High stability diionic liquid salts
The present invention relates to diionic liquid salts of dicationic or dianionic molecules, as well as solvents comprising such diionic liquids and the use of such diionic liquids as the stationary phase in a gas chromatographic column.
1. A diionic liquid salt comprising at least one di-cation of the formula:
A-B-A′
and at least one counter anion; wherein
A and A′ are mono-cationic groups independently selected from the group consisting of protonated tertiary amine of formula —[N(R) 2 H] + , optionally substituted imidazolium, and thionium of formula —[S(R) 2 ] + , wherein
A and A′ are not the same;
each R is independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, phenyl, and benzyl; and
bridging group, B, is an optionally substituted C 4 -C 40 hydrocarbon backbone,
wherein the hydrocarbon backbone optionally contains, in addition to carbon and hydrogen atoms, at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and silicon.
2. The diionic liquid salt of claim 1 , wherein A and A′ comprise different charged elements.
3. The diionic liquid salt of claim 2 , wherein A comprises a monocationic group selected from the group consisting of protonated tertiary amine of formula —[N(R) 2 H] + and optionally substituted imidazolium.
4. The diionic liquid salt of claim 1 , wherein A and A′ are not the same, but comprise the same charged element.
5. The diionic liquid salt of claim 4 , wherein A and A′ are monocationic groups independently selected from the group consisting of protonated tertiary amine of formula —[N(R) 2 H] + , and optionally substituted imidazolium.
6. The diionic liquid salt of claim 1 , wherein A is a protonated tertiary amine of formula —[N(R) 2 H] + and A′ is optionally substituted imidazolium.
7. The diionic liquid salt of claim 6 , wherein A′ is selected from the group consisting of methyl imidazolium, n-butyl imidazolium, dimethyl imidazolium, 2-hydroxyethyl imidazolium, and benzyl imidazolium.
8. The diionic liquid salt of claim 1 , wherein the bridging group, B, is unsymmetric.
9. The diionic liquid salt of claim 8 , wherein the bridging group, B, is unsymmetric and contains one or more heteroatoms in its backbone.
10. The diionic liquid salt of claim 8 , wherein the bridging group, B, is unsymmetric and contains a side chain group.
11. The diionic liquid salt of claim 1 , wherein the at least one counter anion is a diionic counter anion.
12. The diionic liquid salt of claim 1 , wherein the diionic liquid salt comprises two mono-ionic counter anions.
13. The diionic liquid salt of claim 12 , wherein the two mono-ionic counter anions are independently selected from the group consisting of Br − , mono-sulfonate, mono-sulphate, NTf 2 − , BF 4 − , trifilate and PF 6 − .
14. A diionic liquid salt comprising at least one di-cation selected from the group consisting of
and at least one counter anion.
15. The diionic liquid salt of claim 1 , wherein the diionic liquid salt has a solid/liquid transition temperature of about 100° C. or less.
16. The diionic liquid salt of claim 1 , wherein the diionic liquid salt has a solid/liquid transition temperature of about 25° C. or less.
17. The diionic liquid salt of claim 1 , wherein the bridging group, B, is a C 4 -C 40 carbon chain.
18. The diionic liquid salt of claim 1 , wherein the bridging group, B, contains at least one unsaturated group which can facilitate cross-linking or immobilization.
19. The diionic liquid salt of claim 1 , wherein the bridging group, B, contains at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and silicon.
20. A solvent comprising a diionic liquid salt of claim 1 or claim 14 .
21. The diionic liquid salt of claim 1 , wherein A and A′ are independently selected from the group consisting of protonated tertiary amine of formula —[N(R) 2 H] + and optionally substituted imidazolium.
22. The diionic liquid salt of claim 6 , wherein each R of the protonated tertiary amine of formula —[N(R) 2 H] + is independently selected from the group consisting of propyl, butyl, cyclohexanyl, and phenyl.