Novel electrochromic triphenylamine-based polyamides containing quinolin-8-yloxy group as probes for metal ions

- A new series of soluble polyamides (PAs) derived from 4,4'-diamino-4”-(quinolin-8-yloxy) triphenylamine (DAQTPA) were synthesized.
- DAQTPA and PAs performed the most strongly responsive to Cu2+, which were completely different from the response of other metal ions.
- These electrochromic PAs exhibited good thermal stability and solubility.

A new series of soluble electrochromic polyamides (PAs) were synthesized from the reaction of 4,4'-diamino-4”-(quinolin-8-yloxy) triphenylamine (DAQTPA) with five dicarboxylic acid via direct polycondensation process, respectively. These amorphous materials showed the decomposition temperature at 5% weight loss was over 400 °C in N2 atmosphere. The influence of aliphatic structure for spectroscopic properties of PA was measured by UV-vis and fluorescent (PL) spectroscopies and explained by the theory of the frontier molecular orbitals. It can be easily determined that DAQTPA performs the most strongly responsive to Cu2+ with obvious enhancement in UV-vis and quenching in PL profiles, which are completely different from the response of other metal ions. PAs also showed the exclusively selective response for Cu2+ in UV-vis spectra. A pair of obvious redox peaks was observed in the cyclic voltammetry (CV) test of PAs accompanied with the distinct color changed from original yellowish to green or blue. The PA bearing the pendent quinolin-8-yloxy performed as an electron-donating group was more stable in the electrochemical process.