Supramolecular Chemistry (SUPRAMOL CHEM)

Publications in this journal

• Article: A clickable, highly soluble oligopeptide that easily forms organogels

  Ruiying Gong, Yubao Song, Zongxia Guo, Ming Li, Yi jiang, Xiaobo Wan
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  ABSTRACT: An artificial peptide, N3-GVGV-OMe (G, glycine; V, valine), which mimics the repeating GAGA (A, alanine) sequence in Bombix Mori silk, was synthesised via solution-phase synthesis. Compared with N3 -GAGA-OMe sequence, N3-GVGV-OMe showed high solubility in common organic solvents (such as CHCl3, THF and CH2Cl2), and easily formed organogels simply by adding poor solvents (such as toluene or ether) to the peptide solution at room temperature. The hierarchical nanostructure of N3-GVGV-OMe organogel was dependent on the nature of the poor solvents, although in all cases, b-sheets were formed exclusively. Gels formed in ether showed higher level hierarchical assembly, as evidenced by AFM and CD studies. Solution-state FT-IR analysis showed that the pre-organisation of the peptides in solution was not significant, and well-defined antiparallel b-sheets were formed after the addition of the poor solvent. The high solubility and strong tendency for self-assembly of N3-GVGV-OMe, together with its terminal azide group, might facilitate the modification of functional organic molecules even macromolecules for better nanostructure control.
  Supramolecular Chemistry 04/2013; 25(5):269-275.
• Article: Metal-Triggered Nanofiber Formation of His-Containing β-Sheet Peptide

  S. Matsumura, S. Uemura, H. Mihara
  Supramolecular Chemistry 02/2013; 18:397-403.
• Article: Self-assembly properties of bile acid derivatives of L-cysteine, L-valine and L-serine alkyl esters

  Virpi Noponen, Arto Valkonen, Manu Lahtinen, Hannu Salo, Elina Sieva¨nen
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  ABSTRACT: Comprehensive self-assembly studies for nine bile acid amides of amino acid esters are reported. The number of the hydroxyl groups attached to the steroidal skeleton and the character of the amino acid ester moiety were used as variables when examining the self-assembly properties of the compounds. Two of the compounds were shown to undergo self-assembly leading to organogelation. In addition, preliminary self-assembly studies in aqueous mixtures of polar organic solvents were conducted.Microscopic methods (opticalmicroscopy and scanning electron microscopy)were utilised in order to gain a deeper insight into the self-assembled structures. Furthermore, single-crystal X-ray structures for three of the compounds were solved.
  Supramolecular Chemistry 02/2013; 25(3):133-145.
• Article: An aminonaphthalimide-putrescine conjugate as fluorescent probe for cucurbituril host-guest complexes

  Cátia Parente Carvalho, Rita Ferreira, José P da Silva, Uwe Pischel
  Supramolecular Chemistry 02/2013; 25(2):92-100.
• Article: On the Rate of Boronate Ester Formation in ortho-Aminomethyl Functionalized Phenyl Boronic Acids.

  Byron E Collins, Pedro Metola, Eric V Anslyn
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  ABSTRACT: 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.
  Supramolecular Chemistry 02/2013; 25(2):79-86.
• Article: Crystallographic, UV spectroscopic and computational studies of the inclusion complex of a-cyclodextrin with p-aminobenzoic acid

  Kossay Elasaad, Bernadette Norberg, Johan Wouters
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  ABSTRACT: Crystal structure of the cyclomaltohexaose (a-cyclodextrin, a-CD) inclusion complex with p-aminobenzoic acid (pABA) has been determined by X-ray diffraction. The host:guest stoichiometry is 1:1. The pABA molecule is included in the cavity with its axis coincident with the axis of a-CD; the benzoic group is inserted in the cavity, while the amino group sticks out from the cavity. Four water molecules are located near the cavity rims and in interstices between the molecules of a-CD participating in a dense network of intermolecular hydrogen bonds. UV–visible spectroscopy was applied to estimate the stability constant (Kc) at different temperatures on the basis of the Benesi–Hildebrand equation. This allowed calculation of complexation enthalpy and entropy on the basis of the Van’t Hoff equation. The results are in good agreement with the values obtained by other methods in the literature. Phase-solubility profiles indicate that the solubility of pABA is significantly increased in the presence of a-CD at different pH values, and it was classified as AL-type, indicating a 1:1 stoichiometric inclusion complex in solution. A theoretical investigation has also been carried out on the a-CD-pABA systems in order to search for other stable complexes. PM6 semi-empirical calculations were made to investigate equilibrium geometries of inclusion complexes formed between a-CD and neutral, anionic, cationic and zwitterionic forms of pABA. Two possible orientations were considered (A, with the carboxylic end inside the cavity and B, with the amino group inside the cavity). Preference between A and B orientations of each a-CD-pABA form results from different H-bond interaction patterns.
  Supramolecular Chemistry 04/2012; 24(5):312-324.
• Article: Geometrically diverse anions in anion-pi interactions

  Michael Giese, Markus Albrecht, Gergana Ivanova, Arto Valkonen, Kari Rissanen
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  ABSTRACT: The role of different anion geometries in anion–p interactions is discussed. The chemistry described herein is different to the interaction of spherical cations with aromatics. The influence of different geometries makes selective anion recognition more complicated than respective cation sensing. The present structural study reveals attractive interactions between pentafluorophenyl units and geometrically diverse anions (linear, trigonal planar, tetrahedral and octahedral). Due to the electrostatic nature of anion–p interactions, the anion geometry seems to be irrelevant. The size of the anion controls the relative orientation of the anion and the p system (e.g. in compounds 1–3). The dimeric solid-state structure of ammonium tetrafluorophenolate betaine 4 shows p–p as well as anion–p interactions. In the solid-state structure of 5, the linear BrIBr anion is panelled by three pentafluorophenyl units.
  Supramolecular Chemistry 01/2012; 24(1):48-55.
• Article: Structure-selectivity relationships in competitive crystallizations of Urea-functionalized anion-binding capsules

  A. Rajbanshi, R. Custelcean
  Supramolecular Chemistry 01/2012; 24:65-71.
• Article: Acyclic cucurbituril congener binds to local anaesthetics

  Da Ma, Raymond Glassenberg, Soumyadip Ghosh, Peter Y. Zavalij, Lyle Isaacs
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  ABSTRACT: The recognition properties of acyclic cucurbit[n ]uril (CB[n ]) congener 1 towards seven local anaesthetic drugs (2–8) are reported. Job plots constructed from 1H NMR experiments confirm the 1:1 host:guest nature of these complexes, whereas the changes in chemical shift observed upon complex formation (Dd values) provide information about the geometry of the host–guest complexes. For complexes between host 1 and guests 2–5 and 8, a single geometry was preferred, whereas for guests 6 and 7 a mixture of two diastereomeric complexes was indicated. The Ka values for complexes between 1 and 2–8 fall in the range of 103–108M21 as determined by UV–vis and 1H NMR competition experiments. The results further establish that acyclic CB[n ]-type receptor 1 is preorganised into the C-shape required for binding and that its aromatic o-xylylene walls endow it with a potency towards aromatic ammonium ions. The Ka values reported in this paper constitute a blind data-set used in the SAMPL3 challenge aimed at testing computational methods relevant to proteinzligand systems. The work thus highlights the great potential of CB[n ] receptors as model systems to promote synergy between the supramolecular and computational chemistry communities
  Supramolecular Chemistry 01/2012; 24:325.
• Article: Anion binding to a tetracopper resorcinarene-based complex Giuseppe Arena, Raffaele. P. Bonomo, Laura Vagliasindi, Valeria Zito;John D. Lamb,

  Giuseppe Arena, Raffaele. P. Bonomo, Laura Vagliasindi, Valeria Zito, Roger N. Harrison John D. Lamb
  Supramolecular Chemistry 01/2012;
• Article: Chlorhexidine/losartan ionic pair binding and its nanoprecipitation: physico-chemical characterisation and antimicrobial activity

  Denadai, Ângelo M.L, de Oliveira, André M, Daniel, Izabela M.P, Carneiro, Luan A, Ribeiro, Kherolayne C, Beraldo, Heloísa de O, da Costa, Kelen J.R, da Cunha, Vivianne C, Cortés, Maria E, Sinisterra, Rubén D
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  ABSTRACT: Chlorhexidine is a widely used, di-cationic, broad-spectrum antimicrobial agent and losartan is a well-known, anionic-specific antagonist of AT1 renin–angiotensin receptor that acts as an anti-hypertensive agent. The combination of these molecules gives a chlorhexidine di-losartanate (ClxLos2) hydrophobic ion pair that spontaneously aggregates into nanoparticles (NPs). This work investigated the formation of ClxLos2 NPs using the analysis of the solid state by fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy and in aqueous environment by calorimetric, zeta potential and dynamic light scattering titrations. Furthermore, to demonstrate the potential antimicrobial activity of ClxLos2, in vitro antibacterial tests were conducted against Staphylococcus aureus (ATCC 27664), Streptococcus viridans (ATCC 11563) and Enterococcus faecalis (ATCC 14508). Based on these studies, it is proposed that ClxLos2 could be used for controlled drug release based on ionic dissociation during dilution, thereby avoiding the use of any solid matrix.
  Supramolecular Chemistry 12/2011;
• Article: Self-assembly of tert-butyl silanetriol in solution and aggregation with tetrahydrofuran

  Stefan Spirk, Stefan Salentinig, Ferdinand Belaj, Klaus Zangger, Rudolf Pietschnig
  Supramolecular Chemistry 11/2011; 2011(23):805.
• Article: Novel adamantane-bearing anilines and properties of their supramolecular complexes with β-cyclodextrin

  Robert Vícha, Michal Rouchal, Zuzana Kozubková, Ivo Kuřitka, Radek Marek, Petra Branná, Richard Čmelík
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  ABSTRACT: Several novel anilines bearing 1-adamantyl substituents that are useful for drug modification were synthesised from the corresponding 1-adamantyl (nitrophenyl) ketones. The host–guest systems of these prepared ligands with β-cyclodextrin (β-CD) were studied using electrospray ionisation mass spectrometry, NMR spectroscopy, titration calorimetry and semi-empirical calculations. The complexes with 1:1 stoichiometry were found to predominantly exist as pseudorotaxane-like threaded structures with the adamantane cage sitting deep in the cavity of β-CD close to the wider rim. Such geometry was observed for all examined amines and is independent of their structure and/or presence of protic substituents.
  Supramolecular Chemistry 10/2011; 23(10):663-677.
• Article: Supramolecular self-assembled nanowires by the aggregation of a protoporphyrin derivative in low-polarity solvents

  Sheshanath V. Bhosale, Mohan B. Kalyankar, Santosh V. Nalage, Sidhanath V. Bhosale, Cecilia H. Lalander, Steven J. Langford
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  ABSTRACT: The self-assembly of a simple tetraalkyl-substituted protoporphyrin derivative into fibril wire-like nanostructures from CHCl3/cyclohexane solvent mixes is explored. The protoporphyrin IX derivative is synthesised in two efficient steps by amidation of the two propylenic acid groups followed by a cross metathesis of the vinyl groups using Grubbs' second-generation catalyst. The self-assembly of the functionalised protoporphyrin is sensitive to solvent and under favourable conditions forms ‘nanowires’ of micrometre length. The nanowires were characterised by absorption and fluorescence spectroscopy, transmission electron microscopy and atomic force microscopy.
  Supramolecular Chemistry 08/2011; 23(8):563-569.
• Article: Spontaneous self-assembly of designed cyclic dipeptide (Phg-Phg) into two-dimensional nano- and mesosheets

  T. Govindaraju, M. Pandeeswar, K. Jayaramulu, Garima Jaipuria, Hanudatta S. Atreya
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  ABSTRACT: In this study, we present the spontaneous self-assembly of designed simplest aromatic cyclic dipeptides of (l-Phg-l-Phg) and (d-Phg-l-Phg) to form highly stable two-dimensional (2D) nano- and mesosheets with large lateral surface area. Various microscopy data revealed that the morphology of 2D mesosheets resembles the hierarchical natural materials with layered structure. Solution and solid-state NMR studies on cyclo(l-Phg-l-Phg) revealed the presence of strong (N–H–O) hydrogen-bonded molecular chains supported by aromatic π–π interactions to form 2D mesosheets. Interestingly, cyclo(d-Phg-l-Phg) self-assembles to form single-crystalline as well as non-crystalline 2D rhomboid sheets with large lateral dimension. X-ray diffraction analysis revealed the stacking of (N–H–O) hydrogen-bonded molecular layers along c-axis supported by aromatic π–π interactions. The thermogravimetric analysis shows two transitions with overall high thermal stability attributed to layered hierarchy found in 2D mesosheets.
  Supramolecular Chemistry 07/2011; 23(7):487-492.