posted on 2021-12-13, 13:35authored byZhengjiu An, Jie-Min Zhang, Ming-Yu Lv, Xin-Qi Li, Lixin Wu, Hai-Bo Shang, Donghao Li
Regrettably,
conventional chromatographic columns have immutable
polarity, resulting in requirements of at least two columns with polarity
difference and sophisticated mechanical switching valves, which hinders
the development of “micro-smart” multidimensional tandem
chromatography. In this work, light-driven polarity switching was
realized in a single capillary column based on the reversible trans–cis isomerization of 4-[3-(triethoxysilyl)propoxy]azobenzene
as the stationary phase under light irradiation, with the change in
dipole moment. As a result, the stationary phase offers precise and
dynamic control of polarity based on the cis–trans azobenzene ratio, which depends on irradiation wavelength
and time. Thus, the continuous adjustment of polarity enables diversified
chromatographic separation modes, for example, step-polarity gradient
and polarity-conversion separation modes, taking advantage of the
superior freedom of polarity switching in time and spatial dimensions.
The photosensitive column also shows good reproducibility of polarity
photoreversibility and high separation efficiency. The present study
might offer brand new insight into developing miniaturization and
intellectualization of multidimensional chromatography via designing smart responsive switching valves or stationary phases,
besides mechanical means.