Halogen-free chelated orthoborate ionic liquids and organic ionic plastic crystals
Shah, Faiz Ullah, Glavatskih, Sergei, Dean, Pamela M., MacFarlane, Douglas R., Forsyth, Maria and Antzutkin, Oleg N.. (2012) Halogen-free chelated orthoborate ionic liquids and organic ionic plastic crystals. Journal of Materials Chemistry, Vol.22 (No.14). pp. 6928-6938. ISSN 0959-9428Full text not available from this repository.
Official URL: http://dx.doi.org/10.1039/C2JM12657E
Five halogen-free orthoborate salts comprised of three different cations (cholinium, pyrrolidinium and imidazolium) and two orthoborate anions, bis(mandelato)borate and bis(salicylato)borate, were synthesised and characterised by DSC, X-ray diffraction and NMR. DSC measurements revealed that glass transition points of these orthoborate salts are in the temperature range from −18 to −2 °C. In addition, it was found that [EMPy][BScB] and [EMIm][BScB] salts have solid–solid phase transitions below their melting points, i.e. they exhibit typical features of plastic crystals. Salts of the bis(salicylato)borate anion [BScB]− have higher melting points compared with corresponding salts of the bis(mandelato)borate anion [BMB]−. Single crystal X-ray diffraction crystallography (for [Chol][BScB] crystals) and solid-state multinuclear (13C, 11B and 15N) NMR spectroscopy were employed for the structural characterisation of [Chol][BScB], [EMPy][BScB] and [EMIm][BScB], which are solids at room temperature: a strong interaction between [BScB]− anions and [Chol]+ cations was identified as (i) hydrogen bonding between OH of [Chol]+ and carbonyl groups of [BScB]− and (ii) as the inductive C–Hπ interaction. In the other salt, [EMIm][BScB], anions exhibit ππ stacking in combination with C–Hπ interactions with [EMIm]+ cations. These interactions were not identified in [EMPy][BScB] probably because of the lack of aromaticity in cations of the latter system. Our data on the formation of a lanthanum complex with bis(salicylato)borate in the liquid mixture of La3+(aq) with [Chol][BScB] suggest that this class of novel ILs can be potentially used in the extraction processes of metal ions of rare earth elements.
|Item Type:||Journal Article|
|Divisions:||Faculty of Science > Physics|
|Journal or Publication Title:||Journal of Materials Chemistry|
|Publisher:||Royal Society of Chemistry|
|Page Range:||pp. 6928-6938|
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