Part I. Chemistry of Low Energy π-π* Triplet States. The Photoproduction of I-Naphthaldehyde and 2-Acetonaphthone. Part II. Triplet-Triplet Energy Transfer in Solution

Citation

Leermakers, Peter Anthony (1962) Part I. Chemistry of Low Energy π-π* Triplet States. The Photoproduction of I-Naphthaldehyde and 2-Acetonaphthone. Part II. Triplet-Triplet Energy Transfer in Solution. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/K0A0-AY90. https://resolver.caltech.edu/CaltechETD:etd-02112009-095624

Abstract

Part I: Photoreduction of 1-naphthaldehyde and 2-acetonaphthone has been accomplished by the use of tributylstannane as a hydrogen donor. Rate constants for hydrogen abstraction and thermal deactivation of the excited species have been estimated. The π-π* triplet states of the two carbonyl compounds are responsible for the hydrogen abstraction reaction. The naphthoyl compounds do not undergo photoreduction by secondary alcohols. Their low reactivity is attributed to the fact that the π-π* rather than the n-π* triplet is involved. Carbonyl compounds that are easily photoreduced have the n-π* configuration in their lowest triplets. Part II: The phenomenon of energy transfer between triplet states of molecules in solution has been investigated. Two methods have been employed in this investigation. The first involves the photosensitized cis-trans isomerization of piperylene. Aromatic carbonyl compounds were used as sensitizers. The trans/cis ratio in the photostationary state was related to the energy of the lowest triplet state of the sensitizer. The second method involved the study of the effects of quenchers on the quantum yield in the photoreduction of benzophenone by benzhydrol. Many of the quenchers were found to have about the same efficiency. It was concluded that the energy transfer (quenching) reaction is probably diffusion controlled.

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