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

• reduction potential to −0.97 V vs SCE, a value low enough to reduce the ruthenium complex 2, whose potential is estimated at −0.89 V vs SCE, thereby yielding 3, the active species for the metathesis reaction. The catalytic cycle is closed by the reduction of the resulting osmium(III) complex, regenerating

• thiaporphyrins has achieved significantly higher yields (75%) compared to the Ru-based photocatalyst, which has only afforded a modest 18% yield under similar conditions. This enhanced reactivity was attributed to the strong reduction potential of the thiaporphyrin catalysts and their ability to participate in

• redox properties similar to those of squaraine derivatives, enabling key transformations such as the cyclization of anilines with maleimides and the reduction of Umemoto salts for trifluoromethylation of alkenes. With an excited-state reduction potential around 0.80 V, 46 demonstrates the capability to

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• the incorporation of the strong electron-withdrawing dicyanomethylene unit. The study suggested that 3b could be a potential n-type material for OPVs. The incorporation of two dicyanomethylene groups resulted in a material with strong electron affinity and low reduction potential of −0.56 V vs NHE

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• as final product, characterized by significant ring strain [59]. Under light irradiation, PhSSPh is in equilibrium with the corresponding thiyl radical, which is subsequently reduced to thiophenolate by PC•, originating from the reduction of *PC+. The reduction potential of PhS−/PhS• (Epred = +0.45 V

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• there are many reasons for this renewed interest, two major motivations are the unmatched control of oxidation or reduction potential that can be achieved and the environmentally friendly aspect of having electrons as the only consumed reagent. This latter reason is certainly an advantage in many cases

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• , value for Ar = Ph] [14][15][16][17][18] (Figure 1B). 5-Aryldeazaalloxazines 2 have been found to be even more powerful reductants than 1 due to their more negative ground-state reduction potential by ca. 300 mV. Moreover, 2 exhibits higher photostability than 1. Consequently, 5-aryldeazaalloxazine 2f

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• the additional electron transfer to form the corresponding anions is a highly favorable pathway due to the more positive reduction potential of radicals than that of the starting halides [38], employing redox mediators enables the generated aryl radicals to participate in radical arylation reactions

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

• /H2O (9:1). The low reduction potential of singlet-excited Aza-H (PC•+/PC* = –1.87 V vs SCE) led us to propose that the singlet-excited photocatalyst is oxidized by 4-cyanopyridine (4CP) (4CP/4CP•− = −1.81 V vs SCE) as the first step in this multicomponent reaction (Scheme 1, left). The oxidized

• -excited state lifetime), the quenching rate constant is roughly four orders of magnitude lower than singlet quenching (kq ≈ 105 M−1 s−1). This is in good agreement with the reported high triplet energy of 4CP [75] at 3.08 eV compared to 2.32 eV of 3Aza-H and the lower reduction potential provided by the

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• ) potentials of 3 were found to be shifted cathodically compared respectively to those of C60 and 2, indicating the electron-donating effects of the two Dip2Si groups. It is noteworthy that the first reduction potential of 3 (Ered1 = −1.52 V) is the most negative among those of the silylated empty fullerenes

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• state thereof, denoted with an asterisk, possessing a reduction potential of 2.0 V versus SCE (saturated calomel electrode). Subsequently, this excited state undergoes quenching through photoinduced electron transfer (PET) with styrene 5. The resulting vinyl radical cation exhibits electrophilicity at

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• formation of 6 (Table 2, entry 4). In contrast, Ru(bpz)3(PF6)2 did not form the desired product probably due to its too high reduction potential compared to Ts-ABZ (3) (value reported for ABX: E1/2(ABX) = −0.43 V vs SCE) [52] (Table 2, entry 5). In general, organic dyes could not catalyze the transformation

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• − with substrates 1–4. a100 equiv for the reaction screening, 20 equiv for the synthesis of 5a, and 40 equiv for the synthesis of 5b. bRoom temperature for the reaction screening, 50 °C for the synthesis. cIsolated yield. dHPLC yield. First reduction potential and estimated LUMO level of 5a and 5b. The

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• ] (Scheme 7A). Cyclic voltammetry measurements of a model NHPI ester showed a shift in its reduction potential from –1.79 V to –1.51 V (vs SCE in MeCN) in the presence of In(OTf)3. As such, it was hypothesized that the Lewis acid lowers the LUMO of the NHPI ester via interaction with the oxygen lone pair in

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

• -iodobenzyl chloride. Reaction mechanisms for the reactions of dimeric reductants (D2) such as (Y-DMBI)2 derivatives with acceptors (A) such as organic semiconductors or, in this work, organic halides that react further (the relative rates of steps are indicated for cases where the A reduction potential falls

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

• (versus NHE), respectively [3]. However, the molecular hydrogen evolution might compete, as it occurs at a more favorable reduction potential, lowering the selectivity of the catalytic system. While the addition of a proton source is beneficial to lower the overpotential, a metal-hydride (M–H

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• strength and their reactivity with organic semiconductors (SC) does not depend solely on the SC reduction potential, since the first step, at least in many cases, is a hydride transfer rather than an electron transfer [8][9]. Moreover, as well forming the desired semiconductor radical anion SC•−, and the

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

• , the LUMO isosurface in Figure 6, vide infra). Therefore, the higher reduction potential for 4BGIPN suggests that the benzonitrile core has a lower electron density, which is likely associated with extended π-conjugation and two additional electron withdrawing aza-type nitrogen atoms in the

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

• low absorption in the visible region to prevent side reactions and allow the photosensitizer to absorb as much light as possible. The oxidation potential of the sacrificial electron donor must be less positive than the reduction potential of the excited or oxidized photosensitizer for quenching or

• photochemical carbon dioxide reduction research, this technique is used to measure the reduction potential of the oxidized photosensitizer and the oxidation potential of the electron donor. However, the reduction potential of the photoexcited photosensitizer is usually estimated using the Rehm–Weller equation

• photocatalysis. Cyclic voltammetry carried out in standard conditions for mimicking an acetonitrile system had not been close enough to the catalytic conditions to get the required redox potentials. The difference between the oxidation potential of a sacrificial donor and the reduction potential of the excited

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

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

• reduction wave was observed at −1.78 V (vs Fc/Fc+) due to the reduction of the NI unit. For all the dyads containing a native PTZ unit, the oxidation potentials are virtually the same. However, the reduction potential changes to some extent, which is consistent with our molecular design to keep the donor

• after oxidation, and there was still a reversible reduction potential at −1.53 V (vs Fc/Fc+). Slightly cathodically shifted reduction waves were observed for other dyads containing an oxidized PTZ unit, i.e., NI-PTZ-Ph-O and NI-PTZ-C5-O. The redox potentials of the compounds are collected in Table 3

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• and the reaction scope, making possible new types of transformations [32][33][34][35]. On the other hand, it puts additional requirements on the design of the chiral ligand. Another important structurally tunable parameter comprises the oxidation or reduction potential of the complex. Additionally, as

• from ligands L7 and L4. Oxidation and reduction potential values for (GlyNi)L7 and (ΔAlaNi)L7 and comparison with previously reported data for (GlyNi)L1, (ΔAlaNi)L1, (GlyNi)L4 and (ΔAlaNi)L4 [36][37] (Pt, CH3CN, 0.1 M Bu4NBF4, vs Ag/AgCl/KCl(sat.), 100 mV/s). Supporting Information Supporting

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• -induced applications. Similar to porphyrins, fullerene C60 also possesses superior acceptor properties, low reduction potential and low reorganization energy [48][49]. Thus, keeping the diverse properties of fullerene in mind, de Miguel et al. [50] successfully prepared and characterized the triazole

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

• is observed at −1.63 V (vs Fc/Fc+), which is not in line with the presence of two electron-donating PTZ moieties – one would expect, the reduction potential of NI-PTZ2 should be more negative than the one for NI-PTZ. Slightly lower oxidation potentials were observed for NI-Ph-PTZ and NI-PhMe2-PTZ

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• and compared to 3,4,5-tris(4-chlorophenyl)-1,2-diphosphaferrocene. It was found that the position of the chlorine atom on the aryl fragment has an influence on the reduction potential of 1,2-diphosphaferrocenes, while the oxidation potentials do not change. Keywords: cyclopropenyl bromide

• cyclopentadiene fragments. For 1,2-diphosphaferrocene 8b, the reduction potential was positively shifted by 0.32 V as compared to 8c. It should be noted that an increase of phosphorus atoms' number in phosphaferrocenes leads to a greater positive potential, which in turn leads to the formation of dimers, which

• para-substitution of the Cl atoms in the aryl fragments did not significantly effect the oxidation potentials of 1,2-diphosphaferrocenes 8, while the reduction potential of 8b was shifted by 0.33 V to a more negative region as compared to 8c. ORTEP representations for cations 5c (a) and 6c (b) at the

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• sphere. Notably, the Ni template is an important component of the reaction. It is responsible for chirality induction and facilitates the cyclopropane ring opening, significantly decreasing the reduction potential value. It stabilizes the anion formed and serves as a directing group. Thus, the Ni–Schiff

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• generation of (phenylthio)difluoromethyl reactive species from bromodifluoromethyl phenyl sulfide and their synthetic application as well as mechanistic aspects. Results and Discussion Cathodic reduction of bromodifluoromethyl phenyl sulfide (1) At first, the reduction potential (Epred) of

• reduction peak was irreversible. Since the reduction potentials (Epred) of CF3Br and PhCF2Cl are −1.55 V (Pt cathode) and −2.11 V vs SCE (hanging Hg drop cathode), respectively [24][25], the reduction potential of 1 was found to be similar to that of PhCF2Cl. Next, we carried out the constant potential