The acetate-based ionic liquids (ILs), e.g., [ n Bu4N]­OAc, have been developed for challenging 4-electron reduction of CO2 with amines and hydrosilane to afford aminals. Notably, polymethylhydrosiloxane, a cheap byproduct of the silicone industry, also works well as a reductant. Furthermore, an alternative pathway is rationally proposed via thorough density functional theory (DFT) study. In addition, the ILs play a surprisingly significant role through decreasing activation free energy. More importantly, the essence of being kinetically favorable with 4-electron reduction and thermodynamically favorable with 6-electron reduction is unveiled by DFT study, which guides us to successfully get 6-electron reductive products of CO2, i.e., methylamine. This work represents upgrading usage of both carbon and silicon wastes to valuable chemicals via IL catalysis.

A highly fluorescent chemosensor based on 1,8-naphthyridine with high sensitivity and selectivity toward Ni(2+)/Cu(2+) over other cations both in aqueous solution over a wide pH range (4-10) and in cellular environments was developed. Counteranions such as acetate, sulfate, nitrate, and perchlorate have no influence on the detection of such metal ions. Ethylenediamine showed high selectivity toward the in situ-prepared Cu(2+) complex over the Ni(2+) complex, which can be applied to distinguish Ni(2+) and Cu(2+). The Ni(2+)-induced fluorescence on-off mechanism was revealed to be mediated by intramolecular charge transfer from the metal to the ligand, while that by Cu(2+) involves intramolecular charge transfer from the ligand to the metal, as confirmed by picosecond time-resolved fluorescence spectroscopy and time-dependent density functional theory calculations.

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