Synthesis, characterization and near infra-red properties of perylenebisimide derivatives

In this study, several perylene bisimide derivatives are synthesized and their ability to act as cool pigments is investigated. Synthesized pigments are characterized using FTIR, HNMR and XRD techniques. Reflectance of the pigments in the ultraviolet, visible and near-infrared (NIR) regions is investigated on two optically different substrates namely high absorptive substrate and high reflective substrate. The results show that this method is an efficient method to investigate the NIR properties of the pigments. Synthesized pigments exhibit different reflectance extents in the NIR region despite their structural similarities illustrating that the NIR properties are dependent on the N-substituent nature and electronic environment of the pigments. Direct correlation between crystallinity percentage and NIR transparency is observed in this study. However, results of this study are not completely in agreement with previous studies suggesting that the main factor affecting NIR properties of the perylene pigments is missing in the literature.