No abstract

[2]Catenane systems containing copper(II) and nickel(II) as metal centers have been self-assembled using tetraazamacrocyclic complexes and benzo-24-crown-8 as building blocks. A variety of methods, including X-ray crystallography, ESI mass spectrometry, (13)C and (1)H NMR, and electrochemistry, were applied to characterize these new face-to-face bismacrocyclic systems. Weak pi...pi interactions introduced by interlocking transition metal complexes with benzocrown moieties were shown to increase the communication (cooperativity) of metal centers. Introduction of the benzocrown increases the stability of the mixed valence state of the macrocyclic complex, which is reflected in high values of conproportionation constants. Moreover, this effect was found to be stronger than that obtained by shortening the length of the spacer between the two tetraazamacrocyclic subunits in the parent bismacrocycles. The extent of communication is larger for the nickel catenane than for the copper one.

Usurping the crown: A controlled intramolecular motion of the crown moiety from around the Ni to the Cu center takes place in a transition‐metal hetero‐dinuclear [2]catenane in response to an applied potential (see picture).

The paper describes the synthesis and properties of a series of macrobicyclic cage cobalt(III) complexes which have lipophilic substituents . Those with paraffin tails, C8 or larger, have detergent-like characteristics and are able to penetrate biological membranes. A selection of the reagents was tested in vitro against parasitic nematodes, cestodes, trematodes and protozoa. Compounds with tails longer than C8 effectively killed the organisms at concentrations ≤10-3 M. In vivo against cestodes, that activity was also evident and biodistribution following oral administration showed that the compounds were confined to the gastrointestinal tract, unlike organic detergents such as cetylpyridinium chloride which are absorbed systemically. It is argued that the high charge and size of the head group of the complex detergents destabilize the exterior membrane of the organism. This new class of detergents, appropriately formulated, may be an effective new method of treating gastrointestinal parasites via this novel mode of action.