Topic
Fluorenone
About: Fluorenone is a research topic. Over the lifetime, 1067 publications have been published within this topic receiving 17162 citations. The topic is also known as: Diphenylene ketone & 9-Oxofluorene.
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TL;DR: In this article, a test for n-π* transitions, based upon the effect of oxime formation on the absorption spectra, is discussed, and the results of MO calculations clearly establish that the lowest excited singlet state of fluorenone is a (π, π*) state, rather than an (n, ε) state, as previously assigned.
Abstract: The spectroscopic properties of the lower‐lying electronically excited states of fluorenone have been investigated. A test for n—π* transitions, based upon the effect of oxime formation on the absorption spectra, is discussed. Application of the oxime test to fluorenone, in conjunction with an examination of the emission properties, the solvent effects on the absorption spectrum, the vibrational structure of the fluorescence spectrum, the absorption spectra of related molecules, and the results of MO calculations clearly establish that the lowest excited singlet state of fluorenone is a (π, π*) state, rather than an (n, π*) state, as previously assigned.The principal emission observed from fluorenone in solution at room temperature and at 77°K, and from crystalline fluorenone, is demonstrated to be fluorescence. Both the fluorescence spectrum and the quantum yield for fluorescence were found to be solvent and temperature dependent. At room temperature in solution, the fluorescence quantum yield is about 1...
65 citations
TL;DR: In this paper, photolysis of benzophenone in the presence of an amine transferred an electron to an excited triplet state, forming an ion pair that is stable relative to diffusional separation.
Abstract: Studies were initiated utilizing picosecond (ps) absorption spectroscopy, to directly monitor the dynamics of electron transfer from 1,4-diazabicyclo(2.2.2)octane (Dabco) to the excited states of benzophenone and fluorenone. These two systems were chosen because of their contrasting photochemistry. The quantum yield for photoreduction of benzophenone in polar solvents is generally greater than 0.1, while that of fluorenone is zero. In polar solvents, the proposed mechanism dictates that an electron is transferred to the excited singlet state fluorenone, which then back-transfers the electron, regenerating ground-state fluorenone and amine. Photolysis of benzophenone in the presence of an amine transfers an electron to an excited triplet state, forming an ion pair that is stable relative to diffusional separation. The results of this study verify this proposal.
64 citations
TL;DR: N-Vinyl nitrones derived from fluorenone have been prepared via a copper-mediated coupling between fluore None oxime and vinyl boronic acids and undergo subsequent rearrangement and addition reactions that are distinct from the traditional [3 + 2] cycloaddition reactivity of nitrones.
64 citations
TL;DR: In this paper, the photophysical properties of fluorenone and 12 aminofluorenone derivatives were investigated systematically by fluorescence quantum yield and picosecond lifetime measurements in cyclohexane, benzene and benzene.
Abstract: Photophysical properties of fluorenone and 12 aminofluorenone derivatives were investigated systematically by fluorescence quantum yield and picosecond lifetime measurements in cyclohexane, benzene...
61 citations
TL;DR: In this paper, the photophysics of the methoxy derivative is governed by internal conversion to the ground state, which gains in importance with increasing solvent polarity and shows a temperature-dependent rate in nonpolar solvent.
Abstract: Fluorescence lifetimes, fluorescence quantum yields, and triplet yields have been measured for 2-fluorofluorenone and 2-methoxyfluorenone in different solvents having a widerange of polarities. The photophysical characteristics of the fluoro derivative were found to be similar to those of fluorenone itself. The dominating process in nonpolar and moderately polar solvents is singlet-triplet transition with temperature-independent and additional temperature-dependent components. However, the photophysics of the methoxy derivative is governed by internal conversion to the ground state, which gains in importance with increasing solvent polarity and shows a temperature-dependent rate in nonpolar solvent
60 citations