237424-12-3Relevant academic research and scientific papers
Synthesis, protonation and Cu2+ co-ordination studies on a new family of thiophenophane receptors
Aguilar, Juan A.,Diaz, Pilar,Domenech, Antonio,Garcia-Espana, Enrique,Llinares, Jose M.,Luis, Santiago V.,Ramirez, Jose A.,Soriano, Conxa
, p. 1159 - 1168 (1999)
The synthesis of the new thiophenophanes 2,5,8,11-tetraaza[12](2,5)thiophenophane (L1), 2,6,9,13-tetraaza-[14](2,5)thiophenophane (L2) and 2,5,8,11,14-pentaaza[15](2,5)thiophenophane (L3) is described. The stepwise protonation constants of the macrocycles are determined by pH-metric titration and their protonation patterns are analysed by means of 1H and 13C NMR spectroscopy. L1 and L2 present first protonation on the thenylic nitrogens while L3 protonates first on the central nitrogens of the polyamine bridge. Molecular orbital calculations are used to locate the atomic orbitals contributing to the HOMO of the free amines. The interaction with Cu2+ shows for L1 and L3 formation of binuclear complexes which readily hydrolyse to give very stable species. Electrochemical studies show for all three Cu2+-receptor systems an important stabilisation of the Cu+ oxidation state towards its disproportionation into Cu2+ and Cu0 oxidation states.
