The syntheses of three isomeric, wholly aromatic polyketones composed of a trifluoromethylated biphenylene unit and a 2,2'-dimethoxybiphenylene unit were performed via direct electrophilic aromatic acylation polycondensation of finely designed monomers. The two isomers of sequentially controlled wholly aromatic polyketones, i.e. the head-to-tail and head-to-head isomers, composed of 2-trifluoromethyl-4,4'-biphenylene and 2,2'-dimethoxy-5,5'-biphenylene units were synthesized successfully. Furthermore, treatment of 2-trifluoromethylbiphenylene-4,4'-dicarboxylic acid and 2,2'-dimethoxybiphenyl with P2O5-MsOH gave another isomeric polyketone having a random sequence. (C) 2002 Elsevier Science B.V. All rights reserved.