Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-072712-120208


Document Typedissertation
Author NameZoto, Christopher A
URNetd-072712-120208
TitleStructural and Photophysical Properties of Internal Charge Transfer 2-Arylidene and 2,5-Diarylidene Cyclopentanones
DegreePhD
DepartmentChemistry & Biochemistry
Advisors
  • Dr. Robert E. Connors, Advisor
  • Dr. John C. MacDonald, Committee Member
  • Dr. James P. Dittami, Committee Member
  • Dr. John Lombardi, Committee Member
  • Keywords
  • photochemistry
  • solvatochromism
  • internal charge transfer
  • photophysical
  • spectroscopic
  • ketocyanine dyes
  • Date of Presentation/Defense2012-07-24
    Availability restricted

    Abstract

    A series of symmetric and asymmetric 2-arylidene and 2,5-diarylidene cyclopentanone dyes have been synthesized. Their electronic absorption and fluorescence spectra have been measured in a wide variety of nonpolar and polar, aprotic and protic solvents. Absorption and fluorescence spectral maxima have been correlated with the ET(30) empirical solvent polarity scale. Lippert-Mataga analysis (in aprotic solvents) demonstrates the increase in the electronic dipole moment from the ground singlet to excited singlet states, consistent with the internal charge transfer (ICT) nature of the S0 --> S1 excitation. TD-DFT spectral calculations support the ICT natures of these compounds.

    Photophysical properties of these compounds involved measuring both fluorescence quantum yields and lifetimes in various solvents. Investigation of the deactivation kinetics involved determining the first-order radiative and nonradiative rates of decay upon knowledge of the quantum yield and lifetime data. Fluorescence quantum yields and lifetimes of the compounds studied varied depending on the nature of the solvent environments. Excited state protonation in acetic acid was observed for several 2,5-diarylidene cyclopentanones and deltapKa’s have been determined via the Forster Cycle. Thorough work on the photochemistry of (2E,5E)-2,5-bis(p-dimethylaminobenzylidene)-cyclopentanone (bis-dmab) was carried out, consisting of testing bis-dmab as a singlet oxygen photosensitizer, and examination of both the chemical reactivity of bis-dmab with singlet state oxygen (self-sensitized photooxidation) and (E,E) --> (E,Z) photoisomerization.

    Files
  • (WPI)Zoto_PhDThesis.pdf

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