Polycyano derivatives

Most organic acceptors employed in the preparation of organic conducting materials belong to a class of polycyano compounds. The reasons are quite obvious if one takes into consideration the unique properties of the cyano group, which is one of the strongest acceptor substituents known, and also the smallest to cause minimal steric strain. Among other polycyano derivatives to be mentioned are l,4-phenyl-bis(diazocyanide) 58 [83], which its reduced form corresponds to a quinoid structure 58a, and thieno derivatives 59 [84,85], 60, and 61 [86], with acceptor properties similar to those of TCNQ. 

Consequently, we will centre our attention on the main type of acceptors according to their different molecular nature. Thus, we will focus on derivatives of the parent molecules TCNQ, dicyano-p-quinonediimine (DCNQI), other polycyano derivatives, dithiolene metal complexes (l,3-dithioIe-2-thione-4,5-dithiolate, dmit) and some interesting cases in the emerging chemistry of fullerene [13] derivatives as shown in Figure 1.1. 

Symmetric n/p-type supercapacitors based on such non-conventional polymers as polydithienothiophenes [38,44], poly3-phenylthiophene fiuorinated derivatives [33,35,44-46], polycycylopentadithiophenone [47], polycyano-sub-stituted-diheteroareneethylenes [48], and unsymmetric n/p devices mainly based on polythiophene, poly-3-methylthiophene and poly-3-p-fluorophenyl-... 

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