Systematic investigation of absorption, fluorescence and laser properties of some p- and m-oligophenylenes

Nijegorodov, N.; Downey, W. S.; Danailov, M. B.

doi:10.1016/s1386-1425(99)00167-5

Cited by 94 publications

(79 citation statements)

References 10 publications

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“…For these molecules, the S 0 → S 1 emission is usually masked by the S 0 → S 2 transition, and exceptionally large apparent Stokes shifts (defined as the energy spacing between the absorption and emission maxima) are observed. [7,23] If E 00 cannot be evaluated directly from the spectrum, as is the case in room-temperature spectra of B-and C-type molecules, the position of the lowest vibronic feature of the emission (F 1 ) is a reasonable first approximation for E 00 . The "true" adiabatic transition energy E 00 in a room-temperature spectrum can be also determined by convoluting the highly resolved features observed in the low-temperature emission spectrum with a Gaussian of appropriate bandwidth to account for the temperature effect.…”

Section: Experimental Determination Of the S 0 -S 1 Transition Energymentioning

confidence: 99%

“…4.1). This is explained by the fact that the emission originates from a symmetry-forbidden state in 2P, [7,23] while the lowest excited state is optically allowed in longer nP oligomers as well as nPV and nT oligomers.…”

Section: Chain-length Dependencementioning

confidence: 99%

“…Experimental vertical (E vert ,~) and adiabatic (E 00 , determined as the intersection of the absorption and fluorescence spectra, ᭹) transition energies of nPs in cyclohexane [23]. Calculated E vert at the TD-DFT level of theory without geometry constraints (B3LYP/6-31G*,~, [19]).…”

Section: Ab Initio Hartree-fock Rcismentioning

confidence: 99%

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Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

2007

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In this Review, the extreme care that must be taken when predicting the optical properties of conjugated polymers via the oligomer approach, and when comparing theoretical and experimental data, is illustrated. In the first part, conceptual strategies for the correct determination of optical transitions from experimental spectra and relevant extrapolation procedures at the polymer limit are introduced. The impact of conformational, substitution, solvent, and solid‐state effects on the optical properties is discussed in light of experimental data reported for molecular backbones based on phenylene, phenylenevinylene, and thiophene repeat units. A comparison is then made between experimental results and those provided by standard quantum‐chemical methods, to assess their reliability.

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Section: Experimental Determination Of the S 0 -S 1 Transition Energymentioning

confidence: 99%

Section: Chain-length Dependencementioning

confidence: 99%

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Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

2007

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“…2 Optical absorption spectra (left) and emission spectra (right) of the tertiary-butylsubstituted (tb) PV oligomers Table 1 The extinction coefficient per phenylenevinylene (PV) unit (ε) at the first absorption maximum (E A ). The 0,0 band energy (E F ), quantum yield (φ F ), and decay time (τ F ) of the fluorescence, together with the calculated values of the lifetimes towards radiative (τ R ) and non-radiative (τ NR ) decay of the S 1 state of excess polarizability ∆α temperature [20][21][22]. This indicates that the ground states of these molecules are subject to much greater torsional disorder than the PV oligomers.…”

Section: Oligomersmentioning

confidence: 99%

The Opto-Electronic Properties of Isolated Phenylenevinylene Molecular Wires

Grozema

Siebbeles

Warman

2005

Molecular Wires and Electronics

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The optoelectronic properties of dilute solutions of oligomeric and (broken-conjugation) polymeric phenylenevinylene chains were studied using the following techniques: optical absorption and (time-resolved) emission spectrophotometry, flash-photolysis time-resolved (real and imaginary) microwave conductivity, pulse-radiolysis time-resolved microwave conductivity, and pulse-radiolysis time-resolved optical absorption spectrophotometry. The following properties were determined: absorption and emission spectra, fluorescence quantum yields and decay times, exciton polarizabilities and dissociation probabilities, charge mobilities, and radical cation absorption spectra. The experimental results are compared with theoretical calculations of exciton polarizabilities, charge mobilities, and radical cation absorption spectra.

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“…Branched oligomers have become very interesting in the last decade in connection with the search for novel materials with combinations of practically useful properties [1-3]. A promising area for application of branched oligomers containing luminophores is the development of new active additives to plastic scintillators [4], dye lasers [5,6], and light-emitting diodes in semiconducting photodiodes [7][8][9]. The preparation of branched oligomers and polymers with luminophores is a relatively new area.…”

mentioning

confidence: 99%

Analysis of branched oligophenylene by absorption and fluorescence spectra

et al. 2011

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A branched oligophenylene has been synthesized based on 1,3,5-tri(4′-bromophenyl)benzene. Absorption and fluorescence spectra were studied and fluorescence quantum yields and lifetimes were measured for the compound in solution. It is demonstrated that the absorption spectrum is a superposition of p-quaterphenyl, p-terphenyl, and biphenyl chromophore absorption bands in a 1:2:1 ratio. The oligomer fluorescence spectrum is found to depend on the excitation wavelength. It is shown that the oligomer fluorescence is determined by two fluorochromic groups, namely fragments with branched p-terphenyl and p-quaterphenyl units. The main fluorescence maxima for these fluorochromic groups coincide with each other and lie in the vicinity of λ = 360 nm. A very weak fluorescence band found in the region 380-440 nm is excited by light with a wavelength lying beyond the oligomer self-absorption region. The reasons for a decrease in fluorescence quantum yields of branched models and the studied oligophenylene as compared with those of linear p-polyphenylene chromophores are discussed.Introduction. Branched oligomers have become very interesting in the last decade in connection with the search for novel materials with combinations of practically useful properties [1-3]. A promising area for application of branched oligomers containing luminophores is the development of new active additives to plastic scintillators [4], dye lasers [5,6], and light-emitting diodes in semiconducting photodiodes [7][8][9]. The preparation of branched oligomers and polymers with luminophores is a relatively new area. Comparatively few systems of this type have been prepared. Furthermore, their photophysical properties and their property-structure relationships are almost uninvestigated. One of the reasons for this situation is the difficulty of determining their molecular structures because the process for forming branched oligomers is random in nature [10,11].Herein a synthesized branched polymer (the Experimental section describes the synthetic method) is analyzed using spectrophotometry and fluorescence. According to the putative reaction, the produced macromolecule should have p-quaterphenyl (PQP) units at the branches and diphenyl (DP) and p-terphenyl (PTP) chromophores as the terminal groups. Issues with the determination of the ratio of these three chromophores in the produced macromolecule are examined. The units responsible for the fluorescence of the oligomer and the interactions between them are identified. These problems are resolved using a comparison of spectral data for the oligophenylene and the model low-molecularweight compounds PTP, PQP, and their branched analogs containing three PTP and PQP moieties.Experimental. The monomer 1,3,5-tri(4′-bromophenyl)benzene was prepared via the trimerization of 4-bromoacetophenone in benzene in the presence of triethylorthoformate and dry gaseous HCl by the standard method [12]. The oligophenylene was produced by Ni-catalyzed polycondensation of 1,3,5-tri(4′-bromophenyl)benzene by the literature me...

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Systematic investigation of absorption, fluorescence and laser properties of some p- and m-oligophenylenes

Cited by 94 publications

References 10 publications

Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

Optical Bandgaps of π‐Conjugated Organic Materials at the Polymer Limit: Experiment and Theory

The Opto-Electronic Properties of Isolated Phenylenevinylene Molecular Wires

Analysis of branched oligophenylene by absorption and fluorescence spectra

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