Topology macrocycles

Recently considerable attention has been directed at anion binding ligands. Macrobicyclic 27 29) and macrotricyclic amines 30,31) were topologically designed to host anions such as spherical Cl-, linear Nf 32). These anion substrates are incorporated into macrocyclic cavities lined with appropriate anion-binding sites capable of forming hydrogen bonds like those of protonated amines (see /, below). 

Roseophilin (273), a deeply red-colored pentacyclic compound isolated from the culture broth of Streptomyces griseoviridis, is a novel antitumor antibiotic. Compound 273 possesses a topologically unique pentacyclic skeleton, consisting of a 13-membered macrocycle incorporated in an ansa-bridged azafulvene, which in turn is linked to a conjugated heterocyclic ring system. The absolute stereochemistry of roseophilin, as depicted in Fig. 9, was unknown until the first total synthesis published by Tius and Harrington in 2001 [125]. All syn-... 

The template-directed preparation of cycloi is(paraquat-4,4 -biphenylene (a molecular square ) has been achieved the use of a macrocyclic hydroquinone-based polyether template incorporating an ester moiety in one polyether chain afforded a 1 1 mixture of two topologically stereoisomeric [3]catenanes <96CEJ877>. 

Related structures to the binucleating crown (206), in which three or four individual macrocycles are linked by spiro-groups, have been synthesized (Weber, 1979 Weber, 1982). Other ligands of this general type, showing a variety of topological arrangements, are also known (Weber ... 

The stability of cryptate complexes. The cage topology of the cryptands results in them yielding complexes with considerably enhanced stabilities relative to the corresponding crown species. Thus the K+ complex of 2.2.2 is 105 times more stable than the complex of the corresponding diaza-crown derivative - such enhancement has been designated by Lehn to reflect the operation of the cryptate effect this effect may be considered to be a special case of the macrocyclic effect mentioned previously. 

Addison [98] correlated a broad spectrum of published potential data on aqueous Cu(II/I) complexes - including those with N, S, and O donor atoms - to generate an empirical relationship between the various characteristic ligand features and the observed Cu(II/I) potentials. He concluded that closed (macrocyclic) ligand topology had little effect on the 21 values, but... 

Structurally related to these species are the triply branched compound 56+ and its rotaxanes 66+, 76+, and 86+ (Fig. 13.6)9, in which one, two, or three acceptor units are encircled by the electron donor macrocyclic compound 2. Although these rotaxanes cannot behave as degenerate molecular shuttles because of their branched topology, they are nevertheless interesting from the electrochemical viewpoint. 

Before we obtained the X-ray structure determinations of both the knotted and unknotted dicopper(I) complexes, we could identify them after careful comparative H NMR and mass spectroscopy studies performed not only on the dinuclear complexes but also on their respective free ligands afforded by demetalation. Treatment of Cii2(m-43) + by a large excess of potassium cyanide led indeed quantitatively to a plain 43-membered macrocycle whereas an analogous treatment of Cii2(K-86r+ led to the free knot K-86 whose topological chirality could be demonstrated by NMR and mass spectroscopy (Figure 20). 

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