Imidazolium-based liquid salts and methods of use thereof

1. A method of detecting at least one anion by ESI-MS, the method comprising:

adding to a sample at least one dicationic liquid salt comprising a dicationic species corresponding in structure to Formula I:

and at least one counter-anion, wherein the at least one counter-anion is OH − ;

wherein:

R is one or more substituents independently selected from the group consisting of alkyl, alkenyl, hydroxyl, alkoxy, carbocyclyl, carbocyclylalkyl, heterocyclyl, heterocyclylalkyl and hydroxyalkyl;

m is zero, 1, 2, 3 or 4;

B is a divalent fragment composed of a chain of one or more moieties selected from the group consisting of C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, C 2 -C 20 -alkynylene, (—CH 2 -carbocyclyl-CH 2 —) n , (—CH 2 -carbocyclyl-) n and polysiloxyl;

wherein C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, and C 2 -C 20 -alkynylene optionally contain in the chain one or more heteroatoms selected from the group consisting of O, N, S and Si;

wherein B is optionally substituted with one or more substituents selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy and halo;

n is selected from the group consisting of 1 to 20, inclusive, to form a complex; and

identifying the presence or non-presence of the complex formed between the at least one anion and the at least one dicationic liquid salt using ESI-MS.

2. The method of claim 1 , wherein

m is 1, 2, 3 or 4; and

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n .

3. The method of claim 1 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

m is 1, 2 or 3;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n ; and

n is 1 to 12, inclusive.

4. The method of claim 1 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is C 1 -C 10 -alkyl, hydroxyl, carbocyclylalkyl, heterocyclylalkyl, hydroxyalkyl;

m is 1 or 2;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -phenyl-CH 2 —) n or (—CH 2 -cyclohexane-CH 2 —) n , (—CH 2 -phenyl-) n or (—CH 2 -cyclohexane-) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl, Br, methyl, ethyl, propyl, butyl, methoxy, ethoxy, propoxy and butoxy;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1 to 12, inclusive.

5. The method of claim 1 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is methyl, ethyl, propyl, butyl, hydroxyalkyl or benzyl;

m is 1;

B is C 1 -C 8 -alkylene or (—CH 2 -phenyl-CH 2 —) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl and Br;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1.

6. The method of claim 1 , wherein the dicationic species is selected from the group consisting of:

7. The method of claim 1 , wherein ESI-MS is carried out in the positive ion mode.

8. The method of claim 1 , wherein the dicationic liquid salt pairs with a single anion yielding a positively charged complex.

9. The method of claim 1 , wherein the dicationic liquid salt is added to a carrier flow solvent.

10. The method of claim 9 , wherein a dicationic liquid salt solution of about 1-μM to about 200 μM is added to the carrier flow solvent.

11. The method of claim 9 , wherein the carrier flow solvent is a water-miscible organic solvent or a mixture of water and the water-miscible organic solvent.

12. The method of claim 11 , wherein the water-miscible organic solvent is selected from the group consisting of methanol, ethanol, propanol, acetonitrile, tetrahydrofuran and dioxane.

13. The method of claim 1 , further comprising coupling ESI-MS with a separation technique.

14. The method of claim 13 , wherein the separation technique is selected from the group consisting of liquid chromatography, HPLC, ion chromatography, ion-exchange chromatography, SPE, SPME, TS-SPME and solid phase microextraction/MALDI.

15. The method of claim 13 , wherein the dicationic liquid salt is added to the carrier flow solvent following the separation technique.

16. A stationary phase comprising at least one dicationic liquid salt comprising a dicationic species corresponding in structure to Formula I:

and at least one counter-anion;

wherein:

R is one or more substituents independently selected from the group consisting of C 5 -C 20 alkyl, C 3 -C 20 alkenyl, hydroxyl, alkoxy, carbocyclyl, carbocyclylalkyl, heterocyclyl, heterocyclylalkyl and hydroxyalkyl;

m is zero, 1, 2, 3 or 4;

B is a divalent fragment composed of a chain of one or more moieties selected from the group consisting of C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, C 2 -C 20 -alkynylene, (—CH 2 -carbocyclyl-CH 2 —) n , (—CH 2 -carbocyclyl-) n and polysiloxyl;

wherein C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, and C 2 -C 20 -alkynylene optionally contain in the chain one or more heteroatoms selected from the group consisting of O, N, S and Si;

wherein B is optionally substituted with one or more substituents selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy and halo;

n is selected from the group consisting of 1 to 20, inclusive.

17. The stationary phase of claim 16 , wherein the at least one counter-anion is independently F − or OH − ;

m is 1, 2, 3 or 4; and

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n .

18. The stationary phase of claim 16 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

m is 1, 2 or 3;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n ; and

n is 1 to 12, inclusive.

19. The stationary phase of claim 16 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is C 5 -C 20 -alkyl, hydroxyl, carbocyclylalkyl, heterocyclylalkyl, or hydroxyalkyl;

m is 1 or 2;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -phenyl-CH 2 —) n or (—CH 2 -cyclohexane-CH 2 —) n , (—CH 2 -phenyl-) n or (—CH 2 -cyclohexane-) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl, Br, methyl, ethyl, propyl, butyl, methoxy, ethoxy, propoxy and butoxy;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1 to 12, inclusive.

20. The stationary phase of claim 16 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is hydroxyalkyl or benzyl;

m is 1;

B is C 1 -C 8 -alkylene or (—CH 2 -phenyl-CH 2 —) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl and Br;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1.

21. The stationary phase of claim 16 , wherein the dicationic species is selected from the group consisting of:

22. A mixed stationary phase comprising at least one dicationic liquid salt comprising a dicationic species corresponding in structure to Formula I:

at least one stationary phase material, and at least one counter-anion;

wherein:

R is one or more substituents independently selected from the group consisting of C 5 -C 20 alkyl, C 3 -C 20 alkenyl, hydroxyl, alkoxy, carbocyclyl, carbocyclylalkyl, heterocyclyl, heterocyclylalkyl and hydroxyalkyl;

m is zero, 1, 2, 3 or 4;

B is a divalent fragment composed of a chain of one or more moieties selected from the group consisting of C 1 -C 20 -alkylene, C 2 -C 20 alkenylene, C 2 -C 20 -alkynylene, (—CH 2 -carbocyclyl-CH 2 —) n , (—CH 2 -carbocyclyl-) n and polysiloxyl;

wherein C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, and C 2 -C 20 -alkynylene optionally contain in the chain one or more heteroatoms selected from the group consisting of O, N, S and Si;

wherein B is optionally substituted with one or more substituents selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy and halo;

n is selected from the group consisting of 1 to 20, inclusive.

23. The mixed stationary phase of claim 22 , wherein the at least one counter-anion is independently F − or OH − ;

m is 1, 2, 3 or 4; and

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n .

24. The mixed stationary phase of claim 22 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

m is 1, 2 or 3;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -carbocyclyl-CH 2 —) n or (—CH 2 -carbocyclyl-) n ; and

n is 1 to 12, inclusive.

25. The mixed stationary phase of claim 22 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is C 5 -C 20 -alkyl, hydroxyl, carbocyclylalkyl, heterocyclylalkyl, or hydroxyalkyl;

m is 1 or 2;

B is C 1 -C 20 -alkylene, C 2 -C 20 -alkenylene, (—CH 2 -phenyl-CH 2 —) n or (—CH 2 -cyclohexane-CH 2 —) n , (—CH 2 -phenyl-) n or (—CH 2 -cyclohexane-) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl, Br, methyl, ethyl, propyl, butyl, methoxy, ethoxy, propoxy and butoxy;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1 to 12, inclusive.

26. The mixed stationary phase of claim 22 , wherein there are at least two counter-anions independently selected from the group consisting of F − and OH − ;

R is hydroxyalkyl or benzyl;

m is 1;

B is C 1 -C 8 -alkylene or (—CH 2 -phenyl-CH 2 —) n ;

wherein B is optionally substituted with one or more substituents independently selected from the group consisting of F, Cl and Br;

wherein B optionally contains in the chain one or more oxygen atoms; and

n is 1.

27. The mixed stationary phase of claim 22 , wherein the dicationic species is selected from the group consisting of:

28. A method of detecting at least one anion by ESI-MS, the method comprising:

adding to a sample at least one dicationic liquid salt selected from the group consisting of:

and at least one counter-anion, to form a complex; and

identifying the presence or non-presence of the complex formed between the at least one anion and the at least one dicationic liquid salt using ESI-MS.