Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• in water [21]. Crown ether 1 is particularly suited for the sensing of Trp methyl ester, which it binds with a higher affinity than the Phe and Tyr esters. Additionally, the binding of Trp-OMe results in a highly efficient fluorescence quenching of the naphthalene unit in the receptor. Herein, we

• report that receptor 1 can be used for the binding and fluorescent sensing of tryptophan as well as tryptophan residues in short peptides in water. Results and Discussion Having previously demonstrated that 1 binds tryptophan methyl ester in water [21] we wanted to investigate whether it is also suitable

• presence of the naphthyl moiety in the receptor the binding process can be monitored by fluorescence spectroscopy. These results pave the way for further investigations on the binding and fluorescent sensing of tryptophan within biologically relevant peptides by our glucose-based receptor. Furthermore

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• enabled by improving automated experimental screening of existing cavities for new activity (sensing, catalysis) [418]. Crucially, improved access to experimental structure–activity relationships of incrementally developed cavities [21] is required to feed rational or machine learning advances. The unique

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

• noncovalent bonding interactions. It also confers on supramolecular assemblies with higher complexity and multilevel ordering [9][10][11], leading to a vast number of applications, for example, for use in detection and separation [12], sensing [13], photocatalysis [14], release [15], and as thermochromic and

• applications, which includes catalysis [26], gelation [27], sensing [28], color tuning, etc. [29]. However, only several kinds of macrocycles are capable of supramolecular dimerization through host–guest interactions [30]. Shape-persistent macrocycles have captured the interest of chemists for decades [31][32

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• , stirring, heating, and cooling modules for enhanced versatility. In addition, the platform is capable of performing under inert and low-pressure atmospheres, handling separation steps, and pressure sensing for reaction monitoring. Its efficacy and robustness were confirmed through the successful synthesis

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

• applied in various fields, including organometallic catalysis, dye-sensitized solar cells, sensing, artificial olfactory systems, photodynamic therapy (PDT), anticancer drugs, biochemical probes, and electrochemical devices. Relevant examples of these two pyrrolic macrocycles as metal-free organocatalysts

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 fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• . After metalation with Ni(acac)2 and hydrolysis electron-rich porphyrins were obtained, that are equipped with covalently attached long chain acid substituents. The target compounds have potential applications in catalysis, sensing, and materials science. The fluorinated aliphatic carboxylic acids (TfO

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

• quenching had occurred when three equivalents of Cu2+ ions were added, a [Tb(triazole-DPA)3·3Cu]3+ [Tb.1·3Cu]3+ complex was used for the subsequent HS− sensing experiments. We did extend our study to investigate the luminescent quenching of 5 μM Tb.1 upon the addition of Cu2+ ions when 10 mM HEPES buffer

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• porphyrin architectures, which could be used in supramolecular assemblies, catalysis, or sensing. In this work a library of arm-extended dodecasubstituted porphyrins was synthesized through the optimization of the classic Suzuki–Miyaura coupling of peripheral haloaryl substituents with a range of boronic

• nanotubes/nanochannels by intermolecular π–π interactions of the peripheral phenyl groups [59]. Additionally nonplanar supramolecular assemblies have found use in anion capture [12][15], and sensing [60], making the synthesis of these structures desirable from a supramolecular standpoint. Two especially

• assemblies possibly capable of carrying out sensing and or capturing molecules of interest, as well as a dimeric intercalated structure. (A) Structures of tetrasubstituted 5,10,15,20-tetraphenylporphyrin (TPP, 1), dodecasubstituted 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (OETPP, 2), and

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

• , sensing, optoelectronics, photo-responsive actuators, and healable materials, and a range of biomedical applications among many others [6][7][8][9]. To better understand and guide the development of these chemical systems, robust characterisation techniques and protocols are required. These materials

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

• ] cycloaddition–retroelectrocyclization (CA-RE) between electron-rich alkynes and electron-deficient olefins [8]. The [2 + 2] CA-RE click reactions were employed to produce a variety of functional materials, such as nonlinear optical chromophores [9][10], super acceptors [11][12], ion sensing D–A systems [13

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• ), organogels, molecular wires, self-assembly and so forth [14][15][16][17][18][19][20][21][22][23][24][25]. Moreover, nowadays these invaluable compounds have also received great attention of supramolecular chemists, and finds applications in sensing, catalysis, donor–acceptor systems, energy transfer and

• the importance of DPMs in mind due to their utmost significance as a building block in the construction of porphyrinogens, related polypyrrolic macrocycles, and pigments [39][40][41]. As shown in Figure 1, these DPMs and many more have fruitfully been used by several research groups in sensing/binding

• outstanding optical properties [43]. Herein, we present for the first time three new mono-, di-, tri-dipyrromethane appended truxene derivatives with the intention to explore them for future sensing and/or binding properties. Results and Discussion To achieve our goal towards the construction of truxene

Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA

• Yu Fan,
• Ahmed El Rhaz,
• Stéphane Maisonneuve,
• Emilie Gillon,
• Maha Fatthalla,
• Franck Le Bideau,
• Guillaume Laurent,
• Samir Messaoudi,
• Anne Imberty and
• Juan Xie

Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132

• increasingly limited for treatment of infections. PA has been classified as a priority 1 pathogen by the WHO [2][3]. Various approaches to treating PA, in addition to traditional antibiotics, have been developed including inhibition of quorum sensing, biofilm formation, iron chelation, and interfering with

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

• Naziha Tarannam,
• Prashant Kumar Gupta,
• Shani Zev and
• Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

• several significant processes, terpenoids play an indispensable role in cell-wall and membrane biosynthesis, sensing, plant defense, electron transport, or conversion of light into chemical energy [1][2]. Based on the number of hydrocarbon units, terpenes are classified into various families like

A Diels–Alder probe for discovery of natural products containing furan moieties

• Alyssa S. Eggly,
• Namuunzul Otgontseren,
• Carson B. Roberts,
• Amir Y. Alwali,
• Haylie E. Hennigan and
• Elizabeth I. Parkinson

Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88

• the titers of MMFs in native producing strains. However, if titers are similar to that of γ-butyrolactones and butenolides quorum sensing molecules, we would expect them to be between 80 and 2.5 nM [29][30][31]. Given these very low concentrations, cultures would need to be greatly concentrated (≈1000

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• ), limiting the use of this model to predict the heme environment. Nevertheless, this protein–ligand model heme binding between the β-sheet and an α-helix based on similarity to the oxygen-sensing dimeric DosH protein [34]. DosH is also a heme-binding PAS-domain containing protein, further validating the

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• ), which upon sensing ROS, release their repression and activate the expression of various genes [93][94][95]. Wei et al. reported that the production of validamycin A (25) by Streptomyces hygroscopicus 5008 could be activated at the transcriptional level by simply adding hydrogen peroxide (H2O2; which

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

• Yasuhiro Oishi,
• Motoharu Kitatani and
• Koichi Kusakabe

Beilstein J. Org. Chem. 2024, 20, 570–577, doi:10.3762/bjoc.20.49

• can be expected for proteins immobilized on graphene. As a result, we propose a strategy for improving the accuracy of the sensing process in elastic wave measurement sensors through antigen/antibody reactions. Results and Discussion PASE and PASE-derivatives on graphene Among pyrene derivatives, PASE

• conformation 2 in the protein capture step. On the other hand, at the time of sensing, the proteins and sample antigens bound by the linker should be strongly bound on the graphene surface. This makes it easier to observe the increased mass by generating a reflected wave with a strong amplitude relative to the

• other hand, in non-covalent functionalization, the electronic properties of graphene can be preserved [27][28][29]. Therefore, the PASE linker and its properties may be relevant for another type of the electronic sensing strategy, such as field effect transistor-based biosensors. Conclusion We discussed

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• represents prototypes of molecular machines in which guest binding is regulated by stimuli-induced conformational changes between open and closed states (Figure 1). This feature holds significant promise for applications in sensing, drug delivery, or membrane transport within biological systems. Moreover

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• dithienonaphthalene products (e.g., 16) exhibit very different fluorescence properties, S-extrusion from thiophene-annelated thiepines was consequently exploited for peroxide sensing. Very recently, Zhou et al. reported the synthesis of S-doped phenanthrene and triphenylene derivatives via the thermally-induced ring

• dithienonaphthalenes, upon S-extrusion triggered by electrochemical oxidation. Bottom: Exploitation of the S-extrusion process for peroxide sensing, taking advantage of the lability of oxidized dithienobenzothiepine to generate highly fluorescent dithienonaphthalene [63]. Synthesis of S-doped extended triphenylene

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• sensing; Introduction Among the vast number of biologically active quinoline derivatives [1][2], the subclass of 4-quinolones (also referred to as 4-oxo-1,4-dihydroquinolines, quinolin-4(1H)-ones, or 4-hydroxyquinolines) is of great importance with its rich variety of bioactive compounds. Perhaps the

• great research interest, with many reviews published in the recent years [20][21][22]. Some of the compounds are known to act as antibiotics [23][24][25][26], while others function as quorum-sensing signal molecules which regulate the production and release of virulence factors in bacteria, thus helping

• conditions, and allows easy installation of long-chain substituents at the C-2 position of the quinolone core. These characteristics of the synthetic method could be particularly attractive in the search of novel mimics of the Pseudomonas quorum-sensing signal molecules. The high activity of compounds 4d and

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• pharmacological activities [86][87]. Acylhydrazones can exist in either E or Z forms in solution, and they can exhibit good optical properties for applications as photoswitches, in luminescence sensing, and as metallo-assemblies [88][89]. In organic synthesis, acylhydrazones have served as stable imine

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

• -emitting diodes (OLEDs), and bio/chemo-sensing devices. The movement of charge carriers through these materials occurs via a complex interplay of electronic, structural, and energetic phenomena, presenting intriguing challenges and opportunities for scientific exploration [3][4]. Quinoxalines (Qxs) have

• , environmental monitoring, and chemical sensing. Additionally, they can be utilized for biosensing applications by leveraging their ability to absorb and emit light in the near-infrared II range. This range allows for deeper tissue penetration, reduced scattering, and minimized autofluorescence, thereby enabling

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• synthesis of three-dimensional cryptands by Lehn [5], and spherands by Cram [6]. Later on, various classes of macrocyclic compounds were designed, demonstrating remarkable features in areas spreading from simple coordination chemistry [7], through host–guest chemistry, sensing [8], biomedicine [9], and

• . Osuka and co-workers provided novel insight into the meso-appended crown ether porphyrins, namely, chromophore-incorporated and polymer-based systems capable of acting as multitopic receptors for transition, alkali, and alkali-earth metal cations, which were proved as optical sensing agents among other

• axially bound H2O. The water molecule was stabilised by hydrogen bonding to the diaza-crown-6 core. Over the years, significant advancements have been made in crown ether-capped porphyrins, demonstrating their versatile applications in host–guest chemistry, multitopic receptor design, and cation sensing

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• affinity and selectivity towards specific amines. In addition to their potential applications in sensing and molecular recognition, R[4]A have also been studied for their potential pharmaceutical [13] and biochemical [14] applications. R[4]A typically exhibit complex structures containing over a hundred