Tuning the photophysical, thermal properties and electronic energy levels in the triphenylamine derivatives by benzoylhydrazone architecture

• The five triphenylamine derivatives modified by benzoylhydrazone structure were synthesized.
• The effects of the electron-withdrawing/donating group were confirmed by density functional study and photophysical properties.
• The thermostability and electrochemistry properties of the five compounds were found to be distinctively promoted.

A novel of triphenylamine derivatives with more extended π-conjugated systems achieved by benzoylhydrazone architecture were synthesized under mild condition with high yields. The dependence of their photophysical, electrochemistry and thermal properties on their chemical structure is discussed. Compared with the N,N-di(4-methylphenyl)aniline, the thermostability of the five triphenylamine-based hydrozones is dramatically promoted. These compounds are stable up to 345 °C according to thermogravimetric analysis. The energy levels of the four compounds were finely tuned by introducing the electron-donating and -withdrawing groups to the triphenylamine core which are supported by the fluorescence spectra and transit fluorescence spectra of the compounds (–H > –CH3 > –Cl > Pyridine > –NO2). Their multiple cyclic voltammetry study and density functional study suggest these materials to be promising hole-transport properties.

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