Synthesis and Thin Films of Thermally Robust Quartet (S = 3/2) Ground State Triradical
- 31 March 2021
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 143 (14), 5508-5518
- https://doi.org/10.1021/jacs.1c01305
Abstract
High-spin (S = 3/2) organic triradicals may offer enhanced properties with respect to several emerging technologies, but those synthesized to date typically exhibit small doublet quartet energy gaps and/or possess limited thermal stability and processability. We report a quartet ground state triradical 3, synthesized by a Pd(0)-catalyzed radical–radical cross-coupling reaction, which possesses two doublet–quartet energy gaps, ΔEDQ ≈ 0.2–0.3 kcal mol–1 and ΔEDQ2 ≈ 1.2–1.8 kcal mol–1. The triradical has a 70+% population of the quartet ground state at room temperature and good thermal stability with onset of decomposition at >160 °C under an inert atmosphere. Magnetic properties of 3 are characterized by SQUID magnetometry in polystyrene glass and by quantitative EPR spectroscopy. Triradical 3 is evaporated under ultrahigh vacuum to form thin films of intact triradicals on silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy. AFM and SEM images of the ∼1 nm thick films indicate that the triradical molecules form islands on the substrate. The films are stable under ultrahigh vacuum for at least 17 h but show onset of decomposition after 4 h at ambient conditions. The drop-cast films are less prone to degradation in air and have a longer lifetime.Funding Information
- Division of Chemistry (CHE-1665256, CHE-1834750, CHE-1955349)
- Deutsche Forschungsgemeinschaft (CA852/11-1)
- Office of Science (DE-AC02-06CH11357)
- National Institute of General Medical Sciences (R01GM124310-01)
This publication has 88 references indexed in Scilit:
- Playing with organic radicals as building blocks for functional molecular materialsChemical Society Reviews, 2011
- 1,3-Alternate calix[4]arene nitronyl nitroxide tetraradical and diradical: synthesis, X-ray crystallography, paramagnetic NMR spectroscopy, EPR spectroscopy, and magnetic studiesTetrahedron, 2007
- Stable Hydrocarbon Diradical, An Analogue of TrimethylenemethaneJournal of the American Chemical Society, 2005
- Organic Spin Clusters: Annelated Macrocyclic Polyarylmethyl Polyradicals and a Polymer with Very High Spin S=6–18Chemistry – A European Journal, 2004
- Organic Spin Clusters: Macrocyclic-Macrocyclic Polyarylmethyl Polyradicals with Very High Spin S = 5−13Journal of the American Chemical Society, 2004
- Organic Spin Clusters. A Dendritic-Macrocyclic Poly(arylmethyl) Polyradical with Very High Spin of S = 10 and Its Derivatives: Synthesis, Magnetic Studies, and Small-Angle Neutron ScatteringJournal of the American Chemical Society, 2004
- Syntheses and Magnetic Properties of Stable Organic Triradicals with Quartet Ground States Consisting of Different Nitroxide RadicalsJournal of the American Chemical Society, 1998
- The C1s shakeup spectra of Buckminsterfullerene, acenaphthylene, and naphthalene, studied by high resolution x-ray photoelectron spectroscopy and quantum mechanical calculationsThe Journal of Chemical Physics, 1995
- Bis[3-tert-butyl-5-(N-oxy-tert-butylamino)phenyl] nitroxide in a quartet ground state: a prototype for persistent high-spin poly[(oxyimino)-1,3-phenylenes]Journal of the American Chemical Society, 1991
- Advances in charge neutralization for XPS measurements of nonconducting materialsSurface and Interface Analysis, 1988