This paper discusses the third-order nonlinear optical (NLO) properties of metal-free, lead and transition metal phthalocyanines, as well as scandium, yttrium and lanthanide bisphthalocyanines measured by time-resolved degenerate four-wave mixing at 1064 nm. The study focuses on the structure-property relationships and explores the possible mechanisms leading to the enhanced third-order optical nonlinearity measured for this interesting class of NLO materials.