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Coordination complexes, guest metal ions

Nevertheless, the definition does not—and cannot—provide any sharp borderline separating host-guest chemistry and adjacent fields. Most obviously, there is no strict definition of covalent bond. Sometimes, complexation of metal ions with polydentate reagents is thought to be included in the topic discussed (or vice versa, as host-guest complexation may be regarded as a part of generalized coordination chemistry [24]). In this re-... [Pg.95]

The azo complexons, 3-IDA-5-R-HAB (Fig. 1), which have a coordinating iminodiacetate group, show the conformational change in the acid dissociation and the complexation with metal ions.3 The stability of the inclusion complexes of the azo complexons with a-cyclodextrin (oMX)j ) depends on the complementary geometry between the diameter of hydrophobic cavity of a-cyclodextrin and the shape and the size of guest molecule. ... [Pg.765]

Chemical transformations at the macroeyclic chromophorc of expanded porphyrins are still not known. The complexation behavior of expanded porphyrins is very different from that of nonexpanded porphinoid macrocycles. The coordination hole of the expanded porphyrins is often too big for the complexation of a single metal ion, so in fact two metal ions can be chelated. With some expanded porphyrins, anion binding is observable, a striking difference to the nonexpanded porphyrins. The complexation behavior and the host-guest chemistry of expanded porphyrins is a rapidly growing field of research. The work in this field has been reviewed. Ie f... [Pg.715]

The main feature for cation recognition by tetra-bridged phosphorylated cavitands arises from the cooperative effect of the four phosphorus groups and the aromatic molecular cavity. In the phosphorus(IV) cavitands guest binding will be achieved through O (P=0) or S (P=S) coordination with different affinity for hard or soft metal ions. On the other hand, transition metal rim complexes described above can act as host for metal cation. [Pg.74]

Therefore, another strategy was developed, based on the induced-fit concept, which uses flexible receptors in order to optimize the interactions between the donor atoms and the metal ion. In fact, the coordination environment is built upon complexation thanks to the flexibility introduced into the complexation agent, which is now termed predisposed ligand . These receptors are either large macrocycles able to wrap around the guest or small macrocycles fitted with pendant arms. The latter approach has proved to be very successful, particularly with calixarene (Asfari et al., 2001) and cyclen (1,4,7,10-tetraaza-dodecane) (Lukes et al., 2001) derivatives. [Pg.243]


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See also in sourсe #XX -- [ Pg.573 ]




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Complex ions coordination

Coordination metal complexes

Guest complexes

Guest metal complexes

Ion coordination

Metal guest

Metal ion complexation

Metal ion coordination

Metal ions complexes

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