Probing the effect of substituted groups on sensory properties based on single-crystalline micro/nanostructures of perylenediimide dyes

Abstract

Two core-tetrachlorinated perylenediimide derivatives PTCDI-ClC₁₂ and PTCDI-ClC₄F₇ bearing electron-donor dodecyl and electron-withdrawing fluorobutyl groups at the imide positions, respectively, were prepared. The determination of sensing properties based on their conductometric gas sensors revealed that both devices had the same sensitivity to the hydrazine vapor and approximately 4 orders of magnitude in resistance decreased upon exposure to the hydrazine vapor (10 ppm). Whereas approximately 2 orders of magnitude in resistance decreased for another core-unsubstituted PTCDI-C₁₂ gas sensor that was also prepared for comparison purpose. The differential response to the hydrazine vapor for the core-tetrachlorinated PTCDI-ClC₁₂ and core-unsubstituted PTCDI-C₁₂ was independent of their surface area and morphologies and was ascribed to the difference in their reduction potentials that originated from different bay-substituted groups and the twisted skeleton of the PTCDI-ClC₁₂ molecule. The similar LUMO energy levels of PTCDI-ClC₁₂ and PTCDI-ClC₄F₇ led to both of them possessing similar sensing performance, which in turn indicated that the substituents at the imide positions have little effect on the improvement of performance of perylenediimide derivatives gas sensors.