Design and synthesis of binucleating macrocyclic clefts derived from Schiff-base calixpyrroles

Gonzalo Givaja, Manuel Volpe, James W. Leeland, Michael A. Edwards, Thomas K. Young, S. Barnie Darby, Stuart D. Reid, Alexander J. Blake, Claire Wilson, Joanna Wolowska, Eric J. L. McInnes, Martin Schroeder, Jason B. Love

Research output: Contribution to journalLiterature reviewpeer-review

Abstract

The syntheses, characterisation and complexation reactions of a series of binucleating Schiff-base calix-pyrrole macrocycles are described. The acid-templated [2+2] condensations between meso-disubstituted diformyldipyrromethanes and o-phenylenediamines generate the Schiff-base pyrrolic macrocycles H4L1 to H4L6 upon basic workup. The single-crystal X-ray structures of both H4L3 center dot 2 EtOH and H4L6 center dot H2O confirm that [2+2] cyclisation has occurred, with either EtOH or 11,0 hydrogen-bonded within the macrocyclic cleft. A series of complexation reactions generate the dipalladiurn [Pd-2(L)] (L = L-1 to L-5), dinickel [Ni-2(L-1)] and dicopper [Cu-2(L)] (L = L-1 to L 3) complexes. All of these complexes have been structurally characterised in the solid state and are found to adopt wedged structures that are enforced by the rigidity of the aryl backbone to give a cleft reminiscent of the structures of Pacman porphyrins. The binuclear nickel complexes [Ni-2(mu-OMe)(2)Cl-2(HOMe)(2)(H4L1)] and [Ni-2(mu- OH)(2)Cl-2(HOMe)(H4L5)] have also been prepared, although in these cases the solid-state structures show that the macrocyclic ligand remains protonated at the pyrrolic nitrogen atoms, and the Ni-II cations are therefore co-ordinated by the imine nitrogen atoms only to give an open conformation for the complex. The dicopper complex [Cu-2(L-3)] was crystallised in the presence of pyridine to form the adduct [Cu-2(py)(L-3)], in which, in the solid state, the pyridine ligand is bound within the binuclear molecular cleft. Reaction between H4L1 and [Mn(thf){N(SiMe3)(2)}(2)] results in clean formation of the dimanganese complex [Mn-2(L-1)], which, upon crystallisation, formed the mixed-valent complex [Mn-2(mu-OH)(L-1)] in which the hydroxo ligand bridges the metal centres within the molecular cleft.

Original languageEnglish
Pages (from-to)3707-3723
Number of pages17
JournalChemistry - A European Journal
Volume13
Issue number13
DOIs
Publication statusPublished - 2007

Keywords

  • ePR spectroscopy
  • macrocyclic ligands
  • metallation
  • N ligands
  • transition metals
  • ELECTRON SPIN RESONANCE
  • ELECTROCATALYTIC 4-ELECTRON REDUCTION
  • ARYL SUBSTITUTED CORROLES
  • DINITROGEN ELECTROREDUCTION CATALYST
  • BRIDGED COFACIAL BISPORPHYRINS
  • MANGANESE PORPHYRIN DIMERS
  • EXCITED-STATE DYNAMICS
  • CYTOCHROME-C-OXIDASE
  • PAC-MAN PORPHYRINS
  • X-RAY STRUCTURE

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