4,6-Diaminoresorcinol (1) and 2,5-diamino-1,4-benzenedithiol (2) (usually stored as dihydrochloride salts) are key co-monomers for the synthesis of strong, thermally resistant rigid-rod poly(p-phenylenebenzobisoxazole) (PBO) and poly(p-phenylenebenzobisthiazole) (PBT) polymers (Scheme 1) for lightweight structural, nonlinear optical and electronic applications. 1,2 More recently, PBO has been considered for use in the proton-exchange membranes of fuel ...
