Comments on the growth of 'L-threonine phthalate', 'L-threonine phosphate', 'L-threonine formate' and 'L-threonine diformate' crystals

It is proved that the recently reported 'L-threonine phthalate' (Theras et al. Optik. 127 (2016) 3397-3401) 'L-threonine phosphate' (Chinnappan et al., Optik 126 (2015) 5517-5521) 'L-threonine formate' (Hanumantharao and Kalainathan, Optik 124 (2013) 2204-2209) and 'L-threonine diformate' (Viju et al., Optik 125 (2014) 5926-5928) are dubious crystals. Taking the title crystals as examples the importance of nomenclature of nonlinear optical crystals is highlighted.