Synthesis of Aza-m-Xylylene diradicals with large singlet-triplet energy gap and statistical analyses of their EPR spectra
- Univ. of Nebraska, Lincoln, NE (United States)
- Indiana Univ., Bloomington, IN (United States)
We describe synthesis and characterization of a derivative of aza-m-xylylene, diradical 2, that is persistent in solution at room temperature with the half-life measured in minutes (~80–250 s) and in which the triplet ground state is below the lowest singlet state by >10 kcal mol⁻¹. The triplet ground states and ΔEST of 2 in glassy solvent matrix are determined by a new approach based on statistical analyses of their EPR spectra. Characterization and analysis of the analogous diradical 1 are carried out for comparison. Statistical analyses of their EPR spectra reliably provide improved lower bounds for ΔEST (from >0.4 to >0.6 kcal mol⁻¹) and are compatible with a wide range of relative contents of diradical vs monoradical, including samples in which the diradical and monoradical are minor and major components, respectively. This demonstrates a new powerful method for the determination of the triplet ground states and ΔEST applicable to moderately pure diradicals in matrices.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF)
- OSTI ID:
- 1171258
- Journal Information:
- Journal of the American Chemical Society, Vol. 136, Issue 40; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- ENGLISH
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