Pyrroles

Zotti and co-workers recently reported [131] the electrochemical polymerization of the known azopyrrole compounds 2,2'-azopyrrole 31 [98] and 2,2'-azopyrrole  61 [132] (see Figure 4.15). The resulting polymers exhibited unusually narrow bandgaps for pyrrole electropolymers, and this was attributed to the inclusion of electron accepting azo groups, leading to a more easily accessed LUMO. An unexplored aspect of these compounds is their metal complexes; the azo linkage introduces an excellent bidentate coordination site in conjunction with the pyrrole nitrogen.

Figure 4.15: Polymerizable azopyrrole compounds pyrrolyl-2-aldazine (31) and 2,2'-azopyrrole (61)

Pyrrolyl-2-aldazine 31 was successfully prepared in accordance with literature methods [98], and the electrochemical behaviour reported by Zotti was duplicated. The dinuclear bisbipyridyl ruthenium(II) complex 45 was also isolated, but did not polymerize electrochemically.