Date of Award

6-1984

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Chemistry

Language

English

Abstract

The fluorescence energy, shape of the fluorescence spectrum, and the fluorescence efficiency of 9-anthramide (9-CONH2) and N,N-diethyl-9-anthramide (9-CONEt2) have been investigated as a function of solvent. For the 9-CONH2, the Sl energy decreases and the fluorescence spectra become structureless at the polar and nonpolar extremes of the solvent scale. This unusual solvent-dependent fluorescence behavior for 9-CONH2 is explained by a significant geometry change subsequent to excitation, whereby the exocyclic group rotates about the anthracene rings. In contrast, 9-CONEt2 shows solvent-independent behavior. The Sl energy generally remains constant and the fluorescence spectra show well-defined vibrational structure in a wide variety of solvents. It appears that the diethyl substitution has a dramatic effect on the fluorescence properties, inhibiting the rotation that has been proposed for unsubstituted amide, 9-CONH2. This difference in fluorescence behavior appears to correlate with the increased bulkiness and electron-donating ability of the ethyl groups. The fluorescence quantum yield (of) of 9-CONEt2 in aprotic solvents and ethanol does not correlate well with solvent polarity. The of of 9-CONEt2 in these solvents is less than that of methyl-9-anthroate. The data suggest a greater participation of the rr,TT triplet state in activated intersystem crossing for 9-CONEt2 than for the ester.

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