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Part One. Photochemical Cis⇌Trans Isomerization of β-Styrylnaphthalene. Part Two. Photochemistry of N-Methyl-4-Pyridone and N-Methyllutidone


Shim, Sang Chul (1967) Part One. Photochemical Cis⇌Trans Isomerization of β-Styrylnaphthalene. Part Two. Photochemistry of N-Methyl-4-Pyridone and N-Methyllutidone. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/aym7-2k91.



Photochemical cis⇌trans isomerization of β-styrylnaphthalene is studied by direct irradiation with light of various wavelengths and irradiation in the presence of sensitizers. A very unusual "negative" wavelength effect on quantum yields of trans→cis isomerization by direct irradiation is observed. The interpretation of this observation is presented in terms of multiple conformers of electronically excited states which are not interconvertible. The study of fluorescence spectra confirms the interpretation. Sensitizers transfer triplet energy quite efficiently to β-styrylnaphthalene. However, benzophenone whose triplet energy is considered to be high transfers triplet excitation preferentially to the cis isomer. Quenching constants, both kqc and kqt, were expected to be diffusion controlled. However, the study of the photostationary states and quantum yields of sensitized isomerization indicates the opposite for the benzophenone. A significant quantum waste is observed and interpreted in terms of localization of excitation in the naphthalene chromophore. The effect was far more pronounced in direct isomerization perhaps because the excited singlets are shorter lived than triplets made by energy transfer. Definitely a singlet mechanism is involved, perhaps in conjunction with other mechanisms, in direct isomerization. This is confirmed by the studies of quantum yields, photostationar y states, and side reactions. The studies of solvent effect and concentration effect on quantum yields in direct isomerization are also presented. 60Co γ-ray radiolysis of β-styrylnaphthalene in benzene indicates that the triplet mechanism is responsible for the isomerization of β-styrylnaphthalene in the radiolysis of benzene solution. The detailed study of G values and radiostationary states are presented with the discussions of the nature of the reaction. The implications of above studies in the study of other photoreactions are presented.


The photochemistry of the model compounds for pyrimidine bases, N-methyl-4-pyridone and N-methyllutidone, is reported. Spectroscopic and chemical studies on the irradiations of these compounds in aqueous solutions indicate that the hydration occurs at the α-position and leads to ring opening. The products obtained from ring opening undergo some unknown reactions, perhaps photo-oxidations and polymerizations.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Chemistry)
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hammond, George Simms (advisor)
  • Niemann, Carl G. (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:25 May 1967
Record Number:CaltechETD:etd-10072002-103918
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3947
Deposited By: Imported from ETD-db
Deposited On:08 Oct 2002
Last Modified:19 Mar 2024 23:34

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PDF (Shim_SC_1967.pdf) - Final Version
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