The role of spacer length and flexibility in peptide self-assembly

• Julian Link,
• Albin Lahu,
• Manfred Wagner,
• Tanja Weil and
• David Y. W. Ng

Beilstein J. Org. Chem. 2026, 22, 986–996, doi:10.3762/bjoc.22.77

• electronically coupled face-to-face chromophore stacks, whereas 8 remains largely monomeric or in a non-ordered state. Analysis of the emission spectra reveals subtle differences already in the dissolved state: the C0-spacer-containing compound 8 emits at 540 nm, while the C3- (7) and C6-spacer (6) variants both

• emit at 546 nm, indicating a slightly different microenvironment of the fluorophore in 8 even under non-assembling conditions (Figure 3A). Upon transitioning to the aqueous buffer system, 6 and 7 exhibit mild blue shifts of their emission maximum, whereas 8 shows a red shift (Figure 3C). Additionally

• , the fluorescence intensities follow the trend C6 > C3 > C0. While ideal H-aggregates are often associated with fluorescence quenching due to exciton splitting and forbidden lowest-energy transitions, the increased emission intensity observed for 6 and 7 suggests deviation from the idealized limit. The

Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• CuCo2O4 catalyst was prepared via an oxalate decomposition method and extensively characterized using powder X-ray diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Structural analysis revealed the formation of microsheet-like architectures with high

A practical CO₂-mediated synthesis of 5,6-carboxylated silicon-rhodamines for targeted probe development

• Dongjie Hou,
• Shaowei Wu,
• Ning Xu,
• Pengjun Bao,
• Wenhao Jia,
• Qinglong Qiao and
• Zhaochao Xu

Beilstein J. Org. Chem. 2026, 22, 915–924, doi:10.3762/bjoc.22.72

• .22.72 Abstract Silicon-rhodamine (SiR) dyes are among the most important fluorophores for super-resolution imaging owing to their far-red emission, high photostability, and tunable lactone–zwitterion equilibrium. However, their broader application in targeted probe development has been limited by the

• switching and fluorogenic responses, making rhodamines particularly valuable for advanced imaging beyond the optical diffraction limit [14][15][16][17][18][19]. Replacement of the conventional bridging oxygen atom with silicon shifts the emission of rhodamines from red to the far-red region (typically λem

• molecular design framework (Figure 1a). Conformational restriction and optimization of amino substituents have been widely employed to enhance brightness and photostability [8][37][38][39], whereas extension of π-conjugation and electronic tuning have expanded the emission of SiR dyes from the far-red to

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

• pyrazine can be protonated, alkylated or interact with metal ions and Lewis acids such as B(C6F5)3, the excitation energies are modulated by these interactions, leading to a wide range of emission colours (Figure 1) [39]. The B(C6F5)3 adduct, for example, shows orange emission at 77 K which changes to

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

• -configuration) after irradiation with UV light. Furthermore, when a fluorescent pyrene moiety was embedded into the azopeptoids, the emission wavelength could be significantly modulated via the photoinduced azobenzene E/Z switch by allowing Förster resonance energy transfer (FRET) [14]. Azobenzene has also been

Anti-invasive and cytotoxic evaluation of a (+)-pinoresinol-based semisynthetic library against glioblastoma

• Chen Zhang,
• Kah Yean Lum,
• Jonathan M. White,
• Paul I. Forster,
• Nicholas Booth,
• Sunita A. Ramesh and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 691–704, doi:10.3762/bjoc.22.54

• converting resazurin to resorufin, i.e., blue to pink /red in color [40]. Changes in cell viability were detected using fluorescence (excitation at 530–560 and emission at 590 nm) or absorbance (detected at 570 and 600 nm) in a plate reader (FLUOstar Omega, BMG Labtech). In this study, cell viability was

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• structural modifications of the chromophores, aiming for example at moving their absorption from the ultraviolet spectral region to the visible region. This is of importance for efficient exploitation of solar energy, i.e., matching molecular absorption with the solar emission spectrum, or for photodynamic

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• of the more than 14 h [24]. At the same time, however, norbornadiene (1a) has also some major drawbacks with regard to a real MOST application, namely minimal overlap of the absorption spectrum (λonset < 300 nm) [25][26][27][28] with the solar emission spectrum as well as a low quantum yield (Ф = 5

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• of uranium rather than its radiological properties, any of these isotopes could, in principle, be used. Two main factors justify the choice of 238U: its natural abundance and its reliable detectability by gamma spectroscopy, in contrast to 235U, which exhibits weak gamma emission intensity [60]. The

Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• ; electrochemistry; emission; helical elongation; helicene; photophysical; Introduction Chirality is a pervasive feature of natural and artificial systems, and chiral small molecules continue to underpin advances in chemistry and materials science [1][2]. Among them, helicenes – ortho-condensed polycyclic aromatic

• , security inks, and information-storage materials, where both helicity and emission characteristics must be precisely controlled [23][24][25][26]. A central design element in helicene chemistry is helical extension. Increasing the number of ortho-fused rings amplifies π-conjugation, structural rigidity, and

• barriers of 5a and 5b translate into excellent configurational robustness, as demonstrated by the absence of detectable enantiomerization when solutions of (M)-5a were heated at 130 °C for 2.5 h. Optical properties of oxaza[8]helicenes Photophysical features The absorption and emission spectra of oxaza[8

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

• at 550/600 nm and a lifetime of ≈0.39 s that undergoes strong thermal quenching, diagnostic of room-temperature phosphorescence. In contrast, amorphous films show no RTP; their delayed component grows with temperature and shares the same peak position as the prompt emission, consistent with thermally

• -resolved biological imaging [6], chemical and biological sensing [7], as well as energy transfer and upconversion processes [8]. The unique characteristics of organic materials, including their solubility, ease of processing, molecular structure programmability, and the tunability of their emission color

Synthesis of diaryl phosphates using phytic acid as a phosphorus source

• Kazuya Asao,
• Seika Matsumoto,
• Haruka Mori,
• Riku Yoshimura,
• Takeshi Sasaki,
• Naoya Hirata,
• Yasuyuki Hayakawa and
• Shin-ichi Kawaguchi

Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15

• chloride obtained from phosphate rock using white phosphorus as a raw material; this is accompanied by a large electric energy consumption and emission of large amounts of corrosive gases. In our work, the reaction time and temperature can be further improved; however, the obtained results suggest a novel

Design and synthesis of an axially chiral platinum(II) complex and its CPL properties in PMMA matrix

• Daiki Tauchi,
• Sota Ogura,
• Misa Sakura,
• Kazunori Tsubaki and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2026, 22, 143–150, doi:10.3762/bjoc.22.7

• (LL’CT) and metal-to-ligand charge transfer (MLCT) character. Photoluminescence measurements in CH2Cl2 solution revealed dual emission peaks at 427 nm and 596 nm, with a quantum yield of 3%. In PMMA matrix, the emission peaks were blue-shifted to 408 nm and 558 nm, and the quantum yield slightly

• ), revealing two emission bands centered at approximately 427 nm and 596 nm (Figure 2). The corresponding emission decays were well fitted by a three-exponential function, yielding fluorescence components of 3.6 ns (62%), 8.0 ns (20%), and 0.39 ns (18%) at 427 nm, and phosphorescence components of 0.11 μs (64

• ethynyl-linked coordination sites. Therefore, we prepared a PMMA polymer matrix containing 1 wt % of S/R-Pt to investigate the emission behavior under conditions where molecular motion was suppressed. The PMMA matrix was obtained by dissolving S/R-Pt and PMMA in chloroform under heating at 40 °C, casting

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

• also showed significant color changes with increasing polarity. Color changes of 2a; from purple to blue, 2b; blue to green, and 2c; pale orange to pale pink (Figure 2d). Dyes do not show any significant emission. Chemosensor properties Cyanide selectivity study The dyes 2a–c could have the ability to

Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• values ranging between 409–426 nm. In general, the solvatochromic effect of these compounds showed a blue shift in EtOAc, and a red shift in MeCN. The fluorescence emission spectra of these compounds revealed a strong blue to green fluorescence emission, with the maximum emission peaks varying from 535

• to 573 nm for compound 3n and from 479 to 524 nm for compound 4n. Therefore, the fluorescence emission spectra demonstrated a clear dependence on solvent polarity and the maximum emission wavelength λem. Thus, a red shift in the emission bands was observed in solvents with higher polarity, indicating

• greater charge separation in the excited state, which is more stabilized in polar solvents, typical of compounds that undergo an ICT upon excitation [86]. The use of EtOAc showed a hypochromic effect with a decrease in fluorescence emission. Similar results for chlorinated solvents (CH2Cl2, CHCl3) were

Synthesis and characterization of a isothiouronium-calix[4]arene derivative: self-assembly and anticancer activity

• Giuseppe Granata,
• Loredana Ferreri,
• Claudia Giovanna Leotta,
• Giovanni Mario Pitari and
• Grazia Maria Letizia Consoli

Beilstein J. Org. Chem. 2025, 21, 2535–2541, doi:10.3762/bjoc.21.195

• vehicle (DMSO). At the end of incubations, cells were fixed (in 4% paraformaldehyde) and stained with acridine orange solution (50 µg/mL), as previously described [45]. Acridine orange staining was then quantified as the resulting fluorescence intensity (excitation 485/20 nm, emission 528/20 nm) with a

Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles

• Kaylen D. Lathrum,
• Emily M. Hanneken,
• Katelyn R. Grzelak and
• James T. Fletcher

Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194

• -shifting of UV–visible absorbance signals relative to their non-annulated counterparts. Structural rigidity of annulated systems compared to non-annulated counterparts was reflected by emission signals with increased intensity and decreased Stokes shifts. Five benzotriazolophenanthroline regioisomers

• the NMR timescale. These trends were observed similarly for the other analogs of this study (see Supporting Information File 1). Optoelectronic properties of each annulated product and its respective control compound were examined via UV–visible absorption and emission spectroscopy. Figure 6 shows the

• Information File 1). Table 3 summarizes the observed λmax values for absorption and emission bands for each compound in this study. Due to their structural rigidity, annulated compounds comprised of quinoline or isoquinoline subunits generated emission signals with greater intensity and smaller Stokes shifts

Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• mol % at 25 °C. The fluorescent emission of sulforhodamine B was measured before and after 1 minute irradiation with 370 nm light (pink strips) or 467 nm light (purple strips), and after 5 minutes post-irradiation. The LUVs are suspended in a buffer solution containing HEPES buffer (10 mM, pH 7.2) and

• alternating light-irradiation cycles. The fluorescent emission of sulforhodamine B was measured before and after 1 minute irradiation with 370 nm light (pink strips) or 467 nm light (purple strips), and after 5 minutes post-irradiation. The sulforhodamine B (10 mM) was encapsulated in LUVs composed of

• upon light exposure. a) Percentage of sulforhodamine B released from EYPC/Chol 8:2 LUVs containing axle 3 or DMSO as a negative control upon five alternating light-irradiation cycles. The fluorescent emission of sulforhodamine B was measured before and after 1 minute irradiation with 370 nm light (pink

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• hindrance, with a 95.6% lower binding constant of KWDG/KPBG = 0.044, a difference that can be attributed to the synergistic effect of induced fit (PBG) and conformational selection (WDG). Fluorescence emission spectra further corroborated the response of PBG and WDG to iodide ions (Figure 3c and 3d). When

• TBAI is added to two different conformations of the receptor molecule, the fluorescence emission intensity decreases. However, during the whole titration of anion fluorescence spectroscopy, only the fluorescence emission intensity changed, no peak position changed, and no new fluorescence emission

• than the formation of new excited state complexes. As the I− content continued to increase, the fluorescence emission intensity of PBG continued to decrease at 354 nm and 364 nm. Similarly, the fluorescence emission intensity of WDG at 356 nm and 369 nm decreases as the I− content increases

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• fluorescence quenching phenomena with aggregate-induced emission (AIE) in aqueous media. They synthesized a [2]rotaxane with one dithienylethene unit as a stopper, and one BAA and one urea binding site, as well as one DB24C8 macrocycle with a tetraphenylethene (TPE) fluorophore [16] (Figure 7). Addition of

• , fluorescence emission, net charge, and color, which distinguish them from other photoswitches. Thus, incorporating these photoswitches into rotaxanes enables the modulation of the macrocycle–axle interactions, leading to materials and biological applications. The first spiropyran-based rotaxane was reported in

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• the active absorbing species with its absorption band overlapping sufficiently with the emission front of the employed LEDs. Direct absorption of light by acylazolium species has indeed been previously proposed as a mechanistic pathway in light-mediated NHC-catalyzed coupling reactions [22][23][24][25

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• , respectively. Correspondingly, 3a exhibits a deep blue emission at 453 nm with a quantum yield (ΦF) of 0.79, while a hypsochromic shift of the signal for 3b to 424 nm is observed and the ΦF value is decreased to 0.22 due to the electron-deficient character of the 3,5-bis(trifluoromethyl)phenyl groups. The

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

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• describe better the excitation process in the free state, whereas interaction of the sensor with Ba2+ requires the M06L functional. TDDFT analysis of the emission spectra shows larger errors, which have been corrected by means of a structural model. The bicolor behavior is rationalized based on the

• in which two neutrons are converted into two protons by means of the transformation of two quarks down into two quarks up (Figure 1). This process involves the emission of two W− bosons that in turn evolve towards the emission of two electrons. In the two-neutrino double-beta decay (ββ2ν), two

• behavior in the emission spectra. Indeed, initial experiments were successful. However, we observed that translation of the behavior of these FBIs from supramolecular chemistry to solid–gas interfaces raises important issues in terms of both discrimination between free and chelated states and photophysical