Probing for a Leaving Group Effect on the Generation and Reactivity of Phenyl Cations

Phenyl cations are smoothly generated by the <i>photo</i>heterolytic cleavage of an Ar–LG bond (LG = leaving group). With the aim of evaluating the scope of the method, a series of 4-methoxy-2-(trimethylsilyl)­phenyl derivatives (sulfonic, LG = MeSO₃ and CF₃SO₃, phosphate, LG = (EtO)₂(O)­PO esters and the corresponding chloride) have been compared as probes for evaluating the leaving group ability. The photocleavage was a general reaction, with the somewhat surprising order (EtO)₂(O)­PO ∼ Cl > CF₃SO₃ > MeSO₃ (Φ = 0.50 to 0.16 in CF₃CH₂OH and lower values in MeCN–H₂O). The ensuing reactions did not depend on the LGs but only on the structure of the phenyl cation (the silyl group tuned the triplet to singlet intersystem crossing and the electrophilicity) and on the medium (formation of a complex with water slowed the electrophilic reactions)

Polyethylene oxide electrolyte membranes with pyrrolidinium-based ionic liquids

Two pyrrolidinium-based ionic liquids (ILs) with ether groups, and namely N-methoxyethyl-N-methylpyrrolidinium bis-trifluoromethanesulfonimide (PYRA1,2O1) and 1-(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-1-methylpyrrolidinium bis-trifluoromethanesulfonide (PYRA1,2(O2)2O1), were used as plasticizers for the PEO20–LiTFSI solid polymer electrolyte. The ionic liquids differ for the number of oxygens and lateral chain length. The properties of the plasticized polymer electrolytes were investigated by means of thermal analysis, impedance spectroscopy, XRD, FTIR spectroscopy and voltammetry. Both the ILs enhanced the conductivity of PEO20–LiTFSI of about one order of magnitude at 40 ◦C. The polymer electrolyte plasticized with PYRA1,2O1 showed a higher transport number, and a wider electrochemical window

Polyethylene oxide electrolyte membranes with pyrrolidinium-based ionic liquids

Two pyrrolidinium-based ionic liquids (ILs) with ether groups, and namely N-methoxyethyl-N-methylpyrrolidinium bis-trifluoromethanesulfonimide (PYRA1,2O1) and 1-(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-1-methylpyrrolidinium bis-trifluoromethanesulfonide (PYRA1,2(O2)2O1), were used as plasticizers for the PEO20-LiTFSI solid polymer electrolyte. The ionic liquids differ for the number of oxygens and lateral chain length. The properties of the plasticized polymer electrolytes were investigated by means of thermal analysis, impedance spectroscopy, XRD, FTIR spectroscopy and voltammetry. Both the ILs enhanced the conductivity of PEO20-LiTFSI of about one order of magnitude at 40 ◦C. The polymer electrolyte plasticized with PYRA1,2O1 showed a higher transport number, and a wider electrochemical windo

New Ether-functionalized Morpholinium- and Piperidinium-based Ionic Liquids as Electrolyte Components in Lithium and Lithium–Ion Batteries

Here, two ionic liquids, N-ethoxyethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (M1,2O2TFSI) and N-ethoxyethyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide (P1,2O2TFSI) were synthesized and compared. Fundamental relevant properties, such as thermal and electrochemical stability, density, and ionic conductivity were analyzed to evaluate the effects caused by the presence of the ether bond in the side chain and/or in the organic cation ring. Upon lithium salt addition, two electrolytes suitable for lithium batteries applications were found. Higher conducting properties of the piperidinium-based electrolyte resulted in enhanced cycling performances when tested with LiFePO4 (LFP) cathode in lithium cells. When mixing the P1,2O2TFSI/LiTFSI electrolyte with a tailored alkyl carbonate mixture, the cycling performance of both Li and Li–ion cells greatly improved, with prolonged cyclability delivering very stable capacity values, as high as the theoretical one in the case of Li/LFP cell configurations. © 2017 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinhei