The trans-influence in gold chemistry from a catalytic perspective

• Manfred Bochmann

Beilstein J. Org. Chem. 2026, 22, 838–856, doi:10.3762/bjoc.22.66

• other respects, notably in their π-acceptor capacity. This leads to interesting photoluminescence effects. For example, while (C^Npy^C)AuCl shows poor photoemissions in the solid state, this changes if Cl is replaced by strong donors, notably aryl, alkynyl or thiolate anions [39][40]. These raise the

Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity

• Daria A. Burmistrova,
• Vasiliy A. Fokin,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Maxim V. Arsenyev,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2026, 22, 828–837, doi:10.3762/bjoc.22.65

• in the solid state and in solution, highlighting the structural role of the sulfinyl group. Cyclic voltammetry demonstrated that the oxidation potential of the catechol fragment is systematically modulated by the oxidation state of the sulfur atom. The introduction of the S=O group shifts the first

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• molecule displays C2 symmetry, consistent with the simplified NMR spectra, and the solid-state metrics support the proposed pentacyclic structure. Compound 25 (C18H17N4O2 u.d. = 13) has one degree less of unsaturation than the diimine 24 (C18H14N4O2 u.d. = 14) suggesting that a reduction is required for

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• materials [14]. Furthermore, diazafluorenylidenes may exhibit polymorphism, high solid-state emission, and decent charge carrier mobility which makes these molecules promising for use in organic optoelectronics [5][15][16]. Current synthetic approaches to diazafluorenylidenes are limited. The typical method

Halogenated azobenzene acrylates: from efficient solution photoswitching to stable solid-state photochromic materials

• Martina Vachtlová,
• Michaela Fecková,
• Vítězslav Zima,
• Jan Podlesný,
• Milan Klikar,
• Oldřich Pytela,
• Patrik Pařík,
• Jakub Opršal,
• Eliška Juhaňáková,
• Veronika Chrtová and
• Filip Bureš

Beilstein J. Org. Chem. 2026, 22, 782–794, doi:10.3762/bjoc.22.60

• similar photoswitching in the solid-state is much less explored. Since Hartley’s first report on a spatial rearrangement along the N=N double bond of azobenzene [5], a plethora of related molecular photoswitches has been developed and it has also been demonstrated that azobenzene can be covalently bound

• solid-state E/Z isomerization [8][9]. Azobenzene was also incorporated into the structure of liquid crystal elastomers (LCEs) [10][11], where UV-light curing increases thermally induced LCE film actuation or even locks the film in a specific shape during flipping [10]. The phenomenon of photoactuation

• pattern is known to provide a very long half-life of the Z-isomer ranging from tens of days to months [23][24]. Photoswitching properties both in solution and in the solid state were investigated along with a potential use of 1a–f as thermal-sensing labels. For these purposes, differential scanning

Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• ), almost 2 equivalents of gas were produced from 1 equivalent of formic acid within 3 hours. It has to be noted that, since all reactions were conducted in solution, all copper complexes must be considered as monomeric. In fact, dimeric Cu–H and Cu–formato are generally observed only in the solid state [53

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• X-ray crystallographic analysis was performed (CCDC 2513894). The solid-state structure of 1ac shows that the phenyl group on the E-alkene is directed antiparallel to the fused benzene ring. The dihedral angle of the alkene moiety (∠C4–C5–C6–C7) of 1ac is 146.4°, which is distorted by 33.6° from an

Synthesis and anti-cancer activity of naphthalimide–organylselanyl conjugates

• Rajkumar Ravi and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2026, 22, 416–435, doi:10.3762/bjoc.22.29

• solid state structure of the compound 7. All the above-mentioned non-bonded interaction distances are shorter than the sum of the van der Waals radii of the respective elements in contact [55]. Computational analysis To further evaluate the energy-minimised structures useful for molecular

• -crystal XRD coordinate file, while the structure of compound 8 was constructed using Gaussian tools. The C–Se–C bond angle computed from the gas phase optimised structure of 7 is 97.8°. It is in good agreement with the bond angle (102.5°) observed from the solid-state structure of 7. Due to steric reasons

• selenium center. The second important feature is the torsional motion in the propylene linker attached to the imide nitrogen of the naphthalimide core. The calculated O–C–C–C torsional angle from the gas-phase structure of 7 is −61.5°. The observed torsional angle from the solid-state structure of 7 is

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• metal fragment localizes a subset of the π-system, effectively unmasking the latent double-bond character of the aromatic ring. This is strikingly captured in the solid-state structure of the complex. One ring retains near-planarity, with a mean C–C distance of 1.41 Å, which is slightly elongated

Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF

• Ruiyan Wang and
• Yunan Wu

Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16

• analysis indicate that the HOMO and LUMO are localized on the carbazole and phthalimide fragments, respectively, affording a small singlet–triplet energy gap. In the solid state, compound 1 exhibits pronounced phase dependence: powder samples display room-temperature delayed emission with principal bands

• exciton recovery and enhancing device performance in both solution and solid states. Although significant progress has been made in developing systematic molecular and solid-state engineering strategies for RTP and TADF, examples of simultaneous “phosphorescence-delayed fluorescence” switching within a

• single molecule under different environments or phases are still relatively rare [33]. The underlying challenge lies in the different demands that RTP and TADF place on the microscopic configuration and solid-state environment. RTP typically favors molecular rigidity, confinement, and specific

Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH

• Adrian G. Rossebø,
• Hannah G. Kolberg,
• Anders E. Tønder,
• Louise Kjaerulff,
• Poul Erik Hansen,
• Karla A. Frydenvang,
• Jesper Østergaard and
• Jesper L. Kristensen

Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11

• characterization of 25CN-NBOH and report key physicochemical properties in the solid state as well as in the solution state, namely stability, ionization, solubility, partition coefficient, and membrane permeability. We show that the hydrochloride salt is a stable and well-defined crystalline compound that is also

Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection

• Ergin Keleş,
• Alberto Barsella,
• Nurgül Seferoğlu,
• Zeynel Seferoğlu and
• Burcu Aydıner

Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6

• at the B3LYP/6-31+G(d,p) level. Frontier molecular orbitals of a) 2a, b) 2a+CN−. TGA curves of dyes. Synthetic pathway of compounds. Proposed interaction mechanism with CN−. Summary of reaction conditions, yields, and solid state color of dyes 2a–c. Photophysical properties of dyes 2a–c in various

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

• stereoretentive coupling at C2 with aryl bromide 86, yielding 88 as a single diastereomer. Manipulation of the protecting group of 88 arrived at lycoplatyrine A (89). Notably, 87 and related α-hydroxy-β-lactams were obtained via Norrish–Yang cyclization of the corresponding neat α-keto amides in the solid state

• under blue LED irradiation. Solid-state reactions differ from solution-phase processes due to restraints on molecular motions imposed by the crystal lattice, thereby avoiding side reactions caused by unrestricted molecular motions in solution [41]. It has also been demonstrated that for crystalline 1,2

• undergoes SET to form a zwitterion as an intermediate step prior to cyclization [35][43][44]. It is noted that such molecular motions (rotations) are possible in solution but prevented by crystal-lattice restraints in the solid state [37]. In this synthesis, Sarpong et al. utilized the Norrish–Yang reaction

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• along with comparator H2 as solid-state sequestrants for a panel of five dyes (methylene blue, methylene violet, acridine orange, rhodamine 6G, and methyl violet 6B). We find that catechol-walled H2 (OH substituents) is a superior sequestrant compared to G2W1–G2W4 (OMe substituents). X-ray crystal

• violet removal efficiency using triphenylene-walled G2W1. Design, synthesis and characterization of G2W1–G2W4 The sequestration of large planar aromatic dyes from aqueous solution into the solid state requires water-insoluble hosts that possess complementary molecular recognition surfaces. Previously, we

• larger aromatic walls in the form of triphenylene walls. To ensure that the targeted hosts display low aqueous solubility required for solid state sequestrants, we exchanged the O(CH2)3SO3Na groups for OMe groups. Accordingly, we targeted the preparation of W1 and W2 (Scheme 1) which contain large π

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• described above, the C6–C1–C1'–C6' dihedral angles in all conformers of (S)-3a–g and (R)-3h were approximately constant (plus or minus ca. 42 degree). The range of distribution of the angles was also small, ranging from +39.8 to +43.9 degrees, or −40.2 to −45.8 degrees (Figure 5). In the solid state of (S

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

• monomer to 103 min for the polymer. Linear azobenzene polymer solar thermal fuels Linear azobenzene polymers possess excellent processability and serve as ideal solid-state matrices for photoisomerization [49][50][51][52][53][54][55][56][57], making them suitable candidates for solar thermal fuels

• visible light under sunlight irradiation [59], achieving a solar efficiency of 0.4% and a solid-state isomerization efficiency of 72.7% (Figure 5b). Feng and co-workers reported the synthesis of three azopyridine polymers (ortho-, meta-, and para-) [60], with the m-azopyridine polymer exhibiting a

• azobenzene derivatives [82][83][84][85][86][87][88]. From an energy charging perspective, some solvent-free systems store energy in the solid state [89] or via photoinduced solid–liquid phase transitions [61][69][74], which occur because the melting temperature (Tm) of trans-azobenzene is above room

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• ][68][69][70][71][72][73][74][75][76][77][78] mechanisms of cyclic azoalkenes have been studied with experimental and computational techniques for more than six decades, in solution [51][55][59][60][61][64][67][69][70][73][74][75][76][78][79], gas phase [50][55][62][64][65], and solid state [60][63

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• functional groups are isolated together in confined space [7][8][9]. In the solid state, the generation of such multifunctional cavities has been pursued upon nanoporous scaffolds that include polymers of intrinsic microporosity (PIMs) [10][11][12][13], mesoporous silica materials (MSMs) [14][15][16][17

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

• ) [112]. Examples The Aprahamian group reported hydrazone 121, which is emissive in its Z-isomer. The fluorescence can be switched on and off by irradiation with 442 nm and 340 nm, respectively (Scheme 37) [114]. The photophysical and emissive properties were also maintained in bovine serum, in the solid

• state, and in the presence of glutathione, opening the possibility for applications in a biological environment. Some interesting isatin-based arylhydrazones were reported [115][116][117]. Compound 122H is a P-type hydrazone photoswitch. The addition of tetrabutylammonium fluoride (TBAF) deprotonates

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• bistosylates 85/6/7/8 (1.0 equiv), Cs2CO3 (2.0 equiv), CH3CN, 80 °C. Molecular structure of macrocycle (R)-Me-M16 in the solid state (hydrogen atoms are omitted for clarity and thermal ellipsoids are set at the 60% probability level). The ethylene glycol chain is partially disordered, only one component is

• : Experimental procedures and characterization data of new compounds. Supporting Information File 4: Crystallographic Information File (CIF) for the solid-state structure of (R)-Me-M16. Funding J.N. would like to thank the Deutsche Forschungsgemeinschaft DFG (project NI1273/2-2, project NI1273/5-1 and

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• nitration systems (Figure 4b). A significant proportion of nitration substrates are in the solid state, necessitating solvent-mediated dissolution to achieve practical operability in continuous-flow configurations. The common solvents used in nitration reactions include sulfuric acid (24%), dichloromethane

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

• and 8.98 ppm and five doublet signals due to the heterole β-protons in the range of 6.7–5.8 ppm, along with o-phenylene protons around 7 ppm. Single crystals suitable for X-ray diffraction analysis were obtained from a mixture of acetone/n-hexane and the solid-state structure was successfully

• aza[5]helicene-incorporated macrocyclic structure (Figure 4). In the solid-state, the distance between the two aza[5]helicene moieties was found to be 3.185 Å, closely consistent with the DFT-optimized value of 3.136 Å (see Supporting Information File 1). The average dihedral angles between the o

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

• hydrogelator [25], photoregulation of DNA nanosystems [26], in controlling surface wettability [27], and in solar energy conversion [28]. Considering these advantages, we synthesized C3 symmetric tripodal azopyrazole-based derivatives having a trimesoyl core and aroylazole connections as a solid-state

• switchable probe for light-driven reversible printing and erasing applications [29]. Besides exhibiting excellent photoswitching in solution phase, the tripodal photoswitches exhibit extended half-life of the ZZZ isomer in the solid-state as well [22][29]. The overall efficiency of the molecular switch could

• surface at ambient conditions. The fluorine substitution is chosen in FNAAP for its better photoisomerization efficiency (in solution as well as in solid state) and higher molecular stability [29]. Possible photoisomers of FNAAP, EEE, EEZ, EZZ and ZZZ are shown in Figure 1. FNAAP molecules assemble into

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

• reaction of CBBC 1 with methylenetriphenylphosphorane furnished two (exocyclic olefin)-containing macrocycles 3 and 5 as well as an internally functionalized DBC derivative 4. Compounds 3 and 5 adopt a bathtub-like conformation in the solid state. In solution, both figure-eight and bathtub conformations

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

• long-wavelength optical and chiroptical properties [35] (Table 6). In the solid state, 21c emitted in the far-red region at 641 nm (ΦF = 0.10) and demonstrated CPL with |glum| = 2.04 × 10−4. In solution, 21c showed a strong absorption band at 560 nm and a high ФF value of 0.86 at 583 nm, yielding a

• reported azabora[6]helicenes 45a and 45b [60]. However, their enantiomers could not be isolated due to low racemization barriers. The F- and Ph-coordinated derivatives displayed moderate PLQYs in solution (0.26 and 0.18, respectively), which dropped markedly in the solid state (0.02 and 0.04) owing to

• fluorescence in the solid state. The |gabs| in the visible region increase systematically with helical length, reaching values as high as ≈10−2 for compounds 54b and 54c – among the highest reported to date – highlighting their strong potential in chiral optoelectronic applications (Table 18). In 2023, the