Cryptate Macrotricyclic cryptat

F. Fages, J.-P. Desvergne, H. Bouas-Laurent, J.-M. Lehn, J. P. Konopelski, P. Marsau, and Y. Barrans, Synthesis and fluorescence emission properties of a bis-anthracenyl macrotricyclic ditopic receptor. Crystal structure ofits dinuclear rubidium cryptate, J. Chem. Soc., Chem. Commun. 655(1990). 

Various evidence shows that the macrotricyclic ligand 45 forms 1 1 inclusion complexes, [3]-cryptates, with AC s and AEC s (96). NMR spectroscopic data indicate that the cation is non-symmetrically located in the cavity (95). 1 2 complexes with two Ag+ or T1+ cations have also been observed (Pd). Complex formation of ligand 46 with K+, Na+, Li+ and Ca++ has been reported (92). 

Figure 6. X-ray crystal structure of the iodide cryptate of the macrotricyclic quaternary ammonium receptor 16." ...

Spherical recognition of halide ions is displayed by protonated macropolycyclic polyamines. Thus, macrobicyclic diamines yield katapinates [3.9]. Anion cryptates are formed by the protonated macrobicyclic 16-6H+ [2.52] and macrotricyclic 21-4H+ [2.97] polyamines, with preferential binding of F and Cl- respectively in an octahedral and in a tetrahedral array of hydrogen bonds. 

H+ binds Cl- very strongly and very selectively compared with Br- and other types of anions, giving the [Cl- c (21-4H+)] cryptate 26. Quaternary ammonium derivatives of oxygen free macrotricycles of type 21 also bind spherical [3.10a] and other [3.10b] anions. 

Lateral macrobicycles are dissymmetric by design thus, monoelectronic reduction of the Cu(ll) ion bound to the [12]-N2S2 macrocyclic subunit in the bis-Cu(ll) cryptate 45, gives a mixed valence Cu(i)-Cu(ll) complex [4.6]. Macrotricycle 46 forms a dinuclear Cu(ll) cryptate that acts as a dielectronic receptor and exchanges two electrons in a single electrochemical wave [4.7]. Complexes of type 47 combine a redox centre and a Lewis acid centre for the potential activation of a bound substrate [4.8]. 

Graf, E., Lehn, J.-M., Anion cryptates-highly stable and selective macrotricyclic anion inclusion complexes. J. Am. Chem. Soc. 1976, 98, 6403-6405. 

Schmidtchen, F. P., Muller, G., Anion inclusion without auxiliary hydrogen bonds X-ray structure of the iodide cryptate of a macrotricyclic tetra-quaternary ammonium receptor. J. Chem. Soc., Chem. Commun. 1984, 1115-1116. 

Macrotricyclic cryptates may have either spherical or cylindrical topology (90). The cylindrical ligands, such as 5, are formed by linking together two macrocycles and define three cavities, two lateral and one central cavity inside the macrotricycle (18,19,91, 92). The macrotricyclic ligands of spherical topology are Particularly well suited for com-plexation of alkali cations as they define a spherical cavity (93, 94). Ligand 10, for example, contains a spherical cavity (diameter 3.4 A)... 

Macrotricyclic ligands have also been prepared, e.g. the structures shown in Fig. 7047 186 Both compounds form complexes ([3]cryptates) with alkali and other cations. The lower alkali ion selectivity and complex stability of [3] cryptand 1 in comparison to [2] cryptands is probably due to the larger size of its cavity which has a length of approximately 6 A47-. The cavity of ligand 1 can even accommodate two cations which has been demonstrated by X-ray analysis of a LAg2+ complex (L = ligand 1,... 

Graf and Lehn have synthesized the particularly interesting cryptate (1). This macrotricyclic tetramine hexaether is soluble in all solvents from petroleum ether to water. The cavity radius is about 1.8A and is fairly rigid. It forms very... 

The small cryptand 11 (Fig. 11) was obtained with difficulty, because the major compound obtained was a macrotricyclic tetraamide resulting from a dimerization reaction. It was observed that stable proton cryptates of 11 can be obtained. The [1.1.1] bicycle binds one or two protons inside its intramolecular cavity. The diprotonated cryptate 11, 2H. has a high resistance to deprotonation. The monoprotonated cryptate may be obtained with difficulty but this latter species cannot be fully depro-tonated by base to afford the free cryptand. Smaller analogues of 11 containing only carbon atoms in the three chains were also described. They present similar behavior toward the proton. Another class of cryptands able to strongly bind the proton was developed more recently. 

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