Dicarboxylic Acid Separation by Dynamic and Size-Matched Recognition in Solution and in the Solid State

Kumar, V.^a, Pilati, T.^a, Terraneo, G.^a, Ciancaleoni, G.^b, Macchioni, A.^c, Resnati, G.^a, Metrangolo, P.^a

^a DCMIC “Giulio Natta”, Politecnico di Milano, Via L. Mancinelli 7, Milano, 20131, Italy
^b Dip. Chimica e Chimica Industriale, Università degli Studi di Pisa, Via Giuseppe Moruzzi 13, Pisa, 56124, Italy
^c Dipartimento di Chimica, Biologia e Biotecnologie and CIRCC, Università degli Studi, Via Elce di Sotto 8, Perugia, 06123, Italy

Angewandte Chemie - International Edition 2018, 57(5), 1327-1331

Bis(trimethylammonium) alkane diiodides dynamically encapsulate dicarboxylic acids through intermolecular hydrogen bonds between the I− anions of the hosts and the carboxylic OH groups of the guests. A selective recognition is realized when the size of the I−⋅⋅⋅HOOC(CH2/CF2)nCOOH⋅⋅⋅I− superanion matches the dication alkyl chain length. Dynamic recognition is also demonstrated in solution, where the presence of the size-matching organic salt boosts the acid solubility profile, thus allowing efficient mixture separation.