N methylimidazole

For the synthesis of hydroxyl-functionalized ionic liquids (ILs), N-methylimidazole (Sigma-Aldrich, Burlington, MA, USA), 3-chloro-1,2-propanediol (Sigma-Aldrich), ethyl acetate (Neon Química, São Paulo, Brazil), lithium bis(trifluoromethanesulfonyl)imide (LiNT₂F, Sigma-Aldrich, USA), lithium tetrafluoroborate (LiBF₄, Sigma-Aldrich, USA), and sodium hexafluorophosphate (NaPF₆, Sigma-Aldrich, USA) were used. To obtain the PILs, polycarbonate diol (PCD, Mn = 2000 g/mol, Bayer, Berlin, Germany), hexamethylene diisocyanate (HDI, 99%, Merck, Darmstadt, Germany), dibutyltin dilaurate (DBTDL, Miracema Nuodex, Campinas, Brazil), methyl ethylketone (MEK, 99%, Mallinckrodt, Hazelwood, MO, USA) and the obtained ILs glyceryl-N-methylimidazolium chloride [GLYMIM][Cl], and derivatives ([GLYMIM][Cl], [GLYMIM][NT₂F], ([GLYMIM][BF₄] and ([GLYMIM][PF₆]) were used.

The starting material (tBuNH)₂SiMe₂ was prepared according to a published method [42 (link)]. The amino acids α-aminoisobutyric acid (Roth, Karlsruhe, Germany, ≥97%), D-phenylglycine, and L-valine (Merck, Darmstadt, Germany, ≥99%) were commercially available and were used without further purification. (Note: For the chiral amino acids, phenylglycine, and valine, the choice of the respective enantiomer was made by the availability of the starting materials from previous studies.) N-Methylimidazole (Sigma-Aldrich, Steinheim, Germany, ≥99%), chloroform, stabilized with amylenes (Honeywell, Seelze, Germany, ≥99.5%) and CDCl₃ (Deutero, Kastellaun, Germany, 99.8%) were stored over activated molecular sieves (3 Å) for at least 7 days and used without further purification. All reactions were carried out under an atmosphere of dry argon utilizing standard Schlenk techniques. Solution NMR spectra (¹H, ¹³C, ²⁹Si) (cf. Figures S1–S13 in the supporting information) were recorded on Bruker Avance III 500 MHz and Bruker Nanobay 400 MHz spectrometers. ¹H, ¹³C and ²⁹Si chemical shifts are reported relative to Me₄Si (0 ppm) as internal reference. (Note: The referencing of ¹H and ¹³C chemical shifts against solvent signals is not useful in these systems which contain large amounts of strong hydrogen bond acceptors, e.g., NMI. Such components may influence the ¹H and ¹³C chemical shift of chloroform noticeably. For instance, in a ¹H NMR spectrum of a solution of NMI in TMS-containing CDCl₃, which was recorded for a purity check of the NMI used, the residual CHCl₃ signal emerged at 7.37 ppm rather than at 7.26 ppm in neat CDCl₃.) For single-crystal X-ray diffraction analysis of (Phg)SiMe₂-NMI · 2CHCl₃ a crystal was selected under an inert oil on an ice-cooled Petri dish, mounted on a glass capillary and instantly moved to the cold nitrogen stream of the diffractometer. In the case of (Aib)SiMe₂-NMI · CHCl₃, the compound was allowed to melt at room temperature, whereupon a small amount of the melt was transferred into a glass capillary, which was then sealed, mounted on the goniometer, and slowly cooled to allow for the re-crystallization of the compound inside the capillary on the diffractometer. (The crystallization procedure was similar to our approach of crystallizing chlorosilanes for X-ray diffraction analyses [43 (link)].) Diffraction data were collected on a Stoe IPDS-2 diffractometer (STOE, Darmstadt, Germany) using Mo Kα-radiation. Data integration and absorption correction were performed with the STOE software XArea (version 1.75) and XShape (version 2.17), respectively. The structures were solved using SHELXT [44 (link)] and refined with the full-matrix least-squares methods of F² against all reflections with SHELXL-2018/3 [45 ,46 (link)]. All non-hydrogen atoms were anisotropically refined, and hydrogen atoms were isotropically refined in an idealized position (riding model). For details of data collection and refinement see Appendix A, Table A1. Graphics of molecular structures were generated with ORTEP-3 [47 (link),48 (link)] and POV-Ray 3.7 [49 ].
The geometry optimizations were carried out with ORCA 5.0.3 [50 (link)] using the restricted PBE0 functional with relativistically recontracted Karlsruhe basis sets ZORA-def2-TZVPP [51 (link),52 (link)] for all atoms, the scalar relativistic ZORA Hamiltonian [53 (link),54 (link)], atom-pairwise dispersion correction with the Becke–Johnson damping scheme (D3BJ) [55 (link),56 (link)], and COSMO solvation (CHCl₃, ε = 4.8, rsolv = 3.17). Very-TightSCF and slowconv options were applied and the DEFGRID3 was used with a radial integration accuracy of 10 for Si for all calculations. Calculations were started from the molecular structures obtained by single-crystal X-ray diffraction analysis. Numerical frequency calculations were performed to prove convergence at the local minimum after geometry optimization and to obtain the Gibbs free energy (293.15 K). NMR calculations were carried out with ORCA 5.0.3 at the same level of theory as mentioned above. Graphics were generated using ChemCraft [57 ].

3-Glycidoxypropyl-trimethoxysilane (GPTMS) (98%), EGDE (99%), and trimethyltriethoxysilane (TMES) (95%) were used as received and purchased from ABCR Company. n-Methylimidazole (n-MI,99%) and LiTFSI (99.95%) from Sigma-Aldrich was used as an initiator for the epoxy group copolymerization and lithium salt, respectively. LiFFSI was dried at 120 °C in a glovebox. Absolute ethanol (99.5%) from Panreac was distilled (Karl–Fischer titration 55 ppm H₂O) and was used as solvent.
The synthesis procedure consists in the initial formation of the organic network and, then, the sol-gel reactions (hydrolysis and condensation) forming inorganic networks are promoted, according to the procedure that was followed for the development of the termed “star-branched silica based architectures” [25 (link),28 (link),29 (link)]. The preparation of the materials consists of three stages: (i) formation of the organic network; (ii) formation of inorganic environments (sol-gel reactions); (iii) blocking of hydrolyzed groups, uncondensed Si-OH groups, with trimethyltriethoxysilane (TMES), in order to avoid the effect of proton conduction on the conductivity measurement; and, (iv) Once the hybrid structure is formed, the lithium salt (LiTFSI) is added to obtain the desired Li-ion conductive material. The flux diagram describing synthesis strategy for the preparation of GTT: GPTMS/TMES/TPTE compositions are shown in the Figure 1.
Five compositions of the GTT system (Table 1) have been synthesized, varying the ratio between the precursors (GPTMS and TPTE). [Li]/[O] ratio was fixed to 0.10 (based on a previous work [28 (link)]), and also non-doped Li composition was studied for comparison.
The materials have been processed as coatings while using the immersion-extraction process and as self-supported membranes. The coatings were deposited on soda-lime glass slides (2.5 × 7 cm²) and they were processed at room temperature inside a glove box (Ar) that was equipped with a dip-coater. Extraction speeds between 4.5 and 20 cm min⁻¹ were used. The coatings were dried at room temperature for 30 minutes and, subsequently, they were thermally treated at 100 °C for 12 h in an oven (HOBERSAL Model JB-15) (with a constant heating ramp of 1 °C/min.) inside the glove box to complete the drying and sintering of the material. The preparation of the self-supported membranes was based on the casting of the sol in Teflon molds inside the glove box, allowing for the solvent to evaporate for several days at room temperature and, subsequently, treated at 60 °C for 24 h. The membranes were demoulded and treated thermally at 100 °C in order to accelerates condensation of inorganic precursor and consolidate the hybrid structure while using a constant heating ramp at 1 °C/min. for 12 h in an inert atmosphere (Ar).