Fig. 4: Coordination chemistry of GA–Fe and ligand-field-enhanced chemical reactions. | Nature Communications

Fig. 4: Coordination chemistry of GA–Fe and ligand-field-enhanced chemical reactions.

From: Intratumoral synthesis of nano-metalchelate for tumor catalytic therapy by ligand field-enhanced coordination

Fig. 4

a Schematics of the octahedral coordination of four gallate molecules to an Fe center in GA–Fe. b Chelation of four iron centers by one gallate molecule in GA–Fe. c Representative tri-nuclear model of GA–Fe, [Fe3L8H22]−, as well as the distribution of spin density indicating the interaction between Fe center and gallate ligand forming ligand field. d Scheme for the interaction between d (t2g) orbital function of Fe3+ with the π-orbital function of GA4− leading to the formation of two new molecular orbital functions of GA–Fe. e Proposed chemical reactions for the formation of GA–Fe nanoparticles and subsequent sequential oxygen reduction forming O2•− and H2O2. GA• indicates the semiquinone formed after one-electron oxidation of GA4−; GAox is a two-electron oxidation product of GA4−. f Molecular structures of gallate and its one and two-electron oxidation products. As the electronic delocalization can occur within the whole gallate molecule, the loss of two electrons will weaken all the C–O bonds in a whole gallate molecule when coordinated with Fe and the Fe–O bonds as well, rather than forming an o-quinone with two carbon–oxygen double bonds which may triggers the breakage of Fe–O bond.

Back to article page