Aqueous Multivalent Metal-ion Batteries: Toward 3D-printed Architectures.

Energy storage has become increasingly crucial, necessitating alternatives to lithium-ion batteries due to critical supply constraints. Aqueous multivalent metal-ion batteries (AMVIBs) offer significant potential for large-scale energy storage, leveraging the high abundance and environmentally benign nature of elements like zinc, magnesium, calcium, and aluminum in the Earth's crust. However, the slow ion diffusion kinetics and stability issues of cathode materials pose significant technical challenges, raising concerns about the future viability of AMVIB technologies.

Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature.

Molecular cavities that mimic natural metalloenzymes have shown the potential to trap elusive reaction intermediates. Here, we demonstrate the formation of a rare yet stable Fe(IV)-superoxo intermediate at room temperature subsequent to dioxygen binding at the Fe(III) site of a (EtN)[Fe(Cl)(bTAML)] complex confined inside the hydrophobic interior of a water-soluble PdL nanocage. Using a combination of electron paramagnetic resonance, Mössbauer, Raman/IR vibrational, X-ray absorption, and emission spectroscopies, we demonstrate that the cage-encapsulated complex has a Fe(IV) oxidation state characterized by a stable S = 1/2 spin state and a short Fe-O bond distance of ∼1.

Highly regioselective oxidation of C-H bonds in water using hydrogen peroxide by a cytochrome P450 mimicking iron complex.

Cytochrome P450, one of nature's oxidative workhorses, catalyzes the oxidation of C-H bonds in complex biological settings. Extensive research has been conducted over the past five decades to develop a fully functional mimic that activates O or HO in water to oxidize strong C-H bonds. We report the first example of a synthetic iron complex that functionally mimics cytochrome P450 in 100% water using HO as the oxidant.

Selective oxygenation of unactivated C-H bonds by dioxygen via the autocatalytic formation of oxoiron(v) species.

Selective catalytic oxygenation of unactivated C-H bonds for a series of substrates by dioxygen using iron complexes was performed without the use of a co-reductant. Mechanistic studies indicate that the reaction proceeded via the autocatalytic formation of an oxoiron(v) intermediate, which brings high regioselectivity and stereoretention.