Comments on the paper "Synthesis and third order optical nonlinearity studies of toluidine tartrate single crystal supported by photophysical characterization and vibrational spectral analysis"

Abstract

The authors of the title paper (J Photochem & Photobio A:Chem 393 (2020) 112413) claim to have synthesized a toluidine tartrate (TT) crystal and examined its nonlinear optical (NLO) behavior by experimental and theoretical studies. In this critique, it is shown that the so-called TT crystal is a surface degraded material and the experimental and theoretical data contradict literature reports on the 1:1 salt of p-toluidine and L-tartaric acid.