Synthesis of mono-nitroxides and of bis-nitroxides with varying electronic through-bond communication

Angeliki Giannoulis, Katrin Ackermann, Alexey Bogdanov, David Cordes, Catherine Higgins, Joshua Ward, Alexandra Slawin, James Taylor, Bela Bode

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1 Citation (SciVal)


Nitroxides are a unique class of persistent radicals finding a wide range of applications, from spin probes to polarizing agents, and recently bis-nitroxides have been used as proof-of-concept molecules for quantum information processing. Here we present the syntheses of pyrroline-based nitroxide (NO) radicals and give a comparision of two possible synthetic routes to form two key intermediates, namely 2,2,5,5-tetramethylpyrroline-1-oxyl-3-acetylene (TPA) and 1-oxyl-2,2,5,5-tetramethylpyrroline-3-carboxylic acid (TPC). TPC and TPA were then used as precursors for the synthesis of three model compounds featuring two distant NO groups with a variable degree of conjugation and thus electronic communication between them. Using relatively facile synthetic routes, we produced a number of mono- and bis-nitroxides with the structures of multiple compounds unambiguously characterized by X-ray crystallography, while Continuous Wave Electron Paramagnetic Resonance (CW-EPR) allowed us to quantify the electronic communication in the bis-nitroxides. Our study expands the repertoire of mono- and bis-nitroxides with possibilities of exploiting them for studying quantum coherence effects and as polarizing agents.

Original languageEnglish
Pages (from-to)375-385
JournalOrganic & Biomolecular Chemistry
Issue number2
Early online date8 Dec 2022
Publication statusPublished - 14 Jan 2023

Bibliographical note

Funding Information:
AG acknowledges the UK-MRBT-CDT funded by EPSRC (EP/J500045/1), BEB acknowledges the Wellcome Trust Institutional Strategic Support fund (204821/Z/16/Z), JET acknowledges the Leverhulme Trust (Early Career Fellowship; ECF-2014-005). We also thank the EPSRC UK National Mass Spectrometry Facility at Swansea University, Mr Steven Boyer for elemental analyses at London Metropolitan University and Dr Thomas Lebl and Mrs Melanja Smith at the NMR facility at the University of St-Andrews.


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