Comments on "Growth and dielectric studies of toluidine tartrate single crystals: A novel organic NLO material"

Abstract

The authors of the title paper (J.Mol. Struc. 1207 (2020) 127750) claim to have grown a novel organic nonlinear optical (NLO) toluidine tartrate (TT) single crystal. In this letter to the Editor, we prove that the so-called TT crystal is not a novel NLO material but is in fact, the well-known colorless 1:1 salt of p-toluidine and L-tartaric acid. The title crystal's brown color is due to extensive surface degradation.