A Novel Azo-Linked Polymer Bearing Trifluoromethyl Groups for I2 Capture

Abstract

In this work, a novel three nitro-group-bearing monomer 3,6-dinitro-9-(2-trifluoromethyl-4-nitrophenyl)-carbazole (Car-3NO₂ -CF₃ ) via a CN coupling reaction between 3,6-dinitro-9H-carbazole (Car-2NO₂ ) and 2-chloro-5-nitrobenzotrifluoride is synthesized, and obtained single crystal and single crystal analysis data for this compound. The crystal system of Car-3NO₂ -CF₃ is monoclinic and it has a P 21/c space group. This new monomer (Car-3NO₂ -CF₃ ) is also utilized to synthesize a novel azo-linked polymer (Azo-Car-CF₃ ). The trifluoromethyl group has polar CF bonds, and thus it is an effective functional group for the capture of iodine. Azo-Car-CF₃ has great thermal stability with a mass loss of only 10% at 414 °C, as well as good chemical stability as is demonstrated by its low solubility in common organic solvents such as tetrahydrofuran (THF), acetone, methanol, ethanol, and N,N-dimethylformamide (DMF). The specific surface area of Azo-Car-CF₃ can reach as high as 335 m² g^-1 . Azo-Car-CF₃ exhibits an excellent capacity for iodine adsorption and can reach up to 1198 mg g^-1 in cyclohexane solution, and its adsorption capacity for iodine vapor can get to 2100 mg g^-1 . In addition, ethanol can be used to trigger the release of the captured iodine to be easily released from Azo-Car-CF₃ .

Keywords: azo-linkages; iodine captures; polymers; single crystals; trifluoromethyl groups.