Dobre Adela F, Lete Cecilia, Kuncser Victor E, Iacob Nicusor, Madalan Augustin M, Ionita Gabriela, Harada Mai, Kitagawa Yasutaka, Ionita Petre
Faculty of Chemistry, University of Bucharest, Panduri 90, Bucharest 050663, Romania.
Institute of Physical Chemistry, Spl. Independentei 202, Bucharest 060021, Romania.
ACS Omega. 2025 Aug 10;10(32):36662-36671. doi: 10.1021/acsomega.5c05905. eCollection 2025 Aug 19.
Although the DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl) radical is known for its indefinite stability, both in solid and in solution, and therefore no dimerization reaction occurs, the DPPH-dimer has been obtained by an alternative synthesis. Oxidation of the DPPH-dimer led to the corresponding DPPH-diradical, practically exhibiting all of the known properties of the simple DPPH radical. The structures were confirmed using H and C NMR, IR, UV-vis, HR-MS, and electron spin resonance (for the diradical) analyses. Additionally, cyclic voltammetry and superconducting quantum interference device (SQUID) measurements were performed to investigate the electrochemical and magnetic properties of the DPPH-diradical. DFT calculations revealed that the ground state was an open-shell singlet. The diradical character of the ground state and vertical S-T gap were 0.279 and -5.81 kcal mol, respectively.
尽管二苯基苦味酰基自由基（DPPH，即2,2-二苯基-1-（2,4,6-三硝基苯基）肼基自由基）在固态和溶液中都具有不确定的稳定性，因此不会发生二聚反应，但通过另一种合成方法已获得了DPPH二聚体。DPPH二聚体的氧化产生了相应的DPPH双自由基，其实际上表现出简单DPPH自由基的所有已知性质。通过氢核磁共振（H NMR）、碳核磁共振（C NMR）、红外光谱（IR）、紫外可见光谱（UV-vis）、高分辨质谱（HR-MS）以及电子自旋共振（用于双自由基）分析对结构进行了确认。此外，还进行了循环伏安法和超导量子干涉仪（SQUID）测量，以研究DPPH双自由基的电化学和磁学性质。密度泛函理论（DFT）计算表明基态为开壳层单重态。基态的双自由基特征和垂直的单重态-三重态能隙分别为0.279和-5.81千卡/摩尔。
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