Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• is the reduction of acylazolium C to generate a stable benzylic radical D is formed, and this extends the lifetime of the radical, allowing for radical–radical coupling reaction to afford the desired γ-aryloxy ketones 12 in good yields. The utility of this sustainable method was further demonstrated

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• spin-center-shift (SCS) process in forming the core of septosone B (47) [32][33]. The influence of Lewis acids is partially attributable to two effects: (1) the observed elongation of the lifetime of the singlet excited state (from 0.846 ± 0.015 ns to 0.912 ± 0.014 ns), which reduces undesired

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• enables each azobenzene unit to store >200% more energy than isolated molecules, while achieving multi-order-of-magnitude improved storage lifetime and resistance to material degradation during repeated cycling. Feng and co-workers covalently grafted azobenzene groups onto RGO templates (Figure 3b) and

• azobenzene small molecules into polymer fibers [65], enabling solvent-free charging and discharging under visible light (Figure 6a). This material exhibited good capacity for releasing high-temperature heat (80–95 °C) at room temperature and in cold environments, along with an energy storage lifetime

• approaching two years, significantly exceeding the reported storage lifetime of other azobenzene-based solar thermal fuels. Han et al. synthesized a series of bisazobenzene small molecules with various substituents [90], all exhibiting photoinduced solid–liquid phase transitions. In contrast, comparable

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• ]. Absorption red-shift is usually correlated to the shortening of the thermal lifetime [13]. To understand and to predict the thermal lifetime of these photoswitches, it is important to have a closer look at the thermal Z–E isomerisation, for which three main mechanisms have been found to take place: inversion

• to the strong electron conjugation, these compounds usually show much shorter thermal lifetime, alongside with strong bathochromic shifts [17][18][19][20][21][22][23][24][25][26]. They are useful when fast responsive T-type photoswitches are needed. Moreover, some compounds show interesting non

• achieved in virtue of the reduced steric clash [29]. A systematic study on different azoheteroarenes with 5-membered rings demonstrated that the shape of the Z-isomer was responsible for the thermal lifetime of the photoswitch and for the PSS of the photoinduced Z–E isomerisation (Figure 4A) [14]. In case

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• lifetime measurement was performed on a Hamamatsu Photonics Quantaurus-Tau fluorescence lifetime spectrometer system. Specific rotations ([α]Dt) were measured with a HORIBA SEPA-500 polarimeter: concentration “c” is g/dL. Circular dichroism (CD) spectra were recorded on a JASCO J-1500 spectropolarimeter

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• based on fluorescence lifetime measurements in the following section. Since the CT states of these molecules exhibit emissive properties, their excited-state lifetimes were determined from emission decay measurements. Time-resolved fluorescence measurements revealed that the decays of the CT emission

• , IRF) was observed, along with a relatively slower decay component on tens of nanosecond timescales. Notably the lifetime of the slower component (15 ns) was clearly different from that of the CT emission (10 ns). This implies that the slower decay component at 460 nm is different from the CT state

• constant of 10 ns, which subsequently returns to the ground state with a lifetime of 135 μs. In contrast, when the Pe moiety is predominantly excited using a 420 nm pulse, the ground-state bleach and stimulated emission associated with the 1LE state of the Pe moiety are initially observed. However, this

Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer

• Yusuke Matsuo,
• Aoi Nakagawa,
• Shu Seki and
• Takayuki Tanaka

Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119

• structural relaxation in the excited state. The fluorescence quantum yield (ΦF) was determined as 0.078 (λex = 300 nm), and the fluorescence lifetime (τ) using biexponential decay model fitting as 1.7 and 4.4 ns. The partially fused structure of 5 exhibited a well-defined lowest-energy absorption band peaked

• , the ΦF value was modest (0.072), which is lower than those of related aza[n]helicene analogs [27][28]. The fluorescence lifetime (τ) was determined by biexponential decay model fitting as 0.65 and 3.2 ns. DFT calculation was conducted to investigate the electronic structure. The HOMO and HOMO−1 are

Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions

• Himani Malik,
• Sudha Devi,
• Debapriya Gupta,
• Ankit Kumar Gaur,
• Sugumar Venkataramani and
• Thiruvancheril G. Gopakumar

Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112

• be attributed to the electronically decoupled individual photoswitchable units by 1,3,5-functionalization and attainment of non-planar geometry [30]. Molecular switches with multiple switching units having extended lifetime for their non-equilibrium states will be a unique tool for fabricating multi

• barrier and the long lifetime of the non-equilibrium states are at the origin of their remarkable stability at room temperature. The remarkable stability of the states at ambient conditions provides an opportunity to use a single FNAAP molecule as an 8-bit operation. We propose to switch the molecule

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• , bis-olefin 5 fluoresces at 389 nm with a quantum yield of 7.5% and a lifetime of 6.0 ns. The radiative and non-radiative decay rate constants are calculated to be 1.3 × 107 s−1 and 1.5 × 108 s−1, respectively. The CD spectra and the dissymmetry factors (g) of enantiomers of CBBC 1, mono-olefin 3, and

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• | values of approximately 3.0 × 10−3, offering new architectures for CPL-active helicenes [40]. Singh’s group developed fluorophore-conjugated aza[7]helicenes 27a–d, with 27b demonstrating pronounced intramolecular charge transfer (ICT), a high ΦF of 0.71 and an extended fluorescence lifetime (τ) of 15.5

• ns [41]. Wu’s group synthesized a family of expanded azahelicenes 28a–e, where increasing helical length leads to red-shifted emission, prolonged lifetime, and attenuated PLQY [42]. Nonetheless, these compounds exhibit outstanding chiroptical performance, with |gabs|max reaching 4.8 × 10−2, |glum|max

• showed more intense phosphorescence and an extended emission lifetime in dilute solution. Notably, it demonstrated room-temperature dual-emission CPL originating from both prompt fluorescence and long-lived phosphorescence, a rare feature in helicene systems. In a subsequent study, the same group

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• graphitic citric acid-derived carbon dots CD-g-CIT (ΦF = 0.015) and the value for the amorphous citric acid derivative CD-a-CIT (ΦF = 0.74). The measured emission lifetime is also dependent on the nature of the materials, ranging from 2.4 to 13 ns, with a biexponential decay (see Supporting Information File

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• electronic effects will cause the Cz-unit to twist out of conjugation almost completely with the TTM radical core plane, leading to marginal orbital overlap between the D0 and D1 states. The reason for this increase in fluorescence lifetime τ is not completely understood; however, if the emission involves a

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• density distribution in the charge transfer (CT) excited state is facilitated by the presence of an electron-rich moiety and an electron-poor part in the same molecule, increasing the lifetime in the excited state. One of the representative classes of molecules demonstrating dual use in materials

• absorption profile in the visible region, ii) a long lifetime of the excited states, and iii) balanced redox potentials in both the ground and excited states [7]. In 2018, Zeitler and her collaborators conducted an innovative and in-depth study on modulating the photochemical properties of a family of donor

• , making it a promising candidate for new PC designs. While TBA and IMD displayed similar characteristics, the D–A IMD compound showed a shorter lifetime, which proved unfavorable in photocatalytic tests. The differing excited state conformations (bend vs planar) reported for these azepine analogs did not

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