Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

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

• is synthesized with slightly improved ϕ of 2% and a blue-shifted emission compared to PTM with a maximum photoluminescence wavelength λem = 569 nm (in CCl4) [40][42]. The racemization barrier remains almost identical at 21.1 kcal mol−1. Both PTM and TTM exhibit circularly polarized emission (CPL) for

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

• 6a, we observed a blue-shifted absorption profile due to the break of the conjugation in sulfur-based acceptors. Compounds 4a and 6a presented a similar absorption profile, while molecule 5a showed a red-shifted spectrum tailing up to the visible region (Figure 2a). The lack of a significant charge

• . Analyzing the diverse absorption profiles, we can observe an increase in the red-shifted behavior related to the donor strength in compounds 5e, 5d, and 5c. In contrast, the azepine-derived compounds are the most blue-shifted (Table 1, entry 5). The same trend is observed in the emission (Figure 2b). The

• Supporting Information File 1, Table S3). As we expected, due to the blue-shifted absorption presented in molecules 4a and 6a, it was impossible to excite them under visible light (400 nm). Gratifyingly, PC 5a delivered product 8 with a promising 63% NMR yield. Next, we compare the photocatalytic behavior of

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• ) Crystal structure of B4aH (hydrogen atoms are omitted for clarity), and (c) the stacking structure of the crystal of B4aH (the blue dotted lines represent hydrogen bonds). (a) The structures of host and guests, (b) 1H NMR spectra (298 K, 400 MHz, CD3CN) of B4aH upon titration with C62− (c(B4aH) = 1 mM

• ), (c) chemical shift changes of Ha versus titration equivalents c(dicarboxylate)/c(B4aH), and (d) association constants of host and guests. (a–c) DFT-optimized structure of the B4aH-C72− complex. The blue dotted lines represent hydrogen bonds and the black dotted lines represent anion–π interactions

Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation

• Zhihua Liu,
• Ya-Zhi Chen,
• Ji Wang,
• Qingling Nie,
• Wei Zhao and
• Biao Wu

Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68

• colors: green or grey = C, white = H, blue = N, red = O, orange = S, and purple = Cs. For the crystal structure, the overall stoichiometry of Cs+, PO43−, 18-crown-6 and anion receptor is 3:1:3:1. Phosphate anion is encapsulated inside the hexaurea cavity and stabilized by 12 × N–H···O hydrogen bonds

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• , such as OH or OMe, they are shifted towards the blue. Especially for NAc-PAPs, we observe a higher spectral separation of the π→π* and the n→π* transitions of the Z isomers compared to NMe-PAPs and NH-PAPs. For instance, the separation for the π→π* transition band and the n→π* is 176 nm for NAc-PAP-CN

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• and the simultaneous increase of the QC´s band at λmax = 301 nm accompanied by the presence of isosbestic points (Figure 3). Extended irradiation times resulted in a decrease in the QC signal, accompanied by a slight blue shift and the emergence of a new absorption band at λmax = 382 nm, suggesting

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• to the O-azobenzene (AB) photoswitch. (Orthogonal) photoswitching alters the relative spatial orientation of the two sugar units. Glucose (Glc) moieties are colored in blue and mannose (Man) in green according to the symbol nomenclature for carbohydrates (SNFG) [29][30]. A: Wavelength-selective

• ) is depicted as ribbon diagram and the ligands are displayed as stick models (glycoclusters 1 and 2: EE: blue; ZZ: violet; EZ: green; ZE: red). Superposition of the isomers shows the similarity of the binding of the terminal mannoside antenna within the FimH CRD and the different orientations of the

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• ), b) a mixture of C1 (0.5 mM) and Me6PXDA (1.0 mM), c) a mixture of C1 (0.5 mM) and Me6PXDA (0.5 mM), and d) C1 (0.5 mM). Cross-eyed stereoview of the C1·Me6CHDA complex in the crystal. Color code: C, gray; H, white; N, blue; O, red; S, yellow. Cross-eyed stereoview of the crystal packing observed in

• the molecular cell of C1·Me6CHDA. H-atoms are omitted for clarity. N···O distances less than 4.40 Å are indicated with dashed lines. Color code: C, gray; N, blue; O, red; S, yellow. a) Representative plot of DP (μcal s−1) versus time from the titration of C1 (0.1 mM) in the ITC cell with a solution of

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• negative (orange region) in the parent compounds, whereas the phenacene cores turned to be positive (blue) for the F8-phenacenes. Therefore, one can manipulate the polarization of the phenacene cores through the introduction of fluorine atoms without altering the electronic spectral features. The excited

• state. The orange and blue sites, respectively, indicate negative and positive regions (−0.02 ≈ 0.02 hartree). Synthesis of building blocks 10, 13, and 15. Reagents and conditions: a) NaBH4, MeOH, THF, reflux; b) PBr3, reflux; c) N-methylmorpholine-N-oxide, THF, reflux; d) ethylene glycol, p-TsOH

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

• Abstract A new deep-blue emitting and highly fluorescent anthracene (ANTH) derivative containing perfluorobenzyl (BnF) groups, 9,10-ANTH(BnF)2, was synthesized in a single step reaction of ANTH or ANTH(Br)2 with BnFI, using either a high-temperature Cu-/Na2S2O3-promoted reaction or via a room-temperature

• photostability compared to ANTH and 9,10-ANTH derivatives, and a simple synthetic access makes it an attractive material as a deep-blue OLED emitter and an efficient fluorescent probe. Keywords: anthracene; dibromoanthracene; electron poor polyaromatic systems; fluorescence; perfluoroalkylation

• -purity color and improved stability, has been observed. OLED materials have attracted considerable research because they found commercial uses for flat panel displays and solid-state lighting applications. Currently, the design of efficient and highly stable blue fluorescent emitters remains a challenge

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• zinc cations to align 1.1 through the formation of hydrogen-bonded coordination complexes. Thus, when a single crystal of the [Zn(bpe)2(H2O)4](NO3)2·8/3H2O·2/3bpe complex was exposed to UV irradiation (dark blue phosphor lamps, λ = 350 nm) for 25 h, only 46% conversion to 1.2 was observed via 1H NMR

• Na2CO3 was ground in a mortar at room temperature for 3–5 min. Second, the reaction mixture was transferred into a quartz tube, heated to 50 °C (heating mantle) for 18 h, while being irradiated with blue LEDs under air-equilibrated conditions. In these conditions, product 3.3 was isolated in excellent

• : the authors termed this approach “mechanochemically-assisted solid-state photocatalysis” (Scheme 7) [70]. Therein, a custom-built photoreactor was integrated into a standard laboratory ball mill apparatus. This reactor, equipped with blue LEDs, allowed for adjustable light intensity and maintained

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• -electron contributions) for a perpendicular magnetic field over a plane 1 a.u. above the molecular plane of the pyrazole ring of the o-carborane-fused pyrazoles. Red/blue arrows when the component parallel/antiparallel to B is greater than 30% of the vector modulus. Diatropic/paratropic circulations are

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• violet-blue formazan, with absorption maximum in the range of 540–560 nm. The optical density of the solution in this wavelength range is an indirect indicator of the number of live cells in the culture. The cytotoxic activity of the test substance was determined by the decrease in optical density of

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

• driving chemical transformations under mild and efficient conditions. The use of red and near-infrared light enables deeper penetration into reaction media, reducing the high-energy side reactions commonly triggered by UV or blue light. These features make red-light photocatalysis particularly

• -driven transformations. The final section examines applications of red-light photocatalysis within biological and medicinal fields. The capacity of red light to penetrate biological tissues enables processes that are challenging or even impossible under UV or blue light. This section discusses different

• hemoglobin, and silicon by selectively irradiating a specific area of the reaction medium with red light (660 nm) or blue light (456 nm), respectively (Scheme 2). The authors have demonstrated that this polymerization reaction proceeded much more efficiently under red light irradiation. Indeed, red light can

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• , Me: methyl). Cyclic voltammograms of 1 and 2. UV–vis–NIR electronic absorption spectra of 1 (top) and 2 (bottom) during the electrochemical oxidation in 0.1 M n-Bu4N·PF6 in CH2Cl2 at room temperature. The traces are black lines for neutral, blue lines for radical cation, and red lines for dication

• theoretical Raman band at 1730 cm−1. FT-Raman spectra in CH2Cl2 (approx. 10−2 to 10−3 M) of: top) 1 (black), 1•+ (blue), and 12+ (red). Bottom) 2 (black), 2•+ (blue), and 22+ (red). Oxidations are carried out by stepwise addition of NOBF4 in CH2Cl2. Force constants for the CC stretching vibrational

• coordinates of the neutral (black), radical cation (red) and dication (blue) of m-1 and m-2 compared with those obtained, under the same level or theory, for neutral naphthalene (NAP) and cyclobutadiene (CBD). NICS-XY scans, at the (U)B3LYP/6-311G(d,p) level, for neutral m-1 and m-2 (black) and for their

Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

• Misato Suganuma,
• Daichi Kitagawa,
• Shota Hamatani and
• Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

• absorption band in the visible region disappeared and returned to the initial one by stopping UV light irradiation. These results indicate that all molecules exhibit T-type photochromic reactions based on 6π aza-electrocyclic reaction. The absorption bands of compounds I1(c)–I4(c) are blue-shifted compared

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• degassed solvent and light-shielding flask, the oxidative conversion of 12 to the imidate 18 proceeded smoothly. Notably, the transient intermediate 18, exhibiting a sky-blue fluorescence, further underwent a ring opening to afford the tetracyclic 14 with the simultaneous regeneration of both a nitrile and

• gold complex and the silver salt, to efficiently achieve the 6-endo cyclization and subsequent conversions. During the development of this cascade synthesis process, we serendipitously discovered the involvement of a sky-blue fluorescent transient intermediate 18 (Figure 2). We therefore investigated

• displayed a relatively broad peak with a maximum around 490 nm (blue solid line). The excitation spectra of 18 (blue dashed line), corresponding to an emission at 490 nm, was also recorded (Figure S3, Supporting Information File 1 for details). Despite the modest emission quantum yield (Φfl = 0.07, excited

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• Reichardt's dye [53][54][55] as an indicator. These experiments measure the blue shift of Reichardt's dye upon complexation with an HB donor (Figure 3A, and Figures S13–S18 in Supporting Information File 1), from which the dissociation constant (Kd) of the HB complex can be determined. A smaller Kd value

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• promising potential for designing stimuli-responsive and smart polymers in the future. ESIMS spectrum of an equimolar mixture of G1 and H1 in CHCl3/CH3CN (1:1, v/v), including calculated (blue) and experimental (red) isotopic distribution for [H12 + G12 − 2PF6−]2+. Calculated and found m/z = 2444.3373 and

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• ]. Consistently, once the chloride is added, the reduction to free Cu(0) is visually indicated by the immediate disappearance of the blue color of the copper(II) solution, and the formation of a fine suspended black powder. The latter, as metallic copper particles, acts as the actual catalyst. Time plays a

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• the colorless crystal, two of these [5]helicenoid moieties display P and M helix structures respectively, whereas the third moiety (colored in light blue) adopts a structure with approximate plane symmetry, recognized as a transition state for the enantiomerization of helicenes. The central benzene

• represent the helicity of the three [5]helicenoid moieties. The geometry of 3 deviates from ideal C2 symmetry, as the light blue moiety of 3 (top view in Figure 3) is shaped like a saddle. However, the 1H NMR spectrum of 3 shows only 12 different signals in the aromatic region, indicating a two-fold

• clarification). Structure of (M,P,M)-3 in the crystal of 3·CH2Cl2 (carbon and oxygen atoms are shown as grey and red ellipsoid at the level of 50% probability, and hexyl groups and hydrogen atoms are removed for clarity). UV–vis absorption spectrum (black line) and emission spectrum (blue line, excited at 400

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• situation. Dibenzyl ester 11c was prepared using traditional activation of carboxylic acid 6a, although the yield was only 23%. A higher yield of the branched ester 11d (86%, as a mixture of diastereomers) was obtained by carbene insertion, generated by blue LED irradiation of methyl 2-diazo-2-phenylacetate

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

• -containing macrocycles and metalloporphyrins. Despite the impressive progress in photoredox catalysis, due to their most intensive electronic absorption band at 420 nm (Soret band, extinction coefficient of 105 M−1 cm−1), most porphyrin photocatalysts reported so far have been mainly utilized under blue

• light turned out to be as effective as blue light, providing good yields of various photochemical reactions that proceed via both oxidative and reductive quenching mechanisms. Further, using of metal-free porphyrins as photocatalysts in bioorthogonal chemistry was explored. They can be utilized in

• ) using substituted anilines 101 and t-BuONO (Figure 18). The reactions were conducted under light irradiation (blue light/sunlight) for 30 minutes in DMSO within an inert atmosphere. All corroles demonstrated catalytic activity with only 0.5% loading, while control experiments without a catalyst or light

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• derivatives during the photoreaction, whereas the blue-shifted maximum of the photoproduct was formed. In addition, isosbestic points were observed for the derivatives 1h (A), 1i (B), 1k (D), and 1l (E). The irradiations of the derivatives 1h, 1i, 1k, and 1l were stopped once no more changes of the absorbance