Thomas A. Singleton, Kevin S Ramsay, M. M. Barsan
Aug 2, 2012
Citations
2
Influential Citations
47
Citations
Journal
The journal of physical chemistry. B
Abstract
The photoinduced isomerization and thermal back relaxation of an azobenzene-functionalized polymer poly(disperse red 1 acrylate) were investigated at increasing external pressures up to 1.5 GPa inside a diamond-anvil spectroscopic cell. The thermal cis-trans isomerization was monitored by laser pump-probe spectroscopy, which demonstrated an increase in the half-life of the isomerization process with increasing pressure. Additionally, the cis content of the photostationary state gradually decreased as a function of pressure, with complete arrest of the trans-cis photoisomerization above 1.5 GPa. The fact that the photoswitching behavior however could still be observed beyond 1 GPa is remarkable and is effectively a measure of the strength of the azobenzene chromophore as an artificial muscle. The changes in the Raman shifts of both trans- and cis-azobenzene were also investigated from ambient pressure up to 4 GPa, and no discontinuities were observed in the pressure vs wavenumber plots indicating no change in phase. The cis-trans photoisomerization of azobenzene was shown however to still be inducible at all the pressures investigated, confirming the suitability of these molecules for high-efficiency light actuation.