Esters 1–3 contain hydrogen-bondacceptors, namely carbonyl groups, as well as one strong (NH) and one weak (C–H) hydrogen-bond donor. In addition to the hydrogen-bonded sets of ester derivatives, acids4 and 5 present the carboxylic acid moiety, which acts as both a hydrogen-bond donor and acceptor. EDT-TTF-CO-GlyOH has been previously used to afford a new type of hydrogen-bonded acid/zwitterion (1:1)