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Heldt, J.; Józefowicz, Marek; Kamiński, J. Z.

doi:10.1023/a:1016651800320

Cited by 34 publications

(37 citation statements)

References 19 publications

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“…[33] It is, however, consistent with our (see Fig. 6) and previous [74,75] studies of molecular fluorenone solutions, which show a dominant absorption peaked at » 280 nm, with onset at 340 nm and a weak, longerwavelength feature between 340 and 450 nm, both of which would therefore sit within the spectral range covered by PFO absorption and thus not necessarily be very apparent. The weak longer-wavelength absorption has been assigned variously to a p±p* transition [76,77] or the ªforbiddenº n±p* transition [78] of molecular fluorenone.…”

Section: Resultssupporting

confidence: 92%

Understanding the Origin of the 535 nm Emission Band in Oxidized Poly(9,9‐dioctylfluorene): The Essential Role of Inter‐Chain/Inter‐Segment Interactions

Sims

Bradley²,

Ariu

et al. 2004

Adv Funct Materials

248

134

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We present a careful study of the effects of photo‐oxidation on the emissive properties of poly(9,9‐dioctylfluorene) (PFO) that addresses important issues raised by a recent flurry of publications concerning the degradation of blue light‐emitting, fluorene‐based homo‐ and copolymers. The photoluminescence (PL) spectra of thin PFO films oxidized at room temperature comprise two major components, namely a vibronically structured blue band and a green, structureless component, referred to hereafter as the ‘g‐band’. These are common features in a wide range of poly(fluorene)s (PFs) and whilst the former is uniformly accepted to be the result of intra‐chain, fluorene‐based, singlet‐exciton emission, the origin of the ‘g‐band’ is subject to increasing debate. Our studies, described in detail below, support the proposed formation of oxidation‐induced fluorenone defects that quench intra‐chain, singlet‐exciton emission and activate the g‐band emission. However, whilst these fluorenone defects are concluded to be necessary for the g‐band emission to be observed, they are considered not to be, alone, sufficient. We show that inter‐chain/inter‐segment interactions are required for the appearance of the g‐band in the PL spectra of PFO and propose that the g‐band is attributable to emission from fluorenone‐based excimers rather than from localized fluorenone π–π* transitions as recently suggested.

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Section: Resultssupporting

confidence: 92%

Understanding the Origin of the 535 nm Emission Band in Oxidized Poly(9,9‐dioctylfluorene): The Essential Role of Inter‐Chain/Inter‐Segment Interactions

Sims

Bradley²,

Ariu

et al. 2004

Adv Funct Materials

248

134

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“…This relatively weak lowest-lying absorption in Trux-3NBu 2 , which seems to be a mixture of π f π* and n f π* transitions, is also observed in the parent 9H-fluoren-9-one molecule 37 and 3-(dimethylamino)-9H-fluoren-9-one. 38 In addition, weak, low-lying π f π* and n f π* transitions are confirmed by our own ZINDO calculations on this molecule. Results of a ZINDO/S all singly excited configuration interaction calculation (done with Gaussian03 39 ) on Trux-6CN-3NBu 2 suggest that the weak low-lying absorptions are due to π f π* transitions only.…”

Section: Synthesissupporting

confidence: 71%

Synthesis and Characterization of New Truxenones for Nonlinear Optical Applications

et al. 2006

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The synthesis of several new truxenones and one tris(dicyanomethylene) derivative substituted by different amines at positions 4, 9, and 14 is reported. A complete characterization of the NLO properties of representative derivatives was carried out by hyper-Rayleigh scattering; the major electronic effects and the influence of the structural modifications on the NLO properties have been examined. Because of their C 3 symmetry and their large first hyperpolarizability, the chiral versions of the tris(dicyanomethylene) truxene derivatives are of interest for second-order nonlinear optics in uniaxially aligned chiral media.

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“…[50,51] The KCD or fluorenone molecule contains an aromatic carbonyl moiety and forms a hydrogen-bonded complex with alcoholic solvents in both the ground and excited states. [50,63] Ernsting and co-workers also recently applied the ultrafast visible pump-continuum probe transient absorption spectroscopic technique to studying the dynamics of proton-transfer reactions. [62] Using a subpicosecond transient absorption spectroscopic technique, Pines et al studied the solvation process by hydrogen-bonding interactions and proposed some geometric changes in the preexisting hydrogen-bonded complexes between 8-hydroxypyrene-1,3,6-trisdimethylsulfonamide (HPTA) and various oxygen bases following photoexcitation to a higher electronic state.…”

Section: Introductionmentioning

confidence: 99%

The Role of Hydrogen‐Bonding Interactions in the Ultrafast Relaxation Dynamics of the Excited States of 3‐ and 4‐Aminofluoren‐9‐ones

et al. 2009

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The dynamics of the excited states of 3- and 4-aminofluoren-9-ones (3AF and 4AF, respectively) are investigated in different kinds of solvents by using a subpicosecond time-resolved absorption spectroscopic technique. They undergo hydrogen-bonding interaction with protic solvents in both the ground and excited states. However, this interaction is more significant in the lowest excited singlet (S(1)) state because of its substantial intramolecular charge-transfer character. Significant differences in the spectroscopic characteristics and temporal dynamics of the S(1) states of 3AF and 4AF in aprotic and protic solvents reveal that the intermolecular hydrogen-bonding interaction between the S(1) state and protic solvents plays an important role in its relaxation process. Perfect linear correlation between the relaxation times of the S(1) state and the longitudinal relaxation times (tau(L)) of alcoholic solvents confirms the prediction regarding the solvation process via hydrogen-bond reorganization. In the case of weakly interacting systems, the relaxation process can be well described by a dipolar solvation-like process involving rotation of the OH groups of the alcoholic solvents, whereas in solvents having a strong hydrogen-bond-donating ability, for example, methanol and trifluoroethanol, it involves the conversion of the non-hydrogen-bonded form to the hydrogen-bonded complex of the S(1) state. Efficient radiationless deactivation of the S(1) state of the aminofluorenones by protic solvents is successfully explained by the energy-gap law, by using the energy of the fully solvated S(1) state determined from the time-resolved spectroscopic data.

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Untitled

Cited by 34 publications

References 19 publications

Understanding the Origin of the 535 nm Emission Band in Oxidized Poly(9,9‐dioctylfluorene): The Essential Role of Inter‐Chain/Inter‐Segment Interactions

Understanding the Origin of the 535 nm Emission Band in Oxidized Poly(9,9‐dioctylfluorene): The Essential Role of Inter‐Chain/Inter‐Segment Interactions

Synthesis and Characterization of New Truxenones for Nonlinear Optical Applications

The Role of Hydrogen‐Bonding Interactions in the Ultrafast Relaxation Dynamics of the Excited States of 3‐ and 4‐Aminofluoren‐9‐ones

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