D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• basis of the previous considerations, for TADF materials, the energy difference (ΔEST) between the first singlet excited state (S1) and the first triplet excited state (T1) must be small enough to enable the RISC process with the activation of environmental thermal energy [5]. To achieve this, electron

• -dependent density functional theory (TD-DFT) calculations, respectively. The ground state (S0) geometries were optimized on B3LYP/6-31G* level in gas phase, while the lowest triplet excited state (T1) energy levels and the singlet excited state (S1) geometries of those molecules were optimized by TD-DFT on

Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems

• Fabrizio Palumbo,
• Francisco Bosca,
• Isabel M. Morera,
• Inmaculada Andreu and
• Miguel A. Miranda

Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115

• nonsteroidal anti-inflammatory drug that contains the 2-benzoylthiophene (BZT) chromophore and has a π,π* lowest triplet excited state. In the present work, dyads (S)- and (R)-SP-α-Ch (1 and 2), as well as (S)-SP-β-Ch (3) have been prepared from β- or α-Ch and SP to investigate the possible competition between

• significantly more photoreactive than 1 indicating a clear stereodifferentiation in the photochemical behavior. Transient absorption spectra obtained for 1–3 were very similar and matched that described for the SP triplet excited state (typical bands with maxima at ca. 350 nm and 600 nm). Direct kinetic

• singlet oxygen, thus being able to initiate Ch oxidation from their triplet excited states following either of the two competing mechanistic pathways. Keywords: aryl ketones; hydrogen abstraction; lipid peroxidation; photoproducts; triplet excited state; Introduction Among the constituents of cell

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• form N,N-dimethylanilines 1 and maleimides 2 is depicted in Scheme 3. On absorption of visible light, the ground state of Eosin Y (EY) is induced to its single excited state (1EY*), which moves to its more stable triplet excited state (3EY*) through inter system crossing (ISC) [46][47]. 3EY* may

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• -oxoethyl phosphate (14a) quantitatively releases diethyl phosphate upon irradiation in aq MeOH or aq MeCN at 350 nm, with quantum efficiencies ranging from 0.021 to 0.067 depending on the solvent composition. The deprotection reactions originate from the triplet excited state, are robust under ambient

• acidic proton (especially for singlet state reactions). The carbonyl appendage, however, must be responsible for the enhanced heterolysis efficiency [28][29][38] and may influence the formation of the triplet excited state through intersystem crossing (isc) [26] which is the origin of the heterolysis and

• . The controlling feature leading to the change in mechanism for these two examples is more reasonably imbedded in the route to the reactive triplet excited state configuration [10][11]. For pHP, the reactive excited state is a π,π* triplet that is favored only in hydroxylic solvents, especially H2O [15

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• photodegraded to LC whereas in alkaline media it forms LC along with LF. Both these major photoproducts are formed via the triplet excited state through the mediation of FMF, which serves as an intermediate in the photolysis of RF [10][11][18][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][59][78

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• a dye (PS) with an electron acceptor (A) is depicted. After absorption of actinic light (hν), the PS reaches its singlet excited state (1PS*) and after intersystem crossing (kISC), its triplet excited state (3PS*). From both these excited states, an electron transfer can occur from the PS to A (with

• rate constants of singlet and triplet state deactivation to the ground state, respectively; kISC the rate constant of the intersystem crossing from 1PS to 3PS; 1kq/A, 3kq/A, (1kq/D, 3kq/D) the bimolecular electron transfer rate constant of the singlet and triplet excited state of the PS by the acceptor

Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

• Susanna Schmidbauer,
• Andreas Hohenleutner and
• Burkhard König

Beilstein J. Org. Chem. 2013, 9, 2088–2096, doi:10.3762/bjoc.9.245

• these two products could not be elucidated so far. Ir(ppy)3 In contrast, for the green emitting Ir(ppy)3 the presence of oxygen in benzene has a beneficial effect on the compound’s stability. This is likely due to the ability of oxygen to quench the triplet excited state of the complex, thus preventing

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• established that reductive quenching of the triplet excited state of Eosin Y by N-phenyltetrahydroisoquinoline 13 produced the Eosin Y radical anion. An ESR study on the irradiated solution of DMPO (5,5-dimethyl-1-pyrroline-N-oxide), Eosin Y, and N-phenyltetrahydroisoquinoline in air-saturated CH3CN detected

Electron self-exchange activation parameters of diethyl sulfide and tetrahydrothiophene

• Martin Goez and
• Martin Vogtherr

Beilstein J. Org. Chem. 2013, 9, 1448–1454, doi:10.3762/bjoc.9.164

• instant electron return and thereby maximize the number of radical pairs available for generating polarizations, a triplet sensitizer should be used [11]; the long life of a triplet excited state is also the only way to meet the conflicting requirements of bringing the self-exchange rates into the

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• triplet excited-state by sensitization. The triplet excited-state is believed to have a higher biradical and less zwitterionic character [73]. Ortho photocycloaddition of triplet excited benzenes have been extensively studied by Wagner and his group. They investigated [2 + 2] photocycloadditions of

• alkanophenones, which occur from the triplet excited-state and via 1,4-biradicals [74][75][76][77]. The occurrence of such radicals has been proven by the insertion of a cyclopropyl radical trap in the olefin. Upon irradiation of this modified starting material, the ortho cycloadduct could no longer be isolated

• ] pathway is usually observed; upon sensitizing in the triplet excited-state, the [4 + 2] mode prevails (Scheme 31). Such [4 + 4] photocycloadditions have also been observed intermolecularly with very high yields [96]. There are few examples leading to para products in high yield. However, one example is

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• functionality in 1i quenches the triplet excited-state, most likely by the intramolecular self-quenching of the two proximate thiourea groups. Interestingly, upon association of the thiourea units with anions, the DPM reactivity of compound 1i is regained. This observation is consistent with the shorter

Photoinduced homolytic C–H activation in N-(4-homoadamantyl)phthalimide

• Nikola Cindro,
• Margareta Horvat,
• Kata Mlinarić-Majerski,
• Axel G. Griesbeck and
• Nikola Basarić

Beilstein J. Org. Chem. 2011, 7, 270–277, doi:10.3762/bjoc.7.36

• 10.3762/bjoc.7.36 Abstract N-(4-homoadamantyl)phthalimide (5) on excitation and population of the triplet excited state underwent intramolecular H-abstractions and gave products 6 and 7. The major product, exo-alcohol 6 was a result of the regioselective δ H-abstraction and the stereoselective cyclization

• the conversion of the starting material under the same irradiation conditions. Thus, after 1 h photolysis of 5 in acetone, only 5% of 5 was converted to products, whereas after photolysis in acetone–H2O, a 60% conversion was achieved. This suggests that phthalimide in the triplet excited state, in a

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• triplet excited state is very fast, 1011 s−1 for benzophenones, and not affected by heavy atoms, but the ISC process of triplet benzophenones to singlet ground state would be accelerated, reducing lifetime of triplet benzophenones. Finally, triplet benzophenones with a short lifetime would give rise to a