A SPECTROSCOPIC INVESTIGATION OF PHOTO- AND THERMOCHROMISM.
HOUSTON UNIV TX DEPT OF CHEMISTRY
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In nonpolar, nonhydrogen-bonding solvents at 77 K most anils of salicylaldehyde exist in the enol form. The irradiation of most enol forms causes photocoloration which is the result of the formation of trans-keto anil. No photocoloration or eradication results from irradiation of the cis-keto anil. Emission from the enol is actually that of a species closely resembling the cis-keto form. Chromene or its substituted derivatives can be converted to colored forms by irradiation. Fluorescence emission can be obtained from most chromenes but the intensity shows a marked variation as a function of the wavelength of exciting light. A study of the low temperature reactions of the colored forms of chromenes with lithium aluminum hydride was carried out. From this, the structure of the colored form can be assigned as o-quinoallide II. The spectroscopic and photochemical behavior of several spiropyrans has been investigated. The intensity of emission varies with the wavelength of the exciting light. A spectroscopic and photochemical study has been performed on several bianthrones and derivatives. The nature of the photo-produced colored form is identified.
- Radiation and Nuclear Chemistry