High electron affinity substituents

The syntheses and properties of different polymers containing high electron affinity CF3 and oxadiazole groups have been reviewed. It has been shown that when CF3 groups are incorporated into conjugated polymers, such as poly(phenylene vinylene) derivatives, the polymers with CF3 substituents show better electron accepting properties. This makes it possible to use stable aluminum in place of air sensitive calcium as metal cathode in polymer LEDs. 

Hexacyano[3]radialene (50) is a very powerful electron acceptor according to both experiment and MNDO calculations of LUMO energy and adiabatic electron affinity. The easy reduction to the stable species 50 and 50 by KBr and Nal, respectively, has already been mentioned. Similarly, the hexaester 51 is reduced to 51 by Lil. Most [3]radialenes with two or three quinoid substituents are reduced in two subsequent, well-separated, reversible one-electron steps. As an exception, an apparent two-electron reduction occurs for 46 . The reduction potentials of some [3]radialenes of this type, as determined by cyclic voltammetry, are collected in Table i. Due to the occurrence of the first reduction step at relatively high potential, all these radialenes... 

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