1. Galen Sedo 70 th Annual International Symposium on Molecular Spectroscopy MG12, June 22 nd 2015 Microwave Spectra of 9-Fluorenone and Benzophenone

2. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy UVA The Commonwealth of Virginia DC

3. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Substantial Completion – July 2012 (fully operational)

4. Polycyclic Aromatic Compounds (PAC’s) Exhibit chemical stability under a wide range of conditions, similar to their polycyclic aromatic hydrocarbon (PAH) counterparts. – Hazardous air pollutant – Environmental accumulation – Man made sources 9-Fluorenone can be formed from fluorene downwind from PAH producing sites. Gas phase 9-Fluorenone has been observed in measurable quantities in ambient air. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Oxygen containing Polycyclic Aromatic Compounds (O-PAC’s)

5. The University of Manitoba’s cp-FTMW We were given instrument time in the lab of Dr. Jennifer van Wijngaarden over a two week time period: May 13 – May 26, 2014. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

6. O-PAC Sample Preparation Samples of the pure chemicals were purchased from Sigma-Aldrich Canada as low vapor pressure crystalline solids. 9-Fluorenone Melting Point: 83.5°C Boiling Point: 342°C Benzophenone Melting Point: 49°C Boiling Point: 305.4°C MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

7. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy 9-Fluorenone Spectrum Spectra collected from 8 to 13 GHz (5 scans, ~13 hours)

8. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy 9-Fluorenone Spectrum

9. a)Numbers in parentheses represent one standard error in the fit value. b)Number of transitions in the fit. c)The root-mean-square deviation of the fit. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

10. Computational Ground State Structure of 9-Fluorenone MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

11. Conclusions: The first pure rotational spectrum of 9-Fluorenone has been recorded between 8 and 13 GHz. Analysis of the spectrum verified the expected rigid planar structure. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

12. PAH’s with a fjord region are generally more toxic than those with only bay regions. This behavior is thought to be the result of the nonlinear nature introduced by the fjord. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Bay Region Fjord Region The Effect of Substitution on 9-Fluorenone

13. PAH’s with a fjord region are generally more toxic than those with only bay regions. This behavior is thought to be the result of the nonlinear nature introduced by the fjord. Substitution in the Bay (R1) positions can lead to steric distortion or torsion out of the molecular plane. This torsion is widely held to cause a shift in chemical behavior and an increase in toxicity. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Bay Region Fjord Region The Effect of Substitution on 9-Fluorenone

14. PAH’s with a fjord region are generally more toxic than those with only bay regions. This behavior is thought to be the result of the nonlinear nature introduced by the fjord. Substitution in the Bay (R1) positions can lead to steric distortion or torsion out of the molecular plane. This torsion is widely held to cause a shift in chemical behavior and an increase in toxicity. Benzophenone represents the extreme limit where the polycyclic backbone has undergone oxidative cleavage. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Bay Region The Effect of Substitution on 9-Fluorenone

15. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Benzophenone Spectrum Spectra collected from 8 to 14 GHz (6 scans, ~16 hours)

16. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Benzophenone Spectrum

17. a)Numbers in parentheses represent one standard error in the fit value. b)Number of transitions in the fit. c)The root-mean-square deviation of the fit. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

18. Computational Ground State Structure of Benzophenone MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy B3LYP|cc-PVDZ calculations determined the global minimum structure to have C 2 symmetry. The C s and C 2v symmetric structures were found to correspond to the transition states for two different modes of hindered rotation (+13.1 kJ/mol and +50.9 kJ/mol, respectively). CsCs C 2v

19. Computational Ground State Structure of Benzophenone MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Currently Running

20. Gas Phase Benzophenone ~32° The Torsional Angle in Benzophenone Hammond et al. Faraday Discuss. 2007 X-ray analysis of the stable orthorhombic  -form of benzophenone determined a torsional angle of 56° in the crystal, Fleischer et al. (J. Chem. Phys. 2008) MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

21. The Torsional Angle in Diphenolmethane vs Benzophenone Crystal Structure analysis of Barnes et al. (J. Org. Chem. 1981) gives a helical semi-C 2 structure with two angles of 63.9° and 71.1°. Benzophenone 56° MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy The rotationally resolved microwave and UV spectra of Stearns et al. (J. Chem. Phys. 2008), along with numerous computational calculations, predict a gas phase angle at ~55°. (Decrease of 9-16°) Benzophenone ~32° (Decrease of ~24°)

22. The Torsional Angle in Diphenolmethane The experimental P cc values of Diphenolmethane and Benzophenone are 121.7 and 47.6 amu·Å 2,respectively. Churchill et al. (J. Chem. Phys. 2008) predict that the addition of a –CH 2 – functional group to the a,b-plane will increase the value of P cc by 1.56 amu·Å 2. The remaining difference can be accounted for through the predicted decrease in the torsional angle. The rotationally resolved microwave and UV spectra of Stearns et al. (J. Chem. Phys. 2008), along with numerous computational calculations, predict a gas phase angle at ~55°. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy Benzophenone ~32° (Decrease of ~24°)

23. Benzophenone OrbitalsDiphenolmethane Orbitals The (A) highest occupied molecular orbital and (B) second highest occupied molecular orbital predicted using MP2|cc-pVTZ. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

24. Conclusions: The first pure rotational spectrum of 9-Fluorenone has been recorded between 8 and 13 GHz. Analysis of the spectrum verified the expected rigid planar structure. The first pure rotational spectrum of Benzophenone has been recorded between 8 and 14 GHz. Analysis of the spectrum with the aid of computational analysis suggests a semi-rigid C 2 paddle-wheel structure with a torsional angle of ~32 °. MG12, June 22 nd 2015 70 th International Symposium on Molecular Spectroscopy

25. Acknowledgements: Instrument Funding: Canada Foundation for Innovation (CFI) UVA-Wise Project Funding: Fellowship in the Natural Sciences (FINS) Faculty Development (FDC) Dr. Jennifer van WijngaardenMr. Channing West