Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• isomerization of alkenes [18][19], [2 + 2] cycloadditions [20][21][22][23][24], and dearomative [4 + 2] cycloadditions [25][26][27]. When considering conjugated alkenes, the triplet excited state energy and excited state lifetime are intrinsically linked to the degree of conjugation and substitution of a

• ] cycloaddition observed, despite the use of higher catalyst loadings. The efficient isomerization of 1a during these reactions indicated that substrate lifetime for efficient intermolecular reactivity may be problematic. While substrate-tethered reactivity, developed by Brown and co-workers was unsuccessful [49

• as an operational mechanism. While intermolecular alkene quenching to enable [2 + 2] cycloaddition was inefficient, presumably due to poor substrate lifetime, intramolecular [2 + 2] reactivity with both acrylates and alkenylboronic esters was effective. The small 3D, boron-containing fragments could

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• functionalized ruthenium complex and a fragment crystallizable (Fc) ligand anchored to a magnetic bead, enabling the localized generation of singlet oxygen near antibodies (Figure 4B). The short lifetime and limited diffusion of singlet oxygen ensure exclusive reactions with proximal histidine residues. This

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• efficiencies in OLED performance, since lower applied voltages will be required. It has been shown that a desired applied voltage should be below 10 V to obtain significant light intensity from ANTH-based OLEDs [8]. Such low operating voltage may reduce power consumption and increase the lifetime of a blue

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• resistance [2]. Innovative scaffolds for novel antibiotic drug candidates are required to create new methods for safe and effective treatments. Chemically designed drug leads can complement naturally found antibiotics and may engage multiple modes of action and might have a longer lifetime before resistance

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• excitation to the triplet state from the ground state S0. This effect mitigates rapid back-electron transfer from the singlet excited state to the ground state, extending the excited-state lifetime of the photocatalyst. Since the T1 → S0 transition is spin-forbidden, the process increases the overall

• have been calculated and have indicated that this latter could be a viable candidate for use in photoredox catalysis. Additionally, its measured excited-state lifetime (τ = 5.5 ns) is similar to those of other widely used organic photocatalysts, such as carbazole derivatives, further supporting its

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• splitting, high quantum yield for intersystem crossing, and long triplet state lifetime, act as robust electron mediators. This section highlights the use of metal-free porphyrins in organic photoredox catalysis. So far, mainly planar metal-free porphyrins have been explored as photoredox catalysts, paving

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• PL lifetime was measured using a Quantaurus-Tau C11367-34 fluorescence lifetime spectrometer (Hamamatsu Photonics, Japan). (a) Reported photophysics of diphenylacetylene after photoexcitation. (b) Our molecular design to suppress internal conversion. Relationship between the molecular structure of

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• –80%) along with their preliminary photophysical (absorption, emission and time resolved fluorescence lifetime) properties. The condensation reaction for assembling the required DPMs were catalyzed with trifluoroacetic acid (TFA) at 0 °C to room temperature (rt), and the stable dipyrromethanes were

• 457.40), 16 (406.78, 430.48, and 457.40), 17 (406.18, 430.65, and 455.19), 18 (406.78, 430.42, and 457.40). Moreover, as can be seen from Figure 3 and Table 1, the time resolved fluorescence lifetime decays have also been investigated. Noticeably the fluorescence decays at around 457 nm were single

• like 1H NMR, 13C NMR, and mass spectral data. The preliminary UV–vis absorption as well as fluorescence emission spectral data for thus prepared truxene-based compounds were recorded in chloroform and compared as well. Additionally, time-resolved fluorescence lifetime decays were also measured for thus

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• impact on stratospheric ozone [1][2][3]. However, as it was demonstrated in the 1980s, HFCs have significant global warming potential (GWP) [1][2][3]. In the 2000s, a new generation of refrigerants, namely hydrofluoroolefins (HFOs), which have a short atmospheric lifetime and low GWP [4][5], has been

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• catalyst in the sulfonylation/arylation of styrenes and as a triplet sensitizer in energy transfer catalysis. The singlet lifetime is sufficiently long to exploit the exceptional excited state reduction potential for the activation of 4-cyanopyridine. Photoinduced electron transfer generating the radical

• -mentioned methods [39]. However, the longer lifetime of the triplet state usually comes at the expense of a lower energetic driving force. Helicenes in particular show an increased ISC rate compared to planar molecules, which is attributed to an enhanced spin-orbit coupling that is sensitive to their degree

• cage escape quantum yields [67][68]. Aza-H exhibits a relatively long singlet lifetime of 9.6 ns (see Figure 4E), which is sufficient for diffusion-controlled energy or electron transfer at moderate substrate concentrations. Transient absorption (TA) spectra of an Ar-saturated Aza-H solution were

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

• Maksim V. Kvach,
• Stefan Harjes,
• Harikrishnan M. Kurup,
• Geoffrey B. Jameson,
• Elena Harjes and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

• ) quickly converts into the inactive β-ribopyranosyl form in solution, but substituting hydrogen atoms with fluorine atoms in the 2'-position leads to cedazuridine (Ib), which is stable [53] and now used in clinics as a CDA inhibitor in the liver, extending the lifetime of coadministered decitabine [8]. We

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• in chloroform and carbon tetrachloride upon exposure to orange light. The lifetime of Z-11a in CCl4 was significant and the thermal backward reaction occurred in darkness with the restoration of the initial absorption of the E-isomer for 57% after 5 h and for 100% in 18 h. N,N'-Diethylindigo (11b

• particular, the lifetime of Z-11a in CCl4 was found to be only 3.1 s versus 18 h measured previously. Nevertheless, it was obvious that N,N'-dialkylindigos were prone to the reversible photochemical isomerization. In addition, it was also found that the thermal backward Z–E conversion of 11a and 12

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• absorption intensity at 700 nm, corresponding to the triplet excited state of C60 (3C60*), was observed along with the decay of the CS state with a lifetime of 1,380 ps. Conversely, for compound 77, excitation at 387 nm was required for the formation of the CS state and an increase in the absorption

• intensity at 890 nm, indicating the emergence of 1C60* state with a lifetime of 115 ps, was accompanied by a subsequent increase in the absorption intensity at 1,021 nm, corresponding to the formation of the C60 radical anion. The lifetimes of the charge separation and charge recombination events were

• lifetime of 71 ps in toluene. Meanwhile, the absorption at 640 nm, corresponding to the ZnP radical cation, was not observed. The results obtained from Rehm–Weller’s equation [146] suggested that photoinduced electron transfer was thermodynamically permitted in 86. However, ultrafast energy transfer from

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• damage. In order to investigate the involvement of singlet oxygen in the DNA cleavage process, the samples were irradiated in the presence of NaN3 or in D2O (Table 3, Supporting Information File 1, Figure S18). The latter is known to extend the lifetime of singlet oxygen by a factor of ca. 10 as compared

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• amplitude at 654 nm decays with a 1 ps lifetime. The isosbestic point in Figure 4a is consistent with a clean transformation such as monomer formation. The corresponding monomeric radicals are calculated using TD-DFT (M06/6-31G(d,p)) (Figure 4e) to have absorptions at similar energies to those seen in the

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• efficiencies pointed out that DMB-TT-TPA (8) is among the best D–π–A modal fluorophores suitable for an OLED application. Moreover, the photophysical properties of DMB-TT-TPA (8) were investigated through time-resolved fluorescence studies (390 nm laser source in THF). The fluorescence lifetime (τ) of DMB-TT

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• ), while a reductive quenching by BIH could be possible since the oxidation potential of BIH is 0.27 V (ΔG < −0.25 V). We performed Stern–Volmer analyses to verify our hypothesis. As expected, the lifetime of the PS* (τ0 = 14 ns in aerated DMA/TEA 7:1), is reduced upon the addition of the sacrificial

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• spin-coated films, the best fitting of the decay curves of 1 and 2 indicated three and two lifetimes, respectively. Compound 1 displayed a dominant and longer lifetime compared to solution, 25.9 ns (66.83%), attributed to excimer emission, which usually presents longer lifetimes compared to the

• monomeric species [34]. It agrees with the intensity inversion of the vibronic absorption bands and PL redshift in the spin-coated film compared to the solution. The intensity inversion suggests formation of H-aggregates, leading to excimer fluorescence [35]. Due to the similarity to the lifetime in

• solution, the 6.90 ns lifetime in the film is attributed to monomeric emission. The shortest lifetime of 0.90 ns can be related to the emission of aggregated species driven by π–π interactions [36], contributing to almost 20% of the total emission of 1. The longer lifetime of 2 in film (3.84 ns) can be

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• conventional radical polymerization. Most free radicals have an extremely short lifetime due to a diffusion-controlled termination process between two free radicals. The inevitable termination between radicals makes the synthesis of well-defined polymers and co-polymers very difficult. In addition, polymers

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• aerated MCH solution. The reduction in quantum yield on exposure to oxygen is due to quenching of the triplet excited states indicating a TADF luminescence mechanism. PLQY in Zeonex films is 39% in air, which is lower than the PLQY of 87% reported for 4CzIPN [17]. The two-component excited state lifetime

• with prompt and delayed fluorescence is characteristic for the TADF-type luminescence [1]. The excited state lifetime of 4BGIPN has a biexponential decay with a prompt fluorescence τp = 13 ns and a delayed fluorescence τd = 1655 ns components in MCH solution. Zeonex films of 4BGIPN exhibit a similar

• profile remained broad and featureless (Figure 5) in Zeonex matices. Notably, a frozen MCH glass exhibits a new vibronically resolved component at 405 and 470 nm, together with a broad CT profile. The first resolved high-energy PL component at 405 nm (Figure 5 top right) has a lifetime of 13 ns, which we

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• range expected for photosensitizer quenching. Triethylamine has the lowest oxidation potential and is the most reducing of the 3 species (0.69 V vs SCE) which means that it can both reductively quench Ru(bpy)3 and regenerate photooxidized Ru(bpy)3 if the lifetime and electron-transfer rates are

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• , or it is trapped with pyrrole derivatives 3 in a C–C bond formation to afford arylated products 4. Based on the ultrashort lifetime of *PDI•− (τ = 145 ps), the notion of its photochemistry has attracted skepticism and it has been suggested decomposition products of *PDI•− may instead serve as

• a halogen atom transfer (XAT) agent [101]. While yields of the monophotonic oxidative quenching route and the (biphotonic) conPET reductive quenching route were generally well comparable, the RQ route clearly benefits from a longer lifetime of the key catalytic species, shorter reaction times and

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

• unambiguous experimental evidence that the spin–vibronic coupling of 3CS/3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even if the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse

• emitters [32][33]. However, the most popular optical spectroscopic methods previously used in this area, such as the very often used transient photoluminescence spectral measurement or the luminescence lifetime measurement, are unable to detect the dark states of the TADF emitters, i.e., the 3LE and 3CS

• dyads containing native PTZ units in HEX show an obvious double exponential feature. For example, the lifetime of NI-PTZ-F is 24 ns (96.3%)/1.2 µs (3.7%) under N2 atmosphere (Figure 4a). The short-lived component can be attributed to the prompt fluorescence of 1CS → S0, while the long-lived component is