Pyrene fluorescence quenching by aromatic azides

Kamyshan, S. V.; Litvinchuk, S. V.; Korolev, V. Yu.; Eremenko, S.I.; Tsentalovich, Yu. P.; Gritsan, Nina P.

doi:10.1134/s0023158406010125

Cited by 7 publications

(17 citation statements)

References 23 publications

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“…Considering the nature of the emitting states for these complexes, we attribute the transient absorbing species in 7 and 9 to 3 ILCT/ 3 π,π* and those for complexes 10 and 11 to the respective anthracenyl or pyrenyl substituted N^N ligand based 3 π,π* states due to their much longer TA lifetimes. Assigning the nature of the long-lived transient absorbing states in these two complexes to the anthracene and pyrene based 3 π,π* states was excluded because the observed TA spectra of 10 and 11 are quite different from those reported for anthracene and pyrene . The different TA lifetimes and emission lifetimes in 10 and 11 also clearly indicate the different origins of the emitting and TA states.…”

Section: Results and Discussionmentioning

confidence: 99%

Multifunctional Cationic Iridium(III) Complexes Bearing 2-Aryloxazolo[4,5-f][1,10]phenanthroline (N^N) Ligand: Synthesis, Crystal Structure, Photophysics, Mechanochromic/Vapochromic Effects, and Reverse Saturable Absorption

et al. 2017

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A series of 2-aryloxazolo[4,5-f][1,10]phenanthroline ligands (N^N ligands) and their cationic iridium(III) complexes (1-11, aryl = 4-NO-phenyl (1), 4-Br-phenyl (2), Ph (3), 4-NPh-phenyl (4), 4-NH-phenyl (5), pyridin-4-yl (6), naphthalen-1-yl (7), naphthalen-2-yl (8), phenanthren-9-yl (9), anthracen-9-yl (10), and pyren-1-yl (11)) were synthesized and characterized. By introducing different electron-donating or electron-withdrawing substituents at the 4-position of the 2-phenyl ring (1-5), or different aromatic substituents with varied degrees of π-conjugation (6-11) on oxazolo[4,5-f][1,10]phenanthroline ligand, we aim to understand the effects of terminal substituents at the N^N ligands on the photophysics of cationic Ir(III) complexes using both spectroscopic methods and quantum chemistry calculations. Complexes with the 4-R-phenyl substituents adopted an almost coplanar structure with the oxazolo[4,5-f][1,10]phenanthroline motif, while the polycyclic aryl substituents (except for naphthalen-2-yl) were twisted away from the oxazolo[4,5-f][1,10]phenanthroline motif. All complexes possessed strong absorption bands below 350 nm that emanated from the ligand-localized π,π*/ILCT (intraligand charge transfer) transitions, mixed with LLCT (ligand-to-ligand charge transfer)/MLCT (metal-to-ligand charge transfer) transitions. At the range of 350-570 nm, all complexes exhibited moderately strong ILCT/LLCT/MLCT transitions at 350-450 nm, and broad but very weak LLCT/MLCT absorption at 450-570 nm. Most of the complexes demonstrated moderate to strong room temperature phosphorescence both in solution and in the solid state. Among them, complex 7 also manifested a drastic mechanochromic and vapochromic luminescence effect. Except for complexes 1 and 4 that contain NO or NPh substituent at the phenyl ring, respectively, all other complexes exhibited moderate to strong triplet excited-state absorption in the spectral region of 440-750 nm. Moderate to very strong reverse saturable absorption (RSA) of these complexes appeared at 532 nm for 4.1 ns laser pulses. The RSA strength followed the trend of 7 > 11 > 9 > 3 > 2 ≈ 4 > 5 ≈ 10 ≈ 6 ≈ 8 > 1. The photophysical studies revealed that the different 2-aryl substituents on the oxazole ring impacted the singlet and triplet excited-state characteristics dramatically, which in turn notably influenced the RSA of these complexes.

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Section: Results and Discussionmentioning

confidence: 99%

Multifunctional Cationic Iridium(III) Complexes Bearing 2-Aryloxazolo[4,5-f][1,10]phenanthroline (N^N) Ligand: Synthesis, Crystal Structure, Photophysics, Mechanochromic/Vapochromic Effects, and Reverse Saturable Absorption

et al. 2017

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“…Usually, these S 0 ® S 1 transitions manifest themselves as weak long asymmetric tails, 8,20 which is typical of the excitation to the dissociative states. According to our calculations, § the S 0 ® S 1 transition of azide 1 at 309 nm is also characterized as π ® (in plane, π*, azide) excitation (HOMO ® LUMO + 1) and has a very low oscillator strength (3×10 -4 ).…”

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confidence: 99%

“…The formation of the pyrene cation was not detected, and quenching by energy transfer was proposed. 8 However, electron transfer followed by fast N-N bond dissociation and charge recombination could not be excluded. Bonding donor and acceptor residues will facilitate the quenching and make it possible to distinguish between electron and energy transfer mechanisms.…”

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Synthesis, electronic structure and spectroscopy of bridged pyrene-(CH2)n-aryl azide systems

Barabanov

Pritchina

Takaya

et al. 2008

Mendeleev Communications

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“…However, following, e.g., Ref. 40, one can estimate the maximum value of the characteristic radius of exchange quenching R 0 . The rate constant k DT can be represented in the form 41 k DT = 2πLR 2 k ex (R), (18) where the quenching probability is a function of distance (see Ref.…”

Section: Resultsmentioning

confidence: 99%

Intra- and intermolecular quenching of carbazole photoluminescence by imidazolidine radicals

et al. 2010

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Mechanisms of carbazole photoluminescence quenching by the free and chemically bound nitroxyl radicals in the model bound system "carbazole (CBZ)-imidazolidine nitroxyl radical R • " were investigated and the photophysical properties of the system were studied and com pared with those of free CBZ and R • in solution. The quantum yield and lifetime of fluores cence from the local singlet excited state of the carbazole moiety in the bound CBZ-R • system is three orders of magnitude lower than in free CBZ. The lifetime of the local triplet excited state of the carbazole moiety in the bound system is shorter than 50 ns. The rate constants for intermolecular quenching of the singlet and triplet excited states of free CBZ by R • in acetoni trile were found to be (1.4±0.1)•10 10 and (1.5±0.2)•10 9 L mol -1 s -1 , respectively. The most plausible mechanisms of both free and covalently bound carbazole luminescence quenching by nitroxyl radicals are exchange energy transfer and acceleration of internal conversion due to electron exchange.Keywords: spin labeled luminophores, laser flash photolysis, fluorescence quenching.Spin catalysis of chemical reactions by paramagnetic species occurs in triads of paramagnetic species where spin conversion in a pair of species is initiated by the third electron spin. 1,2 This phenomenon was experimentally confirmed for a number of photochemical, biochemical, and radiation chemical systems. 3-5 The third spin plays the role of the source of external magnetic field in which a spin correlated radical pair created in some (e.g., radia tion chemical) way is placed. Systematic research on spin catalysis requires some model compounds comprising a paramagnetic fragment bound to a partner from the rad ical pair.In this connection, spin labeled luminophores are of particular interest. Theoretical calculations predict a num ber of interesting effects in radiation processes involving them. 6 However, in most cases the paramagnetic center acts as an efficient quencher of the luminescence of such compounds. 4,7-9 It should be noted that it was proposed to use the reverse effect, viz., the rise of the luminescence of fluorophore-nitroxide radical dyads due to reduction of the nitroxide group, for the design of sensors for the superoxide radical, antioxidants, hydrogen peroxide in bi ological systems, 10 and for alkyl radicals in polymers. 11The accelerated internal conversion proceeding by the electron exchange mechanism is the main quenching mechanism of the fluorescence of chemically bound sys tems "luminophore-nitroxide radical". 7,8 However, some other mechanisms of quenching in these systems were pro posed, e.g., acceleration of intersystem crossing (ISC) from the excited singlet to triplet state. 7 These assumptions are based on the fact that quenching of singlet states of lumi nophores by free (chemically unbound) nitroxide radicals (this process has been studied in more details) can follow all known channels including energy transfer, 12,13 elec tron transfer, 14 ISC, 15,16 and internal convers...

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Pyrene fluorescence quenching by aromatic azides

Cited by 7 publications

References 23 publications

Multifunctional Cationic Iridium(III) Complexes Bearing 2-Aryloxazolo[4,5-f][1,10]phenanthroline (N^N) Ligand: Synthesis, Crystal Structure, Photophysics, Mechanochromic/Vapochromic Effects, and Reverse Saturable Absorption

Multifunctional Cationic Iridium(III) Complexes Bearing 2-Aryloxazolo[4,5-f][1,10]phenanthroline (N^N) Ligand: Synthesis, Crystal Structure, Photophysics, Mechanochromic/Vapochromic Effects, and Reverse Saturable Absorption

Synthesis, electronic structure and spectroscopy of bridged pyrene-(CH2)n-aryl azide systems

Intra- and intermolecular quenching of carbazole photoluminescence by imidazolidine radicals

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