Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• a certain application, for example where charge transport is more important than photoluminescence quantum yield or vice versa. Introducing alkyl chains can provide solubility, enabling facile solution processing, such as device printing techniques [13]. Hence, there is an ongoing interest in

• , we published a series of ‘bent’ diindenodithienothiophene derivatives (2–4, Figure 2) [16]. It was observed that oxidising the central sulfur atom significantly increased the solution photoluminescence quantum yield (PLQY) from 0.004 (3) to 0.72 (4). The diketo derivative 5 of compound 2 has been

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• obviously differ because of changes in their molecular configuration and equal to 2.86, 3.15, and 3.81 eV, respectively [27][28]. As the number of selenium atoms increases from DH-1 to DH-3, the fluorescence intensity (Figure S19 in Supporting Information File 1) and the fluorescence quantum yield (ΦF

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• fluorescence quantum yield (ΦF) as well as radiative (kr) and non-radiative (knr) fluorescence decay rates (see Table 2). The ΦPF was typical for carbazole–pyrimidine TADF compounds [31][43][44], in the range of 0.01–0.07 and decreased for compounds with stronger acceptor units (see Figure S28b in Supporting

• profiles of the DF decay. Unfortunately, TADF decay rates were inaccessible. Similar emission decay transients were also estimated for RTP compounds 2a and 2d both at singlet and triplet emission peaks (see Figure S31 in Supporting Information File 1). The largest DF quantum yield, ranging from 0.34–0.49

• easily minimized, enabling rather efficient TADF. We have shown that electron-withdrawing substituents connected directly to the pyrimidine unit have a larger impact on TADF efficiency in comparison with those attached through a phenylene bridge. The largest delayed fluorescence quantum yield, ranging

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

• the D–A compound 1 compared to POZ-DBPHZ reflects the contribution of an additional donor to relaxation of the molecular geometry in the excited state. The photoluminescence quantum yield (ΦPL) of the D–A compound 1 is lower (0.13 in cyclohexane) than that of the D–A–D compound POZ-DBPHZ (0.33) [17

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

• nm compared to that of ICzTRZ at 475 nm and showed a comparable photoluminescence quantum yield of 57.1% in a 20 wt % CzSi film versus 63.3% for ICzTRZ. The emitter was then incorporated within a solution-processed organic light-emitting diode that showed a maximum external quantum efficiency of 8.4

• % doped CzSi film of DICzTRZ emits in the blue at 488 nm and shows a photoluminescence quantum yield of 57.1%. The ΦPL of DICzTRZ is slightly lower than that of ICzTRZ (63% under N2 [14]), in line with its lower computed oscillator strength. DICzTRZ shows both prompt and delayed fluorescence, with a τp

• , b) EL spectra and c) current density-voltage-luminance properties. Device efficiency simulation of the fabricated OLEDs depicting the variation in EQE with varied PL quantum yield (vertical axis) and anisotropy factor (horizontal axis). The predicted EQEs are indicated with pink and blue rectangular

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• attributed to a greater electronic conjugation provided by the imine function present in the molecules of the series 3. Photostability and singlet oxygen quantum yield (ΦΔ) assays In order to be efficient for applications in photobiology, organic dyes must be stable when subjected to light irradiation for

• -aminoquinolines and salicylaldehydes and an easy purification methodology with yields of up to 91%. Photophysical experiments with the derivatives exhibited common transitions in these heterocycle units and corroborated the aromatic structures and good fluorescence quantum yield values for all compounds

• −5 M). Photooxidation rate constants and singlet oxygen quantum yield of compounds 3aa–fa and 3bb–be in DMSO solution. Supporting Information Supporting Information File 270: NMR spectra of the compounds, IR spectra, crystallographic data, photophysical and singlet oxygen spectra of new structures

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• given in Figure 4 and Figure 5, respectively. In addition, their plots of fluorescence intensities against absorbances are shown in Figure 6A and 6B. The tetrahydroacridine derivative 4b gave the highest fluorescence quantum yield of 8.2%. In order to elucidate the experimental observations and to

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• emission intensity (dependent on the sequence context) upon hybridization with complementary DNA and RNA [145]. Another analogue, 5,6-BenzopC (Figure 10) had high quantum yield and superior base pairing properties, but its fluorescence was completely quenched upon hybridization with DNA and RNA [146

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• , including the maximum of absorption and emission, fluorescence quantum yield, stokes shift, onset of the absorption wavelengths and optical band gap are summarized in Table 3. Aiming to understand the impact of substituents at arylethynyl groups, spectra of diversely substituted tetrahydroacridines were

• relative method using quinine sulfate [70]. Tetrahydroacridine derivative 4g containing an electron-donating methoxy substituent gave the highest fluorescence intensity as shown in Figure 3 and a quantum yield of 20%. DFT studies The arylethynyl substituents showed an impact on the absorption and emission

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• [120]. At the same time, in vivo experiments have shown the high efficiency of low-molecular-weight isoindigo 71 in oxygen sensitization for cancer therapy [121]. Therein, a high value (84%) of the singlet oxygen quantum yield was obtained. Conclusion To summarize, it can be concluded that isoindigo is

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• ]. More interestingly, the high fluorescence quantum yield as well as the excellent photoluminescence quantum efficiency in addition to extraordinary thermal stability are the most significant characteristics of these systems. Interestingly, this versatile C3-symmetric aromatic framework can also formally

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• . mutabilis germlings were stained with SYBR Gold, a sensitive probe forming a complex with DNA with high fluorescence quantum yield [36]. In the axenic callus-like form, the nuclei of algal cells and the bacterial cells accumulated around the rhizoidal tissue and exhibited the specific fluorescence after

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• deactivation of the excited state by conformational changes, e.g., torsional relaxation [42][43]. Since the fluorescence quantum yield of the parent berberine (1a) does not correlate well with the viscosity of the medium [40], it was concluded that the weak light-up effect in glycerol is mainly caused by the

• suppressed rotation about the Ar–O bond. Nevertheless, as the emission quantum yield of the derivatives 5a–e still remained low, even at high viscosity of the medium, there obviously exist additional relaxation pathways in the excited state, most likely a photo-induced electron transfer (PET) from the 10

• -aryl substituent to the berberine chromophore. The latter has been shown to operate also in resembling cationic, biaryl-type dyes [42][43]. Along the same lines, the low intrinsic emission quantum yield of the parent berberine (1a) has been suggested to result from an internal charge transfer (ICT

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• form the EDA complex, affording acylation product 123 under blue-light irradiation (Scheme 42). The quantum yield of the reaction was determined to be 0.08, suggesting that the reaction proceeded via radical coupling rather than a radical propagation. Moreover, the reaction was compatible with amides

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• approximately 50 nm longer than that of our oxide 3 [16]. The fluorescence wavelength, including the maximum emission (λem), and the quantum yield depend on the nature of the P-modification. Phosphine oxide 3, cation 5, and boron complex 6 emitted blue fluorescence in the visible-light region, with λem at 395

• –426 nm (Table 2). P-methylated cation 5 exhibited the longest wavelength and the highest quantum yield. The electrochemical properties of benzonaphthophosphoindoles were investigated by using cyclic voltammetry, and the electrochemical data are summarized in Table 3 and Figure S4, Supporting

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• satisfy the following criteria: i) a reaction-ready configuration, i.e., a substrate orientation in a configuration favorable for photochemical transformations, ii) in the supramolecular photocatalytic reaction (within the cavity), the quantum yield should be higher than both the unimolecular and

• bimolecular photoreaction quantum yield in an isotropic medium, and iii) the substrate and the products should be released from the supramolecular system via a dynamic exchange, which directs to a better yield and catalytic efficiency. To strengthen the above concepts, supramolecular photocatalysis needs a

• to determine the kinetic rates of the forward and reverse reactions. Instead, the supramolecular photochemical transformation efficiency is calculated via quantum yield and reaction velocity experiments. In addition, the thermodynamic and kinetic functions of the supramolecular systems can be

The fluorescence of a mercury probe based on osthol

• Guangyan Luo,
• Zhishu Zeng,
• Lin Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

• therefore the thermodynamic parameters show that the binding process between OST and Hg2+ was mainly determined by ΔH, with an action ratio of 1:1 and a K value of 1.552 × 105 L ∙ mol−1. Measurement of the fluorescence quantum yield The fluorescence quantum yield of ʟ-tryptophan at an excitation wavelength

• of 293 nm was 0.14, which was taken as the standard (Figure S5, Supporting Information File 1) [29][30]. The integration range of ʟ-tryptophan was 280–540 nm and that of OST–Hg2+ was 300–540 nm, and the fluorescence quantum yield of the aqueous probe solution was measured to be 0.08. Although this

• quantum yield is not high, the selectivity and sensitivity for the fluorescence analysis are good. This can be better used to detect Hg2+ ions and has a certain analytical value. Determination of Hg2+ in a water sample Tap water was directly used for the determination of Hg2+ using the standard addition

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• phosphates examined were barely fluorescent in methanol, with an emission quantum yield (Φem) in the 0.005–0.06 range (see Table 2 and Supporting Information File 1 for further details). We thus focused on compounds 1e, 1h, 3a and 3c as the model substrates. In the case of compounds 1e and 1h, we observed

• of the biradical intermediate 6 [55] preceding the loss of ROP(O)(OH)2 (paths (b), (c), Scheme 3). The long irradiation time required to achieve a complete consumption of the substrates 1 and 3 is in accordance with the low quantum yield values reported for this process [58][61]. Furthermore, a

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• use of pyrene as a fluorophore has two major disadvantages such as poor quantum yield and an emission in the blue region, which is unfavorable for potential applications in biological systems. The Schmuck group successfully developed several peptide-based probes using these approaches for targeting

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• singlet state. In the case of H, the quantum yield rises for increasing water content from 0% to 70%, which is attributed to the AIEE effect. Once it reaches 70%, a growing water fraction leads to an ACQ effect and hence the quantum yield decreases from 80% onwards (Table 2). A similar trend is observed

• of water, and later they drop due to ACQ. Also, it is possible to observe that the lifetimes follow a similar trend, where an increase of the emission intensity accompanies a minor prolongation of the lifetime and subsequently a drop of the quantum yield along with a shortening of the lifetimes

• , we observe a drastic drop in quantum yield when the water fractions are raised from 0% to 30%. As NMe2 is a pure push–pull system, the excited state can interact strongly with the solvent and due to the high polarity of water, a solvent quenching (SQ) effect is expected and also explains the observed

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• photomicroreactor compared to a batch system [17]. Still, it should be kept in mind that such comparisons are often strongly biased due to the difference in the photons absorbed in different reactor geometries and the possible difference in mass transfer limitations. Another benchmark is the quantum yield ϕ. This

• does not account for the quantum yield. Therefore, the molecular and electronic features of the reactants, which could significantly affect the PSTY value, are not accounted for when comparing different reactions. As such, it is hard to make global conclusions just by looking at the PSTY value

• , especially when intermolecular and intramolecular reactions or homogenous and heterogeneous reactions are compared. Since the quantum yield of most photochemical reactions is not known, the PSTY still gives a good comparison between different reactor geometries. The PSTY especially gains importance when

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• quantifier of the efficiency of a photochemical process. The quantum yield (Φ) of a reaction is often used as a mechanistic tool to probe whether a chain reaction is active (Φ > 1) or not (Φ < 1), although it should be noted that a reaction with Φ < 1 could also still include a radical chain process with an

• use of light would result in a greener reaction. where (a) is the definition of quantum yield and (b) is the quantum yield of a radical chain reaction. Review Enantioselective photocatalysis Amine catalysis Much of the history of amine catalysis used in photochemical reactions can be found in a review

• suggests a closed catalytic cycle is in operation; however, subsequent investigations by Yoon [20] found this reaction has a quantum yield >1 (Φ = 18), which signifies a chain propagation process is dominant. Therefore, according to Yoon’s proposed mechanism, the reaction proceeds with the condensation of

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• of all dyes was high in solvents with low polarities such as PhMe and THF, while it decreased with increasing solvent polarities such as DMSO and MeOH. The fluorescence quantum yields of the dyes were found to be very low as compared to fluorescein (ΦF= 0.95 at pH 9). For example, the quantum yield

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• state that collides with nearby molecules to reach its lowest vibrational energy state. Another fate of T1{PS}, permitted by spin–orbit coupling, is the radiative process of phosphorescence. If a molecule exhibits a high triplet quantum yield (rapid ISC and slow phosphorescence), this state is long

• quantum yield of the triplet state and iv) the energy transfer from the PS to the substrate must, overall, be exergonic. An ideal PS is a single, well-characterized pure substance of known composition that is stable at room temperature. In the presence of light, it is not toxic or degrades to toxic

• ® radical cation is regenerated here upon FAT, the authors considered the candidacy of the Selectfluor® radical cation as a chain carrier. However, the quantum yield of the reaction was found to be only Φ = 0.13, strongly evidencing against a radical chain mechanism. The complexation of Selectfluor® with

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U

• colourless and non-fluorescent core-unsubstituted NDI with a new charge transfer band with an absorption maximum in the visible spectral range and a high fluorescence quantum yield (up to 58%) [23][25]. Further, the 2-amino substituent offers the possibility to connect various amino acid side chains, thus

• significant Stokes shifts of emission (+60 nm) characterised by good quantum yield in aqueous solution. Thus, NDIs 3a and 3b are novel intensively fluorescent non-natural amino acid probe molecules with both, N- and C-termini available for incorporation into any peptidoid construct requiring a fluorescent tag