Fig. 1: Strategy for direct observation of thermal ET in solids through X-ray crystallography.
From: Direct observation of electron transfer in solids through X-ray crystallography
a–c Slow-oxidation-associated crystallization of a heteroleptic Zn4 metallocycle [(Zn2+)4(LA)4(LA=O)4]: a The initial homoleptic Zn4 macrocycle [(Zn2+)4(LA)8] is highly soluble in the crystallization solvent (acetonitrile/1,4-dioxane), and thus, no crystal growth can occur. b Slow oxidation of (Zn2+)4(LA)8 by oxygen gradually yields heteroleptic Zn4 metallocycles ((Zn2+)4(LA)(8 – m)(LA=O)m) comprising LA and its corresponding oxidized acridone ligands (LA=O) that have much lower solubility in the crystallization solvent. c Consequently, crystallization occurs gradually with an increasing LA=O/LA ratio, where the Zn4 heteroleptic metallocycle ((Zn2+)4(LA)4(LA=O)4) suitable for one-dimensional columnar stacking crystallizes preferentially over other competing metallocycles. d Direct observation of ET in solids by X-ray crystallography through hole accumulation in electron-donor-incorporated nanotube crystal by solid-state ET oxidation. e Building blocks of heteroleptic Zn4 metallocycle. f Electron donors used in this study.
