Spectral, luminescent, and photophysical properties of dipyrrolylbenzenes

Петрушенко, И.К.; Petrushenko, Konstantin B.; Smirnov, V. I.; Trofimov, B. A.

doi:10.1007/s11172-008-0189-2

Cited by 4 publications

(2 citation statements)

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“…DPB radical cations were reduced with PTZ, which has one of the lowest first ionization potentials among organic compounds; this a priori ensures thermodynami cally favourable conditions for the electron transfer reac tion (6). Furthermore, the PTZ +• radical cation has a typical and well studied electronic absorption spec trum, 15,16 which facilitates the assignment of the interme diates of reaction (6).…”

Section: Resultsmentioning

confidence: 99%

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The nature of transitions in electronic absorption spectra of radical cations of dipyrroles with phenylene bridging groups

et al. 2010

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The electronic absorption spectra of radical cations of dipyrroles with a phenylene bridge were studied by laser flash photolysis and quantum chemical methods. Intense absorption bands of the radical cations in the visible region (λ max ≈ 500 nm, ε max > 2•10 4 L mol -1 cm -1 ) are caused by excitation of electrons from single occupied MOs to the LUMO. In the near IR region, calculations predict additional, relatively intense (f ≈ 0.27-0.29) electronic transitions associated with excitation of electrons from low lying MOs to the single occupied MO.Key words: dipyrroles with a phenylene bridge, laser photolysis, radical cations, electronic absorption spectra, quantum chemical calculations, time dependent density functional theory.Dipyrroles with phenylene bridging groups (hereinaf ter reffered to as dipyrrolylbenzenes, DPB) were first syn thesized as monomers for the synthesis of low bandgap polymers and application in optics. 1-4 The spectral lu minescent and photophysical properties of this type of comonomers show high sensitivity to the nature and posi tion of substituents in the pyrrole and benzene rings and the possibility of fine adjustment of their optical pro perties. 3,5,6 However, the electronic and molecular struc tures of DPB radical cations, which should to a great extent determine the mechanism of polymerization, as well as the injection and charge transport properties, are poorly studied. For this reason, investigations of the spec troscopic properties of DPB radical cations are of con siderable interest. Information on the electronic spectra of radical cations is also needed for reliable identifica tion and interpretation of the nature of the species formed during the chemical, electrochemical, and photochemical synthesis of polyconjugated systems. The chemical syn thesis of the radical cations of pyrrole containing com pounds is strongly complicated by fast polymerization so that the relatively long lived species can be prepared only if the pyrrole rings have substituents in the α positions. 7 Consequently, fast generation of radical cations of the DPB having no substituent in the α positions using nano second laser photolysis (NLP) is very efficient when studying their spectral and kinetic properties.Earlier, 4 we have reported preliminary data on the band positions in the electronic absorption spectra of the radical cations of 1,4 bis(2 pyrrolyl)benzene (1), 1 (2 pyrrolyl) 4 (1 vinyl 2 pyrrolyl)benzene (2), and 1,4 bis[2 (1 vinyl 2 pyrrolyl)]benzene (3) obtained by the NLP method. In the present work, both experimental studies and quantum chemical calculations of the electronic absorption spectra of the radical cations of compounds 1-3 and of the more recently synthesized 4 (3 methyl 2 pyrrolyl) 1 (2 pyr rolyl)benzene (4), 1 (2 pyrrolyl) 4 (1 vinyl 3 methyl 2 pyrrolyl)benzene (5), and 4 (1 vinyl 3 methyl 2 pyrrol yl) 1 (1 vinyl 2 pyrrolyl)benzene (6) were performed to analyze in more detail the nature of electronic transitions in the spectra of radical cations. As the computational method, the t...

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Section: Resultsmentioning

confidence: 99%

“…Furthermore, the PTZ +• radical cation has a typical and well studied electronic absorption spec trum, 15,16 which facilitates the assignment of the interme diates of reaction (6). The PTZ concentration was chosen in such a manner that all DPB +• be consumed in reaction (6) (see Scheme 2).…”

Section: Resultsmentioning

confidence: 99%