Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• , based on 6-(trifluoromethyl)quinoxaline or 6-cyanoquinoxaline acceptors, respectively. The small energy splitting values (0.03–0.04 eV) and long fluorescence lifetimes (5.0 μs) indicated efficient TADF processes. The utilization of these emitters in full-TADF white OLEDs, along with a sky-blue emitter

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• was observed for the dyads containing the native PTZ unit, and the prompt and delayed fluorescence lifetimes changed with different aryl substituents on the imide part. In polar solvents, no TADF was observed. For the dyads with the PTZ unit oxidized, no TADF was observed as well. Femtosecond

• the oxidized PTZ unit do not have long-lived components (Figure 4e and 4f), and their fluorescence lifetimes are basically the same in nitrogen and air atmosphere and the lifetimes are on a nanosecond scale, indicating that the oxidized molecules do not have TADF properties. We reported NI-PTZ

• analogous dyads recently, however, the delayed fluorescence lifetimes were much longer (2.0–14.4 μs) as compared to the current dyads [47]. TADF emitters with shorter delayed fluorescence lifetimes are suitable for fabrication of OLED devices, to suppress the efficiency roll-off effect. The photophysical

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• fluorescence lifetimes of NI-PhMe2-PTZ in CHX, HEX, and TOL were determined to be 1.6 ns (56%)/12.9 ns (44%), 1.2 ns (51%)/7.2 ns (49%), and 2.7 ns (22%)/18.7 ns (78%), respectively (Figure S28 in Supporting Information File 1). In order to determine the 3NI energy in the dyads and in the triad, the

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• emitters in toluene are summarized in Table 1. Time-resolved spectroscopy Further, the fluorescence lifetimes on the nanosecond and microsecond timescales of both emitters were recorded in degassed THF to understand the photon upconversion process (Figure 2 and Tables S6 and S7 in Supporting Information

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• -resolved fluorescence spectroscopy of the two dyes revealed that the fluorescence lifetimes (τfl) are 0.62 ns for OTK-2 and 0.66 ns for OTT-2, indicating that there is a little difference in the τfl values of the two dyes. The radiative rate constant (kr = 6.2 × 108 s−1) for OTT-2 is slightly larger than

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• emission in toluene more surprising. In addition to similarities in fluorescence energy, the D–A (1) and D–A–D (POZ-DBPHZ) compounds share very close calculated fluorescence rates (2.2 × 107 s−1 and 1.8 × 107 s−1, respectively) which translate into prompt fluorescence lifetimes of 45 ns and 54 ns

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• present high photoluminescence quantum yields, ΦPL, of 75.2% and 71.9%, respectively, and delayed fluorescence lifetimes, τd, of 25.48 μs and 34.31 μs, respectively. The devices produced with these materials reached maximum external quantum efficiencies (EQEmax) values of 14.5% and 30% at low brightness

• measurement (Supporting Information File 1, Figure S5b,c) showed multiexponential decay kinetics and lifetimes with an average τp of 8.6 ns [τ1 = 3.5 ns (37.5%), τ2 = 11.6 ns (62.5%)] and an average τd of 156.1 µs [τ1 = 27.98 µs (39.5%), τ2 = 239.7 µs (60.5%)], respectively. The average prompt fluorescence

• lifetimes are of a similar magnitude to that of ICzTRZ (τp = 11.5 ns) [14] while the average delayed fluorescence decays much faster for DICzTRZ (τd = 252.8 µs for ICzTRZ) [14]. We next focused on the photophysical study in a suitably high triplet energy small molecule host material, CzSi (9-(4-tert

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• moderately polar dichloromethane and then highly polar DMSO (Table 2, Figure 3). The fluorescence quenching of 3ac in methanol is attributed to the partial protonation of the carboline unit's nitrogen atoms facilitated by polar-protic solvents [33]. The fluorescence lifetimes were measured by time-correlated

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• Figure 2a and Figures S1–S11 in Supporting Information File 1). The emission spectra for para-bromocarbaldehyde 3 and adamantyltriazole 34 in the solid-state show maxima at 440 nm (for compound 3) and 416 nm (for compound 34) (see Figure 2b). Additionally, fluorescence lifetimes (τ) of 3 and 34 were

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

• Aydan Yadigarli,
• Qimeng Song,
• Sergey I. Druzhinin and
• Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

• dielectric constant for thin PMMA films was mapped by analyzing the position of the fluorescence of NR employed as a reporter dye [15]. Besides polarity, the Young’s modulus of the polymer matrix was found to be related to the fluorescence lifetimes (τf) of NR [21]. Furthermore, the spectral position of NR

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• side ring). As expected, in MeCN quantum yields of nonoxidized compounds with a bithiophene side chain were higher (ca. 8% compared to 1% for a monothiophene derivative), but still moderate. Fluorescence lifetimes were short (0.2 ns), in accordance with moderate quantum yields. The oxidized compounds

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• –130,000 M−1·cm−1), high fluorescence quantum yields (Φfl > 50%) and fluorescence lifetimes of 3–4 ns. All properties that agree well with their structural resemblance to rhodamines and fluoresceines, and triangulenium dyes such as A3-TOTA+ and H-TOTA+ (Figure 1a) can be viewed as extended symmetric

• versions of these prominent dyes [16][22]. The second class of triangulenium dyes, without appended donor groups, are characterized by much less intense transitions (ε ≈ 5,000–20,000 M−1·cm−1), which for some derivatives leads to unusually long fluorescence lifetimes (τfl ≈ 20 ns) [23][24]. This long

• 8, for which the fluorescence spectra are shown in Figure 7, with fluorescence quantum yields of 16% and 12%, respectively. From the measured fluorescence lifetimes and quantum yields (Table 3) it is possible to calculate the radiative lifetimes (τ0), which are found to be in qualitative agreement

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• fluorescence quantum yields are rather low and fluorescence lifetimes are rather short due to ISC into the triplet state [50][51]. NDIs are reversibly reducible and their stable radical anions absorb in the visible to NIR light range [37]. The aromatic core of NDIs can be easily modified by substituents in

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• in single fluorescence lifetimes (3–5 ns) [31]. High and stable quantum yields and single lifetimes in duplexes along with firm stacking are properties that make tC and tCO excellent FRET donors. In order to make evaluation of FRET data more exact, through a high precision in the orientation factor

• monomeric qAN1, implying a firm stacking inside DNA [25]. The fluorescence lifetimes of qAN1 inside dsDNA show biexponential decays (average amplitude-weighted lifetimes ranging from 0.8 to 3.3 ns) for a majority of investigated sequences as compared to triexponential decays in ssDNA [25]. Overall, with a

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• bathochromic with respect to the non-rotaxane 3 counterpart. For the diluted CHCl3 solutions the fluorescence lifetimes of all compounds follow a mono-exponential decay with a time constant of ≈0.6 ns. At higher concentration the fluorescence decay remains mono-exponential for 3·TM-βCD and polymers 3, with a

• polyrotaxane compounds exhibit a granular morphology with lower dispersity and smaller roughness exponent of the film surfaces in comparison with those of the neat copolymer 3. Keywords: energy band gaps; fluorescence lifetimes; permethylated cyclodextrins; polyfluorene; polyrotaxanes; Introduction Over the

• films, increased glass-transition temperatures, enhancements of the surface characteristics. The optical investigations confirmed that the encapsulated compounds exhibited higher PLQE and fluorescence lifetimes. These complex architectures showed interesting electrochemical characteristics, which were

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• we performed a time-resolved fluorescence study of 3a, 4 and 5. The fluorescence decay curves are shown in Figure 3, whereas the fluorescence lifetimes and decay rate constants are presented in Table 2. All of the compounds under study displayed monoexponential decays, thus indicating one emitting

• . Synthesis of diethyl 1-(pyrene-1-carbothioamido)alkylphosphonates 2a–d, diethyl 1-(pyrene-1-carboxamido)alkylphosphonates 3a–d and (pyrene-1-carboxamido)methylphosphonic acid (4). Steady-state absorption and emission data for 3a–d, 4, 5 in CHCl3 solutions (c = 10−6 M). Fluorescence lifetimes and decay rate

Terminal lipophilization of a unique DNA dodecamer by various nucleolipid headgroups: Their incorporation into artificial lipid bilayers and hydrodynamic properties

• Emma Werz and
• Helmut Rosemeyer

Beilstein J. Org. Chem. 2015, 11, 913–929, doi:10.3762/bjoc.11.103

• (cFLA) Next, the fluorescence lifetime values of the LONs 10–15 were measured and are listed in Figure 17A–C as well as in Table 6. The fluorescence lifetime of the free Cy5 dye is reported to be 0.91 ns [27], 1.0 ns [28][29], and 1.0–1.4 ns [30]. In the literature, fluorescence lifetimes of free Cy5

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• 4 counterpart. The fluorescence lifetimes of polyrotaxanes follow a mono-exponential decay with a value of τ = 1.14 ns compared with the non-rotaxane, where a bi-exponential decay composed of a main component with a relative short time of τ1 = 0.88 (57.08%) and a minor component with a longer

• granular morphology with a lower dispersity supported by a smaller roughness exponent compared with the non-rotaxane counterpart. Keywords: cyclodextrins; energy band gaps; fluorescence lifetimes; persilylated cyclodextrins; supramolecular encapsulation; surface morphology; Introduction Semiconducting π

• properties of 4, 4a and 4b copolymers. Supporting Information FTIR spectra of the TMS-β-CD and copolymers, 1H NMR spectra of the TMS-β-CD, non-rotaxane 4 and 4b polyrotaxane copolymers, the fluorescence lifetimes of the non-rotaxane 4 and 4b polyrotaxane copolymers, the diagram with HOMO/LUMO levels of the