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Efficient CO2 capture by ionic liquids needs a thorough understanding of underlying mechanisms of the CO2 interaction with ionic liquids, especially when it involves chemisorption. In this work we have systematically investigated the mechanism of CO2 capture by 1,3 di-substituted imidazolium acetate ionic liquids using density functional theory. Solvent effects are analyzed using QM/MM and QM/QM approaches with the help of molecular dynamics simulations and ONIOM methods. The investigation of different stepwise mechanisms shows that CO2 could be involved in the first step of the reaction mechanism, also a new two-step mechanism is proposed. The final stabilization step is analyzed and pointed out to be responsible for important experimentally-observed features of the reaction.

Single molecule fluorescence detection of barium is investigated for enhancing the sensitivity and robustness of a neutrinoless double beta decay (0νββ) search in 136 Xe, the discovery of which would alter our understanding of the nature of neutrinos and the early history of the Universe. A key developmental step is the synthesis of bariumselective chemosensors capable of incorporation into ongoing experiments in high-pressure 136 Xe gas. Here we report turn-on fluorescent naphthalimide chemosensors containing monoaza-and diaza-crown ethers as agents for single Ba 2+ detection. Monoaza-18-crown-6 ether naphthalimide sensors showed sensitivity primarily to Ba 2+ and Hg 2+ , whereas two diaza-18-crown-6 ether naphthalimides revealed a desirable selectivity toward Ba 2+ . Solution-phase fluorescence and NMR experiments support a photoinduced electron transfer mechanism enabling turn-on fluorescence sensing in the presence of barium ions. Changes in ion-receptor interactions enable effective selectivity between competitive barium, mercury, and potassium ions, with detailed calculations correctly predicting fluorescence responses. With these molecules, dry-phase single Ba 2+ ion imaging with turnon fluorescence is realized using oil-free microscopy techniques. This represents a significant advance toward a practical method of single Ba 2+ detection within large volumes of 136 Xe, plausibly enabling a background-free technique to search for the hypothetical process of 0νββ.