The Effects of Hydrogen Bonding on the Spectral Properties of 2-Acetonaphthone
Abstract
The effects of hydrogen bonding on the luminescent properties of 2'-acetonaphthone (2-AN) have been studied. Solvents of varying hydrogen bond donor abilities such as perfluorohexane(PFH), cyclohexane, ethanol, methanol, water, trifluoroethanol(TFE), and hexafluoroisopropanol(HFIP) have been used. An attempt is made to find a relationship between solvent hydrogen bond donor ability, the energy and efficiency of fluorescence emission and changes in 2-AN electronic absorption in these solvents. The 2-AN spectral properties have also been studied in mixed solvent systems where the molecule is dissolved in a nonpolar solvent, either PFH of cyclohexane, and one of the fluorinated alcohols (TFE or HFIP) is added to see how the spectrum of the solution is altered. The addition of these hydrogen bonding alcohols results in the formation of a 2-AN/alcohol complex. This complex causes a new electronic absorption band to appear in these solutions. Using the Benesi-Hildebrand equation, equilibrium constants can be calculated for the complex formation in the ground state. The presence of weak hydrogen bonders such as ethanol or propanol are observed to quench the fluorescence emission of 2-AN in a polar solvent and blue shift the maximum.
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