IrIII-AuI luminescent bimetallic complexes have drawn growing interest for applications in photonics, catalysis, and biomedicine. Here, we report the synthesis of a new photoluminescent IrIII-AuI complex, the [(ppz)2Ir(μ-bbip)AuBr]PF6, incorporating 1,3-dibenzyl-1H-imidazo[4,5-f][1,10]phenanthrolin-3-ium bromide (bbip) as a bridging N-heterocyclic carbene (NHC) ligand. Among the various characterizations employed, single-crystal X-ray diffraction (SC-XRD) confirmed the structure of the complex, validating the proposed molecular formulation and coordination sphere. For comparative purposes and under similar conditions, the monometallic IrIII complex [Ir(ppz)2(bbip)](PF6)2 was synthesized and also validated by SC-XRD. Both complexes showed broad UV-vis excitation and orange-to-red emission in all tested solvents. Notably, the IrIII-AuI complex exhibited lower solvent polarity sensitivity than the mono-IrIII analog, with AuI coordination to bbip causing a slight emission blue shift. The incorporation of AuI significantly enhanced the photoluminescent properties, doubling both, the emission lifetime (τ) from 278 to 554 ns and the quantum yield (Φ) from 25 to 61% in degassed DCM. Notably, Φ remained high (30%) even in air-equilibrated DCM.

Salen-type tetradentate Schiff base ligands are ubiquitous in coordination chemistry because of their straightforward synthesis, derivatization, and versatility as ligands for metals across the periodic table. The present work was motivated by our interest in expanding the library of bifunctional salophen systems, where basic sites are incorporated in the secondary coordination sphere of salophen-ligated metals. Here, we report and describe seven previously unreported structures of nickel-, copper-, and zinc-salophen derivatives, including two complexes that integrate amine bases in the ligand periphery. These are {4,4'-di-tert-butyl-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II) toluene 1.33-solvate, [Ni(C28H30N2O2)]·1.33C7H8 or (tBu-salophen)Ni·1.33C7H8, {4,4'-di-tert-butyl-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}copper(II), [Cu(C28H30N2O2)] or (tBu-salophen)Cu, aqua{4,4'-di-tert-butyl-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}zinc(II) tetrahydrofuran monosolvate, [Zn(C28H30N2O2)(H2O)]·C4H8O or (tBu-salophen)Zn(OH2)·THF, {4,4'-bis(trifluoromethyl)-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II), [Ni(C22H12F6N2O2)] or (CF3-salophen)Ni, {4,4'-bis(trifluoromethyl)-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}(pyridine)zinc(II), [Zn(C22H12F6N2O2)(C5H5N)] or (CF3-salophen)Zn(py), {4,4'-di-tert-butyl-6,6'-bis[(diisopropylamino)methyl]-2,2'-[1,2-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II), [Ni(C42H60N4O2)] or (tBu-salophen-NiPr2)Ni, and {4,4'-di-tert-butyl-6,6'-bis[(diphenylamino)methyl]-2,2'-[(pyridine-3,4-diyl)bis(nitrilomethylidyne)]diphenolato}(pyridine)zinc(II) pyridine monosolvate, [Zn(C53H51NO2)(C5H5N)]·C5H5N or (tBu-salpyr-NPh2)Zn(py)·py. The metal centers in these compounds adopt structures consistent with what has been observed for other salen-type ligands described in the literature, with near ideal square-planar structures around nickel or copper, and a distorted square-pyramidal structure for the zinc complexes. The primary coordination sphere around these metals expands slightly across the row, as anticipated based on the increase in d-electron count from nickel to zinc. The solid-state packing of these compounds is also discussed, including the tendency for their flat extended π-systems to pack parallel to one another. Differences in packing are observed as functional groups at the ligand periphery are varied or where the compounds cocrystallize with solvent molecules.

A computational screening study of Dual-Metal M1M2@1T-MoS2 with various coordination environments as catalysts for the hydrogen evolution reaction

Single-atom nanozymes: Bridging atomic design and biomedical function through structure-activity-property relationships.

Eu3+-doped hydroxyapatite nanoparticles were functionalized with anionic porphyrin to investigate their spatial arrangement on the surfaces. The porphyrin selectively coordinates to Eu3+ rather than Ca2+ sites. Photoluminescence changes in both the porphyrin and Eu3+ indicated that the coordination environment around Eu3+ evolved with increasing porphyrin loading. The photoluminescence property variations by the Eu3+ suggested a transition from mono- to multicoordination, resulting in the symmetric arrangement of multiple molecules around Eu3+.

A Cu(II) binding site involving Cys18 and His22 displays a buffering effect in copper-induced aggregation of cataract-related human γD crystallin.

Directed evolution of a thermostable laccase from Geobacillus stearothermophilus for efficient reduction of oxygen.

Iron-based polyanionic Na3Fe2(PO4)(P2O7) (N3F2PP) has emerged as a compelling cathode candidate for sodium-ion batteries (SIBs) owing to its cost-effectiveness and structural stability. Nevertheless, its practical application is constrained by intrinsically sluggish Na+ diffusion kinetics and limited accessible capacity. Herein, a trace Li substitution strategy at alkali sites was proposed to address these limitations. Partial substitution of Na+ with smaller Li+ induces localized lattice contraction and optimizes the local structural environment, thereby promoting Na+ transport. Moreover, Li incorporation subtly modifies the local Fe-O coordination environment, alleviating the lattice strain associated with the Fe2+/Fe3+ redox reaction. As a result, the optimized Na2.95Li0.05Fe2(PO4)(P2O7)@C (NLF2PP@C-0.05) cathode delivered a remarkable discharge capacity of 113.2 mAh g-1 at 0.1 C, along with outstanding rate capability (84.1 mAh g-1 at 20 C) and cycling stability (97.5% capacity retention after 2000 cycles at 20 C). This work highlights alkali-site substitution as a novel design paradigm for polyanionic cathodes, offering an effective complement to conventional Fe-site engineering strategies.

Single-atom catalysts architecture on quantum dots: A new catalytic frontier for renewable energy and environmental applications.

LLM-assisted meta-analysis reveals a global shift toward non-radical dominance in peroxymonosulfate-based advanced oxidation.

Regulating the local coordination environment of CoN₄ single-atom catalysts for the rational design of highly efficient bifunctional electrocatalysts: A density functional theory study

Precisely modulating the coordination structure of neighboring metal atomic sites is urgently required yet remains technically challenging. Herein, we report a carbon-vacancy-induced Fe coordination environment modulation in FeZn dual-atom sites (FeZnN6-VC) to boost bifunctional oxygen electrocatalysis. Finite element simulation and electronic structure characterization reveal that carbon vacancies promote electron transfer from Fe-N4 to neighboring Zn-N4 sites, establishing favorable electronic interactions. In situ Raman spectroscopy further identifies the key O-O- intermediate (corresponding to OOH*) and the FeOOH active phase during oxygen evolution reaction (OER), both showing significantly lowered onset potentials. Compared with conventional FeZn dual-atom catalysts, FeZnN6-VC achieves a 174 mV decrease in OER overpotential at 10 mA cm-2 and exhibits improved oxygen reduction reaction performance in alkaline media. The corresponding quasi-solid-state Zn-air battery delivers a long cycling life of 82.3 h at 50 mA cm-2. This work offers a versatile carbon-vacancy strategy to tune the local coordination of dual-atomic sites for advanced electrocatalysis.

Tailored coordination environment of cobalt-zinc bimetallic MOFs for efficient photocatalytic carbon dioxide reduction

Effects of secondary coordination regulations for ORR on dual-atom catalysts are clarified over fabricated CoNx + FeNy moieties with P/S-coordination in outer coordination shells of metal atoms, which modulates the electronic asymmetry of dual-metal sites and effectively boosts the ORR catalytic activity.

Thermal-catalytic conversion of one-carbon (C1) molecules into fuels and value-added chemicals represents a cornerstone of heterogeneous catalysis, driven by its profound implications for energy sustainability and environmental protection. The pursuit of high catalytic performance has spurred the rise of single-atom catalysts (SACs) with maximized metal utilization efficiency and atomic dispersion configuration. In this review, we first elucidated the critical role of the coordination environment in SACs for regulating catalytic performance. Furthermore, recent progress in SACs for the thermal catalytic conversion of key C1 molecules, including carbon monoxide, carbon dioxide, methane, methanol, formaldehyde, and formic acid, was systematically summarized. Based on these discussions, the common reaction mechanism in C1 chemistry and the design principle of SACs have been proposed. Furthermore, the inherent limitations, in terms of activity, selectivity, and stability, were also examined. Building upon the insights, the recent developments in ensembled structures derived from SACs, including single-atom-nanoparticle synergistic catalysts, dual-atom catalysts, "nano-island"-structured SACs, and single-atom alloy catalysts, were highlighted. Finally, future directions for SACs in C1 chemistry were discussed, focusing on key aspects including AI-driven rational design of SACs, regulating the microenvironment of SACs, stabilizing high-density SACs, characterizing SACs under operando conditions, and promoting the industrial application of SACs.

Catalytic activity is influenced by the local coordination environment. Cryptomelane-type octahedral molecular sieve (OMS-2) catalysts doped via K+ substitution in the tunnels rarely exhibit photoactivation effects for volatile organic compound (VOC) abatement. We incorporated Co ions into the framework of OMS-2, not by replacing K+ in the tunnels, thereby facilitating the formation of Co-O-Mn asymmetric sites. Engineering Co-incorporated OMS-2 efficiently promotes the generation of oxygen vacancies, the facile release of lattice oxygen, the reducibility of the catalysts, and a low formation energy of oxygen vacancies, as evidenced by experimental and theoretical results. Thus, the Co-OMS-2 catalysts exhibit excellent thermocatalytic activity for the oxidation of benzene. More importantly, Co-O-Mn asymmetric sites induce a photoactivation effect. A particularly marked enhancement of photothermocatalytic activity is observed over the Co-OMS-2 catalysts. Photoactivation further weakens the Mn-O bonds, promoting the release of lattice oxygen and increasing the concentration of oxygen vacancies. Furthermore, light irradiation induces distinct low-temperature shifts in both the H2 consumption and O2 release peaks relative to those observed in the dark. The reactivity of lattice oxygen is enhanced by a photoactivation effect. In situ DRIFTS provides further evidence for the synergy of Co-O-Mn asymmetric sites and photoactivation. This work proposes an effective approach to enhance photothermocatalytic VOC degradation through the rational design of asymmetric bimetallic sites.

Identifying and understanding active sites in single-atom catalysts (SACs) remains a fundamental challenge, particularly under working conditions. Here, taking platinum (Pt) single atoms loaded on graphitic carbon nitride as a prototypical SAC model, we track the ultrafast electronic and structural dynamics with three different initial coordination environments via real-time time-dependent density functional theory. Our results demonstrate that single Pt atoms coordinated with three nitrogen atoms form a highly photoactive center, significantly enhancing light absorption and promoting efficient spatial separation of photogenerated carriers. Notably, compared to other environments, the critical interplay between the dynamic evolution of local atomic configurations and oxidation state of Pt during the reaction synergistically enhances the catalytic activity of single atoms, that is, stimulating an effective charge transfer to the antibonding orbital of the adsorbate molecule and ultimately leading to successive water splitting. These findings provide microscopic mechanistic insights into the working state of active sites and offer valuable guidance for rational design of SACs.

Boron is characterized by its small atomic radius, strong electron-accepting ability, and high electronegativity. Oxoboron (B-O) clusters can modify the coordination environment of transition metals, thereby tuning the band gap structure of catalysts and enhancing the light absorption properties of TMAPs. {BnNi6SiW9}2 (n = 0, 1, 2, 3, corresponding to compounds 1/2/3/4, respectively). As the number of boron atoms increased, the band gap structures of catalysts 1-4 were rapidly adjusted, with conduction band (CB) positions following the trend 4 < 3 < 2 < 1, leading to progressively enhanced photocatalytic performance. Additionally, the incorporation of B-O clusters enhanced light absorption in the near-infrared region, improving photothermal conversion.

Developing efficient bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for metal-air batteries and regenerative fuel cells. Among the most promising candidates, transition-metal single-atom catalysts (SACs) supported on N-doped graphene offer high atomic utilization and tunable coordination environments, but their rational design remains challenging because their molecule-like electronic states often fall outside conventional descriptor frameworks based on linear scaling relations or d-band concepts. Here, we show that the bifunctional activity of these SACs is governed by an electron-counting rule defined by the total number of metal s and d valence electrons, Nds. By combining subgroup discovery, first-principles calculations, projected-density-of-states and COHP analyses, we uncover a three-regime adsorption mechanism in which intermediate binding is controlled by the interplay among metal-adsorbate hybridization, antibonding-state occupation, and shell saturation. As Nds increases, the adsorption strength first increases, then decreases, and finally partially recovers, leading to a nonmonotonic periodic dependence of the binding energies of *OH, *O, and *OOH, and consequently of bifunctional ORR/OER activity. Guided by this mechanism, we develop physics-informed predictive models that enable high-throughput screening of more than 1000 candidate SACs and identify optimal bifunctional systems. Experimental synthesis and electrochemical characterization of Rh-SAC and Co-SAC systems confirm the predicted trends and their benchmark-level bifunctional performance. These results establish electron counting as a unifying physical principle for oxygen electrocatalysis on single-atom catalysts and provide a general route toward mechanism-driven catalyst discovery.

Superabsorbent polymer microparticles incorporating with crown ether for swelling-enhanced selective and rapid lithium capture.