1. From the Bottom Up: Hydrogen Bonding in Ionic Liquids 6/19/2014 Olga Gorlova, Conrad Wolke, Joseph Fournier, Christopher Johnson and Mark Johnson

2. Ionic Liquids Purely Ionic Salt Like Notably low vapor pressures + + + + + + + + + - - - - - - - - - o Large & Asymmetric Cation (EMIM + ) m (BF 4 ¯) n (EMIM + ) m (Cl¯) n (EMIM + ) m (Tf 2 N¯) n Liquids at Room Temperatures

3. ESI Needle Temperature Controlled Ion Trap Mounted to He Cryostat Ion Optics 2m Flight Tube Wiley- McLaren TOF Reflectron DC-Turning Quad MCP Detector Differential Aperture Skimmers Heated Capillary RF-Ion Guides Experimental Setup hv = 600-4300 cm -1 Collisional cooling in 3D Paul Trap -Pulsed He and N 2 gas Pulsed Valve Ions inIons out Paul Trap 10 K RF Cryogenic Ion Trap

4. ESI Needle Temperature Controlled Ion Trap Mounted to He Cryostat Ion Optics 2m Flight Tube Wiley- McLaren TOF Reflectron DC-Turning Quad MCP Detector Differential Aperture Skimmers Heated Capillary RF-Ion Guides Experimental Setup hv = 600-4300 cm -1 Room Temperature Ion Cold “Tagged” Ion Photofragment Absorption Evaporation

5. 1-Ethyl-3-methylimidazolium (EMIM + ) (BF 4 ¯) (EMIM + ) m (BF 4 ¯) n

6. % Abs. 60080010001200140016002800300032003400 Photon Energy / cm -1 Bulk FT-IR (EMIM + ) (BF 4 ¯) Et/Me CH stretches Ring CH stretches

7. % Abs. 60080010001200140016002800300032003400 Photon Energy / cm -1 Bulk FT-IR (EMIM + ) (BF 4 ¯) Et/Me stretches Ring CH ip bends Et/Me bends Ring CH stretches Ring stretches EMIM + (calc) Calc. Int. (EMIM + ) (BF 4 ¯) * 2 PEAKS? Red shift caused by H-bond?

8. Pred. Yield % Abs. EMIM + 60080010001200140016002800300032003400 Photon Energy / cm -1 Bulk FT-IR Et/Me stretches Ring CH ip bends Et/Me bends Ring CH stretches Ring stretches EMIM + (calc) Calc. Int. * Isolated (EMIM + ) Spectrum Same Red Shifted Peak in Bare Ion * Anion Contribution ?

9. Pred. Yield % Abs. ν3ν3 ν1ν1 11 BF 4 ‾ EMIM + 60080010001200140016002800300032003400 Photon Energy / cm -1 Bulk FT-IR Et/Me stretches Ring CH ip bends Et/Me bends Ring CH stretches Ring stretches EMIM + (calc) Calc. Int. * * Low Energy Band Broadened asymmetric B-F stretch C.J. Johnson, et. al, J. Chem. Phys. 139, 224305 (2013)

10. Pred. Yield % Abs. ν3ν3 ν1ν1 11 BF 4 ‾ EMIM + 60080010001200140016002800300032003400 Photon Energy / cm -1 (2,1) Bulk FT-IR Et/Me stretches Ring CH ip bends Et/Me bends Ring CH stretches EMIM + (calc) Calc. Int. (EMIM + ) 2 (BF 4 ¯) Spectral response to assembly? C.J. Johnson, et. al, J. Chem. Phys. 139, 224305 (2013)

11. Deuteration Isolate the C (2) H 8001000120014001600240026002800300032003400 Photon Energy / cm -1 C (2) D ip bend C (2) D Pred. Yield Ring CH ip bends Et/Me bends Ring stretches Et/Me stretches Ring CH stretches

12. [d (2) -EMIM][BF 4 ] bulk Predissociation Yield Photon Energy / cm -1 d (2) -EMIM + d (2) -(2,1) EMIM + (2,1) Bare C (4,5) H stretches Bare C (4,5) H stretches C (2) D stretch 220024002800300032002300290031003300 (EMIM + ) 2 (BF 4 ¯) Deuterated Et/Me stretches Ring CH stretches -4 -10 C.J. Johnson, et. al, J. Chem. Phys. 139, 224305 (2013)

13. Forcing the Hydrogen Bond Cl¯  Should strengthen the cation-anion interaction  Still a spherical anion  Will simplify the problem

14. 8001000120014001600280030003200 Predissociation Yield Photon Energy (cm -1 ) Hydrogen Bonding x5 (EMIM + ) (EMIM + ) 2 (BF 4 ¯) (EMIM + ) 2 (Cl¯) Ring CH ip bends Et/Me bends Ring stretches Et/Me stretches Ring CH stretches

15. 800120016002000240028003200 Photon Energy (cm -1 ) Predissociation Yield ν C(2)D ν C(2)H (2,1) (1,0) x5 (EMIM + ) 2 (Cl¯) Deuterated

16. Ionic Liquids BF 4 ¯ Anion Effects Tf 2 N¯ Cl¯

17. Ring CH ip bends 80010001200140016002800300032003400 N-shuttle C-F/C-S stretch S-O stretch Et/Me bends Ring Stretches Et/Me stretches Ring CH Stretches (1,0) (0,1) (1,2) (EMIM + ) 1 (Tf 2 N¯) 2 Predissociation Yield Photon Energy (cm -1 )

18. Predissociation Yield 2000220024002600280030003200 Photon Energy (cm -1 ) H-Bonding 2360 - 223 (EMIM + ) (Cl¯) 2 (EMIM + ) (Tf 2 N¯) 2 ~0 Is it Hydrogen Bonding? Deuterated Spectra

19. Conclusions A true hydrogen bond can be observed with the Cl¯, while Tf 2 N¯ and BF 4 ¯ have minimal hydrogen bonding character. Deuteration serves to isolate the acidic H- bonding position from other C-H stretches and Fermi resonances to better study the nature of the hydrogen bonding at the acidic position.

20. Acknowledgements Conrad Wolke Joseph Fournier Chris Johnson Patrick Kelleher Steph Craig Gary Weddle Mark Johnson RG07 – Protonated Water Clusters

22. Pred. Yield % Abs. ν3ν3 ν1ν1 11 BF 4 ‾ EMIM + (2,1) 60080010001200140016002800300032003400 Photon Energy / cm -1 (1,2) x10 x5 * 10 BF 4 ‾ Bulk FT-IR Et/Me stretches Ring CH ip bends Et/Me bends Ring CH stretches Ring stretches 2x Ring stretches (EMIM + ) m (BF 4 ¯) n

23. 8001000120014001600280030003200 Predissociation Yield Photon Energy (cm -1 ) (2,1) (1,2) (1,0) (EMIM + ) m (Cl¯) n

24. 800120016002000240028003200 Photon Energy (cm -1 ) Predissociation Yield δ C(2)D δ C(2)H ν C(2)D (2,1) (1,2) (1,0) x5 (EMIM + ) m (Cl¯) n Deuterated

25. Predissociation Yield 2000220024002600280030003200 Photon Energy (cm -1 ) H-Bonding 2360 - 49 - 223 (EMIM) (EMIM + ) (BF 4 ¯) 2 (EMIM + ) (Cl¯) 2 (EMIM) (Tf 2 N¯) 2 2360 Hydrogen Bonding