Tren-cryptand

Fabbrizzi and coworkers reported the synthesis of dicopper(II) complexes of bis-tren cryptands 61-63. The metal center was coordinated by a tren subunit oriented to a trigonal bipyramidal geometry which had an available binding site for anions at a vacant axial position. The complex 61 [49] showed the highest... 

Due to the success on the TREN cryptands, Bowman-James, and co-workers synthesized bicyclic and tricyclic cyclophane capsules 16 and 17 which contain three or four flexible diethylamine chains and two phenyl groups as caps [48]. Although the cavity of 16 and 17 was too small to encapsulate anions, 16 displayed tight binding for F K = 21,000 M ), while 17 showed slightly less affinity for H2P04 = 21,000 M ). The single X-ray crystal structure of 16 [FHF] showed... 

Cryptands, 7, 731-761 alkali metal complexes NMR, 7, 740 reactivity, 7, 743-744 alkaline earth complexes reactivity, 7, 743-744 anion complexes, 7, 747-748 applications, 7, 753-761 as biological models, 7, 753-754 bis-tren... 

Severin and coworkers reported (146) the reaction of tris(2-aminoethyl)amine and 4-formylphenylboronic acid with penta-erythritol to give, via multicomponent assembly, the boronic acid based macrobicyclic cage 35 (Fig. 25). The cage has the form of an ellipsoid with a diameter of 20.5 A and binds two Cud) ions in a fashion similar to the smaller tren-based cryptands. The reversible formation of boronic esters has also been employed to build other hollow structures such as nanotubes (147) and porous covalent organic frameworks (148,149). 

Ring opening of the cryptand derived from condensation of the branched tetraamine tren with 2,6-diacetylpyridine (in a 2 3 molar ratio) in the presence of manganese(II) acetate, NaBF4," " and NEts yielded the dinuclear complex Mn2L(CH3COO)](BF4)3 (where L = XH5) which was proposed as a structural model for active sites in natural systems. The Mn—Mn separation is 4.82 A compared with that of 4.9 A found in the D-xylose isomerase from Streptomyces rubiginosus. 

As seen in Figure 14 the ellipsoidal cryptands may be prepared by the simultaneous formation of three bridges. This route has found limited use due to low yields but has been employed in the synthesis of some cryptands including the tris-pyridino system (36) (81TL3035) and bis-tren (18) (80UP52100). 

Martell et al. (33g) while studying the complex equilibria of a new octaaza macrobicyclic cryptand, (MX)3(tren)2 (containing two tren moieties and three m-xylyl groups) reported the synthesis and... 

Linear recognition is displayed by the hexaprotonated form of the ellipsoidal cryptand bis-tren 33, which binds various monoatomic and polyatomic anions and extends the recognition of anionic substrates beyond the spherical halides [3.11, 3.12]. The crystal structures of four such anion cryptates [3.11b] provide a unique series of anion coordination patterns (Fig. 4). The strong and selective binding of the linear, triatomic anion N3" results from its size, shape and site complementarity to the receptor 33-6H+. In the [N3 pyramidal arrays of +N-H "N- hydrogen bonds, each of which binds one of the two terminal nitrogens of N3-. 

Macrobicyclic cascade cryptands have also been prepared such as the series of bis(tren) derived (tren = tris(2-aminoethyl) amine, see Section 4.4.3) compounds 5.9. The di-nickel(II) and di-copper(II) complexes of the cages with various spacers all bind a metal cation into each tren unit. These metal... 

Menif, R. Reibenspies, J. Martell, A. E. Synthesis, protonation constants, and copper(II) and cobalt(II) binding constants of a new octaaza macrobicylic cryptand (MX)3crystal structures of the cryptand and of the carbonato-bridged dinuclear copper(II) cryptate, Inorg. Chem. 1991, 30, 3446-3454. 

Synthesis of [Cu2L(CI04)4] L is a Schiff Base Cryptand Derived from the Direct 2+3 Cyclocondensation of fr/s(2-aminoethyl)amine (tren) and 2,6-b/s[formylphenoxymethyl]pyridine (bfpp) [130f]... 

To prepare the cryptand L H20, a solution of tren (4mmol) in MeOH (20 mL) was added to a warm solution of bfpp (6 mmol) in MeOH (300 mL) and refluxed for 2 hr. The hot solution was filtered and left to stand in a refrigerator overnight. The resulting suspension was filtered to leave a pale yellow solid. Yield 54%. 

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