Comments on the paper ‘Co-crystals of urea and hexanedioic acid with third-order nonlinear properties: An experimental and theoretical enquiry’

Abstract

The authors of a recent paper (J. Mol Struc. 1202 (2020) 127237) claim to have grown a so-called ‘urea hexanedioic acid’ (UHA) cocrystal by the slow evaporation of an aqueous solution containing equimolar amounts of urea and hexanedioic acid. In this comment, many points of criticism, concerning the crystal growth, single crystal data, IR spectrum and theoretical study of the so called UHA crystal are highlighted to prove that the title paper is completely erroneous.