Synthesis, characterization, and visible–near infrared properties of some perylene‐3,4,9,10‐tetracarboxylic bisimide derivatives

BACKGROUND Perylene bisimide pigments are one of the high performance pigment categories that are utilized in near infrared reflective coatings. The relationship between structure and near infrared activity in the perylene pigments has been unknown to date. RESULTS Some of the factors suggested by previous researchers as affecting the near‐infrared (NIR) reflectance of perylene‐bisimide derivatives were investigated in this study and some are validated, while some others are rejected. In the visible region, there are substantial differences between the absorption spectra of the pigments in their solid‐state and dissolved form, indicating that crystallochromic phenomenon present in the pigments. The NIR properties of the synthesized pigments are investigated and the results exhibit an obvious correlation between the imide substitution structure and NIR properties of the pigments. However, a direct relationship cannot be established. Aliphatic substituted PDIs usually exhibit lower reflectance values in comparison to aromatic substituted ones but there are some exceptions in this regard. The results of UV‐visible–NIR reflectance spectra of each pigment were reported in both white and black substrates and, in this regard, the synthesized pigments were classified. All the PDIs fall into the absorbent‐transparent category in the NIR region. Thermogravimetric analysis indicates that all the PDIs have a heat resistance of at least 200 °C. CONCLUSION The structure‐NIR reflectance relationship of the five synthesized perylene pigments is evaluated and the results illustrate that the N‐substitution of the imide group can significantly influence the cool activity of the pigments. © 2021 Society of Chemical Industry (SCI).