Emiliano Tamanini

University of Cambridge, Cambridge, ENG, United Kingdom

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Publications (9)45.69 Total impact

  • Angewandte Chemie International Edition 06/2011; 50(25):5725-8. · 11.34 Impact Factor
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    ABSTRACT: In an effort to improve upon the recently reported cyclam based zinc sensor 1, the "click"-generated 1,8-disubstituted analogue 2 has been prepared. The ligand shows a 2-fold increase in its fluorescence emission compared to 1 exclusively in the presence of Zn(II) that is typical of switch-on PET fluorescent sensors. Single crystal X-ray diffraction of complexes of model ligand 10 reveals that the configuration adopted by the macrocyclic framework is extremely sensitive to the metal ion to which it coordinates. For Zn(II), Mg(II), and Li(I) the metal ions adopt an octahedral geometry with a trans III configuration of the cyclam ring. In contrast for Ni(II) the ligand adopts the rare cis V configuration, while for Cu(II) a clear preference for five-coordinate geometry is displayed with a trans I configuration of the macrocyclic ring being observed in two essentially isostructural compounds prepared via different routes. The ligand displays an increased selectivity for Zn(II) compared to 1 in the majority of cases with excellent selectivity upheld over Na(I), Mg(II), Ca(II), Mn(II), Ni(II), Co(II), and Fe(III). In contrast for Cu(II) and Hg(II) little improvement was observed for 2 compared to 1 and for Cd(II) the selectivity of the new ligand was inferior. In the light of these findings and the slower response times for ligand 2, our original "click"-generated cyclam sensor system 1 was employed in a proof of concept study to prepare a heterogeneous sol-gel based material which retains its PET response to Zn(II). The versatile nature of the sol-gel process importantly allows the simple preparation of a variety of nanostructured materials displaying high surface area-volume ratio using fabrication methods such as soft lithography, electrospinning, and nanopipetting.
    Inorganic Chemistry 03/2010; 49(8):3789-800. · 4.59 Impact Factor
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    ABSTRACT: Supramolecular nanotubes derived from naphthalenediimide (NDI) dicarboxylic acids can act in chloroform solution as size-selective receptors for a range of guests including pyrenes and aromatic and aliphatic ion pairs. CD spectroscopy indicates that the nanotube remains intact after complexation. Guest binding increases in the presence of low concentrations of added methanol, perhaps indicating that the binding process is primarily solvophobic.
    Faraday Discussions 01/2010; 145. · 3.82 Impact Factor
  • Emiliano Tamanini, G Dan Pantoş, Jeremy K M Sanders
    Chemistry 11/2009; 16(1):81-4. · 5.93 Impact Factor
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    ABSTRACT: An azamacrocyle doped polypyrrole is considered as a material showing heavy metal cation sensitivity and examples with Ni2+, Zn2+, and Cu2+ cations are tested. Heavy metal ion binding agent: 1,4,8,11-tetraazacyclotetradecane (cyclam) or its derivatives were introduced into a conducting polymer film in different ways: i) neutral cyclam was incorporated by polymerization from 1,4,8,11-tetraazacyclotetradecane containing solution, ii) 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetate anions (TETA) were introduced, acting as co-dopant ions in chloride containing solutions, iii) polymerization was carried out from solution containing pyrrole and a composite of pyrrole with Ni(II) cyclam derivative complex: N-(4-amino-6-(1,3,5,8,12-pentaazacyclotetradecan-3-yl)-1,3,5-triazin-2-yl)-1H-pyrrole-2-carboxamide nickel(II) perchlorate (ET679). In KCl and NiCl2 solutions the freshly obtained oxidized polypyrrole layers modified by cyclam or TETA anions exhibited typical anion exchanging properties as confirmed in voltammetric and potentiometric experiments. Potentiometric cationic sensitivity and selectivity towards nickel ions was induced after conditioning or polarization in alkaline (NaOH or KOH) media and Ni2+ solution; this was accompanied by Ni(II) retention in the polymer film. Similar cationic sensitivity was observed also for polypyrrole with cyclam in case of Zn2+ and Cu2+ ions.
    Electroanalysis 07/2009; 21(17‐18):2044 - 2053. · 2.82 Impact Factor
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    ABSTRACT: Chemical sensing is a mature field, and many effective sensors for small anions and cations have been devised. Metal complexes have been used widely for this purpose, but there are fewer reports of their use in the detection of organic and biological analytes. To date metal complexes have been used in sensing via the direct displacement of a pre-existing ligand by an analyte, or by an adventitious complementarity between the complex and analyte. These strategies do not permit a general approach to the sensing of biological molecules with metal complexes because of the demands to engineer molecular recognition into the complex architecture. We describe a fundamentally new approach to this field-the "allosteric scorpionate" metal complex. The binding partner of a biological analyte is attached to a scorpionate ligand on a metal complex, remote from the metal centre. Binding of the analyte causes a change in the primary coordination sphere at the metal, thereby revealing the presence of the biological molecule. We show that azamacrocyclic complexes with a triazole scorpion ligand may be easily assembled with the [3+2] Huisgens 'click' cycloaddition. We demonstrate the synthesis of a biotin-functionalised cyclam derivative using this methodology. This, and our previously communicated zinc sensor, are to the best of our knowledge the first examples of a triazole being employed as a scorpion ligand on an azamacrocycle. Coordination by the triazole to the metal is perturbed by the binding of avidin to the pendant ligand. This event can be sensitively detected with EPR spectroscopy, and the details of the coordination change probed with ENDOR spectroscopy, confirming the loss of the axial triazole nitrogen donor upon binding to avidin. This represents the first metal complex where remote, 'allosteric' coordination of an analyte has been shown to cause a change in the primary coordination sphere of the metal. Since the synthesis is modular and straightforward, other biological ligands may easily be introduced, and the associated binding events may be probed.
    Chemistry 03/2009; 15(15):3720-8. · 5.93 Impact Factor
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    ABSTRACT: A cyclam-based macrocyclic sensor has been prepared using synthetically simple "click" chemistry to link a fluorophore to the macrocyclic receptor. This sensor shows high selectivity for Zn(II) over a range of other metals, providing a significant enhancement of fluorescence intensity over a wide pH range. As such, this is the first cyclam-based sensor demonstrated to be selective for Zn(II) and is the first example of a triazole being used as a coordinating ligand on an azamacrocycle. The sensor can access biologically available zinc in mammalian cells, sensing the Zn(II) flux that exists during apoptotic cell death.
    Inorganic Chemistry 01/2009; 48(1):319-24. · 4.59 Impact Factor
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    ABSTRACT: The biotin-(strept)avidin interaction remains a gold standard of model biological recognition events. The biotinylation of azamacrocycles permits the investigation of signal transduction between this recognition event and the metal center of an azamacrocycle complex, of wide potential interest in biosensing. There are no generally applicable procedures in the literature for such functionalizations. We report here a comprehensive investigation into the attachment of biotin to TACN, cyclen, and cyclam. Effective methods have been found for each ring. The efficacy of the functionalization is critically dependent on the nature of the azamacrocycle.
    The Journal of Organic Chemistry 11/2007; 72(22):8280-9. · 4.56 Impact Factor
  • Emiliano Tamanini, Michael Watkinson, Matthew H. Todd
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    ABSTRACT: An improved synthesis of 3-azido-4-hydroxy cyclopentanoic acid 2 is presented. This molecule is useful as a synthetic scaffold for β-turn mimetics on solid phase, with the selectivity of the turns being dependent on the diastereomer employed. A high diastereoselectivity in the synthesis of this molecule in solution is reported, which may then be attached to the solid phase for the synthesis of peptidomimetic libraries.
    Tetrahedron Asymmetry 01/2006; 17(15):2235-2239. · 2.12 Impact Factor

Publication Stats

76 Citations
45.69 Total Impact Points

Institutions

  • 2009–2011
    • University of Cambridge
      • Department of Chemistry
      Cambridge, ENG, United Kingdom
  • 2009–2010
    • Queen Mary, University of London
      • School of Biological and Chemical Sciences
      London, ENG, United Kingdom
  • 2006–2009
    • University of London
      Londinium, England, United Kingdom