PHOSPHORESCENCE MICROWAVE DOUBLE-RESONANCE STUDIES OF THE T1 STATES OF SUBSTITUTED 1-INDANONES AND RELATED MOLECULES

The magnetic and dynamic properties of the 3ππ* states of substituted 1-indanones in durene and 1,4-dimethoxybenzene hosts were investigated using the optically detected magnetic resonance (ODMR) technique and the results are compared with those of 3ππ* substituted benzaldehydes. It was found that there are notable differences between the properties of the T1 states of 1-indanones and those of benzaldehydes, although the properties of the T1 states of 1-indanones can be explained in terms of the models previously used to explain the properties of benzaldehydes. The differences result primarily from the following reasons. (1) Spin-orbit coupling matrix elements between 3nπ* and 3ππ* states for 1-indanones are about 1/2 of those for benzaldehydes. (2) Because of more rigid planar structure of 1-indanone direct mixing between 3nπ* and 3ππ* states is less important in 1-indanone than in benzaldehyde and acetophenone. It was also noted that the magnetic and decay properties of the T1 states of 1-indanones are sensitive to the environment as in other 3ππ* aromatic carbonyls. © 1979 American Chemical Society.