磷酸酯（BNPP）为底物，研究了L1和L2的Zn(II)配合物在存在下切割磷酸酯键的能力。与L2的双核配合物显示出显著的水解活性，这是由于该配合物中同时存在两种金属和两个疏水单元。事实上，两个Zn(II)在底物结合中协同作用，可能是通过磷酸酯的桥连相互作用；菲咯啉单元与BNPP的对硝基苯基之间的π-堆积配对和疏水相互作用进一步加强了这种相互作用。
