Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• exhibited high luminescence (with a quantum yield of 68%) and displayed the characteristic trivalent terbium emission bands with emission peaks at 491 nm, 545 nm, 583 nm, and 621 nm, corresponding to transitions from the 5D4 excited state to the 7F6, 7F5, 7F4, and 7F3 ground states, respectively (Figure 2

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

• diphenylacetylene structure as the π-conjugated core. As a part of our research projects, we have begun to explore diphenylacetylene-based luminescent molecules despite diphenylacetylene not exhibiting fluorescence at room temperature because it undergoes a πσ* excited state that rapidly forms a trans-bend

• structure (Figure 1a) [14][15][16]. Our extensive efforts have revealed that introducing electron-donating alkoxy and electron-withdrawing cyano groups at both ends of the diphenylacetylene scaffold slows the internal conversion to the πσ* excited state. Further incorporating four fluoro substituents in the

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

• excited state, Mes-Acr+*. This excited state then reductively interacts with the sulfinate anion to produce a CF3 radical. The CF3 radical subsequently attacks the target substrate, forming an intermediate radical, which undergoes further oxidation to yield the desired product (Scheme 47a). The Wu group

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

• photocatalysts (PC) that act as oxidants in the excited state [27]. The direct functionalization of amides with alkenes has been a relatively underexplored area in research, as evidenced by the limited number of examples reported in the literature. An interesting observation was made by the Nicewicz group during

• , enhances charge transfer by stabilizing the mesityl moiety. Conversely, the introduction of tert-butyl groups increases the life time of the excited state [52][53][54][55][56]. As a consequence, the PC IV is a strong oxidant in the excited state and displays unique oxidizing properties (E1/2[*PC+/PC

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• . Appropriate selection of the phosphine reagent was the key to success in the process. Due to the lower oxidation potential, electron-rich PMe2Ph preferentially transferred a single electron to the excited state of the photocatalyst rather than the alkene, which was essential for obtaining the desired product

• iridium photocatalyst [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 leads to excited-state *[Ir(III)], Ered (*[Ir(III)]/[Ir(II)]) = +1.21 V, possessing sufficient energy to oxidize PPh3, forming the triphenylphosphine radical cation. Subsequently, benzoic acid undergoes deprotonation facilitated by a base, producing

• excited-state photocatalyst oxidizes the cesium alkyl oxalate via SET, followed by elimination of two carbon dioxide molecules, generating a tertiary alkyl radical that easily combines with an electron-deficient alkene, providing the product. This protocol was well compatible with a wide range of acceptor

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

• ][13][14][15]. Most of the established organic catalysts (acridinium salts [16][17][18][19], cyanoarenes [8][20][21][22], quinones [23][24], etc.) [10][25] are cationic or electron-deficient and tend to act as excited state oxidants in a reductive quenching cycle. Only recently, more reducing catalyst

• classes have been investigated, including second-generation cyanoarenes [8], arylamines [26], phenothiazines, phenazines and phenoxazines [9][27][28], which can act as excited state reductants comparable to precious metal-based photoredox catalysts. Singlet-excited organic chromophores often have short

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• singlet vertical electronic excited state energy values computed with the TD-M062X/6-311++G** utilizing Gaussian 16. The data was extracted by considering the half width of 0.33 at the half height of the optical spectrum. The calculated spectral data including the absorption onset (λonset), the first

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

• is worthy of being called anti-Markovnikov hydrochlorination was reported by Nicewicz in 2014 [90]. The inversion of regioselectivity is best understood by examination of the proposed catalytic cycle (Figure 8). First, electronic excitation of photoredox catalyst 149 at 450 nm results in an excited

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• photodynamic therapy photosensitizers (PDT PSs) [41] and magnetic resonance imaging contrast agents (MRI CAs) [42], which are the most relevant topics in fullerene biological studies. Aggregated fullerenes in the micelle structure may cause self-quenching of the excited state of PS fullerenes or may inhibit

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

• studies [45] a plausible photocatalytic cycle could be proposed (Scheme 5). Upon light irradiation, single-electron reduction of Ts-ABZ (3) (E1/2red = −0.62 V vs SCE) [45] by the excited state photocatalyst (E1/2 [RuIII/RuII*] = −0.86 V vs SCE) [53] can occur to form an azide radical, which upon addition

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

• (3.15 to 2.06 × 105 s−1) [34] when employing catalytic IrIII excited state reductants with moderate reducing potentials (E1/2red[IrIV/*IrIII] ≈ −1.13 V vs Fc0/Fc+ in MeCN) [35]. This suggests that in the absence of a sufficiently strong driving force, BET and fragmentation compete to influence the

• ], have been employed as suitable photocatalysts (Scheme 4B). Under visible light irradiation the photocatalyst (PC) is excited into its corresponding excited state (*PC), where it can be reduced by a suitable electron donor such as DIPEA or Hantzsch ester to generate the reduced form of the photocatalyst

• a reductive quenching mechanism. However, since the overall transformation is redox-neutral, no stoichiometric reductant was employed. Instead, fluorescence-quenching studies suggested that the reductive quenching of the iridium excited state (*IrIII) was taking place "off-cycle" via oxidation of

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

• benzene (Figure 3). This indicates that in addition to structure I, which is traditionally used to depict indigo, intraionic resonance structures II and III with single C–O bonds and double C=N bonds make a pronounced contribution in the ground state of indigo (Figure 3) [13][14]. In the excited state

• hypsochromic shifts of the absorption maxima [24]. These effects can be easily explained considering the direction of the charge transfer in the H-chromophore of indigo upon excitation. Thus, in the excited state, the electron density shifts from the N towards the O atom (Figure 4). Therefore, an increase in

• interest and, therefore, has been investigated comprehensively. To understand the photochemical and photophysical properties of indigo, a great number of theoretical and experimental studies [25][26][27][28][29][30][31][32][33][34][35] have been performed so far, which allowed to characterize excited state

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

• of 63 in toluene revealed that the lowest singlet excited state (S1) decays mono-exponentially to the ground state (S0) within approximately 1 ps, suggesting the existence of an accessible CI between S1 and S0. In the S1 minimum conformation of 63, the PCBD moiety adopted a planar orientation

• room-temperature solution (dichloromethane) and as a frozen matrix at 77 K [123]. This is in contrast with the typical homoleptic phenanthroline-based CuI complexes renowned for their emissions from a triplet metal-to-ligand charge transfer excited state. The absence of luminescence may be attributed

• the plausible energy transfer from the local charge-separated (CS) state of the push–pull chromophore (namely N,N-diethylanilino (DEA)•+–TCBD•−) to the singlet excited state of C60 (1C60*). In transient absorption spectral measurements conducted via the femtosecond laser-flash photolysis of compound

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

• by the reaction with C-radicals 4 and 5 to give peroxides such as 6 (Scheme 4), by cycloaddition of 1O2 to alkene and diene units, or by deactivation of the excited state in a triplet-triplet annihilation [90], all of which leading to a reduced photocleavage efficiency. However, with much longer

Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

• Laura Abella,
• Gerard Novell-Leruth,
• Josep M. Ricart,
• Josep M. Poblet and
• Antonio Rodríguez-Fortea

Beilstein J. Org. Chem. 2024, 20, 92–100, doi:10.3762/bjoc.20.10

• analyzed the interaction between C60 and the nanotube within the peapod. Next, we have found that some dimeric C60–C60 fullerene structures inside the carbon nanotube are thermodynamically favorable. Experiments indicate that, besides C60 sensitization via a singlet excited state, the [2 + 2] cycloaddition

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

• : if photoinduced cleavage occurs we would expect the scope of RX cleavage to be more-or-less limited by the reducing strength of D• (E(D+/D•) = ca. −2.4 V for both species used here), whereas the singlet excited state of the dimer, D2*, should be more reducing, allowing more challenging substrates to

• longer-time spectra with Cyc-DMBI• having a blue-shifted absorption relative to N-DMBI•, consistent with the observed features arising from the monomeric radicals. Intersystem crossing (ISC) from the singlet to triplet excited state is also a possibility and TD-DFT calculations suggest that the dimer T1

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

• (excitation at λmax), respectively, leading to a mega Stokes shift (>100 nm) of 109 nm, which could be explained to be due to a fast relaxation from the excited state to the ground state as a result of a powerful intramolecular energy transfer between the TPA and boron groups through the thieno[3,2-b

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

• − (−1.67 V) is plausible, albeit the difference is not high. Estimation of the redox potentials of the excited state of PS (Eox* and Ered*) was done assuming that the energy difference (E00) between the energies of the excited and ground states, both at their zero levels, is the same as the emission

• accumulation of the reduced PS− species. We propose the following mechanism (Scheme 1). The PS absorbs a photon (420 nm) and in its excited state is quenched by BIH, which is deprotonated by the base (TEA) and forms a radical (BI·). Since this radical is highly reducing, it can happen that this species can

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

• at the Colhex–Iso transition. The reduction of PL at the Cr–Colrect transition also reflects stronger molecular π-stacking of 2 in the Colrect phase compared to the crystalline state. The excited state lifetimes of 1 and 2 in chloroform solutions and spin-coated films, both excited at 401 nm, are

• within B3LYP/def-TZVP(-f) level of theory and their frontier orbitals (b). Molecular structures of compounds 1 and 2. Characteristics of 1 and 2 extracted from [17] and [18], respectively. Excited state lifetimes and relative amplitudes of 1 and 2 in chloroform solutions and spin-coated films at room

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

• high-performance red/orange TADF emitters (Qx65). The team successfully transitioned the emission type from local excited-state to charge-transfer state by carefully tuning the molecular structure and energy levels, leading to efficient TADF. The Qx65a-based orange TADF OLEDs exhibit a maximum EQE of

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• transition orbitals [31][32][33]. In these molecules, the lowest excited state still shows moderate or large oscillator strengths or a mixing of two excited-state components, locally excited (LE) state and CT excited state. This kind of excited state was later known as a hybridized local and charge transfer

• . To further figure out excited-state properties of TPECNz, the natural transition orbitals (NTOs) of singlet (S) and triplet (T) excited states were executed based on time-dependent (TD)-DFT calculations at the CAM-B3LYP/6-31G(d) level of theory. As shown in Figure 1b, the hole and particle of TPECNz

• maxima shifting towards longer wavelengths with increasing solvent polarities. Particularly, the maximum PL peaks in low polar solvents showed little shifts because of the LE character, whereas red shifts of the PL maxima apparently occurred in higher polar solvents due to CT excited state; therefore

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• stabilization of the first excited state in relation to the stabilization of the ground state, which is observed in other PDIs when installing the electron-withdrawing nitrile group on the polycyclic aromatic core [27][28]. The molar extinction coefficients (ε) of all compounds in ethyl acetate were determined

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

• (Scheme 12B). Boydston and co-workers [91], systematically studied various pyrylium and thiopyrylium PCs (Scheme 13). It is necessary for these PCs having a high excited-state redox potential to oxidize the enol ether initiators. A range of enol ether initiators that has been successfully applied in metal

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

• spectra showing both broad and resolved components, thus supporting the assignments of the 3CT and 3LE(donor) excited states. The excited state lifetime of the broad CT component has a multiexponential decay with averaged lifetimes of 0.7 ms in MCH glass and up to 212 ms in Zeonex films, which we assigned