Generation-Dependent Intramolecular CT Complexation in a Dendrimer Electron Sponge Consisting of a Viologen Skeleton

A Highly Luminescent Tetramer from a Weakly Emitting Monomer: Acid‐ and Redox‐Controlled Multiple Complexation by Cucurbit[7]uril

“…Among the multitude of chromophoric moieties investigated, pyridinium and bipyridinium chromophores (also known as viologens, namely, 1,1′‐disubstituted‐4,4′‐bipyridinium salts) are some of the most extensively studied functional entities by virtue of their photochemical and electrochemical properties 13. 14 They are widely employed as electron‐acceptor recognition sites and redox switching units in supramolecular systems such as dendrimers,15–18 rotaxanes,19–21 and catenanes 22. 23 Moreover, they have been investigated as components for electrochromic displays,24, 25 molecular batteries,26 redox mediators,27, 28 and redox sensors 29.…”

Bistable and Multistable Systems

“…Polycationic dendrimers containing 21 [161] and 45 [162] 4,4 0 -bipyridinium units have been prepared (see, e.g., 24 42þ , Figure 8.26) and their electrochemical behavior has been investigated. For compound 24 42þ , containing 21 4,4 0 -bipyridinium units [161], it has been found that only a part of the bipyridinium units can be reduced, namely, 14 units in electrochemical experiments (MeCN solution), 9 on reduction with bis(benzene)chromium (MeCN solution), and 13 by photoinduced electron transfer with 9-methylanthracene as a photosensitizer and triethanolamine as a sacrificial reductant in CH 2 Cl 2 solution.…”

TEMPO‐Labeled Viologen Dendrimers: Synthesis, Characterization, and Preliminary Distance Measurements

“…Dendrimers with redox‐active subunits in their core, periphery, or branching unit play an essential role as the resulting dendritic effects concern redox protein mimics, redox gradient, charge‐transfer complex‐based conductivity, electron sponges, and redox sensors . Especially the dendrimers based on viologen (i.e., quaternized 4,4′‐bipyridyl) subunits are interesting as viologen exhibits unique redox behavior .…”

“…The positive charge that they exhibit in their dissociated state is useful in complexing anionic dyes, forming donor–acceptor complexes with strong electron donors. Because of these properties, viologen‐based dendrimers were used to study electrostatic charge interactions, charge storing abilities, CT (charge‐transfer) complexes, etc . The two consecutive one‐electron reductions of the viologen subunit first leads to a cation radical intermediate and then a neutral species.…”