Determination of ground- and excited-state isomerization barriers for the oligothiophene 3',4'-dibutyl-2,2':5',2''-terthiophene

DeWitt, L.; Blanchard, G. J.; LeGoff, Eugene; Benz, Michael; Liao, Ju‐Hsiou; Kanatzidis, M. G.

doi:10.1021/ja00078a064

Cited by 101 publications

(86 citation statements)

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“…This seemed quite incompatible with a "single" inter-ring bond in the ground state and a more double inter-ring bond in the lowest excited singlet state. Very recently, reinvestigation 44 of the same molecule at higher resolution now suggests a ground state barrier of 0.5-1 kcal/mol with the excited state barrier similar to that reported earlier. 44 These new data are now compatible with our findings (see later discussion).…”

Section: Resultssupporting

confidence: 80%

“…X-ray data of trithiophene (R3) 43 give a clear indication that the tt is the more stable, that is, this is the conformeric form in the crystal with inter-ring angles of about 6°-9°. Also, a dibutylsubstituted trithiophene has a tt configuration 44 with a higher angle of inter-ring twist than for R3 itself (not unexpected). However, the barrier to rotation was given to be 19.7 kcal/mol in the ground state and 4.2 kcal/mol in the lowest excited singlet state using 1 H NMR.…”

Section: Resultsmentioning

confidence: 86%

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Comprehensive Evaluation of the Absorption, Photophysical, Energy Transfer, Structural, and Theoretical Properties of α-Oligothiophenes with One to Seven Rings

et al. 1996

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A large basis set of R-oligothiophenes with two to seven rings (R2-R7), also including thiophene, R1, have been investigated in five solvents regarding absorption, fluorescence and phosphorescence, quantum yields of fluorescence (φ F ) and triplet formation (φ T ), lifetimes of fluorescence and the triplet state, quantum yields of singlet oxygen production (φ ∆ ), all rate constants k F , k IC , k ISC , and several of the foregoing as a function of temperature. Ten different theoretical calculations across several levels including three levels of ab initio have been carried out regarding which conformer is lowest in energy and the ∆H's among all conformers of R2, R3 and R5, as well as calculations of transitions energies of the R-oligothiophenes. We have shown that the (l) 1 Bu state is the lowest singlet state for all R2-R7 in any solvent, in contradiction to previous predictions for the higher members. Based on absorption and fluorescence data and calculations of atomic charges in S 0 and S 1 , the ground state is twisted while the excited state is planar (quinoidal-like). Significant charge transfer occurs between S 0 and S 1 but not S 0 and T 1 . For all R2-R7, φ IC is small, k 0 F is approximately constant while k ISC decreases significantly from R2 to R7. The decrease is k ISC is believed to arise from a decrease in matrix elements of the type 〈 1 Ψ CT |H′| 3 Ψ 1 〉. The essential lack of phosphorescence is assigned as originating from inter-ring twisting mode coupling between T 1 and S 0 . Triplet energy transfer to 3 O 2 to produce 1 O 2 is highly efficient for R2-R5. Based on all data, the first Rn representative of R-polythiophene is R5.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 86%

Comprehensive Evaluation of the Absorption, Photophysical, Energy Transfer, Structural, and Theoretical Properties of α-Oligothiophenes with One to Seven Rings

et al. 1996

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“…S1, S2 (ESI †) and are summarized in Table 1. As these properties have already been widely investigated, [61][62][63][64][65][66] only a brief summary of the results is presented for purposes of comparison to the electrochemical and ECL results.…”

Section: -60mentioning

confidence: 99%

Electrochemistry and electrogenerated chemiluminescence of thiophene and fluorene oligomers. Benzoyl peroxide as a coreactant for oligomerization of thiophene dimers

et al. 2012

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The electrochemical properties of oligomers of thiophene (with number of monomer units, n, from 2 to 12) and fluorene (n ¼ 3 to 7) were investigated. Both sets of oligomers were characterized by the presence of two oxidation and two reduction waves as determined by cyclic voltammetry (CV), with the reversibility of the waves depending on the structural properties of the compounds. The addition or removal of a third electron was found to be difficult relative to the second, a finding shown for conjugated oligomers with chain lengths up to 7 in the case of the fluorenes and up to 12 for the thiophenes. The oligothiophenes showed a larger separation between the electrochemical waves for the same chain length, and also substantial electrogenerated chemiluminescence (ECL) signals, whose intensity increased with oligomer size. In contrast, the ECL intensity of the fluorene oligomers was essentially independent of chain length. The ECL spectra for the thiophene dodecamer were obtained with concentrations as low as 20 pM, a result that reflects a high ECL efficiency, close to that of the well-known ECL standard Ru(bpy) 3 2+. Oligomers were also formed on electrochemical reduction of an appropriately functionalized dimer in the presence of benzoyl peroxide producing a longer wavelength emission (maximum at $540 nm) as opposed to the spectrum of the dimer (l em ¼ 390 nm).

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“…Fluorescence lifetimes ( 0 f ) are determined by using a timecorrelated single-photon-counting spectrometer, which has been described elsewhere [49]. In this system, the second harmonic of a continuous-wave mode-locked Nd:YAG laser (Coherent, model Antares 76-S) is used to excite a cavitydumped, synchronously pumped dye laser (Coherent, model 702-2, 325 nm, 1 mW).…”

Section: Determination Of Fluorescence Lifetimesmentioning

confidence: 99%

Investigation of common fluorophores for the detection of nitrated explosives by fluorescence quenching

Meaney

McGuffin

2008

Analytica Chimica Acta

142

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Determination of ground- and excited-state isomerization barriers for the oligothiophene 3',4'-dibutyl-2,2':5',2''-terthiophene

Cited by 101 publications

References 1 publication

Comprehensive Evaluation of the Absorption, Photophysical, Energy Transfer, Structural, and Theoretical Properties of α-Oligothiophenes with One to Seven Rings

Comprehensive Evaluation of the Absorption, Photophysical, Energy Transfer, Structural, and Theoretical Properties of α-Oligothiophenes with One to Seven Rings

Electrochemistry and electrogenerated chemiluminescence of thiophene and fluorene oligomers. Benzoyl peroxide as a coreactant for oligomerization of thiophene dimers

Investigation of common fluorophores for the detection of nitrated explosives by fluorescence quenching

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