Issue 2, 2023

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

Abstract

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.

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

Supplementary files

Article information

Article type
Paper
Submitted
11 Oct 2022
Accepted
07 Dec 2022
First published
08 Dec 2022
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2023,21, 375-385

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

A. Giannoulis, K. Ackermann, A. Bogdanov, D. B. Cordes, C. Higgins, J. Ward, A. M. Z. Slawin, J. E. Taylor and B. E. Bode, Org. Biomol. Chem., 2023, 21, 375 DOI: 10.1039/D2OB01863B

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