Synthesis of tricyclic fused pyrrolidine nitroxides from 2-alkynylpyrrolidine-1-oxyls

• Mark M. Gulman,
• Yuliya F. Polienko,
• Sofia Yu. Trakhininа,
• Yuri V. Gatilov,
• Tatyana V. Rybalova,
• Sergey A. Dobrynin and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2026, 22, 344–351, doi:10.3762/bjoc.22.22

• , Novosibirsk, 630090, Russia 10.3762/bjoc.22.22 Abstract Rotational correlation time is a key parameter for organic radical contrast agents (ORCA) for magnetic resonance imaging (MRI). Design of polycyclic systems with incorporated nitroxide moieties in which rotation of the radical separately from the

• components of many high-tech materials, such as energy storage and organoelectronics devices [1][2][3][4][5][6][7][8], catalysts [9][10], bioactive coatings and nanoparticles [11][12], organic radical contrast agents (ORCAs) for magnetic resonance imaging (MRI) [13][14], etc. For these applications, numerous

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

• -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 new tetra- and pentacyclic, methylenedioxy- and ethylenedioxy-substituted derivatives of the dibenzo[c,f][1,2]thiazepine ring system

• Gábor Berecz,
• András Dancsó,
• Mária Tóthné Lauritz,
• Loránd Kiss,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2645–2656, doi:10.3762/bjoc.21.205

• -crystal X-ray diffraction (SC-XRD) measurements were carried out on a Rigaku R-Axis Spider diffractometer with an imaging plate area detector using graphite monochromatic Cu Kα radiation. Single crystal X-ray structures were deposited at the Cambridge Crystallographic Data Centre under the following

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

• first irradiation cycle due to efficient azobenzene photoisomerization, whereas axle 3 requires multiple cycles before a sudden release occurs (Figure 7a), indicating a less efficient and irreversible process. Moreover, microscopy imaging shows reversible changes to membrane tension in response to

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• developed for photothermal and photodynamic therapy, where their π-conjugated frameworks contribute to both imaging and therapeutic functions [19]. Some other TT-based compounds have been reported to inhibit specific carbonic anhydrase isoforms [20], protein tyrosine phosphatase 1B [21], as well as to act

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• diffractometer with an imaging plate area detector using graphite monochromatic Cu Kα radiation. Single crystal X-ray structures were deposited at the Cambridge Crystallographic Data Centre under the following numbers: CCDC 2447633 (3b), CCDC 2447638 (3d), CCDC 2447632 (3e), CCDC 2447636 (3g), CCDC 2447639 (3h

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

• ). Partial γ-acyloxy-Cy7 possesses a high fluorescence quantum yield and high photothermal conversion efficiency in PBS, two pivotal parameters in fluorescence imaging and image-guided photothermal therapy [196]. A dimerization of furfural has been found to occur at the early stage of formation of humins

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

• irradiation (550 nm). Figure 7a was reprinted with permission from [74] Copyright © 2020 American Chemical Society. This content is not subject to CC BY 4.0. (b) Real-time infrared thermal imaging images of a charged self-heating wristband under blue light irradiation (450 nm). Figure 7b was reprinted from

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• a chemotherapeutic agent (pyridinium camptothecin, CPT-Py). This platform was designed for imaging-guided phototherapy to alleviate hypoxia. They created a new supramolecular amphiphile that enabled rapid drug release and efficient cellular internalization, potentially providing a robust platform

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• emerged as staple building blocks in smart materials, from light-responsive norbornadienes in molecular solar thermal energy storage [2] to pH-sensitive spiropyrans in cell imaging [3], and redox-active viologens in memory junctions [4]. Among the different molecular switches azobenzenes stand out due to

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

• tapping mode and an ATM300 from RHK Technology, respectively. Aluminum-coated silicon cantilevers from Nanosensors (PPP-NCHR) were used as AFM probes. The force constant and resonance frequency of the cantilevers during the imaging were 30–34 N/m and ≈300 kHz, respectively. A Pt/Ir (80:20) tip was

• mechanically prepared and used as a probe for STM imaging. The XY and Z scales of STM images are calibrated using the graphite lattice. All the AFM and STM images are post-processed using WSxM from Nanotec [46]. Mesh averaging implemented in WSxM [46] is used for enhancing the contrast of STM images. Current

• green dashed lines. Two resonances are rotated by ≈120° and correspond to the major orientations of the domains in the 1D phase. Constant current STM topographs (300 pA, 0.3 V) of the FNAAP adlayer on HOPG (a, b) deposited from the corresponding ethanolic solution. Imaging is performed at the HOPG–air

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

• solvents, highlighting their potential for NIR bio-imaging applications. In parallel, Církva’s group synthesized a series of aza[n]helicenes 14a–d via photocyclodehydrochlorination [27]. These compounds exhibited dual fluorescence bands, with emission red-shifting progressively with increasing helical

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

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• with an electrophilic handle for the covalent attachment of the surrogate to the RNA. The resulting irreversibly tethered dye–RNA complexes have opened up new avenues for RNA imaging in live cells. Here, we report the syntheses of such modified HBC530 ((4-((2-hydroxyethyl)(methyl)amino)benzylidene

• )cyanophenylacetonitrile) fluorophores for easy access, which will contribute to the rapid dissemination of the RNA imaging approaches associated therewith. Keywords: covalent RNA labeling; FLAP; fluorophore synthesis; HBC530; self-alkylating ribozymes; Introduction The discovery of fluorescent reporters, such as green

• , however, there was no complementary RNA-based tool with comparable live-cell-imaging properties. Based on the autocatalytically generated fluorophore 4-(p-hydroxybenzylidene)imidazolidin-5-one (HBI) in GFP, in vitro selection on derivatives of HBI led to the discovery of the first fluorogen-activating

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

• effects, too, e.g., modulating lipophilicity [44][113][114][115], enabling target-binding interactions to be elucidated [116][117], or providing the opportunity for 19F and 18F imaging. Other reviews have covered many of these aspects [118][119], but here we will focus exclusively on the conformational

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• specifically recognizes and binds to surface antigens present on tumor or other targeted cells. (2) Linker: the linker connects the antibody to the payload. The nature of the moiety linking the drug/radiolabel/imaging agent to the antibody plays a crucial role in the pharmacokinetic properties [4][5

• trodelvy, used in a treatment for patients with triple-negative breast cancer, the linker may release the drug prior to internalization. (3) Payload: The payload may be a subunit used in cellular tracking, imaging, or most commonly toxic drug therapeutics. The overall goal of ADCs is to deliver the payload

• directly to target cells via the antibody without affecting normal, healthy tissue. Importantly, the use of antibodies in modern medicine is not restricted solely to ADCs and cancer therapy. For example, mABs now find routine use in the context of radionuclide (PET) imaging agents, informing therapeutic

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• method [52][53][54][55]. For example, a CD-based [3]rotaxane framework was found to be an effective motif for organ imaging by combining it with a metal complex owing to the densely placed hydroxy groups [52]. As described above, the synthesis methods for CD-based (poly)rotaxane species have been

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• ], positron emission tomography (PET) imaging [24], fluorescent probes and labels [25][26][27] detecting H2S in foodstuff, water, and living cells [28], Fe3+ ions [29], Hg2+ ions [30], and cyanide anions [31], for acid–base vapor sensing [32], and as candidate material for photonics devices, optical switches

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• general, a significant increase in the yield of the products was observed compared to the submillimole state. Physical properties The compounds such as benzoxazepines, benzothiazepines, benzodiazepines, and pyrrole have shown promising applications in optoelectronics, biophotonics, and cell imaging due to

• numerous reports, quantum yield is one of the most important photophysical parameters for describing luminescent molecules and materials since high quantum efficiency is important for a wide range of applications, including displays, lasers, bio-imaging, solar cells, and accurate measurement of the quantum

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• small angle scattering (SAS) and imaging. Scattering giving us indirect information about the systems, whereas imaging is often looking at the material directly. In this review, we discuss the benefits, caveats and power of using both these techniques separately and together for the characterisation of

• from being achieved. In this review, we aim to highlight and discuss a number of strengths and limitations provided by these techniques and will show how using these characterisation methods to complement each other can provide a much better understanding of self-assembling systems. Review Imaging

• techniques Imaging is the most widely used and accessible technique for characterising these gel materials. Researchers are looking for the presence of fibrous structures, coils, entanglements, spherulites and other such features that can give them some insight into how the gel is formed in the network via

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

• Nian Li Ruzal Sitdikov Ajit Prabhakar Kale Joost Steverlynck Bo Li Magnus Rueping KAUST Catalysis Center (KCC), King Abdullah University Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrasse 55

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• high efficiency under physiologically active conditions and the absence of any toxic metal ions. SpAAC is biorthogonal, which allows for the specific labeling and imaging of biomolecules even in living cells and organisms. Recently, a more rapid click reaction was desired and the strain-promoted

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• fluorescence quantum yields, ranging from 0.66 to 0.83, confirming their potential applications in fluorescence imaging, sensors, and optoelectronic devices. A comprehensive discussion of the potential uses of these fluorescent substances in areas such as materials science, biology, or chemistry may provide a

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

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• 0.1% w/v poly-ʟ-lysin solution in water (Sigma-Aldrich) and immediately deposited onto freshly cleaved mica to be incubated for 10 min at room temperature to allow adsorption. The surface was then rinsed using 600 µL of ultrapure 0.2 µm filtered water and slowly dried using compressed air. Imaging was

• performed using a Digital Instruments NanoScope V, acquiring 1024 samples per line with silicon nitride cantilevers possessing a nominal spring constant of 0.32 Nm−1 and a 0.8–1.0 Hz scan rate. Imaging was conducted at room temperature using the ScanAsyst™ air mode. Images were processed using NanoScope