1. 1 The Competition Between Insertion and Surface Binding of Benzene to the Water Heptamer Patrick S. Walsh 1, Daniel P. Tabor 2, Edwin Sibert 2, and Timothy S. Zwier 1 1 Deparment of Chemistry, Purdue University 2 Department of Chemistry, University of Wisconsin- Madison WH09

2. Experimental Methods: Conformation-Specific Spectroscopy RIDIR Resonant Ion-Dip Infrared Spectroscopy M (S 0 ) M* (S 1 ) M + + e - M (S 0 ) M* (S 1 ) M + + e - R2PI Resonant Two-Photon Ionization 20 Hz 10 Hz Δt=200ns 20 Hz Calculations: M06-2x/6-311++g(2d,p) 2 Turbo MCP Turbo TOF Tube

3. 3 Initial Studies on the Benzene-(H 2 O) n Clusters Benzene-(H 2 O) n n=1-8 R.N. Pribble and T.S. Zwier, "Size-Specific Infrared Spectra of Benzene-(H 2 O) n with n=1-7: Evidence for the Transition from Cyclic to Non- cyclic (H 2 O) n structures", Science 265, 75-79 (1994). Bz-(H 2 O) 1 Bz-(H 2 O) 2 Bz-(H 2 O) 3 Bz-(H 2 O) 4 1:5 1:6 1:7 No firm assignments for the Benzene-(H 2 O) 6,7 clusters Proposed minor conformer of Benzene-(H 2 O) 7, but no IR spectrum

4. 4 Results from the Benzene-(H 2 O) 3-5 Clusters: Addition to the most Stable Water Clusters Benzene-(H 2 O) 3 Benzene-(H 2 O) 4 Benzene-(H 2 O) 5 1.91 Å 1.85 Å 2.01 Å 1.89 Å 1.91 Å 1 2 3 Lengthen Shorten All AD Now  DA 1.77 Å 1.84 Å 1.82 Å 1.76 Å 1.74 Å Lengthen 1 2 3 4 Shorten 1.74 Å 1.76 Å 1.74 Å 1.73 Å 1.80 Å 1.79 Å 1.74 Å 1.71 Å Lengthen 1 2 3 4 5 Shorten

5. 5 What Happens with Benzene-(H 2 O) 6,7 ? Key size regime: Evidence of 3D Structures. Next two talks by Danny Tabor will answer this question in more depth, please stick around! W6 Book W6 Cage W6 Prism W7 EB W7 Prism

6. 6 Excitation Spectrum in the Benzene-(H 2 O) 5 Mass Channel D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995.

7. 7 Benzene-(H 2 O) 7 Major Conformer: S 4 Inserted Cube Structure Full Discussion of this Spectrum and Assignment will be provided in the next talk! S4S4 1 2 3 4 5 6 7 2.91 2.82 2.64 2.89 2.70 2.85 2.77 2.68 2.80 D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995. 4 Free π Double-DonorAaD AAD Single-Donor Water

8. 8 Comparison of RIDIR Spectra fo the Major and Minor Conformers Minor Conformer Major Conformer: S 4 inserted cube D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995. Single-Donor Water Double-Donor Water

9. 9 Is the Minor Conformer the D 2d Inserted cube structure? NO, Poor Fit to Experiment!!

10. 10 Predicted (H 2 O) 7 Structures and Observed Conformers from CP- FTMW Spectroscopy (C. Perez, Pate Group) Expanded Prism Expanded Cage Expanded Book Predicted Families Cycle Tetrahedral Observed Conformations Major Conformer Minor Conformer C. Perez, et al., Chem. Phys. Lett., 157 (2013), 1-15.

11. 11 Low Energy Expanded Book and Cage Structures are Poor Fits D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995.

12. 12 Prism Bound Structure: Return to Earlier Trend D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995. Prism1-3 Isomer 0.0 kJ/mol Prism2-2 Isomer 3.9 kJ/mol Double-Donor Water

13. 13 Benzene-(H 2 O) 7 Prism Structures: Bare vs. Benzene Bound D.P. Tabor, et al., J. Phys. Chem. Lett., 6 (2015), 1989-1995. C. Perez, et al., Chem. Phys. Lett., 157 (2013), 1-15. Complexation Benzene Binds to a Face/Corner of Pre-formed Water Clusters

14. 14 Benzene-(H 2 O) 3-8 : Complexation Pathways Insertion Addition Expansion/ Replacement BW 3 BW 4 BW 5 BW 6 BW 7 Minor (PR) BW 7 Major (S 4 ) BW 8 (S 4 ) BW 8 (D 2d )

15. 15 Acknowledgements The Zwier Research Group: Prof. Timothy Zwier Dr. Ryoji Kusaka Daniel P. Tabor Prof. Ned Sibert U. Wisconsin-Madison

16. 16 PR1-3 Conformer Harmonic Calculation Results

17. 17 PR2-2 Conformer Harmonic Calculation Results

18. 18 New Linear Scaling Approach

19. 19 Energetics of the Clusters

20. 20 X

21. 21 X

22. 22 X

23. 23 X

24. 24 X

25. 25 X

26. 26 X

27. 27 X

28. 28 X

29. 29 X