Azobenzene dye-coupled quadruply hydrogen-bonding modules as colorimetric indicators for supramolecular interactions

• Yagang Zhang and
• Steven C. Zimmerman

Beilstein J. Org. Chem. 2012, 8, 486–495, doi:10.3762/bjoc.8.55

• and exhibit a range of vivid colors. Furthermore, the application of azobenzenes in chemistry is quite broad and includes their use as switches [42], in nonlinear optics [43], sensing devices [44], and in nanostructured films for optical storage [45]. Although this work does not focus on switching

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

• Nicholas G. White and
• Paul D. Beer

Beilstein J. Org. Chem. 2012, 8, 246–252, doi:10.3762/bjoc.8.25

• that the redox-active macrocycle is capable of sensing chloride in CH3CN solution. Keywords: anion binding; C–H···anion interactions; electrochemistry; ferrocene; triazolium; Introduction The copper(I)-catalysed cycloaddition of alkynes and azides (CuAAC) [1][2] to give the 1,2,3-triazole group is

• investigate its anion binding and electrochemical-sensing properties. Results and Discussion Synthesis The CuAAC reaction of ferrocene bis(azide) 1 [12], with a large excess of 1,6-heptadiyne afforded 2 in 50% yield. An intramolecular Eglinton cyclisation reaction was used to prepare the ferrocene bis

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

Synthesis of dye/fluorescent functionalized dendrons based on cyclotriphosphazene

• Aurélien Hameau,
• Sabine Fuchs,
• Régis Laurent,
• Jean-Pierre Majoral and
• Anne-Marie Caminade

Beilstein J. Org. Chem. 2011, 7, 1577–1583, doi:10.3762/bjoc.7.186

• differences in the polarity of the solvents, enhanced by the hydrophobic nature of the dansyl part, and to their close proximity in the dendron. Variations of the emission wavelengths must be related to the variations in the viscosity of the mixtures. Such findings demonstrate that dendron 10 is a new sensing

Planar-bilayer activities of linear oligoester bolaamphiphiles

• Jonathan K. W. Chui,
• Thomas M. Fyles and
• Horace Luong

Beilstein J. Org. Chem. 2011, 7, 1562–1569, doi:10.3762/bjoc.7.184

• form the basic elements from which action potentials and other complex electrophysiological behaviors are constructed [1]. With recent technological breakthroughs, such as stochastic sensing [2] and the construction of ionic networks [3][4], the control and understanding of ion-channel attributes at a

Highly efficient cyclosarin degradation mediated by a β-cyclodextrin derivative containing an oxime-derived substituent

• Michael Zengerle,
• Florian Brandhuber,
• Christian Schneider,
• Franz Worek,
• Georg Reiter and
• Stefan Kubik

Beilstein J. Org. Chem. 2011, 7, 1543–1554, doi:10.3762/bjoc.7.182

• binding properties, and their relatively straightforward chemical modification have made cyclodextrins indispensable tools in applications such as sensing [2], nanotechnology [3][4], polymer chemistry [5][6][7][8], medicinal chemistry [9][10], food chemistry [11], and others. Importantly, the scope of

Ratiometric fluorescent probe for enantioselective detection of D-cysteine in aqueous solution

• Xiao-bo Zhou,
• Wing-Hong Chan,
• Albert W. M. Lee and
• Chi-Chung Yeung

Beilstein J. Org. Chem. 2011, 7, 1508–1515, doi:10.3762/bjoc.7.176

• ; fluorescence; ratiometric; Introduction The rapid, sensitive, and selective sensing of biologically relevant thiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) has attracted significant interest in the sensor community (Figure 1) [1]. All three of these thiols are present in living

• coworkers [6]. A number of novel sensing strategies have been designed that mostly relied on the high nucleophilicity of the sulfhydryl group. For instance, Michael addition of thiols onto fluorescent “acceptors” can trigger a change in the fluorescence outputs of the sensory materials [7][8][9][10][11

• ]. The facile cyclization of β- or γ-aminothiols with aldehydes containing fluorescent probes forms the basis for the development of several fluorescent probes [12][13][14][15][16][17]. In addition, cleavage of disulfide-based probes by thiols [18][19][20][21] and other thiol-sensing tactics have been

Fluorometric recognition of both dihydrogen phosphate and iodide by a new flexible anthracene linked benzimidazolium-based receptor

• Kumaresh Ghosh and
• Debasis Kar

Beilstein J. Org. Chem. 2011, 7, 254–264, doi:10.3762/bjoc.7.34

• of 1 with H2PO4− in the gas phase [34]. In the complex, benzimidazolium protons (C+–H) and amide protons are cooperatively involved in hydrogen bonding with H2PO4−. Anthracene, being a fluorophore in 1, has the advantage of being considered as a flat hydrophobic fluorophore probe for sensing of

• in emission in CHCl3 containing 0.1% CH3CN (Supporting Information File 1). These observations thus intimate that solvent polarity is an important aspect for monitoring the sensing behavior of benzimidazolium-based receptors. In our opinion, CH3CN in the present case participates in H-bonding with

• anthracene group in solvents of different polarities. Two benzimidazolium motifs with an isophthaloyl spacer group in 1, act cooperatively for successful detection of H2PO4− in CH3CN. In comparison, under the same experimental condition, a single benzimidazolium unit in 2 is inefficient in sensing H2PO4− ion

Synthesis and self-assembly of 1-deoxyglucose derivatives as low molecular weight organogelators

• Guijun Wang,
• Hao Yang,
• Sherwin Cheuk and
• Sherman Coleman

Beilstein J. Org. Chem. 2011, 7, 234–242, doi:10.3762/bjoc.7.31

• groups did show more promise than saturated hydrocarbons. Polydiacetylenes have interesting optical and electronic properties, and diacetylene containing gels may have useful applications as advanced sensing materials [35][40][41]. The morphologies of the self-assembled structures can be retained by

pH-Responsive chromogenic-sensing molecule based on bis(indolyl)methene for the highly selective recognition of aspartate and glutamate

• Litao Wang,
• Xiaoming He,
• Yong Guo,
• Jian Xu and
• Shijun Shao

Beilstein J. Org. Chem. 2011, 7, 218–221, doi:10.3762/bjoc.7.29

• anions [3][4][5][6][7], the development of artificial receptors for amino acids is quite limited. The effective and selective molecular recognition or sensing of unprotected amino acids in aqueous solution is still a challenging problem due to their highly hydrophilic character [8]. Several studies have

• shown that aspartate (Asp) and glutamate (Glu) are important neurotransmitters [9][10][11], thus the recognition or sensing of these amino acids by synthetic receptor molecules is of great interest [12][13][14]. The bis(indolyl)methene molecule 1 (Figure 1), possessing an acidic H-bond donor moiety and

• a basic H-bond acceptor moiety, could act not only as a color-reporting group but also as a binding affinity control group. The anion sensing properties of 1 based on acidic H-bond donor moiety have been studied previously in our laboratory [15]. The strong hydrogen bonding to, or protonation

Exceptionally small supramolecular hydrogelators based on aromatic–aromatic interactions

• Junfeng Shi,
• Yuan Gao,
• Zhimou Yang and
• Bing Xu

Beilstein J. Org. Chem. 2011, 7, 167–172, doi:10.3762/bjoc.7.23

• ., response to external stimuli and flow in response to shear force [2]) and applications in several areas (e.g., bioanalysis [3][4], chemical sensing [5][6][7], food processing [8], cosmetics [9], drug delivery [10][11], and tissue engineering [12][13]). Inspired by the existing and potential applications of

An easy assembled fluorescent sensor for dicarboxylates and acidic amino acids

• Xiao-bo Zhou,
• Yuk-Wang Yip,
• Wing-Hong Chan and
• Albert W. M. Lee

Beilstein J. Org. Chem. 2011, 7, 75–81, doi:10.3762/bjoc.7.11

• for sensing dicarboxylates. Their binding affinities toward dicarboxylates, aspartate and glutamate have been investigated in acetonitrile solution by fluorescence titration experiments. Both fluorescent sensors exhibited some ability to discriminate the antipodal forms of aspartate and glutamate

• . Keywords: amino acids; dicarboxylate ion recognition; enantioselectivity; mesitylene scaffold; Introduction The recognition and sensing of anionic substrates by positively charged or electrically neutral synthetic receptive molecular systems has emerged as a key research area because of the fundamental

• roles of anions in many chemical and biological processes [1][2][3][4][5]. Being the key structural moieties of many bioactive molecules such as amino acids and proteins, dicarboxylates are one of the most attractive targets for anion recognition and sensing. In addition, dicarboxylates are essential

A new fluorescent chemosensor for fluoride anion based on a pyrrole–isoxazole derivative

• Zhipei Yang,
• Kai Zhang,
• Fangbin Gong,
• Shayu Li,
• Jun Chen,
• Jin Shi Ma,
• Lyubov N. Sobenina,
• Albina I. Mikhaleva,
• Guoqiang Yang and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2011, 7, 46–52, doi:10.3762/bjoc.7.8

• recognition and sensing purposes in aprotic solvents. We present here a new example of a receptor, 3-amino-5-(4,5,6,7-tetrahydro-1H-indol-2-yl)isoxazole-4-carboxamide (receptor 1), which contains pyrrole, amide and amino subunits. This receptor shows both changes in its UV–vis absorption and fluorescence

• emission spectra upon the addition of F−, resulting in highly selectivity for fluoride detection over other anions, such as Cl−, Br−, I−, HSO4−, H2PO4− and AcO− in CH3CN. 1H NMR titration, time-dependent density functional theory (TDDFT) calculations and other experiments confirm that the sensing process

• Discussion Anion-sensing in CH3CN solution The selectivity of receptor 1 for F− anion over other anions was studied. Variations in the UV–vis absorption spectra and fluorescence spectra of 1 in acetonitrile (5 μM) in the presence of anions such as F−, Cl−, Br−, I−, HSO4−, H2PO4− and AcO− (50 equiv as their

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• processes. In this context, detection and sensing of these molecules by fluorescence spectroscopy offers a variety of advantages such as different detection modes (fluorescence quenching, enhancement and life time), high sensitivity, low instrumentation cost, time efficiency, and the possibility of

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• important especially in the in vivo study of biological samples. Otherwise the background blue emission of the biological samples interferes with the fluorescence sensing. The mechanism of fluorescence sensing often involves excited state intramolecular charge transfer (ICT) [8][9][10][11], photoinduced

• and also by substituting donor-acceptor groups along the conjugation [23][24][25]. In addition, pyrene also exhibits excimer emission at a longer wavelength compared to monomer emission which can be used in sensing applications [26][27][28][29][30]. The pyrene chromophore can act as a donor or as an

• acceptor depending upon the substituent. Pyrene- π spacer-donor and pyrene- π spacer-acceptor type molecules have been widely studied and they have been used in sensing, photo and electro-luminescence applications [31][32][33][34][35][36]. Unlike pyrene, the triphenylene chromophore has not been widely

RAFT polymers for protein recognition

• Alan F. Tominey,
• Julia Liese,
• Sun Wei,
• Klaus Kowski,
• Thomas Schrader and
• Arno Kraft

Beilstein J. Org. Chem. 2010, 6, No. 66, doi:10.3762/bjoc.6.66

• protein enrichment and purification, sensing and diagnostics applications, as well as therapeutic uses involving interference with critical protein–protein interactions. Multivalency represents the key to generate high-affinity materials for biomacromolecules with a sufficient number of binding sites for

Anthracene coupled adenine for the selective sensing of copper ions

• Kumaresh Ghosh and
• Tanushree Sen

Beilstein J. Org. Chem. 2010, 6, No. 44, doi:10.3762/bjoc.6.44

• presumably occur by the chelation enhanced anthracene → Cu2+ π-cation interactions, the paramagnetic effect of Cu2+ [34][35][36]. To understand the selective sensing of Cu2+ by both 1 and 2, we recorded the emission spectra of the receptors with the addition of 10 equivalents of Cu2+ to the receptor

• decreased in the presence of Cu2+ compared to 2 and thus underlines the fact that the sensing ability for metal ions of adenine motif is appreciable and effective when the fluorescent probe resides in close proximity to the WC/HG site. We believe that these observations regarding the interaction between the

Preparation, structures and preliminary host–guest studies of fluorinated syn-bis-quinoxaline molecular tweezers

• Markus Etzkorn,
• Jacob C. Timmerman,
• Matthew D. Brooker,
• Xin Yu and
• Michael Gerken

Beilstein J. Org. Chem. 2010, 6, No. 39, doi:10.3762/bjoc.6.39

• cleft that displays an inverted electrostatic potential could thus find application in sensing of electron-rich guests, or even anions [11][12][13]. Possible frameworks include the seemingly trivial fluorinated analogues of known frameworks (Scheme 1), but so far only a few groups have investigated

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• substituent will influence the binding. The co-ordination of primary ammonium ions salts with varying steric demand was investigated. The sensing ability of fluorescently labelled 1,10-diaza-18-crown-6 (16) was compared to the analogous monoaza-18-crown-6 coumarin sensor (15) [130]. The co-ordination

Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

• Ajit Kumar Mahapatra,
• Giridhari Hazra and
• Prithidipa Sahoo

Beilstein J. Org. Chem. 2010, 6, No. 12, doi:10.3762/bjoc.6.12

• for selective binding and sensing of certain anions, especially F−, AcO−, H2PO4−, etc. In particular, the selective sensing of fluoride has gained attention due to its significant role in clinical treatments e.g. dental care [9], osteoporosis [10] and for the detection of fluoride in bones as a result

• fluoride have been reported as chromogenic chemosensors, but a indolocarbazole ligand for the anion remains to be developed. Recently, Bhardwaj et al. reported a tripodal receptor [39] bearing catechol groups [40] for the chromogenic sensing of fluoride ions. Numerous bis(indolyl)methanes and their

• molecular receptor 1 for the selective sensing of anions by investigating the effect of the addition of tetrabutylammonium salts ([Bu4N]+X−, X = F−, Cl−, Br−, I−, AcO−, HSO4−, and H2PO4−). Receptor 1 (Figure 1) was particularly important as a chemosensor for fluoride owing to its noticeable color change in

Synthesis and binding studies of two new macrocyclic receptors for the stereoselective recognition of dipeptides

• Ana Maria Castilla,
• M. Morgan Conn and
• Pablo Ballester

Beilstein J. Org. Chem. 2010, 6, No. 5, doi:10.3762/bjoc.6.5

• higher conformational flexibility compared with the cyclic analogs. This enhanced conformational flexibility allows them to adopt a more effective binding conformation for the sensing of the substrate’s chirality. Conclusion We have designed two macrocyclic receptors for the stereoselective recognition

Quinoline based receptor in fluorometric discrimination of carboxylic acids

• Kumaresh Ghosh,
• Suman Adhikari,
• Asoke P. Chattopadhyay and
• Purnendu Roy Chowdhury

Beilstein J. Org. Chem. 2008, 4, No. 52, doi:10.3762/bjoc.4.52

• value and did not form any excimer upon complexation with the same acids under similar conditions. This established the role of quinoline ring nitrogen in binding with the acids. Keywords: carboxylic acid recognition; excimer emission; naphthalene; quinoline; Introduction The sensing and monitoring of

• ions and molecules by designed synthetic receptors is currently of major interest in the area of molecular recognition [1][2][3]. Among various sensing techniques available for clinical, biological and environmental analyses, fluorescence sensing is unique because of high sensitivity and compatibility

• for online and real-time analyses [4]. A large number of examples of fluorescent sensors capable of sensing ions and molecules have appeared over the past few years [5][6][7]. In this context, fluorescent sensors, which rely on guest-induced folding of flexible receptors bringing the fluorophore

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• have been synthesized by O-alkylation of the parent calix[4]arene. The compounds are formed in the cone conformation. They are soluble in several fluorous solvents and show promise for use in sensing, selective extractions and other applications. Keywords: calixarene; fluorous; hydrofluoroethers

• enhance the formation of a single conformer [12]. Of the four possible conformations, the cone is the most desirable for molecular recognition and sensing applications because it has the largest available surface area for host-guest interactions [10]. With appropriate functionality and conformation, the