Water Solvation of Copper Hydroxide Brett Marsh-UW Madison

Water Solvation of Copper Hydroxide

Brett Marsh-UW Madison

Background

Copper

Catalytic

Relatively cheap

Abundant

CuOH-Possible water splitting catalyst

Experiment

ElectrosprayNeedle

Cryogenic ion trap (10K)For cooling and H2-tagging

Ion steeringoptics

Flight TubeReflectron

Tunable infrared laser

600-4500 cm-1

CapillarySkimmer

Radio-frequencyion guides

Ion reaction cell LN2 cooled

(77-350K)

Spectroscopylaser

Pulsed valves

Ion Trapping and Tagging

H2 has ideal binding energy (~400 cm-

1 typically) and vapor pressure at trap

temperature (10 K)

H2 tagging may produce multiply tagged species

M.Z. Kamrath, R.A. Relph, T.L. Guasco, C.M. Leavitt, M.A. Johnson, Int. J. Mass. Spec. 2011, 300, 91-98

Predissociation Spectroscopy

E. Garand et. al. Phys. Chem. Chem. Phys., 2012,14, 10109–10113

Experiment

ElectrosprayNeedle

Cryogenic ion trap (10K)For cooling and H2-tagging

Ion steeringoptics

Flight TubeReflectron

Tunable infrared laser

600-4500 cm-1

CapillarySkimmer

Radio-frequencyion guides

Ion reaction cell LN2 cooled

(77-350K)

Spectroscopylaser

Pulsed valves

ResultsBy varying voltages in ion source multiple species of interest can be selected for study

Results-CuOH(H2O)+

Addition of 2nd deuterium tag distorts spectrum

Strong H2O-D2 interaction?

Multiple conformations for 1 tag complex?

Results-CuOH(H2O)+

CAM-B3LYP/6-311+G(d,p) level of theory

Results-CuOH(H2O)2+

Severe peak suppression occurs after attachment of 2nd deuterium molecule

Possible solvent assisted isomerization?

Results-CuOH(H2O)2+

Isomers separated by~1450 cm-1

Multiple lines hidden under same peak?

Probe for H-bond stretches (2800-3100 cm-1)

CAM-B3LYP/6-311+G(d,p) level of theory

Solvent Assisted Isomerization

Excess solvation energy (in this case from D2) can push the molecule into a more stable well

Excess D2 then evaporates to leave isomer 2+2D2

Results-CuOH(H2O)2+

Strong free H2O interaction withD2 tag

Theory matches well with experimentalspectrum

CAM-B3LYP/6-311+G(d,p) level of theory

Results-CuOH(H2O)2+

CAM-B3LYP/6-311+G(d,p) level of theory

Results-CuOH(H2O)3+

Addition of 2nd deuterium tag seems to have no effect on spectrum

Conclusions

Hydrogen tags can not be assumed to offer little perturbation in metal species

Attachment of tags may distort the isomeric composition of ions of interest

Future Work

ElectrosprayNeedle

Cryogenic ion trap (10K)For cooling and H2-tagging

Ion steeringoptics

Flight TubeReflectron

Tunable infrared laser

600-4500 cm-1

CapillarySkimmer

Radio-frequencyion guides

Ion reaction cell LN2 cooled

(77-350K)

Spectroscopylaser

Pulsed valves

Tunable infrared laser

600-4500 cm-1

Acknowledgements

Crim Group

Garand Group

University of Wisconsin Chemistry Department