Impact of alkyl chain and bay-phenoxy unit on the sensing performance of perylenediimide derivatives

Abstract

In this contribution, three perylenediimide derivatives (PDIs) substituted on the 1,6,7,12-positions with phenoxy groups were prepared, on which the substituted groups are tetraphenoxy (pH), para-tertbutylphenoxy (TpH) and para- tetramethylbutylphenoxy (OpH). Studies on their sensing properties in hydrazine vapor (5ppm) suggested these materials have good sensing performance. In these three PDIs, OpH shows the best sensing performance owing to its better crystalline structure, smallest torsion angle and activation energy with face-to-face stacking mode. A well-ordered crystalline structure with smaller interplanar spacing and modest activation energy leads TpH exhibiting middle-grade of sensing performance in these PDIs. While the largest activation energy, a greater torsion angle with poor crystalline structure induce the least-efficiency sensing performance of pH sensors. This study indicates the aromatic groups, the length and branched point of alkyl chain on bay region have significant impact on sensing performance of PDIs devices by modulating crystalline structure, π-π overlap and energy level.