Synthesis Of Twisted Substituted Perylene Diimide And Study Of Base-driven Hydrazine-sensing Performance

Gas sensor plays an irreplaceable role in the field of environmental detection.It is a top focus topic to devolping a gas sensor with characteristics of easy-fabricating,high sensitivity,fast response and long-term stability.Perylene diimides has potential application in the field of gas sensor due to its unique photoelectric properties.However,it is prone to form aggregates in solid state,which is bad for the formation of gassy structure and have a bad effect on the device performance.Thus,one of the problems demanding prompt solution is to improve performance of gas sensor through optimazing aggregation structure by altering the molecular structure of perylene diimides.In this paper,two perylene diimides(s-THBPDI and d-THBPDI)bearing one and two twisted oxygen bridged heptatomic biphenyl(THB)in the bay positions were designed and synthesized.The structure of them was characterized by FT-IR,1H NMR.The aggregation behaviors were studied by concentration-depended UV-vis absorption and PL spectra,which proved that the introduction of the THB definitely had an inhabitit effect on the intermolecular aggregation compared to that unsubstituted perylene diimide.The energy level were studied by cyclic voltammetry,the result indicating that they possesses a lower reduction potential and transform into generate radical anion.by accepting electron.Then the reduction of d-THBPDI was carried out in N,N'-dimethylformamide in the presence of organic bases like hydrazine,ethanediamine and triethylamine,and the formation of the radical anions was monitored by UV-vis and PL spectra.In addition,the reduction mechanism was discussed by comparing the reduction of d-THBPDI under different organic bases and the base-driven keto-enol anion tautomerism was proposed.Base on the reduction mechanism of d-THBPDI in the present of hydrazine,a film device based on d-THBPDI was fabricated by solution-processing.The gas sensing performance and the sensing mechanism of it were investigated.The results revealed that the d-THBPDI film device exhibits high sensitivity,fast response/recovery time and excellent reusability.In addition,the sensing mechanism is based on the reduction of the perylene diimide under bases.