Transcript of Characterization of Structural Motifs for CO 2 Accommodation in Two Model Ionic Liquid Systems Using...
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Characterization of Structural Motifs for CO 2 Accommodation in
Two Model Ionic Liquid Systems Using Cryogenic Ion Vibrational
Predissociation Spectroscopy Joseph A. Fournier, Conrad T. Wolke,
Christopher J. Johnson, and Mark A. Johnson Sterling Chemistry
Laboratory, Yale University June 20, 2013
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CO 2 Capture and Activation Masel, Science, 2011, 334, 643. CO
2 CO + O 2 V eq = 1.3 V In water: 2.1 V required to produce CO 0.8
V overpotential In [emim]BF 4 : 1.5 V required to produce CO 0.2 V
overpotential
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Ionic Liquids Liquid at or near room temperature Nonvolatile:
Green solvents High CO 2 solubility Anion dependence: Ac > Tf 2
N > TFA > PF 6 > BF 4 J.F. Brennecke, E.J. Maginn. JACS,
2004, 124, 5300.
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The Instrument ESI Needle Temperature Controlled Ion Trap
Mounted to He Cryostat Ion Optics 2m Flight Tube Wiley- McLaren TOF
Reflectron-1 Coaxial TOF Reflectron-2 DC-Turning Quad Pulsed Valve
Electron Gun MCP Detector MCP Detector Nd:YAG OPO/OPA Tunable IR
600-4500 cm -1 Ion Optics Differential Aperture Skimmers Heated
Capillary RF-Ion Guides Nd:YAG OPO/OPA Tunable IR 600-4500 cm -1 +
e +
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Predissociation Yield 1200140016001800200022002400 Photon
Energy / cm -1 Ac Ar Ac CO 2 Ac 2CO 2 Ac 4CO 2 Ac asym. OCOAc sym.
OCO 3 CO 2 * Ac (CO 2 ) m
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Pred. Yield 1200140016001800200022002400 Calculated Intensity
Photon Energy / cm -1 Ac (CO 2 ) 1 Pred. Yield
1200140016001800200022002400 Calculated Intensity Photon Energy /
cm -1 Ac (CO 2 ) 2 MP2/6-311+G(d,p)
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Pred. Yield Calculated Intensity 16001800200022002400 Photon
Energy / cm -1 Ac (CO 2 ) 4
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How About a Real Ionic Liquid? [(emim) 2 BF 4 ] + +N 2 +2N 2
+3N 2 300320340360380400 m/z 334336338340 m/z 10 B 11 B 13 C 1 2 3
4 5
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The IL Building Block 60080010001200140016002800300032003400
Calculated Intensity Photon Energy / cm -1 Pred. Yield Why the
complexity? B3LYP/6-31+G(d,p) Ring CH str. Me/Et CH str. Ring Str.
Me/Et CH bends CH ip bend Mixed BF 4 /Ring Modes CH oop bends
Conrad Wolke
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80010001200140016002800300032003400 Photon Energy / cm -1 N 2
Predissociation Yield [(emim) 2 BF 4 ] + [(emim) 3 (BF 4 ) 2 ] +
Ring CH str. Me/Et CH str. Ring Str. Me/Et CH bends CH ip bend
Mixed BF 4 /Ring Modes C 2 -H oop bend Absorption (%) Bulk Are the
Gas-Phase Clusters Related to the Bulk??
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Isomers? Pred. Yield Ion Dip Signal 280029003000310032003300
Photon Energy / cm -1 NO! Single Isomer! 80010001200
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Identifying the CHs Photodissociation Yield
80010001200140016002800300032003400 Photon Energy / cm -1 X X
X
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Identifying the CHs The Evidence: 1.Red-shifting of the ring
CHs (10-15 cm -1 ) from (2,1) to (3,2) cluster. 2.Double resonance
reveals a single isomer. 3.Loss of specific bands upon methyl
substitution at the C 2 position.
60080010001200140016002800300032003400 Photon Energy / cm -1 C 2 -H
C 4 -H/C 5 -H C 2 -H ip bend C 4 -H/C 5 -H oop bend C 2 -H oop
bend
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300320340360380400420 m/z CO 2 Condensation in the Ion Trap +CO
2 +2CO 2 Optimal conditions: 5% CO 2 buffer gas, 90 K
340360380400420440460 m/z [(emim) 2 BF 4 ] + [(bmim) 2 BF 4 ] + +CO
2 +2CO 2 WOW!!!
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CO 2 Condensation in the Ion Trap: emim Pred. Yield
8001000120014001600240026002800300032003400 Photon Energy / cm -1 5
5 6 9 4 3.3 5.3 3.1 2.8 3.5 2.7
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Outlook Electrospray acetate-based ionic liquid Condense CO 2
onto the cluster in the trap Transfer intact, dissolved CO 2
-acetate complex from solution Determine structure of other ionic
liquids (PF 6 -, TFA, Tf 2 N - ) and tag with CO 2 Next-generation
instrumental improvements (trap-to-trap, reaction of ESI ions with
CO 2 cluster beam, etc.)
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Acknowledgments Prof. Mark Johnson Prof. Gary Weddle Chris
Johnson Chris Leavitt Andrew DeBlase Arron Wolk Conrad Wolke Olga
Garlova
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Im(CO 2 ) m CO 2 Predissociation Yield
800120016002000240028003200 Photon Energy / cm -1 x3 Im(CO 2 ) 2
Im(CO 2 ) 3 Im(CO 2 ) 6 IHB 3 CO 2 1 CO 2
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Pred. Yield 800120016002000240028003200 Calculated Intensity
Photon Energy / cm -1 Im(CO 2 ) 2 Pred. Yield
800120016002000240028003200 Calculated Intensity Photon Energy / cm
-1 Im(CO 2 ) 3
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Predissociation Yield 1200140016001800200022002400260028003000
Photon Energy / cm -1 (CO 2 ) 7 Im(CO 2 ) 2 vs Py(CO 2 ) 2