Macrocycles pentameric

The major components are series of homologous trimers, tetramers, and pentamers of the three acids 44-46, along with smaller quantities of dimers, hexamers, and heptamers. Furthermore, the secretion contains several isomers of each oligomer, furnishing a combinatorial library of several hundred macro-cyclic polyamines [51, 52]. Using repeated preparative HPLC fractionation, the most abundant trimeric, tetrameric and pentameric earliest-eluting compounds were isolated. One and two-dimensional H NMR spectroscopic analyses showed that these molecules were the symmetric macrocyclic lactones 48, 49, and 50 (m, n, o, p, q=7) derived from three, four or five units, respectively, of acid 46. Moreover, using preparative HPLC and NMR methods, various amide isomers, such as 53,54, and 55 (Fig. 9) were also isolated and characterized [51,52]. 

The X-ray crystal structures of the related, though less complex, anticrown mercury-containing macrocycles 45 and 46 have also recently been reported. Complex 45 may form either 1 1 complexes with Br or I" or a 3 2 complex with Cr. In the case of the bromo derivative, crystallographic results reveal an infinite chain of alternating Br and 45 with each halide bridging between six Hg atoms, Hg- Br 3.07-3.39 A. It is postulated that the related 3 2 chloride complex exhibits a similar, though finite layered structure. The related pentameric species 46 forms... 

Macrocycle 9.105, in the form of its pentaligated uranyl complex, was first characterized by Marks and Day. While earlier reports had claimed the successful preparation of normal U02-phthalocyanine from the reaction of U02 and phthalonitrile, the results of Marks and Day revealed that it is the pentameric uranyl superphthalocyanine, contaminated with only small quantities of metal-free phthalocyanine, that is the dominant product obtained as the result of such a process. The findings of Marks and Day were thus consistent with one other earlier report (see reference 57 and references therein) wherein mass spectrometric evidence... 

Macrocyclic imidazolylboranes can exist in various structural types depending on the substituents of both the imidazole and borane component. In the crystal structure of pentameric 31, all imidazole rings are almost perpendicular to the plane of the molecule. The average N-B-N angle of 109.3(6)° is very close to that of a perfect pentagon. The tetramer 32 shows that the two opposite imidazole rings lie in the plane of the molecule while the other two are perpendicular to it <2000AGE547>. 

Knochel s method provided the pentameric peptide 224. Hydrogenation followed by treatment of the resulting amino acid with EDC and HOBt afforded macrocycle 225. Hydrolysis of methyl ester 225, and imidazolone formation via the acid chloride, followed by Boc deprotection provided kapakahine F (219) in significant quantity. Final coupling of 219 with Boc-Phe-OH followed by Boc removal afforded kapakahine B (218) (Scheme 40). 

Figure 25 Self-assembly of 83 to form pentameric 84 and hexameric 85 macrocycles (a) FeCl2-4H20, MeOH, 25 °C, 24 h (left). TEM images of hierarchical self-assembled macrocycles 84 and 85 into fibers (center). Scale bars (a 500 nm b 100 nm c 500 nm d 100 nm). Space-filling models of 84 and 85 (e and f, respectively). Adapted with permission from Ref. 10CEJ1768. Copyright 2010 WiLEY-VCH Veriag GmbH Co. KOaA, Weinheim.

Organocopper and -silver macrocycles are also known and it would be interesting to check their molecular recognition of anions, if any. Thus, the pentameric (jU-mesityl)copper(I) derivative [21] and the tetrameric (/i-mesityl)silver(I) derivative [22] would be interesting candidates as receptors in host-guest chemistry. 

Whereas the unsubstituted parent compounds prepared by Jenny et al. (Section 2.2.1) were not considered likely to be able to act as ligands or hosts, some indications of the capacity of a//-homocalixarenes and -calixpyridines to bind to guests are given by the results of X-ray structure analyses. The cluster type inclusion of water by the pentameric pyridine macrocycle 38 via hydrogen bonds seems... 

However, these pentameric macrocycles are t) picaUy obtained after 15-16 steps with an overall yield of 1-2 % [45], greatly limiting their potential uses in targeting biological pentamers [39], searching such as novel ID molecular magnets, or as... 

Garcia F, Kowenicki RA, Kuzu I et al (2005) The first complex of the pentameric phosphazane macrocycle [ P(1-N Bu) 20-NH)]5 with a neutral molecular guest Synthesis and structure of [ P(1-N Bu) 2(1-NH)]5(CH2C12)2. Inorg Chem Commun 8 1060-1062... 

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