A homogeneous cobalt complex mediated electro and photocatalytic O/HO interconversion in neutral water.

The O/HO redox couple is vital in various renewable energy conversion strategies. This work delves into the Co(L-histidine) complex, a functional mimic of oxygen-carrying metalloproteins, and its electrochemical behavior driving the bidirectional oxygen reduction (ORR) and oxygen evolution (OER) activity in neutral water. This complex electrocatalyzes O via two distinct pathways: a two-electron O/HO reduction (catalytic rate = 250 s) and a four-electron O to HO production (catalytic rate = 66 s).

Expanding the Horizon of Bio-Inspired Catalyst Design with Tactical Incorporation of Drug Molecules.

The development of potent H production catalysts is a key aspect in our journey toward the establishment of a sustainable carbon-neutral power infrastructure. Hydrogenase enzymes provide the blueprint for designing efficient catalysts by the rational combination of central metal core and protein scaffold-based outer coordination sphere (OCS). Traditionally, a biomimetic catalyst is crafted by including natural amino acids as OCS features around a synthetic metal motif to functionally imitate the metalloenzyme activity.

Improving the synthetic H production catalyst design strategy with the neurotransmitter dopamine.

The strategic incorporation of the neurotransmitter dopamine around a cobaloxime core resulted in excellent electrocatalytic (rate 8400 s) and photocatalytic H production under neutral aqueous conditions. The influence of the synthetic outer coordination sphere features continues even with a phenylene-diimino-dioxime motif-coordinated cobalt core.

Exploring the Cobalt-Histidine Complex for Wide-Ranging Colorimetric O Detection.

Developing a robust, cost-effective, and user-friendly sensor for monitoring molecular oxygen (O) ranging from a minute to a medically relevant level (85-100%) in a stream of flowing breathable gas is vital in various industrial domains. Here, we report an innovative application of the cobalt(l-histidine) complex, a bioinspired model of O-carrying metalloproteins, for rapid and reliable sensing of O from 0 to 100% saturation levels under realistic conditions. We have established two distinct colorimetric O detection techniques, which can be executed with the use of a common smartphone camera and readily available color-detecting software.

Redox-Induced Structural Switching through Sporadic Pyridine-Bridged CoCo Dimer and Electrocatalytic Proton Reduction.

The homodinuclear Co helicate complex [Co(DQPD)] () was prepared by treating [Co(HO)](ClO) with the deprotonated form of the ligand ,-bis(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH). Complex represents a discrete homodinuclear helicate complex with two Co centers having a distorted-octahedral geometry through an unprecedented pyridine bridge. Complex , upon treatment with HO, undergoes oxidation at one of the Co centers followed by a structural deformation to generate the mixed-valence complex [CoCo(DQPD)](ClO) ().

Proton reduction by a nickel complex with an internal quinoline moiety for proton relay.

The complex Ni(DQPD) (where DQPD = deprotonated N(2),N(6)-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH2)) behaves as a visible light driven active catalyst to reduce protons from water when employed with the photosensitizer fluorescein (Fl) and triethylamine (TEA) as the sacrificial electron donor. The photocatalytic system shows very high activity, attaining 2160 turnovers and an initial turnover rate of 0.032 s(-1) with respect to the catalyst.