Benzylic viologen dendrimers: a review of their synthesis, properties and applications

Here, the synthesis of benzylic viologen dendrimers, their guest complexation, photophysical and biological applications have been reviewed. Divergent and convergent approaches reported by Walder et al. and Balzani et al. for the synthesis of benzylic viologen dendrimers are also discussed. Electron sponge behaviour and their use as electron storage devices are elaborated. In addition, CT (charge transfer) complexation with guest anionic dye molecules and their use as charge storing devices are discussed. It has been shown that these dendrimers sequentially complex organic anions guided through molecular recognition. Anions with matching symmetry showed sharp chemical shifts in H-1 NMR titration studies. The existence of a potential gradient is explained for such a preferential complexation mechanism. Thus, the sequential complexation of organic anions inside these dendrimers as confirmed by H-1 NMR titration studies are briefly discussed. Further, the biological applications focusing on their antiviral, antibacterial and antifungal activities reported so far have been addressed.