1. Dynamic Studies of Equilibria Phenomena in Silca Sol-Gel Materials Chris Huber University of Minnesota 69th International Symposium of Molecular Spectroscopy

2. Motivation Molecule-interface interactions – Relevance – Liquid Chromatography Confined Volume Shell vs. Core dynamics – 1-2 nm Core Shell

3. 2DIR Background Wavelengths Absorbed Wavelengths Emitted 2 1 3 Echo τ Tw echo t3t3 213

4. 2DIR Background Wavelengths Absorbed Wavelengths Emitted Time

5. Sol-Gel Background TMOS TriMOS H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H HH H H H H

6. Project Overview Samples – 50 microns between two CaF 2 windows – Alcogels (pentane, DMF, CHCl 3, IPA) – Aerogel (originally in IPA) Porosity Solvent Accesibility Solvent Sensitivity – FTIR – Dynamics

7. Porosity and Sensitivity Aerogel Xerogel Spun Type I isotherm <1.5 nm Pores DMF alcogel IPA alcogel Pentane alcogel CHCl 3 alcogel Aerogel

8. 2DIR Spectra DMF IPA CHCl 3 PentaneAerogel 0.3 ps 15.0 ps

9. Ellipticity DMF alcogel IPA alcogel Pentane alcogel CHCl 3 alcogel Aerogel

10. Ellipticity DMF alcogel IPA alcogel Pentane alcogel CHCl 3 alcogel Aerogel Ellipticity Solvent τ pp (ps) A0A0 A1A1 t 1 (ps) A2A2 t 2 (ps) Pentane 11.08(0.52) 0.2400.709249.88 --- Chloroform 13.89(0.73) 0.7290.19875.420.04111.09 Isopropanol 11.56(0.33) 0.5170.369177.500.03031.85 DMF 10.65(0.63) 0.8880.0304.14 --- Aerogel 14.36(0.37) 0.9260.0234.54 --- The system is sensitive to solvent dynamics!!!

11. Conclusion Checklist – Porous glass – Probes are solvent accessible – Probe sensitivity We have made a successful sol-gel construct that can measure confined dynamics! Bulk solvent comparison Pore size study Non-Equilibrium dynamics of gel formation

12. Acknowledgements Massari Group Funding Lester C. and Joan M. Krogh Endowed Fellowship

14. Solvatochromism Linear Solvation Energy Relationships Γ 0 = 2254.7, a = 3.21, b = -4.12, c = 0.36, d = -0.80, R 2 = 0.83

15. Porosity and Accesibility Aerogel Xerogel Spun THF Alcogel Spun Type I isotherm <1.5 nm Pores 12% SiH remains 82% SiH remains

16. Solvation effects DMF alcogel IPA alcogel Pentane alcogel CHCl 3 alcogel Aerogel

17. Why 2DIR? Frequency

18. Why 2DIR? Frequency

19. Why 2DIR? Frequency

20. Conclusions Checklist – Porous glass – Probes are solvent accessible – Probe sensitivity We have made a successful sol-gel construct that can measure confined dynamics!