Solvent and concentration effects on the steady state fluorescence of fluorenone
15 Feb 1996-Journal of Photochemistry and Photobiology A-chemistry (Elsevier)-Vol. 94, Iss: 1, pp 1-5
TL;DR: In this paper, the effects of fluorenone concentration in various solvents in the range 10 −6 −10 −3 M on the spectral properties are discussed, and the mechanism of excimer formation has been explained.
Abstract: The electronic absorption and steady state fluorescence spectra of fluorenone in the regions 280–340 and 320–420 nm respectively have been obtained at room temperature for various concentrations in a series of non-polar and polar solvents. The effects of fluorenone concentration in various solvents in the range 10 −6 −10 −3 M on the spectral properties are discussed. In addition to the monomer fluorescence, we have also observed another fluorescence band at longer wavelength in the region 420–600 nm which has been ascribed to excimer formation. The monomer and excimer fluorescence lifetimes of fluorenone in typical solvents such as benzene and acetonitrile have been determined experimentally. By combining our results of steady state fluorescence and measurements of fluorescence lifetimes with previously reported studies of laser-induced fluorescence, the mechanism of excimer formation has been explained. The absence of excimer formation in hexane, cyclohexane and alcohols is discussed.
Citations
More filters
TL;DR: In this paper, a guest specific solid-state fluorescence enhancement in 2,7-bis-(3-hydroxy-3,3-diphenylprop-1-ynyl)fluoren-9-one host:guest complexes may be ascribed to changes in the packing modes and hence host-host intermolecular interactions leading to excimer formation in the solid state.
Abstract: Guest specific solid-state fluorescence enhancement in 2,7-bis-(3-hydroxy-3,3-diphenylprop-1-ynyl)fluoren-9-one host:guest complexes may be ascribed to changes in the packing modes and hence host–host intermolecular interactions leading to excimer formation in the solid-state and the occurrence (or lack thereof) of specific intermolecular interactions.
61 citations
TL;DR: In this paper, a poly(9,9-dioctylfluorene-co-fluorenone) with 1% fluorenone, (PFO-F(1%)), was synthesized as a model compound to investigate the optical and electrical effects of fluorescence defects in poly (9, 9-diolluorenyl-2,7-diyl), PFO.
54 citations
TL;DR: The photophysics of several fluorenone derivatives was studied using fluorescence and laser-induced optoacoustic spectroscopy in this article, where electron-donating substituents increased the energy of the key upper triplet state (T 3 ) which, for the parent compound, is responsible for the increased intersystem crossing quantum yield in nonpolar solvents.
Abstract: The photophysics of several fluorenone derivatives was studied using fluorescence and laser-induced optoacoustic spectroscopy. Electron-donating substituents increase the energy of the key upper triplet state (T 3 ) which, for the parent compound, is responsible for the increased intersystem crossing quantum yield in non-polar solvents. Electron-withdrawing substituents decrease the energy of T 3 , and an increase in the intersystem crossing rate constant is observed. Halogen substitution leads to a heavy-atom effect, which is partially compensated by a decrease in the intersystem crossing rate constant due to changes in the energy gap between S 1 and T 3 . For most compounds, an increase in the internal conversion rate constant is observed. The magnitude of this increase is a function of the nature of the substituent and its position on the fluorenone ring.
35 citations
TL;DR: In this paper, the green emission band observed as a result of oxidation in dialkyl-fluorene polymers was examined and it was shown that an excimeric or intra-molecular fluorenone-based excited state is involved.
Abstract: This study examines the underlying nature of the green emission band observed as a result of oxidation in dialkyl-fluorene polymers Specifically, we set out to further determine whether an inter- (excimeric) or intra-molecular fluorenone-based excited state is involved The emission properties of poly(9,9-dihexylfluorene) dispersed at low concentration in a solid polystyrene matrix are carefully explored In situ, time-resolved photoluminescence measurements are made during photo-oxidation of the blend and during subsequent exposure to an atmosphere saturated with the vapour of a good solvent The polystyrene matrix suppresses the appearance of the green emission band during oxidation but the subsequent solvent vapour exposure then activates it The same effect (activation of the green emission) can be achieved by thermally annealing the matrix above its glass transition temperature Moreover, the activation of the green emission can be reversed by dissolving the film and re-casting This behaviour is attributed to controlling the phase structure of the polyfluorene/polystyrene blend and is considered strong evidence for an origin of the green band emission in the formation of excimer-like states between co-facially arranged fluorenone moieties The photoluminescence behaviour of 9-fluorenone and fluorene molecular mixtures in solution is also studied This model system allows analysis of the green emission band independent of relative intra- and inter-molecular energy transfer effects since this system is affected only by inter-molecular energy transfer These results provide further evidence for an excimeric origin of the green emission
31 citations
TL;DR: In this article, fluorenone and benzophenone were used as probes to study the nature of the adsorption process onto microcrystalline cellulose, and the fluorescence quantum yields (ΦF) determined were about 0.10 when dichloromethane, cyclohexane, and benzene were used for sample preparation.
Abstract: Benzophenone and fluorenone, which have a nonrigid and a rigid structure, respectively, were used as probes to study the nature of the adsorption process onto microcrystalline cellulose. Diffuse reflectance techniques were used in the UV−vis and infrared regions. Luminescence studies revealed that whenever fluorenone or benzophenone are entrapped into the natural polymer chains and in close contact with the substrate, a strong quenching effect exists for both probe's luminescence at room temperature. For fluorenone, the fluorescence quantum yields (ΦF) determined were about 0.10 when dichloromethane, cyclohexane, and benzene (solvents which do not swell cellulose) were used for sample preparation, while for dioxane, acetone, ethanol, and methanol (solvents which efficiently swell cellulose) ΦF was approximately 0.01. These values are about 1 order of magnitude higher than those obtained in solution, showing the importance of the rigid dry matrix in reducing the nonradiative pathways of deactivation of the...
31 citations
References
More filters
1,233 citations
TL;DR: In this article, the authors discuss advances in photochemistry and photochemistry advances in the field of photochemistry, and propose a method to improve photochemical advances in terms of photochemical properties.
Abstract: Advances in photochemistry , Advances in photochemistry , کتابخانه دیجیتال جندی شاپور اهواز
445 citations
Book•
01 Jan 1978
TL;DR: Biology old ncert class 11 and 12 before 2005 edition for, bioadhesive drug delivery systems fundamentals novel approaches and development drugs and the pharmaceutical sciences, biotechnology academic cell update edition, bond 11 maths assessment papers 9 10
Abstract: biology and chemistry of beta glucan volume 2 beta glucan structure chemistry and specific application, biologia volume unico sonia lopes2013, bmw 1er handbuch f20, bmw 750i owners manual, bodies that matter on the discursive limits of sex routledge classics, biology old ncert class 11 and 12 before 2005 edition for, biology 121 laboratory manual and workbook, bioadhesive drug delivery systems fundamentals novel approaches and development drugs and the pharmaceutical sciences, biotechnology academic cell update edition, bond 11 maths assessment papers 9 10
313 citations
01 Feb 1967
TL;DR: Parker et al. as discussed by the authors outline the principles of all these techniques and draw attention to some unusual results obtained with them, including the observation of delayed fluorescence, which was until recently of interest only to the photochemist, but it has now been shown to have potential value as an analytical technique also.
Abstract: From its first analytical applications (Bowman et al, 1955: Parker, et al, 1957) the technique of fluorescence photoelectric spectrometry developed within a decade to become a standard technique for trace organic and inorganic analysis. Reviews and text-books (Bartholomew, 1958: Parker, et al, 1962: Hercules, 1966) deal with the principles of its analytical application and the excellent text book of Udenfriend (1962) covers the applications in the biochemical field. The possibility of using phosphorescence measurement for analytical purposes was first suggested by Lewis and Kasha (1944) and was subsequently taken up by Freed and Salmre (1958) and by Parker and Hatchard (1962). It now promises to rival fluorescence measurement as a method for the trace analysis of organic materials. The observation of delayed fluorescence was until recently of interest only to the photo-chemist, but it has now been shown to have potential value as an analytical technique also (Parker et al, 1965). The object of this paper is to outline briefly the principles of all these techniques and to draw attention to some unusual results obtained with them.
191 citations