Pyrroles

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The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Atul Chaskar - One of the best experts on this subject based on the ideXlab platform.

Jonathan L Sessler - One of the best experts on this subject based on the ideXlab platform.

  • Pyrrole- and Naphthobipyrrole-Strapped Calix[4]Pyrroles as Azide Anion Receptors
    Journal of Organic Chemistry, 2018
    Co-Authors: Gabriela I. Vargas-zúñiga, Vincent M Lynch, Jonathan L Sessler
    Abstract:

    The binding interactions between the azide anion (N3–) and the strapped calix[4]Pyrroles 2 and 3 bearing auxiliary hydrogen bonding donors on the bridging moieties, as well as of normal calix[4]pyrrole 1, were investigated via 1H NMR spectroscopic and isothermal titration calorimetry analyses. The resulting data revealed that receptors 2 and 3 have significantly higher affinities for the azide anion in organic media as compared with the unfunctionalized calix[4]pyrrole 1 and other azide receptors reported to date. Single crystal X-ray diffraction analyses and calculations using density functional theory revealed that receptor 2 binds CsN3 in two distinct structural forms. As judged from the metric parameters, in the resulting complexes one limiting azide anion resonance contributor is favored over the other, with the specifics depending on the binding mode. In contrast to what is seen for 2, receptor 3 forms a CsN3 complex in 20% CD3OD in CDCl3, wherein the azide anion is bound only vertically to the NH p...

  • calix 4 Pyrroles versatile molecular containers with ion transport recognition and molecular switching functions
    Chemical Society Reviews, 2015
    Co-Authors: Jonathan L Sessler
    Abstract:

    Over the last two decades, calix[4]Pyrroles have attracted considerable attention as molecular containers. Used in this capacity, they have been exploited as strong and selective receptors and as extractants for both anions and ion pairs. More recently, calix[4]Pyrroles have found application as carriers, systems capable of transporting ions and ion pairs across lipophilic membranes. The use of calix[4]Pyrroles as building blocks for the preparation of stimulus-responsive material has also been demonstrated. In this latter context, as well as others, the conformational switching, from 1,3-alternate to cone upon anion binding has been exploited to control both structure and substrate binding. In this Review, we describe recent results involving the use of calix[4]pyrrole systems for ion transport. Also summarised is work devoted to the formation of higher order supramolecular aggregates and studies of their response to external stimuli. Taken together, these examples serve to highlight new uses of calix[4]Pyrroles as molecular containers.

  • perrhenate and pertechnetate anion recognition properties of cyclo 8 pyrrole
    Supramolecular Chemistry, 2015
    Co-Authors: Evgeny A Kataev, Grigory V Kolesnikov, Patricia Pantos, Elizabeth Karnas, Ivan G. Tananaev, Vincent M Lynch, Jonathan L Sessler
    Abstract:

    Cyclo[8]pyrrole, an octapyrrolic expanded porphyrin with no meso-linking atoms, was found to interact with a series of anions in the solid state and in a chloroform solution. The anion selectivities have been determined relative to a structurally characterised salt, H2cyclo[8]pyrrole2+·I− ·I3 − , via counter anion exchange. Although cyclo[8]pyrrole demonstrates a general selectivity for sulfate, it interacts well with both the pertechnetate and perrhenate anions. Moreover, it has been shown to act as a phase-transfer catalyst facilitating the extraction of pertechnetate from an aqueous to an organic phase in the presence of sulfate.

  • Formation and properties of cyclo[6]pyrrole and cyclo[7]pyrrole.
    Journal of the American Chemical Society, 2003
    Co-Authors: Thomas Köhler, Vincent M Lynch, Daniel Seidel, Zhongping Ou, Karl M. Kadish, Jonathan L Sessler
    Abstract:

    Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]Pyrroles, as well as the known cyclo[8]pyrrole. This “matched set” of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.

  • a building block approach to functionalized calix 4 Pyrroles
    Tetrahedron Letters, 2000
    Co-Authors: Hidekazu Miyaji, Jonathan L Sessler, Wataru Sato, Vincent M Lynch
    Abstract:

    Abstract Iodocalix[4]pyrrole 2 and trimethylsilylethynylcalix[4]pyrrole 3 are key intermediates en route to the preparation of the alkynyl-substituted calix[4]pyrrole system 4 . This latter species, in turn, provides a versatile precursor that can be used to prepare a range of arylalkynyl-functionalized calix[4]Pyrroles (viz . , 5 – 9 ) by reacting with an appropriate aryl iodide under Sonogashira conditions (i.e., in the presence of tetrakis(triphenylphosphine)palladium(0)). Significant red-shifts in the λ max values and broadenings of the absorption peaks are seen in the UV–vis spectra of systems 6 and 7 upon addition of anions ( e.g ., F − , Cl − , H 2 PO 4 − ) in CH 2 Cl 2 , a finding that leads to the suggestion that these or other analogous systems could find application as anion sensors.

Hanuman P Kalmode - One of the best experts on this subject based on the ideXlab platform.

Vincent M Lynch - One of the best experts on this subject based on the ideXlab platform.

  • Pyrrole- and Naphthobipyrrole-Strapped Calix[4]Pyrroles as Azide Anion Receptors
    Journal of Organic Chemistry, 2018
    Co-Authors: Gabriela I. Vargas-zúñiga, Vincent M Lynch, Jonathan L Sessler
    Abstract:

    The binding interactions between the azide anion (N3–) and the strapped calix[4]Pyrroles 2 and 3 bearing auxiliary hydrogen bonding donors on the bridging moieties, as well as of normal calix[4]pyrrole 1, were investigated via 1H NMR spectroscopic and isothermal titration calorimetry analyses. The resulting data revealed that receptors 2 and 3 have significantly higher affinities for the azide anion in organic media as compared with the unfunctionalized calix[4]pyrrole 1 and other azide receptors reported to date. Single crystal X-ray diffraction analyses and calculations using density functional theory revealed that receptor 2 binds CsN3 in two distinct structural forms. As judged from the metric parameters, in the resulting complexes one limiting azide anion resonance contributor is favored over the other, with the specifics depending on the binding mode. In contrast to what is seen for 2, receptor 3 forms a CsN3 complex in 20% CD3OD in CDCl3, wherein the azide anion is bound only vertically to the NH p...

  • perrhenate and pertechnetate anion recognition properties of cyclo 8 pyrrole
    Supramolecular Chemistry, 2015
    Co-Authors: Evgeny A Kataev, Grigory V Kolesnikov, Patricia Pantos, Elizabeth Karnas, Ivan G. Tananaev, Vincent M Lynch, Jonathan L Sessler
    Abstract:

    Cyclo[8]pyrrole, an octapyrrolic expanded porphyrin with no meso-linking atoms, was found to interact with a series of anions in the solid state and in a chloroform solution. The anion selectivities have been determined relative to a structurally characterised salt, H2cyclo[8]pyrrole2+·I− ·I3 − , via counter anion exchange. Although cyclo[8]pyrrole demonstrates a general selectivity for sulfate, it interacts well with both the pertechnetate and perrhenate anions. Moreover, it has been shown to act as a phase-transfer catalyst facilitating the extraction of pertechnetate from an aqueous to an organic phase in the presence of sulfate.

  • Formation and properties of cyclo[6]pyrrole and cyclo[7]pyrrole.
    Journal of the American Chemical Society, 2003
    Co-Authors: Thomas Köhler, Vincent M Lynch, Daniel Seidel, Zhongping Ou, Karl M. Kadish, Jonathan L Sessler
    Abstract:

    Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]Pyrroles, as well as the known cyclo[8]pyrrole. This “matched set” of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.

  • a building block approach to functionalized calix 4 Pyrroles
    Tetrahedron Letters, 2000
    Co-Authors: Hidekazu Miyaji, Jonathan L Sessler, Wataru Sato, Vincent M Lynch
    Abstract:

    Abstract Iodocalix[4]pyrrole 2 and trimethylsilylethynylcalix[4]pyrrole 3 are key intermediates en route to the preparation of the alkynyl-substituted calix[4]pyrrole system 4 . This latter species, in turn, provides a versatile precursor that can be used to prepare a range of arylalkynyl-functionalized calix[4]Pyrroles (viz . , 5 – 9 ) by reacting with an appropriate aryl iodide under Sonogashira conditions (i.e., in the presence of tetrakis(triphenylphosphine)palladium(0)). Significant red-shifts in the λ max values and broadenings of the absorption peaks are seen in the UV–vis spectra of systems 6 and 7 upon addition of anions ( e.g ., F − , Cl − , H 2 PO 4 − ) in CH 2 Cl 2 , a finding that leads to the suggestion that these or other analogous systems could find application as anion sensors.

  • Hexaalkyl Terpyrrole: A New Building Block for the Preparation of Expanded Porphyrins
    Chemistry: A European Journal, 1995
    Co-Authors: Jonathan L Sessler, Steven Jeremy Weghorn, Yoshio Hiseada, Vincent M Lynch
    Abstract:

    A new, general synthesis of the first β-substituted tetra- and hexaalkyl terPyrroles is described. Also described are two new classes of expanded porphyrins derived from the hexaalkyl terpyrrole. The key step in the terpyrrole formation is the copper(II)-mediated oxidative coupling of the LDA-derived enolates of α-keto Pyrroles. The first new expanded porphyrin reported here, the so-called “orangarin”, contains five pyrrolic subunits and two bridging carbon atoms, and is formally a 20π-electron nonaromatic macrocycle. The second new class of expanded porphyrins, the “amethyrins”, are 24π-electron nonaromatic macrocycles containing six pyrrole units. Both of these new macrocycles, as well as one of the new terpyrrolic precursors have been structurally characterized by single crystal X-ray diffraction analysis.

Kamlesh S Vadagaonkar - One of the best experts on this subject based on the ideXlab platform.