An azobenzene container showing a definite folding – synthesis and structural investigation

• Abdulselam Adam,
• Saber Mehrparvar and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2019, 15, 1534–1544, doi:10.3762/bjoc.15.156

• far, a series of receptors based on these macrocycles were synthesized. They have been designed for the selective recognition of sulfate ions [4][5][6], di- and triphosphate ions [7], for sensing of pyrophosphate ions in aqueous solutions [8], as receptors for phenols [9], α-chiral primary

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• ]. Tetralactam macrocycles with four amide NH residues have been studied for ca. three decades and used in a wide range of fields including molecular recognition, optical sensing, molecular machine etc. [2][3][4][5][6][7][8][9][10][11][12][13]. The amide N−H groups directed into the cavity could form hydrogen

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• sensing properties [4][5]. In particular, noble metal nanoparticles of sizes smaller than the wavelength of the incident light show interesting optical behavior as a result of collective oscillations of the valence electrons. This leads to surface plasmon resonance (SPR), which is highly dependent on size

• 20-fold higher binding constant to β-CD (6.5 × 104 M−1) [32] than unmodified azobenzenes (2.5 × 103 M−1) [33]. Therefore, the competitive binding of CTAB to β-CD has been applied previously, e.g., in sensing applications [34] or to enhance the water solubility of a cyclodextrin polymer [35]. On

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• and potential applications according to the diverse photophysical responses are provided. Keywords: calixarene; host–guest complexation; luminescent dyes; macrocycles; photophysical properties; Introduction Fluorescence sensing represents a powerful detection methodology due to its low cost, ease of

• -consuming syntheses. Alternatively, supramolecular chemistry provides a non-covalent approach to achieve fluorescence sensing [2]. An elegant supramolecular strategy, named indicator displacement assay (IDA), was established and popularized by Anslyn and co-workers (Scheme 1a) [3][4]. The complexation of a

• fluorophores through supramolecular encapsulation using artificial macrocyclic hosts has always been an active research area [10][11][12]. The complexes of macrocycles with luminescent dyes not only act as reporter pairs for sensing [13][14][15], but also offer various applications in bioimaging [16][17

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• machinery [22]. In contrast, the actual contribution seeks to explore the utility of supramolecular rearrangements [23] for sensing and detection, in particular with an emphasis on high selectivity. As a notable example of the latter category, Nitschke recently reported the guest-induced transformation of

• porphyrin edge capsules to cone-shaped inclusion complexes depending on the presence of C60/C70, however, a process that was not selective for one of the guests [24]. A spectacular case of guest sensing, but not guest-induced recognition, was demonstrated by Clever in a supramolecular cage-to-cage

• to the fact, that the interconversion is accompanied by a diagnostic change in the fluorescence spectra, the present system represents a supramolecular reporter for the selective detection of DABCO. It is thus a rare example of DABCO sensing by luminescence [41]. Molecular structures of ligands 1, 2

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• bind inorganic anions with high binding affinity and selectivity in both organic media and water [13][14]. Previously we used bambusurils to recognize and quantify anions in their complex mixtures at sub-micromolar concentrations by means of NMR [15]. However, sensing of anions by less expensive UV–vis

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• stability, and high resistance to photobleaching. Thus, fluorescent C-dots have been widely applied in the fields of imaging, catalysis, and sensing [5][6][7]. With the rapid development of fluorescent C-dots, much effort has been made to tune their electrical, optical, and chemical properties via doping

• , symmetrical structures, superior host–guest properties, supramolecular assembly characteristics, and versatile functionalities [11][15][16]. Carboxylatopillar[5]arene (CP[5]) is one of the most popular functional pillarenes that has been exploited in many research areas, especially in sensing and detection

• [16][17][18][19][20][21]. To our best knowledge, only few reports on pillarene-modified C-dots can be found in the literature [19], not to mention their potential applications in ion sensing. Herein, we prepare fluorescent C-dots, namely CCDs, by linking various CP[5] rings on N-doped C-dots (CN-dots

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• the study of electron transfer [26][27] or for building surface molecular devices for different purposes, commonly called integrated molecular systems [19]. These molecular systems are mainly used for pH sensing [28][29][30], inorganic- [31][32][33], organic- and biosensors [34][35]. Self-assembled

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• ; diacylglycerols; lipids; mechanochemistry; Introduction In addition to being guided by chemical signals, cells respond to mechanical cues by sensing and transducing external mechanical inputs into biochemical and electrical signals [1]. Consequently, every time a cell is subjected to mechanical loads, the

Synthesis and biological activity of methylated derivatives of the Pseudomonas metabolites HHQ, HQNO and PQS

• Sven Thierbach,
• Max Wienhold,
• Susanne Fetzner and
• Ulrich Hennecke

Beilstein J. Org. Chem. 2019, 15, 187–193, doi:10.3762/bjoc.15.18

• are associated with quorum sensing and virulence of the human pathogen Pseudomonas aeruginosa, have been prepared. While the synthesis by direct methylation was successful for 3-unsubstituted 2-heptyl-4(1H)-quinolones, methylated derivatives of the Pseudomonas quinolone signal (PQS) were synthesized

• from 3-iodinated quinolones by methylation and iodine–metal exchange/oxidation. The two N- and O-methylated derivatives of the PQS showed strong quorum sensing activity comparable to that of PQS itself. Staphylococcus aureus, another pathogenic bacterium often co-occurring with P. aeruginosa especially

• in the lung of cystic fibrosis patients, was inhibited in planktonic growth and cellular respiration by the 4-O-methylated derivatives of HQNO and HHQ, respectively. Keywords: antibiotic acitivity; methylation; Pseudomonas aeruginosa; quinolones; quorum sensing; Introduction 2-Alkyl-4(1H

N-Acylated amino acid methyl esters from marine Roseobacter group bacteria

• Hilke Bruns,
• Lisa Ziesche,
• Nargis Khakin Taniwal,
• Laura Wolter,
• Thorsten Brinkhoff,
• Jennifer Herrmann,
• Rolf Müller and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 2964–2973, doi:10.3762/bjoc.14.276

• Roseobacter group (Rhodobacteraceae) are important members of many marine ecosystems. Similar to other Gram-negative bacteria many roseobacters produce N-acylhomoserine lactones (AHLs) for communication by quorum sensing systems. AHLs regulate different traits like cell differentiation or antibiotic

• derivatives; 2-aminobutyric acid; homoserine lactones; natural products; quorum sensing; Introduction The identification and structural elucidation of naturally occurring compounds traditionally requires isolation and NMR investigation as key method to detect novel compounds and new structural classes

• habitats with a broad metabolic potential [4][5][6][7]. Especially attached-living roseobacters produce diverse secondary metabolites, e.g., N-acylhomoserine lactones (AHLs) that the bacteria use for communication by quorum sensing [8][9][10]. AHLs are extensively investigated because of the broad

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• NO transport, storage and sensing as well as heme metabolism [36]) usually constitute eight to ten antiparallel β-strands and tightly packed hydrophobic or hydrophilic barrel interiors [37]. Membrane-bound β-barrels are confined to mitochondrial and chloroplast membranes and the outer membranes of

Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus

• Jakob Bouton,
• Kristof Van Hecke,
• Reuven Rasooly and
• Serge Van Calenbergh

Beilstein J. Org. Chem. 2018, 14, 2822–2828, doi:10.3762/bjoc.14.260

• product hamamelitannin and several of its analogues have been identified as quorum sensing inhibitors. In this paper the synthesis of pyrrolidine-based analogues of a more lead-like hamamelitannin analogue is reported. A convergent synthetic route based on a key ring-closing metathesis reaction was

• ; quorum sensing; Staphylococcus aureus; Introduction Antimicrobial resistance is rapidly becoming a global threat [1][2]. It is estimated that worldwide, at least 700 000 people die every year from drug-resistant strains of common bacterial infections. Strategies to deal with the global antimicrobial

• clinical infections. In S. aureus, virulence is mainly mediated by quorum sensing, a bacterial cell-to-cell communication system based on the secretion of signal molecules [9][10][11]. The natural product hamamelitannin (1) has been identified as a non-peptide analogue of RIP (RNAIII-inhibiting protein

Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

• Stephen M. Geddis,
• Teodora Coroama,
• Suzanne Forrest,
• James T. Hodgkinson,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

• analogues was observed to inhibit production of the virulence factor pyocyanin in the human pathogen Pseudomonas aeruginosa, which may be a result of their similarity to the Pseudomonas quinolone signal (PQS) quorum sensing autoinducer. This provided new insights regarding the effect of N-substitution in

• PQS analogues, which has been hitherto underexplored. Keywords: antibiotics; cross-coupling; heterocycles; quorum-sensing; structure–activity relationships; Introduction The quinolone core has long been implemented in structures possessing formidable activity in a broad range of fields, including

• -position, there is a structural resemblance to the Pseudomonas quinolone signal (PQS), and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ), which are vital to the cooperative behaviour of the human pathogen Pseudomonas aeruginosa via quorum sensing (QS). This is a means by which bacteria alter

Non-native autoinducer analogs capable of modulating the SdiA quorum sensing receptor in Salmonella enterica serovar Typhimurium

• Matthew J. Styles and
• Helen E. Blackwell

Beilstein J. Org. Chem. 2018, 14, 2651–2664, doi:10.3762/bjoc.14.243

• Matthew J. Styles Helen E. Blackwell Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI 53706, USA 10.3762/bjoc.14.243 Abstract Quorum sensing (QS) allows many common bacterial pathogens to coordinate group behaviors such as virulence factor production

• and antagonism. Keywords: N-acyl L-homoserine lactone; LuxR-type receptor; Quorum sensing; Salmonella enterica serovar Typhimurium; SdiA; Introduction In the fight against bacterial infections, microbes have a decisive advantage over the medical community: evolution [1]. Using bacteriocidal or

• to complement antibiotics, and the interception of quorum sensing (QS) in bacteria has attracted considerable attention in this regard [7][8][9]. QS, a type of intra- and interspecies chemical communication, has been found to occur in many common bacterial pathogens [10][11]. These pathogens use QS

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• , 66123 Saarbrücken, Germany German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Saarbrücken, Germany 10.3762/bjoc.14.241 Abstract The Gram-negative opportunistic pathogen Pseudomonas aeruginosa causes severe nosocomial infections. It uses quorum sensing (QS) to regulate and

• highlights the published drug discovery efforts providing insights into the compound binding modes if available. Furthermore, suitability of the individual targets for pathoblocker design is discussed. Keywords: anti-infectives; pathoblockers; PQS; Pseudomonas aeruginosa; quorum sensing; Introduction In

• disruption of the Pseudomonas quinolone signal quorum sensing system (pqs QS). Review Antimicrobial resistance and clinical relevance of Pseudomonas aeruginosa P. aeruginosa is one of the threatening ESKAPE pathogens and has regularly been attributed with the label ‘superbug’ [11]. In 2017, the World Health

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

• Matthew B. Calvert,
• Varsha R. Jumde and
• Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

• . Keywords: antimicrobial resistance; bacterial adhesins; bacterial toxins; pathoblockers; quorum sensing; Review 1. Antimicrobial resistance crisis for bacterial infections The current crisis caused by antimicrobial resistance [1][2] demands new strategies to fight infections. Antibiotics have served as

• a suitable target to prevent toxin secretion. The anti-PcrV antibody KB001 [68] and the bifunctional antibody MEDI3902 [69], which targets PcrV and the biofilm-associated exopolysaccharide psl, are both currently in phase II clinical trials. 6. Bacterial communication Quorum sensing (QS) is employed

• that activates quorum sensing-controlled processes (Figure 5). Many virulence traits are influenced by quorum sensing and thus developing methods to reduce virulence by interfering with bacterial communication is currently a topic of intense research efforts. Quorum sensing exists in Gram-negative and

Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

• Carmen Curutiu,
• Florin Iordache,
• Veronica Lazar,
• Aurelia Magdalena Pisoschi,
• Aneta Pop,
• Mariana Carmen Chifiriuc and
• Alina Maria Hoban

Beilstein J. Org. Chem. 2018, 14, 2580–2588, doi:10.3762/bjoc.14.235

• of Agronomical Sciences and Veterinary Medicine, Faculty of Veterinary Medicine, Bucharest, Romania Institute of Cellular Biology and Pathology Nicolae Simionescu of Romanian Academy, Romania 10.3762/bjoc.14.235 Abstract Pseudomonas aeruginosa relies on the quorum sensing (QS) signaling system as a

• develop anti-QS therapeutic strategies to fight against P. aeruginosa infections. Keywords: adhesion; host–pathogen interaction; inflammation; Pseudomonas; quorum sensing; Introduction Pseudomonas (P.) aeruginosa is an opportunistic pathogen that causes severe and persistent infections in immune

• compromised individuals and in patients with bronchiectasis or cystic fibrosis. The infections become chronic, as P. aeruginosa develops resistance to conventional antibiotics due to its ability to produce virulence factors and modulate immune defenses by quorum sensing (QS) and biofilm production

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• Paris E. Georghiou Shofiur Rahman Abdullah Alodhayb Hidetaka Nishimura Jaehyun Lee Atsushi Wakamiya Lawrence T. Scott Department of Chemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador A1B 3X7, Canada Aramco Laboratory for Applied Sensing Research, King Abdullah

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• donors and transition metals as electron-deficient acceptors. Diverse functionalities embedded in these homometallic architectures have found useful applications in chemical sensing [24][25][26][27][28][29][30][31][32][33][34][35], catalysis [11][36][37][38][39][40][41][42][43][44][45][46], drug delivery

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• interesting properties as nanodevices for catalysis [5][6][7][8], recognition, and sensing [9][10][11][12][13]. Beyond these ascertained potentialities, interpenetrated architectures show fascinating structures that still stimulate the imagination of scientists. An amazing aspect of rotaxanes and catenanes is

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• for nucleotides sensing through a dye replacement procedure. It is unusual that disubstituted macrocycles 10a,b bind more effectively a less charged adenosine 5'-diphosphate (ADP) than adenosine 5'-triphosphate (ATP). A simple colorimetric method based on polydiacetylene vesicles decorated with 10b

• attention to the synthesis of host molecules with high affinity to biologically important anions [1][2][3][4][5]. Among these anions, nucleotide recognition and sensing represents an especially important research area due to the great biological significance of these anions. Adenine-containing nucleotides

• sensing purposes. Thereby, premicellar concentrations of calixarenes 10a,b (6 and 4 µM, respectively) and 12a,b (4 and 2 µM, respectively) were selected to design a receptor system based on the principle of competitive EY displacement by the guests. At these concentrations, a bathochromic shift

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• Mohammad A. Alnajjar Jurgen Bartelmess Robert Hein Pichandi Ashokkumar Mohamed Nilam Werner M. Nau Knut Rurack Andreas Hennig Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany Chemical and Optical Sensing Division, Bundesanstalt für

• fluorescent dyes directly enables (bio)sensing applications through the indicator displacement principle [16][17]. Therein, the fluorescence properties of a dye are altered when encapsulated by the host, and when a competitive binder displaces the dye from the cavity, the properties of the non-encapsulated

• sufficient for the desired sensing applications (Table 1) [20][53]. Surprisingly, and despite the hexaalkylated core was used, the fluorescence quantum yields of protonated as well as unprotonated 3 were more than 100-fold lower than the quantum yields of the other derivatives. Such reduced quantum yields

Recent advances in materials for organic light emitting diodes

• Eli Zysman-Colman

Beilstein J. Org. Chem. 2018, 14, 1944–1945, doi:10.3762/bjoc.14.168

• (LEECs), two types of electroluminescent devices; (ii) sensing materials employed in electro-chemiluminescence; and (iii) photocatalysts employed in photoredox catalytic reactions.

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• , Tianjin 300071, China 10.3762/bjoc.14.157 Abstract Based on the indicator displacement assay (IDA) approach, we herein report the fluorescence “switch-on” sensing and quantitative detection of bisphosphonates (BPs), a class of drugs extensively used in the treatment of patients with various skeletal

• BPs in buffer solution, and more importantly, in artificial urine. Calibration lines were therefore set up in untreated artificial urine, allowing for quantifying the concentrations of BPs in the biologically relevant low range. Keywords: bisphosphonate; calixarene; fluorescence sensing; macrocyclic

• in view of low cost, ease of use and high sensitivity of optical sensing modalities, but remains a challenge since BPs are considered as unlabeled analytes. With the development of the host–guest concept in supramolecular chemistry, the indicator displacement assay (IDA), pioneered by Prof. Anslyn