1 / 8

Solvatochromism and Photo-Induced Intramolecular Electron Transfer

Solvatochromism and Photo-Induced Intramolecular Electron Transfer. Katelyn Billings, Dr. Bret Findley Saint Michael’s College. Abstract. Develop a laboratory exercise for a physical chemistry course Major topics covered Solvatochromism Intramolecular photo-induced electron transfer

Download Presentation

Solvatochromism and Photo-Induced Intramolecular Electron Transfer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Solvatochromism and Photo-Induced Intramolecular Electron Transfer Katelyn Billings, Dr. Bret Findley Saint Michael’s College

  2. Abstract • Develop a laboratory exercise for a physical chemistry course • Major topics covered • Solvatochromism • Intramolecular photo-induced electron transfer • Method • Steady state absorption • Steady state fluorescence • Goal • Determine the change in dipole moment between ground and excited electronic states • Compounds used • Coumarin 153 • 4-amino-N-methylphthalimide • 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate

  3. ReactionPathway Background A - D + heat k-ET, non-rad kET hυ1 A- - D+ A* - D A - D A* —D k-ET, rad Electron Transfer A- —D+ hυ2 A-D + Solvent Relaxation A- —D+ hυ1 E hυ2 A—D A—D Energy Diagram Key Terms • Solvatochromism Bathochromic Shift Hypsochromic Shift

  4. Experimental Method • Take fluorescence measurements for Coumarin 153 in a variety of solvents (with different polarities). • Plot , the maximum emission frequency in cm-1, versus Δf, a solvent polarity parameter. • Slope of this line yields Δμ, the difference in excited and ground state dipole moment of the solute. • We plan to make similar measurements with other compounds.

  5. ~ ~ Relevant Equations1 ~ ~ Where: • Δf = the solvent factor (change in the reaction field) • ε = the solvent dielectric constant • n = the refractive index • h = Planck’s constant • c = speed of light • vct = frequency of maximum emission in cm-1 • vct (0)= frequency of maximum emission in the gaseous phase in cm-1 • Δμ = difference in excited and ground state dipole moment • ρ = the radius of the solute cavity • 4πε0 = gas permittivity constant (1) Hermant, R. M.; Bakker, N. A. C.; Scherer, T.; Krijnen, B.; Verhoeven, J. W.; J. Am. Chem. Soc, 1990, 112, 1214-1221.

  6. 3 Solutes Studied N Coumarin 153 O Reichardt’s Dye 4-amino-N-methylphthalimide

  7. Fluorescence Spectra for Coumarin 153 Sample Results for Coumarin 153 Maroncelli value2: Theoretical Δμ = 3.9D Empirical Δμ = 6.0D (assuming ρ=3.9A) **Note the Bathochromic Shift Our Experimental Δμ : 7.05D (2) Maroncelli, Fleming. "Picosecond solvation dynamics of coumarin 153: The importance of molecular aspects of solvation." J. Chem. Phys. 86 (11)(1987): 6221-6239.

  8. Future Plans A Quick Review of the Lab • Run spectra for the Reichardt’s Dye and for Coumarin 153 or 4-amino-N-methylphthalimide • Solvents • Chlorobenzene • Dichloromethane • Dimethyl Sulfoxide • Acetonitrile • Calculate the change in dipole moment for Reichardt’s Dye • Reevaluate our data—Check Fluorimeter Calibration/Correction of max values • Test lab and submit for publishing

More Related