4,4’-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid;3,5-bi(4-carboxyphenoxy)benzoic acid;3,5-bis(4-carboxyphenoxy)benzoic acid;4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid;3,5-bi(4-carboxy-phenoxy)-benzoic acid;