Guest viologen-type

Fig. 6.23 Uptake of a dendritic viologen-type guest molecule in the cavity of molecular tweezers (schematic according to...

A head to head double calix[4]arene system linked at the 1 -distal upper rim positions of tetrapropyloxy calix[4]arene with 2,6-diamino-pyridine groups was obtained by condensation of l,3-diaminocalix[4]-arene with pyridine dialdehyde and showed binding abihty toward viologen type guest molecules (2002T9019). 

A very simple calix[6]arene-based molecular machine operated by intermolecular photoinduced proton transfer was realized by employing wheel 1, N-decyl pyridylpyridinium axle-like [IT]", that upon protonation could act as a viologen-type guest, and the spiropyran photochrome SP (Fig. 29.9) [33]. This latter component has been selected because its acid-base properties can be photocontroUed so that it can... 

Klarner et al. undertook detailed studies of the host/guest relationships between molecular tweezers formed from condensed hydrocarbon arenes and symmetrically and asymmetrically dendryl-substituted viologens - with a 4,4 -bi-pyridinium core acting as -electron acceptor and a Frechet-type dendron as 71-electron donor (Fig. 6.23). The strong fluorescence of the 1,3-dimethylenoxyben-zene units of the Frechet dendron is quenched as a result of the donor/acceptor interaction. Accordingly, in dichloromethane solution the 4,4 -bipyridinium core... 

Ong W, Grindstaff J, Sobransingh D, Toba R, Quintela JM, Peinador C, Kaifer AE (2005) Electrochemical and guest binding properties of Frechet- and Newkome-type dendrimers with a single viologen unit located at their apical positions. J Am Chem Soc 127 3353-3361... 

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