Manifesting the multi-stimuli-responsive behaviour of triazole-substituted triphenylamine

The development of multi-stimuli-responsive (MSR) materials is a tempting yet intriguing challenge due to the absence of a defined design approach. In this study, we designed and synthesised two compounds based on triphenylamine, namely, TPA-Tz1 and TPA-Tz2. The photoluminescent investigations reveal the MSR behaviour of both compounds. TPA-Tz1 shows reversible mechanochromism with a blue-shifted emission due to changes in intermolecular interactions. Furthermore, both compounds exhibit solvatochromism in solvents of varying polarity. Detailed studies suggest that solvatochromism in TPA-Tz1 can be attributed to twisted intramolecular charge transfer (TICT), while in TPA-Tz2, it is due to intramolecular charge transfer (ICT). Additionally, both compounds display acidochromic properties in solution as well as in the solid state due to the protonation of the triazole ring. All changes in emissions are corroborated through theoretical calculations. The results provide insights into the intricate interplay of molecular interactions and structural rearrangements that contribute to the compound's multifaceted responsiveness.