ISMSC 2007 - Università degli Studi di Pavia

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PSB 67 Cooperative Complexation of -Cyclodextrin with Micelle-like Aggregates Formed from Amphiphilic Polyanions Daisuke Taura, Akihito Hashidzume, and Akira Harada Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan Molecular recognition in biological systems often exhibits high selectivity to form precisely controlled supramolecular structures, which express various functions necessary for maintaining living activities. We have been aware of the importance of macromolecular chains in the biological molecular recognition for the past decade, and thus studying the interaction of cyclodextrins (CDs) with hydrophobic side chains attached to water soluble polymers (WSPs). The previous studies focused on the interaction of CDs with WSPs modified with a small amount of hydrophobes, whereas this study focuses on the interaction of CDs with WSPs bearing a number of hydrophobes to investigate the effect of competition with self-association of hydrophobes. In this study, we employed alternating copolymers of sodium maleate and dodecyl vinyl ether with different molecular weights (pC12MAn, Figure 1). Steady state fluorescence and sedimentation equilibrium measurements confirmed that pC12MAn formed micelle-like aggregates in aqueous media. The interaction of -, -, and -CDs with pC12MAn was investigated by several NMR techniques. These spectra indicated that only -CD interacted significantly with dodecyl (C12) groups in pC12MAn. Then, the complexation equilibrium between -CD with pC12MAn was explored by 1 H NMR spectra measured in the presence of varying concentrations of -CD. These spectra exhibit resonance bands due to free and complexed C12 groups separately at intermediate -CD concentrations, indicating slow exchange between the free and complexed states comparing with the NMR time scale. Using the concentrations of free and complexed C12 groups, the concentrations of free and complexed -CD (CCD,f and CCD,c, respectively) were calculated. Values of CCD,c were plotted against CCD,f to prepare binding isotherms. The binding isotherms exhibit sigmoidal curves, indicative of cooperative complexation of -CD with pC12MAn. Figure 1 shows a conceptual illustration for the cooperative complexation of -CD with pC12MAn. The binding isotherms were analyzed using a model based on one dimensional lattice model although it may not be a proper model. The analysis indicated that -CD interacted more cooperatively with pC12MAn of a higher molecular weight. Dissociation Kinetics of Tl + , Pb 2+ , Cd 2+ , and Bi 3+ Cryptates Gary. L. N. Smith, Olajumoke O. Oluwu, Baige Bian, Richard W. Taylor Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, USA Cryptands form stable complexes with heavy metal ions such as Tl + , Pb 2+ , Cd 2+ , and Bi 3+ . Structural factors that affect the complexation selectivity include: i) cavity size, ii) type of donor atoms (O, N, S), and iii) backbone substituents (benzo, cyclohexano). We have studied the dissociation kinetics for the compounds shown below to examine the role of these structural factors. In the presence of excess strong acid the observed rate constant, kobs, shows several types of [H + ] dependence. For most cryptates studied, a linear dependence on [H + ] is observed (kobs = kd + kH [H + ]), where kd and kH are the rate constants for the acid-independent and aciddependent pathways, respectively. However, the dissociation of Tl(2.2.2) + shows saturation type behavior (kobs = (kd + kH [H + ])/(1 + k’[H + ]). For complexes with polyaza-cryptands such as Pb(2N.2.2) 2+ and Bi(2N.2N.2N) 3+ pathways indicating higher-order [H + ] dependence are observed (kobs = (kd + kH1 [H + ] + kH2[H + ] 2 ). The role of various structural factors on the dissociation kinetics and the detailed mechanisms consistent with [H + ] dependence of kobs are discussed. O N O O N O O N O O N a a = 1; 2.2.1 a = 2; 2.2.2 a = 3; 3.2.2 R O O O O R R = C 6H 4 ; 2 B.2 B.2 R = C 6H 10 ; 2 C.2 C.2 X X N O O N O O X = O; 2.2.2 X = S; 2 S.2.2 X = N; 2 N.2.2 NH HN H N N N H N NH HN 2 N.2 N.2 N O O N O O N O O An2.2.2 N N N O O N O O 2.2.2 BIPY PSB 68
Investigation of -cyclodextrin binding affinity to some purine alkaloids. Irina Terekhova Institute of Solution Chemistry of Russian Academy of Sciences, 1 Akademicheskaya str., Ivanovo 153045, Russia, E-mail: ivt@isc-ras.ru PSB 69 Cyclodextrins (cyclooligosaccharides) are a family of macrocyclic receptors, which are able to form inclusion complexes with a wide variety of organic compounds. Physical-chemical and biological properties of guest molecules included into cyclodextrin cavity during the complex formation can be significantly modified. An inclusion complexation phenomena of cyclodextrins determines their numerous practical applications. Primarily, cyclodextrins are used as solubilizing and stabilizing agents in cosmetic, food and pharmaceutical industries, as well as drug carriers. Therefore, the aim of present work was to reveal the capability of native and substituted -cyclodextrins to form inclusion complexes with caffeine and theophylline in aqueous solution. These alkyl substituted xanthines referred to the class of purine alkaloids are the substances of biological and pharmaceutical importance. Interactions of - and hydroxypropyl--cyclodextrins with caffeine and theophylline in water at 298.15 K were studied by calorimetry, 1 H NMR and solubility methods. Systems with complex formation and weak interactions were characterized by the thermodynamic parameters of complexation (K, cG, cH and cS) and enthalpic virial coefficients (hxy), respectively. The obtained results demonstrate that: - -Cyclodextrins display low binding affinity to caffeine and theophylline. - Structure of purine alkaloids influences the thermodynamics of interaction and binding affinity of cyclodextrins. In comparison with theophylline, caffeine forms more stable complexes with -cyclodextrin. - Complex formation of -cyclodextrin with caffeine is enthalpy-entropy driven, whereas its binding with theophylline is only entropically favourable. However, the entropy contribution in the free energy is dominant in both cases. - Partial substitution of OH-groups surrounding the -cyclodextrin molecule by hydroxypropyl-groups results in weakness of binding. Probably, hydroxypropyl substituents may be too bulky hindering complexation of hydroxypropyl--cyclodextrin with caffeine and theophylline. - Insignificant enhancement of aqueous solubility of purine alkaloids under study in the presence -cyclodextrin was observed. This work was supported by the Russian Foundation for Basic Research (grant no. 06-03- 96313) and by the Russian Science Support Foundation. Ditopic dithiophosphoramides and acylthiourea ligands as metal salt extractants Jy Chartres, Shalima Shawuti, Peter A. Tasker * , Christine C. Tong University of Edinburgh, School of Chemistry, Joseph Black Building, West Mains Road, Edinburgh, Scotland EH9 3JJ email: ctong@staffmail.ed.ac.uk Ditopic ligands are those that have binding sites for a cation and anion in a single covalent molecule and are effective ligands for transferring metal salts from aqueous to water-immiscible phases. [1-2] As such, ditopic ligands provide an effective strategy for isolating metal value from mining leachates and provide access to more environmentally friendly metal recovery processes. Metal salts are extracted from the aqueous phase into the organic phase using a ditopic ligand. The metal cation and anion can then be stripped into aqueous solution by adjusting the pH. Separate cation and anion stripping is effected by the differences in pKa of the cation and anion binding sites (Fig. 1). This paper reports the synthesis and characterization of 1 and 2 as well as their efficacy as ditopic metal salt extractants, thereby elaborating on the existing successful (but limited) motifs for ditopic extractants for base metals. [3-4] AH AH ligand salt +2NH3 -[NH4]2X HB + X 2- HB + +H2X -MX AH B AH B free ligand A - M 2+ A - + MX metal-salt complex HB + X 2- HB + HB + AH Y AH 2- HB + ligand salt 1 2 [1] L. A. J. Chrisstoffels, F. de Jong, D. N. Reinhoudt, Chem. Euro. Journal 2000, 6, 1376. [2] R. A. Coxall, L. F. Lindoy, H. A. Miller, A. Parkin, S. Parsons, P. A. Tasker, D. J. White, Dalton Trans. 2003, 55. [3] N. Akkus, J. C. Campbell, J. Davidson, D. K. Henderson, H. A. Miller, A. Parkin, S. Parsons, P. G. Plieger, R. M. Swart, P. A. Tasker, L. C. West, Dalton Trans. 2003, 1932. [4] S. G. Galbraith, P. G. Plieger, P. A. Tasker, Chem. Comm. 2002, 2662. +H2Y +2NH3 -[NH4]2Y +2NH3 -[NH4]2X +H2X +2H2Y -MY A - M 2+ A - metal-only complex +MY -[NH4Y] Fig. 1 Schematic diagram of pH controlled loading and stripping of ditopic ligands coordinated to metal salts. The uncoordinated salts are in the aqueous phase. For our interests, M = Cu 2+ , Ni 2+ , Zn 2+ and Co 2+ and X = SO4 2- . N S S P P N H t-Bu t-Bu t-Bu O S NH N N B B PSB 70
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nd International Symposium on Macro
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Eric Anslyn University of Texas at
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1 Map of Salice Terme 7 5 6 3 9 2 8
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Symposium Program All sessions will
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11:40 - 12:00 Oral Presentation: V.
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PSA 22 Anion Receptors Based On The
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PSA 72 Molecular Tectonics: STM Stu
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PSB 11 Dual binding properties of p
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PSB 57 Removal Of Heavy Metal Ions
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40 years of polyazamacrocycles. A p
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PL 5 Anion-Templated Assembly of In
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Exercising Demons: Synthetic Molecu
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Synthetic Strategies and Structural
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Anion binding as a conformational a
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Supramolecular control of a metal c
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OP 3 Control of molecular architect
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Catalyst discovery using dynamic co
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Cucurbit[n]uril Molecular Container
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OP 15 From non-mesomorphic nature t
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OP 19 Pyrrolic Tripodal Receptors f
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PSA 1 Efficient synthesis of pseudo
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Tetra-Cationic phthalocyanines Yasi
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PSA 9 Cell penetrating borosilica n
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PSA 13 Halide anion interactions wi
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Sensing with cavitands: Moving from
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Lead(II) complexation by calix[4]-h
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Functional [2×2] Grids Xiao-Yu Cao
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Neutral supramolecular systems inco
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PSA 33 Ratiometric Ion Sensors by R
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A photocontrollable receptor for Cu
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New emitters for mass spectrometric
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PSA 45 A fast-moving electrochemica
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Macrocyclic Porphyrin-Bidentate Che
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PSA 53 Electronic spectroscopy of e
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PSA 57 Self-assembly of calixarene/
Page 71 and 72: PSA 61 Piperazine Containing Polyam
Page 73 and 74: PSA 65 Synthesis of Self-Assembly S
Page 75 and 76: PSA 69 Assembly of Metallomacrocycl
Page 77 and 78: Supra-Biomolecular Tandem Assays -
Page 79 and 80: PSA 77 Synthesis and molecular reco
Page 81 and 82: PSA 81 Reaction of phthalic aldehyd
Page 83 and 84: Binding of perrhenate and pertechne
Page 85 and 86: PSA 89 Supramolecular assemblies of
Page 87 and 88: Polytopic Ligands for the Recovery
Page 89 and 90: PSB 1 Rosette Nanotubes as Scaffold
Page 91 and 92: PSB 5 Towards the development of ne
Page 93 and 94: PSB 9 A Quantitative [2]Rotaxane Sy
Page 95 and 96: Metal Complexes of the Polyether Io
Page 97 and 98: PSB 17 Metal controlled anion inter
Page 99 and 100: Crown Ether-tert-Ammonium Salt Comp
Page 101 and 102: PSB 25 A Minimalist Design for Self
Page 103 and 104: PSB 29 Control of Translation of th
Page 105 and 106: PSB 33 Multinuclear NMR, ESI MS and
Page 107 and 108: PSB 37 New Anthracene-based cycloph
Page 109 and 110: PSB 41 1,3,5-Tris(2-aminophenyl)ben
Page 111 and 112: Simple Isophthalamide Derivatives A
Page 113 and 114: PSB 49 On Sokolov’s approach to a
Page 115 and 116: PSB 53 New chromogenic sensors usin
Page 117 and 118: PSB 57 Removal of heavy metal ions
Page 119 and 120: PSB 61 Molecular Recognition of Ele
Page 121: PSB 65 Switching of Self to non-Sel
Page 125 and 126: Novel ditopic probes for different
Page 127 and 128: PSB 77 Synthesis, supramolecular ar
Page 129 and 130: PSB 81 Tripodal polyamines as anion
Page 131 and 132: PSB 85 Templated Synthesis of Large
Page 133 and 134: PSB 89 Direct C-C coupling of 1,2,4
Page 135 and 136: PSB 93 The study of cytotoxicity ef
Page 137 and 138: PSB 97 Development of innovative so
Page 139 and 140: Campbell B. PSA 39 Campbell F. PSB
Page 141 and 142: Jensen L.G. PSA 82 Jeppesen J.O. IL
Page 143 and 144: Peters A.J. PSB 39 Peters A.J. PSB
Page 145 and 146: Sponsors of ISMSC 2007 The contribu
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