Guests dendronized

Molecular recognition processes between amphiphilic biaryl dendrimers 2 (with carboxylic acid moieties) as host compounds and the protein chymotryp-sin as guest were compared with those involving corresponding benzyl ether dendrons 1 (Fig. 4.26) [44]. In the biaryl dendrimers both the carboxylic acid groups of the periphery and those located in the inner shells are available for... 

H-NMR studies and analysis of sensor responses in the CD spectrum - after addition of sugar as guest to the dendrocleft host - show that the ability of this dendritic host to enantioselectively recognise monosaccharides decreases with increasing generation number of the dendron surrounding the chiral core unit. 

In contrast, the diastereoselectivity of the dendritic host increases. This indicates that on shielding of the chiral core unit with sterically more demanding dendrons in higher-generation dendroclefts the monosaccharide guests are no longer bound in the immediate vicinity of the chiral core unit instead, a less specific host/guest interaction takes place with the dendrimer scaffold. 

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... 

Balzani, Vogde et al. demonstrated for dendritic cyclam compounds that signalling units are dendritically amplified by increasing the number of peripheral fluorophores. Opportunities for these PET sensor systems exist in the combination of selective coordination sites with the dendritic architecture. The mechanism resembles that described above, but can be influenced by the introduction of dendritic units of different generations into the sensor system. The distance between the terminal naphthalene groups of the dendron and the receptor (ion as guest in the cyclam core) is of crucial importance for electron transfer (ET) (Fig. 8.15) [53],... 

Sobransingh D, Kaifer AE (2006) New dendrimers containing a single cobaltocenium unit covalently attached to the apical position of newkome dendrons electrochemistry and guest binding interactions with cucurbit[7]uril. Langmuir 22 10540-10544... 

Scheme 28 Reverse dendrons with coumarin 2 hosts and coumarin 343 guest by Frechet and coworkers [85,86]...

These two attributes - responsivity and the loadable interior - of the dendronized polymers can, in principle, be exploited to create smart delivery vehicles in which the release of guest molecules can be triggered by conformational changes of the responsive dendritic envelope. Additionally, unlike conventional polymers. 

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