Firstly, they have prepared a new class of azobenzene (AZO)-based photoresponsive ionic liquids through the covalent bonding of azobenzene moiety and ILs. They have received a Chinese invention patent for the preparation technique. (Patent name: Photoresponse ion liquid and preparation thereof; Patent no.: No. ZL200710307474.0.) The ILs show distinct and reversible solvent-dependent photoresponsive conductivity, which can be related to photoisomerism-induced reversible change of aggregation behavior of ionic clusters. The result demonstrates the possibility of in-depth investigation of the aggregation behavior of ILs. The findings have been published in Chem. Commun. (2011, 47, 6641-6643).

Solvent-dependent photoresponsive conductivity of azobenzene-appended ionic liquids (Image by DENG Youquan et al.)

Then have prepared a new type of quinolizinium ILs featuring an unbranched cation core. Different from traditional ILs, the new ILs exhibit special thermal decomposition property and can stabilize some strongly nucleophilic anions. They also show extremely high fluorescence quantum yields in solution (Φf > 99%, λem near 334 nm) and bright cyan fluorescence in molten state (λem near 465 nm). The findings have been published in J. Mater. Chem. (2011, 21, 8979-8982).

Quinolizinium ionic liquids and their unexpected intensive fluorescence (Image by DENG Youquan et al.)

The work has received support from the National Natural Science Foundation of China.

Chem. Commun. Paper

J. Mater. Chem. Paper