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  • Syntheses of ester and amide derivatives of calix[6]arene and their complexation affinities towards La3+, Eu3+, and Yb3+
    Supramol. Chem. (IF 1.66) Pub Date : 2019-08-01
    Marina Tranfić Bakić; David Klarić; Maria Soledad Espinosa; Saša Kazazić; Leo Frkanec; Paola Alejandra Babay; Nives Galić

    One hexaester (1) and three hexaamide derivatives (2–4) of calix[6]arenes were prepared for the first time in one synthetic step, under microwave radiation. Compounds 2 and 3 were novel ones, while ester calix[6]arene derivative 1 and amide derivative 4 were prepared previously, by conventional syntheses. Microwave-assisted syntheses shortened the reaction times from 48 to 2 h. The binding properties of calix[6]arenes towards selected lanthanide cations (La3+, Eu3+, Yb3+) were studied by spectroscopic and mass spectrometric techniques. No complexation was observed with the ester derivative, while compounds 2–4 formed 1:1 complexes. Based on spectrophotometric titrations, the stability constants of resulting complexes could only be estimated (lg K ≥ 6). Calixarene derivatives, as well as their complexes, were analysed by ESI MS and MS/MS spectrometry. Corresponding fragmentation pathways were proposed, and in some cases confirmed by MS3 experiments. The results obtained by different techniques were in accordance.

    更新日期:2020-01-24
  • A simple chemosensor for ultrasensitive fluorescent “turn-on” detection of Fe3+ and alternant detection of CN-
    Supramol. Chem. (IF 1.66) Pub Date : 2019-11-17
    Qin-Peng Zhang; Tai-Bao Wei; Jun-Nian An; Yan-Yan Chen; Guan-Fei Gong; Qi Zhou; Hai-Long Yang; Hong Yao; You-Ming Zhang; Qi Lin

    ABSTRACT It is worth noting that Fe3+ is paramagnetic in nature. Thus, in most of the cases, Fe3+ behave as fluorescent quencher which makes it difficult to develop a fluorescent ‘turn-on’ chemosensor. Therefore, it is still a big challenge to devise and synthesise a simple chemosensor that could selectively detect Fe3+ via fluorescent ‘turn-on’ response. In this paper, A simple fluorescence chemosensor T based on N,N-(3,3-dimethyl biphenyl)-bis(2-methoxyphenol) has been synthesised. T could selectively detect Fe3+ via fluorescent ‘turn-on’ response. Meanwhile, the fluorescent spectrum limit of T towards Fe3+ was 0.178 nM, the detection limit was much lowest than previously reported fluorescent chemosensor and has reached to ultrasensitive level. In addition, T could also alternately detect CN−. Intriguingly, IMPLICATION logic gate was successfully constructed. Finally, the test papers and films based on T were prepared, which could be used as a fluorescent display material for the detection of Fe3+ and CN−.

    更新日期:2020-01-24
  • Aryl ethers decorated gallic acid–naphthalimide conjugate: aggregation and sensing towards amines and F−
    Supramol. Chem. (IF 1.66) Pub Date : 2019-11-24
    Chiranjit Pati; Kumaresh Ghosh

    A gelator 1 containing naphthalimide and gallic acid derivatives has been designed and synthesised. It forms instant orange-coloured gels from different solvents such as CH3CN-1,4-dioxane (5:1, v/v), toluene-1,4-dioxane (5:1, v/v) and dimethylsulfoxide (DMSO). The morphology of the gels reveals the fibrous network. CH3CN-1,4-dioxane (5:1, v/v) gel exhibits higher mechanical strength than toluene-1,4-dioxane (5:1, v/v) gel as confirmed from lower tan δ value (tan δ = G″av/G′av) in rheological experiment. The CH3CN-1,4-dioxane (5:1, v/v) gel of 1 exhibits sharp response towards aliphatic amines over the aromatic amines causing rapid gel-to-gel transition with colour change. On the other hand, toluene-1,4-dioxane (5:1, v/v) gel of 1 selectively senses fluoride ion (F−) from a series of other basic anions by exhibiting colour change (from orange to blackish brown) of the gel state. By contrast, CH3CN-1,4-dioxane (5:1, v/v) gel underwent gel-to-sol transition in the presence of several anions and did not show any selectivity in sensing. Gelator 1 also shows measurable interaction towards aliphatic amines, F− and AcO− in CH3CN with distinguishable features in electronic spectra and colour change. Compound 1 and F−-coated paper strip which exhibits colour change on heating and cooling has been successfully used as writing kit.

    更新日期:2020-01-21
  • An ultrasensitive and selective ‘turn off’ fluorescent sensor with simple operation for the determination of trace copper (II) ions in water and various beverage samples
    Supramol. Chem. (IF 1.66) Pub Date : 2019-12-12
    Sukriye Nihan Karuk Elmas; Ibrahim Berk Gunay; Kenan Koran; Furkan Ozen; Duygu Aydin; Fatma Nur Arslan; Ahmet Orhan Gorgulu; Ibrahim Yilmaz

    Considering vital roles of trace copper ions for the health of humans, it is critical to sensitively detect it in foodstuffs. Herein, an ultrasensitive and cost–effective coumarin based fluorescent strategy with a “turn–off” signal was developed for specific detection of trace Cu2+ ions. Synthesis of 6,7-dihydroxy-3-(3-methylphenyl)coumarin (TMAC) probe was performed and characterized. The developed fluorescent probe presented excellent selectivity. The limit of detection of the sensor can reach as low as 5.13 nM in ACN/H2O (v/v=95/5) buffered by 5 μM HEPES buffer at pH = 7.0, and it is below the World Health Organization (WHO) guideline for drinking water (31.5 μM). The probable stoichiometry of TMAC–Cu2+ complex (1:1) was determined by Job's plot method and confirmed by FT–IR and ESI–MS. We further successfully applied TMAC for Cu2+ detection in water and various beverage samples with good recovery (90.24-109.75 %).

    更新日期:2020-01-21
  • Mechanism for efficient separation of eugenol and eugenol acetate with β-cyclodextrin as a selective solvent
    Supramol. Chem. (IF 1.66) Pub Date : 2019-12-17
    Zujin Yang; Yuxin Chai; Dan Zhou; Xingdong Yao; Hongbing Ji

    Separation of active components from essential oils is very difficult due to some similar chemical and physical properties. In this work, a facile method is developed to reduce the separation cost. β-Cyclodextrin (β-CD) is used for the separation of eugenol and eugenol acetate by forming the inclusion complexation of non-covalent host–guest interactions. The separation was achieved by a co-precipitation method, using ethanol:water (1:4, v/v) as a solvent at the temperature of 50 °C for 2 h. The molar ratio of guests to β-CD for complexation was 4:1. The inclusion rate of eugenol increased to 60% with a separation factor of 2.5, and the purity of eugenol was up to 99% from 50% after one cycle. β-CD can be easily recovered with industrial ethanol (95%,v/v) and used repeatedly. A possible mechanism is also proposed based on the experimental and computational methods. The results indicate that β-CD is suitable to separate the aromatic constituents from the natural products.

    更新日期:2020-01-21
  • Efficient removal of carcinogenic azo dyes by novel pyrazine-2-carboxylate substituted calix[4, 8]arene derivatives
    Supramol. Chem. (IF 1.66) Pub Date : 2020-01-14
    Ömer Güngör

    In this study, novel pyrazine-2-carboxylate derivatives of calix[4, 8]arene have been synthesised and fully characterised. Furthermore, this study presents removal of carcinogenic azo dyes [Reactive Black 5 (RB5), Trapaeolin 000 (TP), Chicago Sky Blue (CSB), Methyl Orange (MO) and Evans Blue (EB)] from the aqueous solution by solid-liquid extraction using these novel compounds. The maximum sorption of azo dyes was achieved at pH 3. Calix[8]arene derivative (3) showed higher sorption as it formed a more stable complex with azo dyes than calix[4]arene derivative (6). An excellent regeneration for at least five times in sorption capacity indicates that calix[8]arene derivative (3) was highly applicable for the removal of carcinogenic azo dyes from industrial wastewater. The stoichiometric ratio between the calixarene derivatives (3 and 6) and selected azo dyes was estimated through job’s plots.

    更新日期:2020-01-21
  • Acyclic cucurbit[n]uril type receptors: secondary versus tertiary amide arms
    Supramol. Chem. (IF 1.66) Pub Date : 2019-07-28
    Weijian Xue, Peter Y Zavalij, Lyle Isaacs

    Two acyclic CB[n]-type hosts (1 and 2) which possess four 2° or 3° amide arms are reported. Host 2 has four 3° amide arms that exist as a mixture of E- and Z-isomers. 1H NMR was used to qualitatively investigate the binding properties of 1 and 2 which indicates they retain the essential binding features of macrocyclic CB[n] hosts. We measured the Ka values of 1 and 2 toward guests 6–14 by ITC. Neutral hosts 1 and 2 bind less tightly than tetraanionic hosts M1, ACB1, and ACB2. We attribute the lower Ka values to the absence of secondary ion-ion electrostatic interactions for host•guest complexes of 1 and 2. The secondary amide functionality on 1 decreases affinity by the formation of intramolecular NH•••O=C H-bonds. Tertiary amide host 2 binds even more weakly than 1 due to backfolding of the amide N-CH3-groups of 2 into its own cavity.

    更新日期:2019-11-04
  • Photo-physical aspects of BODIPY-coumarin conjugated sensor and detection of Al3+ in MCF-7 cell
    Supramol. Chem. (IF 1.66) Pub Date : 2019-09-12
    Kumari Somlata Kashyap, Sumit Kumar Hira, Swapan Dey

    BODIPY azine bearing chemosensor R1 has been synthesised for selective detection of Al3+with visual colour change from red-purple to purple and photo-physical studies were explained through Förster Resonance Energy Transfer (FRET) mechanism. Chemosensor showed good sensing capability with high binding constant and lower Limit of Detection (LOD) towards Al3+. Cell viability and fluorescence microscopic experiments illustrated about the cytocompatibily of the sensor in presence of Al3+ in living cells (MCF-7).

    更新日期:2019-11-04
  • Hydrogen-bonding interactions in crown-(thio)urea complexes with anions, chemical warfare agents and simulants
    Supramol. Chem. (IF 1.66) Pub Date : 2019-09-01
    Hannah Cave, Jayne A. Ede, Mark R. Sambrook, Howard Dodd, Flavia Fucassi, Alexander S. Cragg, Adam H. Lansley, Peter J. Cragg

    Benzocrown ethers incorporating phenyl and nitrophenyl urea and thiourea moieties were synthesised. Both the nitrophenyl urea and thiourea derivative gave a fluoride-specific colorimetric response but only the urea derivative bound the organophosphonate nerve agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP). This suggested an application as sensors for the nerve agents sarin, soman and cyclosarin which release fluoride upon hydrolysis. Although no fluoride-induced response was observed in the UV-visible spectrum, binding to soman was determined by 1H NMR. DFT computational simulations suggested that the two crowns adopt different conformations in which both can bind fluoride but only the urea derivative can bind DMMP, DIMP and soman. The results show that, for this system, simulant- and soman-binding behaviours are in good agreement.

    更新日期:2019-11-04
  • Controllable and reversible proton transfer for inorganic cyanide visual sensing based on the deprotonation of azo-phenolic hydroxyl group
    Supramol. Chem. (IF 1.66) Pub Date : 2019-10-15
    Jun Wang, Jinjun He, Jinsheng Zhang, Zhiming Chen, Xiaogang Yin

    Methods for optical detection of inorganic cyanide based on the single molecule sensor with high selectivity and sensitivity have attracted increasing interest recently due to the high toxicity of cyanide ions. In this work, a visual sensor (S1) containing both imidazole NH and azo-phenolic OH was synthesised and characterised. The spectral experimental data indicated that protic aqueous solution facilitated enhancing the selectivity of cyanide ions with the nanomolar-level detection limit in semi-aqueous solution. The visual sensing mechanism arising from the deprotonation of azo-phenolic OH and the enhancement of intramolecular charge transfer could be clearly demonstrated by titration experiments of 1H NMR, HR MS and energy changes between the HOMO−LUMO band gaps. Furthermore, the reversibility and reusability of S1 upon alternating addition of CN− and H+ were studied.

    更新日期:2019-11-04
  • Bis-amidopyrrolyl Receptors Based on Anthracene and Carbazole.
    Supramol. Chem. (IF 1.66) Pub Date : 2010-02-18
    Dustin E Gross,Vinay Mikkilineni,Vincent M Lynch,Jonathan L Sessler

    A new set of diamide receptors containing anthracene and carbazole bridging subunits and either pyrrole or phenyl substituents were synthesized. The four systems produced in this way were shown to bind representative anions in DMSO-d(6) solution and in the solid state. A higher relative affinity for two test oxoanions, namely dihydrogen phosphate and benzoate, over chloride anion was seen in solution, with the anions in question being studied in the form of their respective tetrabutylammonium salts. However, the specifics of the anion recognition process were seen to depend on structure, with the pyrrole-containing systems displaying higher relative affinities than their corresponding phenyl-containing congeners, and the carbazole receptors proving more effective than the anthracene analogues. Such observations provide support for the notion that both the carbazole NH and the pyrrolic NH protons play an important role in stabilizing the receptor-bound anions in solution. Structural analyses of several anion complexes of the diamidopyrrole carbazole receptor reveal that this is not necessarily the case in the solid state; specifically, the pyrrole NH protons are seen to interact with the amide oxygen of another molecule. The net result is an extended a one-dimensional coordinaton polymer.

    更新日期:2019-11-01
  • Self-assembly of Au Nanoparticle-containing Peptide Nano-rings on Surfaces.
    Supramol. Chem. (IF 1.66) Pub Date : 2006-01-01
    Nurxat Nuraje,Kai Su,Jacopo Samson,Amit Haboosheh,Robert I Maccuspie,Hiroshi Matsui

    The peptide nano-rings containing Au nanoparticles inside their cavities were self-assembled on dithiol SAMs patterned as an array by AFM-based nanolithography. The peptide nano-rings were aligned as a line on these SAMs, and Au formed lines with the spacing between these nanoparticles as the peptide nano-rings functioned as spacers. This type of array fabrication will provide improved tunability in their optical properties of resulting nanoparticle-assembled arrays. In addition, optimization of the inter-particle distance of nanoparticles in the array with various spacers may allow one to design new types of photonic crystals with desired optical properties.

    更新日期:2019-11-01
  • Assessment of the in vitro toxicity of calixarenes and a metal-seamed calixarene: a chemical pathway for clinical application.
    Supramol. Chem. (IF 1.66) Pub Date : 2019-08-03
    Arnab Dawn,Xue Yao,Ying Yu,Jianxiong Jiang,Harshita Kumari

    Calixarenes are known to form host-guest complexes and supramolecular nanoassemblies with well-defined architectures. However, the use of these materials in conjunction with drug moieties is still under explored. One reason is the insuffcient biocompatibility studies. Our present study represents a systematic in vitro investigation of the cytotoxicity associated with C-methylresorcin[4]arene, C-methylpyrogallol[4]arene, p-phosphonated calix[8]arene and a metal-seamed calixarene-copper(II) complex, using human HEK293 and rat C6G cell lines and two different cell viability assays (MTT and CellTiter-Glo) to avoid species-biased results. All compounds showed low to moderate toxicity. The trend in the CC50 values indicated that the suppression of the coordination ability and the presence of phosphonate groups decrease the overall cytotoxicity of the compounds. The results of this study not only establish calixarenes and their immediate families as potential drug carriers and drug modifiers, but also reveal a pathway for fine-tuning their toxicological behaviour by appropriate chemical modification.

    更新日期:2019-11-01
  • Cationic acyclic cucurbit[n]uril-type containers: synthesis and molecular recognition toward nucleotides.
    Supramol. Chem. (IF 1.66) Pub Date : 2016-10-18
    David Sigwalt,Peter Y Zavalij,Lyle Isaacs

    We report the synthesis of M2NH3 which is a tetracationic analogue of our prototypical acyclic CB[n]-type molecular container M2. Both M1NH3 and M2NH3 possess excellent solubility in D2O and do not undergo intermolecular self-association processes that would impinge on their molecular recognition properties. Compounds M1NH3 and M2NH3 do, however, undergo an intramolecular self-complexation process driven by ion-dipole interactions between the ureidyl C=O portals and the OCH2CH2NH3 arms along with inclusion of one aromatic wall in its own hydrophobic cavity. The Ka values for M1NH3 and M2NH3 toward seven nucleotides were determined by 1H NMR titration and found to be quite modest (Ka in the 102 - 103 M-1 range) although M2NH3 is slightly more potent. The more highly charged guests (e.g. ATP) form stronger complexes with M1NH3 and M2NH3 than the less highly charged guest (e.g. ADP, AMP). The work highlights the dominant influence of the ureidyl C=O portals on the molecular recognition behavior of acyclic CB[n]-type receptors and suggests routes (e.g. more highly charged arms) to enhance their recognition behavior toward anions.

    更新日期:2019-11-01
  • Tuning supramolecular G-quadruplexes with mono- and divalent cations.
    Supramol. Chem. (IF 1.66) Pub Date : 2015-01-01
    Mariana Martín-Hidalgo,Marilyn García-Arriaga,Fernando González,José M Rivera

    Supramolecular G-quadruplexes (SGQs) are formed via the cation promoted self-assembly of guanine derivatives into stacks of planar hydrogen-bonded tetramers. Here, we present results on the formation of SGQs made from the 8-(m-acetylphenyl)-2'-deoxyguanosine (mAGi) derivative in the presence of various mono- and divalent cations. NMR and HR ESI-MS data indicate that varying the cation can efficiently tune the molecularity, the fidelity and stability (thermal and kinetic) of the resulting SGQs. The results show that, parallel to the previously reported potassium-templated hexadecamer (mAGi16·3K+), Na+, Rb+ and [Formula: see text] also promote the formation of similar supramolecules with high fidelity and molecularity. In contrast, the divalent cations Pb2+, Sr2+ and Ba2+ template the formation of octamers (mAGi8), with the latter two inducing higher thermal stabilities. Molecular dynamics simulations for the hexadecamers containing monovalent cations enabled critical insights that help explain the experimental observations.

    更新日期:2019-11-01
  • The thermodynamics of guest complexation to octa-acid and tetra-endo-methyl octa-acid: reference data for the sixth statistical assessment of modeling of proteins and ligands (SAMPL6).
    Supramol. Chem. (IF 1.66) Pub Date : 2019-09-27
    Matthew R Sullivan,Wei Yao,Bruce C Gibb

    Although computer-aided drug design has greatly improved over time, its application in the pharmaceutical industry is still limited by the accuracy of association constant predictions. Towards improving this situation, the Statistical Assessment of the Modeling of Proteins and Ligands (SAMPL) is a series of community-wide blind challenges aimed to advance computational techniques as standard predictive tools in rational drug design (https://en.wikipedia.org/wiki/SAMPL_Challenge). As an empirical contribution to the sixth assessment (SAMPL6), we report here the association constant (Ka ) and thermodynamic parameters (∆G, ∆H, -T∆S) of eight guests (G0-G7) binding to two subtly different hosts (OA and TEMOA) using ITC. Both hosts contain a unique, well-defined binding pocket capable of storing guests with up to ten non-hydrogen atoms, whilst the selection of amphiphilic guests contain a range of saturated and unsaturated substituents from C6 to C10. The thermodynamic data from this study will allow the challenge participants of SAMPL6 to test the accuracy of their computational protocols for calculating host-guest affinities.

    更新日期:2019-11-01
  • Steric Effects of pH Switchable, Substituted (2-pyridinium)urea Organocatalysts: a Solution and Solid Phase Study.
    Supramol. Chem. (IF 1.66) Pub Date : 2018-01-01
    Nicholas B Wageling,Daniel A Decato,Orion B Berryman

    The study of hydrogen bonding organocatalysis is rapidly expanding. Much research has been directed at making catalysts more active and selective, with less attention on fundamental design strategies. This study systematically increases steric hindrance at the active site of pH switchable urea organocatalysts. Incorporating strong intramolecular hydrogen bonds from protonated pyridines to oxygen stabilizes the active conformation of these ureas thus reducing the entropic penalty that results from substrate binding. The effect of increasing steric hindrance was studied by single crystal X-ray diffraction and by kinetics experiments of a benchmark reaction.

    更新日期:2019-11-01
  • Surface Ligands in the Imprinting and Binding of Molecularly Imprinted Cross-Linked Micelles.
    Supramol. Chem. (IF 1.66) Pub Date : 2018-01-01
    M D Arifuzzaman,Wei Zhao,Yan Zhao

    Molecular recognition in water is challenging but water-soluble molecularly imprinted nanoparticle (MINP) receptors were produced readily by double cross-linking of surfactant micelles in the presence of suitable template molecules. When the micellar surface was decorated with different polyhydroxylated ligands, significant interactions could be introduced between the surface ligands and the template. Flexible surface ligands worked better than rigid ones to interact with the polar moiety of the template, especially for those template molecules whose water-exposed surface is not properly solvated by water. The importance of these hydrophilic interactions was examined in the context of different substrates, density of the surface ligands, and surface-cross-linking density of the MINP. Together with the hydrophobic interactions in the core, the surface hydrophilic interactions can be used to enhance the binding of guest molecules in water.

    更新日期:2019-11-01
  • Efficient Fluorescence Detection of Aromatic Toxicants and Toxicant Metabolites in Human Breast Milk.
    Supramol. Chem. (IF 1.66) Pub Date : 2017-01-01
    Dana J DiScenza,Julie Lynch,Molly Verderame,Nicole Serio,Lindsey Prignano,Lauren Gareau,Mindy Levine

    Once chemical contaminants are released into the environment, there are a number of concerns that arise regarding the environmental persistence of the contaminants, their known and suspected toxicities, and their potential disruption to the ecosystem. One class of contaminants that is of continuing concern is polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants that are significant components of oil spills. PAHs have been found in the breast milk of nursing mothers living in oil spill affected regions, and can harm the nursing children. We report herein the sensitive and selective detection of 10 PAHs and PAH metabolites in human breast milk using fluorescence energy transfer from the PAH to a high quantum yield fluorophore, and array-based statistical analyses of the resulting fluorescence responses. This detection system was able to separate and identify the PAHs with 100% success in human breast milk and at concentrations as low as 0.17 μM. These results have significant implications in public health and in the monitoring and mitigation of environmental disasters.

    更新日期:2019-11-01
  • Probing the Protein-Nanoparticle Interface: The Role of Aromatic Substitution Pattern on Affinity.
    Supramol. Chem. (IF 1.66) Pub Date : 2015-01-01
    Zeynep Ekmekci,Krishnendu Saha,Daniel F Moyano,Gulen Yesilbag Tonga,Hao Wang,Rubul Mout,Vincent M Rotello

    A new class of cationic gold nanoparticles has been synthesized bearing benzyl moieties featuring -NO2 and -OMe groups to investigate the regioisomeric control of aromatic nanoparticle-protein recognition. In general, nanoparticles bearing electron withdrawing group demonstrated higher binding affinities towards green fluorescent protein (GFP) compared to electron-donating groups. Significantly, a ~7.5 and ~4.3 fold increase in binding with GFP was observed for -NO2 groups in meta- and para-position respectively, while ortho-substitution showed similar binding compared to the unsubstituted ring. These findings demonstrated that nanoparticle-protein interaction can be controlled by the tuning the spatial orientation and the relative electronic properties of the aromatic substituents. This improved biomolecular recognition provides opportunities for enhanced biosensing and functional protein delivery to the cells.

    更新日期:2019-11-01
  • Anion-directed self-assembly of a 2,6-bis(2-anilinoethynyl)pyridine bis(amide) scaffold.
    Supramol. Chem. (IF 1.66) Pub Date : 2016-04-26
    Blakely W Tresca,Orion B Berryman,Lev N Zakharov,Darren W Johnson,Michael M Haley

    Bis(sulfonamide) receptors based on the 2,6-bis(2-anilinoethynyl)pyridine scaffold form persistent dimers with water and halides in solution and in the solid-state. The structurally related bis(amide) receptor derived from 3,5-dinitrobenzoyl chloride is a dimer in the solid-state with two HCl molecules directing the self-assembly. The 2+2 dimer, with a twisted "S"-shaped backbone, is held together by six hydrogen bonds. Dissolution of the (H2+·Cl- )2 adduct in CHCl3 results, however, in a monomeric structure. DOSY and 1H NMR experiments were used to identify the dominance of monomer in solution for both 2 and H2+·Cl- . The 'OFF-ON' fluorescence response of 2, 6-bis(2-anilinoethynyl)pyridine is retained with amide arms.

    更新日期:2019-11-01
  • Super-secondary structure peptidomimetics: design and synthesis of an α-α hairpin analogue.
    Supramol. Chem. (IF 1.66) Pub Date : 2013-09-01
    Laura Nevola,Johanna M Rodriguez,Sam Thompson,Andrew D Hamilton

    The α-α helix motif presents key recognition domains in protein-protein and protein-oligonucleotide binding, and is one of the most common super-secondary structures. Herein we describe the design, synthesis and structural characterization of an α-α hairpin analogue based on a tetra-coordinated Pd(II) bis-(iminoisoquinoline) complex as a template for the display of two α-helix mimics. This approach is exemplified by the attachment of two biphenyl peptidomimetics to reproduce the side-chains of the i and i+4 residues of two helices.

    更新日期:2019-11-01
  • Differentiation of Functional Groups and Biologically Relevant Anions Using AT-PAMAM Dendrimers.
    Supramol. Chem. (IF 1.66) Pub Date : 2013-11-14
    S Reid Long,Marco Bonizzoni,Brenton M Ray,Eric V Anslyn

    Biological anions have often proven to be difficult analytes to differentiate in solution. Many of the anions bear similar structural characteristics and similar charge states. Using a commercially available indicator and AT-PAMAM dendrimers, a sensing ensemble for a number of biological anions was constructed. The system was able to identify each of the different analytes as well as the regioisomers of three different tricarboxylates. The system shows responsiveness to not only functional group identity but also the charge state and identity of the anionic species.

    更新日期:2019-11-01
  • Oligonucleotide-Based Systems for Input-Controlled and Non-Covalently Regulated Protein-Binding.
    Supramol. Chem. (IF 1.66) Pub Date : 2013-11-05
    Cooper Battle,Xiaozhu Chu,Janarthanan Jayawickramarajah

    Supramolecular chemists continuously take inspiration from complex biological systems to develop functional molecules involved in molecular recognition and self-assembly. In this regard, "smart" synthetic molecules that emulate allosteric proteins are both exciting and challenging, since many allosteric proteins can be considered as molecular switches that bind to other protein targets in a non-covalent fashion, and importantly, are capable of having their output activity controlled by prior binding to input molecules. This review discusses the foundations and passage toward the development of non-covalently operated oligonucleotide-based systems with protein-binding capacity that can be precisely regulated in an input-controlled manner.

    更新日期:2019-11-01
  • An improved synthesis of 'octa-acid' deep-cavity cavitand.
    Supramol. Chem. (IF 1.66) Pub Date : 2011-06-15
    Simin Liu,Sarah E Whisenhunt-Ioup,Corinne L D Gibb,Bruce C Gibb

    An improved synthesis of a water-soluble deep-cavity cavitand (octa-acid, 1) is presented. Previously (Gibb, C. L. D. & Gibb, B. C., J. Am. Chem. Soc., 2004, 126, 11408-11409) we documented access to host 1 in eight (non-linear) steps starting from resorcinol; a synthesis that required four steps involving chromatographic purification. Here we reveal a modified synthesis of host 1. Consisting of seven (non-linear) steps, this new synthesis involves only one chromatographic step, and avoids a minor impurity observed in the original approach. This improved synthesis will therefore be useful for the laboratories that are investigating the properties of these types of host.

    更新日期:2019-11-01
  • Control of Nanospaces with Molecular Devices.
    Supramol. Chem. (IF 1.66) Pub Date : 2011-03-02
    Fabien Durola,Henry Dube,Dariush Ajami,Julius Rebek

    Cavitands and capsules define nanoliter spaces for recognition, isolation and reactions of small molecules. These systems are usually self-assembled and factors such as solvent size, stoichiometry, and packing factors determine what goes into the spaces. Here we examine two switching devices to control what and when guests get in and out of these hosts: bipyridyl-metal chelation and azobenzene photoisomerization. The effects are reversible by treatment with conventional chelating agents and brief heating, respectively. Accordingly, it is possible to trigger reactions that take place within a cylindrical capsule by light, even though the reaction process is not photochemical by nature. Likewise the presence of metals can regulate reactions without acting as direct catalysts.

    更新日期:2019-11-01
  • Self-assembled cation transporters made from lipophilic 8-phenyl-2'-deoxyguanosine derivatives.
    Supramol. Chem. (IF 1.66) Pub Date : 2011-01-08
    Mariana Martín-Hidalgo,Karla Camacho-Soto,Vladimir Gubala,José M Rivera

    We have previously reported that 8-phenyl-2'-deoxyguanosine derivatives (8PhGs) are able to extract metal cations from an aqueous phase into an organic phase. Herein we report on the ability of 8PhGs to transport metal cations across a bulk lipophilic liquid membrane. The experiments were performed using lithium, sodium, potassium, and strontium picrate salts with the parent lipophilic Gi, two isomeric 8PhG derivatives, cis-dicyclohexano-18-crown-6 (CD18C6) and [2•2•2] cryptand as reference compounds. The relative amounts of the picrate salts were measured by UV spectroscopy in both, the source phase and the receiving phase over a period of 24 h. The results show that the transport efficiency of the self-assembled ionophores formed by 8PhGs is either similar or superior to that of CD18C6, and in all but one case higher than the parent compound Gi. The varying efficiencies between the derivatives can be attributed to the stability (kinetic and thermodynamic) and the different molecularities of the supramolecules formed by these 8PhGs. The ease of the synthesis of 8PhGs, their anion independent assembly and the fact that the transport efficiency can be modulated as a function of the structure of the 8PhGs bode well for the use of such compounds in the development of novel antimicrobial agents and cation sensing devices.

    更新日期:2019-11-01
  • Effect of Stopper Size on Squaraine Rotaxane Stability.
    Supramol. Chem. (IF 1.66) Pub Date : 2009-01-01
    Na Fu,Jeremiah J Gassensmith,Bradley D Smith

    A series of new squaraine rotaxanes have been synthesized with a tetralactam macrocycle and stopper groups of varying sizes and functionalities. In chloroform solvent, the relative size of the stopper group appears to have little influence on the high mechanical stability of the rotaxane structure. There is no evidence for unthreading (sometimes referred to as deslipping), even in the presence of competing chloride salts or elevated temperatures. A difference in rotaxane stability emerges as the polarity of the organic solvent is increased. Squaraine rotaxanes with small stopper groups undergo unthreading in the polar aprotic solvent DMSO. However, a water soluble tetracarboxylic acid derivative was found to be highly stable in aqueous solvents containing serum.

    更新日期:2019-11-01
  • Recent Advances in Synthetic Membrane Transporters.
    Supramol. Chem. (IF 1.66) Pub Date : 2007-01-01
    Beth A McNally,W Matthew Leevy,Bradley D Smith

    It is 25 years since the first report of a synthetic ion channel transporter. Today, dozens of molecular and supramolecular designs have been developed to facilitate ion and small molecule transport across a bilayer membrane. Presented here is a concise summary of the advances made over the past four years. The transporters are grouped into three mechanistic classes: mobile carrier, monomeric channel, and self-assembled pore. Common building blocks are crown ethers, steroids, cyclodextrins, peptides, curcubiturils, and calixarenes. The eventual goal is to produce functional supramolecular devices such as sensors, enzyme assays, and lead candidates for pharmaceutical development.

    更新日期:2019-11-01
  • Resorcinarene-Encapsulated Gold Nanorods: Solvatochromatism and Magnetic Nanoshell Formation.
    Supramol. Chem. (IF 1.66) Pub Date : 2009-01-31
    Matthew N Hansen,Ling-Shao Chang,Alexander Wei

    Gold nanorods (GNRs) were encapsulated and dispersed into organic solvents by tetrabenzylthiol resorcinarene (TBTR) and by a poly(dithiocarbamate) derived from tetra- N-methyl(aminomethyl)resorcinarene (TMAR-DTC), formed by the in situ condensation of TMAR with carbon disulfide. The latter proved to be highly effective at enabling the redispersion of GNRs in various organic solvents. GNRs encapsulated in TMAR-DTC exhibited a strong solvatochromic response, with a refractive index sensitivity of over 300 nm/RIU. The resorcinarene-encapsulated GNRs could withstand high temperatures for a short period of time, and could be used to nucleate the growth of magnetic nanoshells.

    更新日期:2019-11-01
  • Effect of Bridging Anions on the Structure and Stability of Phenoxide Bridged Zinc Dipicolylamine Coordination Complexes.
    Supramol. Chem. (IF 1.66) Pub Date : 2013-08-06
    Edward J O'Neil,Hua Jiang,Bradley D Smith

    A series of four related phenol derivatives, with 2,2'-dipicolylamine substituents at the ortho positions, were prepared and their Zn2+ coordination complexes studied by spectroscopic methods. X-ray crystal diffraction analysis of a dinuclear zinc complex with two bridging acetate anions showed a ternary structure with highly charged interior and lipophilic exterior, which helps explain why this class of water-soluble complexes can effectively diffuse through cell membranes. The stability of the dinuclear zinc complexes in aqueous solution was found to be strongly anion dependent; that is, bridging oxyanions, such as acetate and pyrophosphate, lock the two Zn2+ cations to the surrounding ligand and greatly enhance ligand/zinc affinity. Overall, the results provide new insight into the structural and mechanistic factors that control the recognition and chemosensing performance of phenoxide bridged dipicolylamine molecular probes.

    更新日期:2019-11-01
  • On the Rate of Boronate Ester Formation in ortho-Aminomethyl Functionalized Phenyl Boronic Acids.
    Supramol. Chem. (IF 1.66) Pub Date : 2013-02-27
    Byron E Collins,Pedro Metola,Eric V Anslyn

    The role of the ortho-aminomethyl functional group in phenyl boronic acids for sugar complexation is a topic of debate. To decipher its effect on the kinetics of boronate ester formation, we first performed pseudo-first order kinetics analyses at five pH values up to 4 mM in fructose, revealing a first-order kinetic dependence upon fructose. Under these conditions, the reaction is in equilibrium and does not reach completion, but at 50 mM fructose saturation is achieved revealing zero-order dependence upon fructose. This indicates rate-determining creation of an intermediate prior to reaction with fructose, which we propose involves leaving group departure of inserted solvent. Further, the region of kinetics displaying zero-order dependence has a kinetic isotope effect (KIE) of 1.42, showing involvement of a proton transfer in the leaving group departure. The ratio of forward and reverse rate constants branching from the intermediate shows that fructose is several thousand times more nucleophilic than the solvent. Overall, the data supports a mechanism where the o-aminomethyl group lowers the pK(a) of the proximal boronic acid and acts as a general-acid (as an ammonium) to facilitate leaving group departure. Consequently, by microscopic reversibility the resulting amine must perform general-base catalysis to deliver fructose.

    更新日期:2019-11-01
  • Optimising the synthesis and red-green-blue emission of a simple organic dye.
    Supramol. Chem. (IF 1.66) Pub Date : 2009-01-01
    Martha Sibrian-Vazquez,Robert Strongin

    Synthetic dyes have been widely used in supramolecular chemistry not only to probe fundamental chemical interactions but also as components of functional materials. Most current efforts in this regard are directed at designing new host systems for the dyes. Herein we report on the study of a versatile new organic fluorophore. We describe a synthesis which affords improved yields in a convenient one pot procedure. Moreover, a simple method for predicting and controlling the dye's responses to external stimuli affords a potentially practical method for achieving red-green-blue and concomitant white light generation.

    更新日期:2019-11-01
  • Enantiopure Cryptophane-129Xe Nuclear Magnetic Resonance Biosensors Targeting Carbonic Anhydrase.
    Supramol. Chem. (IF 1.66) Pub Date : 2014-12-17
    Olena Taratula,Yubin Bai,Edward L D'Antonio,Ivan J Dmochowski

    The (+) and (-) enantiomers for a cryptophane-7-bond-linker-benzenesulfonamide biosensor (C7B) were synthesized and their chirality confirmed by electronic circular dichroism (ECD) spectroscopy. Biosensor binding to carbonic anhydrase II (CAII) was characterized for both enantiomers by hyperpolarized (hp) 129Xe NMR spectroscopy. Our previous study of the racemic (+/-) C7B biosensor-CAII complex [Chambers, et al., J. Am. Chem. Soc. 2009, 131, 563-569], identified two "bound" 129Xe@C7B peaks by hp 129Xe NMR (at 71 and 67 ppm, relative to "free" biosensor at 64 ppm), which led to the initial hypothesis that (+) and (-) enantiomers produce diastereomeric peaks when coordinated to Zn2+ at the chiral CAII active site. Unexpectedly, the single enantiomers complexed with CAII also identified two "bound" 129Xe@C7B peaks: (+) 72, 68 ppm and (-) 68, 67 ppm. These results are consistent with X-ray crystallographic evidence for benzenesulfonamide inhibitors occupying a second site near the CAII surface. As illustrated by our studies of this model protein-ligand interaction, hp 129Xe NMR spectroscopy can be useful for identifying supramolecular assemblies in solution.

    更新日期:2019-11-01
  • ITC and NMR Analysis of the Encapsulation of Fatty Acids within a Water-Soluble Cavitand and its Dimeric Capsule.
    Supramol. Chem. (IF 1.66) Pub Date : 2016-03-22
    Kaiya Wang,Punidha Sokkalingam,Bruce C Gibb

    We report here NMR and ITC studies of the binding of ionizable guests (carboxylate acids) to a deep-cavity cavitand. These studies reveal that the shortest guests favored 1:1 complex formation, but the longer the alkyl chain the more the 2:1 host-guest capsule is favored. For intermediate-sized guests, the equilibrium between these two states is controlled by pH; at low values the capsule containing the carboxylic acid guest is favored, whereas as the pH is raised deprotonation of the guest favors the 1:1 complex. Interestingly, for one host-guest pair the energy required to de-cap the 2:1 capsular complex and form the 1:1 complex is sufficient to shift the pKa of the guest by ~ 3-4 orders of magnitude (4.1-5.4 kcal mol-1). The two largest guests examined form stable 2:1 capsules, with in both cases the guest adopting a relatively high energy J-shaped motif. Furthermore, these 2:1 complexes are sufficiently stable that at high pH guest deprotonation occurs without de-capping of the capsule.

    更新日期:2019-11-01
  • Pb, Sr and Ba calix[6]arene hexacarboxylic acid octahedral complexation: a dramatic effect of dealkylation.
    Supramol. Chem. (IF 1.66) Pub Date : 2016-01-12
    Birendra Babu Adhikari,Cuong-Alexander To,Tetsuo Iwasawa,Michael P Schramm

    Calix[6]arene hexacarboxylic acid binds instantly and with low symmetry to Pb, Sr and Ba. Later a highly symmetric up-down alternating conformation emerges. The solution structures are identical to their p-tert-butylcalix[6]arene hexacarboxylic acid counterparts. With either receptor an octahedral cage is formed around the metal. The transformation from low to high symmetry however proceeds at significantly faster rates for the de-t-butylated host.

    更新日期:2019-11-01
  • Synthesis of a Disulfonated Derivative of Cucurbit[7]uril and Investigations of its Ability to Solubilize Insoluble Drugs.
    Supramol. Chem. (IF 1.66) Pub Date : 2015-05-06
    Elizabeth L Robinson,Peter Y Zavalij,Lyle Isaacs

    Cucurbit[7]uril (CB[7]) is currently being investigated as a solubilizing agent for insoluble drugs. We recently found that acyclic CB[n]-type receptors that bear sulfonate solubilizing groups are well suited for this application. Herein, we report cucurbit[7]uril derivative (1) that bears two sulfonate groups on its convex face that we hypothesized would be a superior solubilizing excipient for insoluble drugs. Before using 1 for drug solubilization experiments we showed that 1 does not self-associate and that it retained its ability to bind to diammonium compounds as common guests for CB[7] sized cavities. X-ray crystallography shows that 1 maintains the key structural features of CB[7] with only minor ellipsoidal deformations at the equator and carbonyl portals of 1. Unfortunately, the aqueous solubility of 1 (20 mM) is slightly lower than CB[7] (20-30 mM) which limits its potential as a solubilizing excipient for insoluble drugs. We created phase solubility diagrams for the solubilization of three drugs (camptothecin, albendazole, cinnarizine) with two different containers (1 and CB[7]). CB[7] and 1 exhibit comparable solubilization abilities (e.g. Ka and maximum solubility) toward camptothecin and albendazole but 1 is an inferior solubilizing agent for cinnarizine because of the low solubility exhibited by the 1•cinnarizine complex.

    更新日期:2019-11-01
  • Cyclodextrin-promoted energy transfer for broadly applicable small-molecule detection.
    Supramol. Chem. (IF 1.66) Pub Date : 2014-01-01
    Nicole Serio,Chitapom Chanthalyma,Lindsey Prignano,Mindy Levine

    Reported herein is the development of non-covalent, proximity-induced energy transfer from small-molecule toxicants to organic fluorophores bound in the cavity of γ-cyclodextrin. This energy transfer occurs with exceptional efficiency for a broad range of toxicants in complex biological media, and is largely independent of the spectral overlap between the donor and acceptor. This generally applicable phenomenon has significant potential in the development of new turn-on detection schemes.

    更新日期:2019-11-01
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