Substituent dependence of imidazoline derivatives on the capture and release system of carbon dioxideElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nj03133e

• Main Authors: Yoshida, Yoshiaki, Aoyagi, Naoto, Endo, Takeshi
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c7nj03133e

The reversible capture-release behaviors of CO 2 by imidazoline derivatives bearing several 2-substituents were investigated under dry conditions containing a very small amount of water. The imidazoline having a cyclic guanidine moiety only captured CO 2 quantitatively, and then the cyclic guanidine derivative gave the guanidinium bicarbonate by CO 2 fixation together with a slight amount of water. In contrast, the imidazolines bearing n -butylthiol and n -pentyl groups never captured CO 2 even with the addition of an equimolar amount of water. Furthermore, the binding structure between CO 2 and the cyclic guanidine derivative was studied in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculations in order to predict the CO 2 capture-release mechanisms depending on the imidazoline structure. The imidazoline having a cyclic guanidine moiety only captured CO 2 quantitatively, and then the cyclic guanidine derivative gave the guanidinium bicarbonate by CO 2 fixation together with a slight amount of water.