Polyaza cryptands

Successful anion complexation was also achieved with larger macrobicyclic ligands. Thus, the macrobicycle 17 (Fig. 17). SI binds halide anions and the linear triatomic azide anion with a very high stability constant. The x-ray structure revealed an efficient shape and size complementarity between N3 and the cavity. A whole series of polyazacryptands was obtained in high yields by a simple Schiff base [2 + 3] condensation between the triaminotriethylamine (tren) and various dicarboxalde-hydes. The hexaimine macrobicycles prepared by this way lead, after reduction, to the polyaza cryptands, which in... 

We have studied the interactions of LI and L2 with Cu " ", Zn " " and Cd " ". The reactions of these metal ions with both LI and L2 in aqueous solution are too slow at 298.1 K to determine confidently the stability constants of their complexes at this temperature, as already found for other polyaza cryptands. For this reason, the determination of the equilibrium constants for the reactions of both ligands with the above metal ions have been carried out at 318.1 K in 0.15 mol dm NMe4C104 aqueous solution, and the results are reported in Table 3. 

Sepulchrates, the polyaza cage macrobicycles analogous to the cryptates, were first synthesized in 1977.178 The cobalt(lII) complex shown in Figure 3 (19) is the octaazasepulchrate analog of the [2.2.2] cryptand (Figure 3 16), and is commonly written [Co(sep)]3+ (sep = sepulchrate). 

Polyaza-, polythia-ligands. Recognition of transition metal ions. Replacing the oxygen sites with nitrogen or sulphur yields macrocycles and cryptands that show marked preference for transition metal ions and may also allow highly selective complexation of toxic heavy metals such as cadmium, lead and mercury [2.41-2.44, A.14]. 

Polyaza macrobicyclic cryptands synthesis, crystal structures of a cyclophane type macrobicyclic cryptand and of its dinuclear copper(I) cryptate, and anion binding features, J. Jazwinski, J.-M. Lehn, D. Lilienbaum, R. Ziessel, J. Guilhem and... 

Polyaza-oxa cryptands with one or two ruthenocene units have been reported [154, 155]. They form Mg + host guest complexes. 

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