Salt-induced thermochromism of a conjugated polyelectrolyte

Peterhans, Lisa; Alloa, Elisa; Sheima, Yauhen; Vannay, Laurent; Leclerc, Mario; Corminboeuf, Clemence; Hayes, Sophia C.; Banerji, Natalie (2017). Salt-induced thermochromism of a conjugated polyelectrolyte. Physical Chemistry Chemical Physics, 19(42), pp. 28853-28866. Royal Society of Chemistry 10.1039/C7CP02734F

	Text C7CP02734F_proofs.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (3MB)
Preview	Text Peterhans_PCCP_2017_accepted_version.pdf - Accepted Version Available under License Publisher holds Copyright. Download (2MB) | Preview

We report here the photophysical properties of a water-soluble conjugated polythiophene with cationic side-chains. When dissolved in aqueous buffer solution (PBS, phosphate buffered saline), there is ordering of the polymer chains due to the presence of the salts, in contrast to pure water, where a random-coil conformation is adopted at room temperature. The ordering leads to a pronounced colour change of the solution (the absorption maximum shifts from 400 nm to 525 nm). Combining resonance Raman spectroscopy with density functional theory computations, we show a significant backbone planarization in the ordered phase. Moreover, the ratio of ordered phase to random-coil phase in PBS solution, as well as the extent of intermolecular interactions in the ordered phase, can be tuned by varying the temperature. Femtosecond transient absorption spectroscopy reveals that the excited-state behaviour of the polyelectrolyte is strongly affected by the degree of ordering. While triplet state formation is favoured in the random-coil chains, the ordered chains show a weak yield of polarons, related to interchain interactions. The investigated polyelectrolyte has been previously used as a biological DNA sensor, based on optical transduction when the conformation of the polyelectrolyte changes during assembly with the biomolecule. Therefore, our results, by correlating the photophysical properties of the polyelectrolyte to backbone and intermolecular conformation in a biologically relevant buffer, provide a significant step forward in understanding the mechanism of the biological sensing.

Interest & Impact

Downloads

181 since deposited on 21 Nov 2018
10 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item