Breaking the Semi‐Quinoid Structure: Spin‐Switching from Strongly Coupled Singlet to Polarized Triplet State. Issue 38 (31st July 2014)

• Record Type: Journal Article
• Authors: Ravat, Prince; Teki, Yoshio; Ito, Yoshikazu; Gorelik, Elena; Baumgarten, Martin
• Is Part Of: Chemistry. Volume 20:Issue 38(2014)
• Page Start: 12041
• Page End: 12045
• Publication Date: 2014-07-31
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201403338
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>2, 7‐TMPNO (4, 5, 9, 10‐tetramethoxypyrene‐2, 7‐bis(<italic>tert</italic>‐butylnitroxide)) was found to exist in semi‐quinoid form with unprecedented strong intramolecular magnetic exchange interaction of 2 <italic>J/k</italic>_B=1185 K operating over a distance of 10 Å. Structural transformations with the activation energy of Δ<italic>E</italic>_eq=949 K were observed by varying the temperature, from more quinoid structure at low temperature to more biradicaloid structure at higher temperature. Moreover, this molecule undergoes a transient spin transition from singlet to polarized triplet state upon photoexcitation revealed by TREPR spectroscopy. The spin Hamiltonian parameters were determined to be <italic>S</italic>=1, <italic>g</italic>=2.0065, <italic>D</italic>=−0.0112 cm⁻¹, and <italic>E</italic>=−0.0014 cm⁻¹ by spectral simulation with the hybrid Eigenfield/exact diagonalization method.</p> </abstract>