Ultrahigh Nitric Oxide Capture by Tetrakis(azolyl)borate Ionic Liquid through Multiple-Sites Uniform Interaction

Abstract

A synchronous strategy for improving the absorption/desorption to achieve highly efficient nitric oxide (NO) capture is proposed by the use of tetrakis(azolyl)borate ionic liquid (IL) [P66614][B(Im)4] with multiple nonconjugated interaction sites. This IL exhibited an ultrahigh absorption capacity up to 8.13 mol of NO per mol of IL, good desorption, and excellent reversibility. Through a combination of absorption experiments, DFT calculations, and FT-IR and NMR characterizations, the results indicate that the ultrahigh NO capacity by [P66614][B(Im)4] originated from multiple-sites chemisorption through the formation of diazeniumdiolates (NONOates), while uniform interaction of multiple nonconjugated sites was responsible for the unusual S-shaped absorption isobar, leading to good desorption and excellent reversibility, which was different from traditional ILs. We believe this work provides a new method for designing highly efficient gas absorbents.