Fig. 4
The molecular mechanisms. a Reference compounds of 2 and 3. b Cyclic voltammetry (CV) of 1 mM 1 (red) and 1 mM 3 (blue). The mechanism for CV redox and dimerization processes is prosed in Eqs. (1) and (2). c The ESR titrations with hydrazine hydrate. 1 to 4 denote the concentration change of base (hydrazine hydrate) added. 1, the initial state; 5, the colorless state. Field [G]: 3430-3530, Center Field 3484.00, Sweep width 100.0[G]; g = 2.00826; Spin Trap PBN. d The mechanism for hydrazine catalyzed dimerization process. MNBOD is reduced to a radical-anion (D/E) by hydrazine through the intermolecular electron transfer process. The radical-anions E are readily combine into the dianion F while the hydrazine cation (B) can be further reduced in to hydrazine cation (C). The dimer (F) and (C) combine into the final complex (G). e Calculated frontier molecular orbitals of 3, D32−, 1 and D12−, HOMO and LUMO orbitals are all obtained by DFT calculations
