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

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• ]. Natural products that are structurally related to 1–6 were discovered in Pseudomonas aeruginosa. It was shown that these compounds function as signaling molecules involved in quorum sensing and stress response [24] which might be an explanation for their low bioactivity against the tested bacteria. Upon

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• extensive attention owing to their potential applications in biomedicine, chemical sensing and as catalysts [1][2]. It is possible to regulate the formation and breakdown of supramolecular structures using external stimuli, such as pH, light, temperature, enzymes, and competing reagents [3][4]. Among these

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• microwave irradiation conditions. The prepared nanoparticles from free-base PPCs showed colorimetric aqueous pH sensing, which suggests that the PPC nanoparticles could serve as chemical sensing applications. In 2008, the Crossley’s group [59] reported the synthesis of a ‘capped’ porphyrin 142 forming a

• reaction conditions and gives higher yields of product than directly linked azido or alkynyl porphyrins. Many applications for porphyrin click products have been proposed, including chemical sensing, anion-binding affinity, photovoltaics devices, light-harvesting materials, and in the synthesis of water

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• the purealidin bromotyrosine structure class, however, quorum sensing inhibition and antifouling activities against several strains of bacteria and microalgae appears in the literature [33][34], while HIV-1 replication inhibition and anti-Leishmania and Plasmodium activity has also been recorded [35

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• stabilization of the complex through weak hydrophobic interactions of with tert-butyl groups of Boc. We believe that by adjustment of the substituents on the amide/carbamate groups, receptors for supramolecular sensing of alcohols [44] could be designed based on 3N-TAADs of type 4. Further research in this

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• thermally activated delayed fluorescence (TADF) characteristics are emerging due to the potential applications in optoelectronic devices, time-resolved luminescence imaging, and solid-phase sensing. Herein, we synthesized two (4-bromobenzoyl)pyridine (BPy)-based donor–acceptor (D–A) compounds with varying

• as well as the relevance for fluorescence-based acid–base sensing. Keywords: intramolecular charge transfer; molecular aggregates; sensing; thermally activated delayed fluorescence (TADF); Introduction Metal-free organic solid-state emitters have gained increasing interest in recent years due to

• the potential applications in optoelectronic devices [1][2][3][4], solid-phase sensing [5], bioimaging [6][7], security [8], and storage devices [9]. The optical and electrochemical properties of the organic emitters can be tuned by external stimuli, such as mechanical force, heat, solvent, acid and

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• intermolecular mechanism, considered as post-synthesis of new luminescent compounds offers promising applications in sensing and electroluminescence by manipulating the frontier molecular orbital energy levels of organic conjugated materials, simply based on Lewis acid–base chemistry. Keywords: excitons

• ][32], e.g., organic thin-film transistors [45][46], organic photovoltaics [47], and chemical sensing [48]. Chemical structures of Lewis acid examples. Chemical structures of Lewis basic fluorescent polymer poly{2,5-pyridylene-co-1,4-[2,5-bis(2-ethylhexyloxy)]phenylene} 1 and D–A–D compound 2,5-bis((N

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• have led to a multitude of extremely useful functional applications (molecular recognition, ion sensing, catalysis, etc.) [9][22]. Since most of these structures are homoleptic in nature, i.e., they are constructed from a single type of ligand [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• topic is divided into three subcategories, namely (mechano)intramolecular chirality transfer (section 2.1), stereoselective catalysis (section 2.2), and stereoselective sensing (section 2.3). Finally, we give a short conclusion about BINOL as a chiral element in interlocked molecules. Review 1

• slightly higher barrier, which is probably the reason for the low overall stereoselectivities. 2.3 Stereoselective sensing As last part of this minireview, we will present the application of BINOL-based interlocked molecules for stereoselective chemosensing. This research field was pioneered by Beer and co

• to slightly better stereodiscrimation of the guest molecules (see Figure 17). Subsequently, Beer and co-workers reported the first example of a chiral halogen-bonding [3]rotaxane for the recognition and sensing of dicarboxylate anions [64]. The [3]rotaxane (S)-68 was prepared in a two-fold clipping

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• ions at submicromolar concentrations always by means of NMR spectroscopy [33]. Nevertheless, sensing by UV–vis or fluorescence spectra was hard to realize, for there is no chromophore in the frameworks. While hemicucurbit[n]urils with improvement in solubility, they still remain poor in derivatization

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• organic molecules are finding use in numerous areas ranging from organic electronics [1][2][3][4][5], ions sensing [6][7], and solar cell development [8][9][10]. Within this background, acridines represent an interesting class of heteroaromatic π-conjugated compounds [11][12][13][14] which show great

• perspectives in medicinal chemistry [15][16][17][18][19][20][21][22][23], dye industries [24][25][26], and metal chemo sensing [27][28][29]. More recently, acridines have received growing attention in organic electronics [30][31][32], due to their strong electron-donating ability [33][34] and remarkable

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• fields of biomedicine, sensing or catalysis, for instance. In addition, some review articles on the respective architectures and polymers in principle are listed. Responsive polymers with UCST behavior In this section, we would like to give the reader a brief overview and update of known polymeric

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• , antihypertensive, anti-Parkinson, anti-inflammatory, anticonvulsant, vasodilatory, antidiabetic, antitubercular, antifungal, and antibacterial activities [32][33][34][35][36][37][38], pH-sensing [39], OLEDs [40], chemiluminescent materials [41][42], metal complexes (Figure 1) [43][44][45][46], liquid crystal [47

• tautomerization A with a [1,7]-H shift 13 would be formed. Alternatively, in the second mechanism, 13 is thought to occur by tautomerization B and a [1,5]-H shift (Scheme 9). Photophysical properties In our previous work, we examined the photophysical and fluoride sensing properties of dihydropyridazine

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• have led to promising applications of helicenes. The latter have been studied with respect to conductivity [12][13][14][15], nonlinear optics [16][17], circularly polarized luminescence [18][19][20][21][22][23][24], organocatalysis [25][26][27][28][29], conformational analysis [30], chirality sensing

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• substitution and environment is reported with potential applications in sensing, bioimaging and optoelectronics. Keywords: aggregation caused quenching (ACQ); aggregation-induced emission enhancement (AIEE); naphthalonitriles (NCNs); solution and solid state emitters (SSSE); solvent quenching (SQ

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• sensing is an active area of research which has developed tremendously in the last few decades [1][2][3][4]. The importance of anion sensing stems from its importance in various practical applications which range from identifying and detecting environmentally toxic anions to medical diagnostics. In recent

• general challenging to design high-affinity synthetic probes for anion sensing under such competitive conditions [7]. One of the strategies that has proven to be quite successful in this regard, not only for bio-anions, rather for a variety of several other analytes also, is multivalency [8][9][10][11

• adenosine phosphates (ADP and AMP) and pyrophosphate (PPi). The detection of ATP was also possible in the presence of 150 mM NaCl. The modular nature of the sensing platform provided by the multivalent nano-assemblies of the bisimidazolium amphiphiles can in principle be extended for the detection of other

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• water/methanol 1:2 (v/v). These anions caused the bright red solutions of the nanoparticles to change their color because of nanoparticle aggregation followed by precipitation, whereas halides or oxoanions such as sulfate, nitrate, or carbonate produced no effect. The sensitivity of phosphate sensing

• depended on the nature of the anion, with diphosphate and triphosphate inducing visual changes at significantly lower concentrations than hydrogenphosphate. In addition, the sensing sensitivity was also affected by the ratio of the ligands on the nanoparticle surface, decreasing as the number of

• introducing a method to assess whether certain biologically relevant anions are present in an aqueous solution within a specific concentration range. Keywords: chemosensor; diphosphate; gold nanoparticles; optical sensing; triphosphate; Introduction Gold nanoparticles (AuNPs) are versatile platforms for the