Synthesis of salicylamide and bipyridine containing ligands for iron(II) and iron(III) coordination

Redox‐Driven Intramolecular Anion Translocation between a Metal Centre and a Hydrogen‐Bond‐Donating Compartment

“…For instance, the profile of the absorbance at 325 nm (circles in Figure 3b) shows a definite change of slope after the addition of one equivalent of Br À . Also in this case, the steepness of the 0-1 equivalent segment prevents the determination of K 1 , whose value should be higher than 10 6 . On the other hand, the smooth profile observed after one equivalent would allow the determination of a binding constant.…”

“…The titration profile in Figure 2b shows an abrupt slope change on addition of one equivalent of Br À , indicating that the formation equilibrium of the [Cu II (1)(Br)] 3 + species is characterised by a constant K 1 whose value is higher than 10 6 . On further addition of bromide, minor spectral changes are observed, as emphasised by the very moderate slope of the titration profile over the interval of 1-2 equivalents of Br À .…”

“…Figure 6a shows the visible portion of the spectra taken over the course of the titration, while Figure 5b displays the titration profile at 450 nm. Bestfitting of titration data was achievA C H T U N G T R E N N U N G ed by assuming the occurrence of equilibria (5) and (6), to which the following constants corresponded: logb 1 = 4.23 AE 0.01 and logb 2 = 6.7 AE 0.1. The values are in good agreement with those obtained from the titration experiments illustrated in Figure 4 (metal added to the ligand).…”

“…[3] A further type of controlled motion concerns the translocation of an ionic particle between two non-equivalent compartments of a molecular system. [4] Most examples involve the externally driven translocation of transition-metal ions and are based on two distinct protocols: 1) the metal exists in two oxidation states of comparable stability, and oxidation-reduction processes cause its transfer between two compartments of definitely different coordinating tendencies; [5][6][7][8][9][10][11][12] and 2) the coordinating properties of only one compartment towards a given metal ion are altered through an acid-base process, so that consecutive addition of H + and OH À ions induces a reversible intramolecular metal displacement. [13][14][15][16][17][18] On the other hand, examples of anion translocation are rare and all refer to the redox-driven transfer of an anion between two metal centres within a hetero-dinuclear complex.…”

Self-assembly in self-organized inorganic systems: a view of programmed metallosupramolecular architectures

“…Its formation illustrates the concept of sequential complexation, inasmuch as the first metal ion added organizes the ligands disposed in the 5,5'-positions to accomodate the second metal ion. The synthesis of sequential oligodonor ligands constitutes a very interesting approach to heteronuclear coordination compounds and to the construction of switches 161 . Thus, the strategy depicted here seems very attractive to the design of novel supramolecular inorganic architectures, starting from carefully synthesized ligands 158 .…”