Mn Centers Research Articles

Modulating Electronic Spin State of Perovskite Fluoride by Ni─F─Mn Bond Activating the Dynamic Site of Oxygen Reduction Reaction.

Establishing the relationship between catalytic performance and material structure is crucial for developing design principles for highly active catalysts. Herein, a type of perovskite fluoride, NH4MnF3, which owns strong-field coordination including fluorine and ammonia, is in situ grown on carbon nanotubes (CNTs) and used as a model structure to study and improve the intrinsic catalytic activity through heteroatom doping strategies. This approach optimizes spin-dependent orbital interactions to alter the charge transfer between the catalyst and reactants. As a result, the oxygen reduction reaction (ORR) activity of NH4MnF3 on CNTs is significantly enhanced by partial substitution of Mn sites with Ni, such as a half-wave potential (E1/2) of 0.86V and a limiting current density of 5.26mA cm-2, which are comparable to those of the commercial Pt/C catalysts. Experimental and theoretical calculations reveal that the introduction of Ni promotes lattice distortion, adjusts the electronic states of the active Mn centers, facilitates the transition from low-spin to intermediate-spin states, and shifts the d-band center closer to the Fermi level. This study establishes a novel approach for designing high-performance perovskite-based fluoride electrocatalysts by modulating spin states.

Insights into the MOF-Based Classic Configuration for the Differences in Effective Dye Adsorption, Magnetic Properties, and Computational Analyses.

Two 3D/2D anionic metal-organic frameworks (MOFs), [Cu(HL)]n (1) and [Mn3(L)2(DMF)4]n (2) (DMF = N,N-dimethylformamide), were synthesized by the solvothermal reaction of metal salts and 5'-(4-carboxyphenyl)-2',4',6'-triethyl-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic acid (H3L). Single-crystal X-ray diffraction analyses revealed that complex 1 shows three-dimensional (3D) frameworks with a (3,6)-connected 3-fold interpenetrated topology with the Schläfli symbols of {4.62}2{42.610.83}, whereas the topology of the two-dimensional (2D) architecture can be defined as 2-fold stacked layers with the Schläfli symbols of {43}2{46.66.83} for complex 2. In addition, density functional theory calculations, together with UV-vis adsorption spectroscopy, zeta potential, effective aperture size analysis, TEM, and SEM, were also performed to determine the accurate adsorption sites and significant differences in dye adsorption for complexes 1 and 2. Interestingly, UV-vis studies confirm that Mn-MOF displays remarkable adsorption efficiency for cationic rhodamine B, methylene blue, malachite green, and methyl green, and the removal rate reached 95.2, 95.0, 87.0, and 78.0%, respectively, while almost no adsorption capacity was detected for anionic cresol red and methyl orange. However, Cu-MOF failed to efficiently adsorb any selected dyes. Moreover, the magnetic properties were also investigated through experimental and theoretical calculations in detail, which revealed the weak and stronger antiferromagnetic interactions that occurred between Cu(II) and Mn(II) centers, respectively. Finally, this work provides the profound mechanisms for magnetism and dye adsorption.

Unveiling a unique outer-sphere pathway in manganese-catalyzed acceptorless dehydrogenation reaction.

First-row transition metals are widely used in acceptorless dehydrogenative coupling reactions, making the detailed investigation of their catalytic mechanisms crucial for the rational design of efficient catalysts. In this study, density functional theory (DFT) was employed to explore the mechanism of an acceptorless dehydrogenation reaction catalyzed by a bifunctional complex based on a high-spin Mn(II) center. The computational results reveal that the Mn(II) catalyst follows a novel dehydrogenation pathway, where the external base KOH first coordinates to the metal center, and dehydrogenation proceeds via an outer-sphere mechanism. The hydride transfer step is identified as the rate-determining step, with an energy barrier of 26.3 kcal mol-1, consistent with experimental results. To further investigate the selectivity of the mechanism, energy decomposition analysis (EDA) and extended transition state-natural orbitals for chemical valence (ETS-NOCV) analysis were conducted on key transition states. The results show that the small steric hindrance and strong orbital interactions of the external base KOH are the key factors contributing to the selectivity of this mechanism. These findings not only deepen our understanding of the reaction mechanism but also provide valuable theoretical insights for the design and optimization of future acceptorless dehydrogenation catalysts.

Cytotoxic ROS-Consuming Mn(III) Synzymes: Structural Influence on Their Mechanism of Action.

ROS (i.e., reactive oxygen species) scavenging is a key function of various Mn-based enzymes, including superoxide dismutases (SODs) and catalases, which are actively linked to oxidative stress-related diseases. In this study, we synthesized and characterized two novel Mn(III)-based synzymes (i.e., synthetic enzymes), designated C1 ([MnL1Cl(H2O)]Cl·3H2O) and C2 ([MnL2Cl2]·2H2O), which differ in the presence of a bridging aliphatic or aromatic group in the chelator. Using a range of analytical techniques, we found that the aromatic C2 bridge significantly influences the Mn(III) center's cis-β configuration, unlike C1, which adopts a trans configuration. We then thoroughly evaluated the oxidation-reduction properties of C1 and C2, including their redox potentials (by cyclic voltammetry) and capacity to consume various ROS species (using DPPH, hydroxyl radical, hydrogen peroxide, and superoxide UV-visible spectrophotometric assays). The specific kinetics of the H2O2 dismutation process, as measured by a Clark-type electrode and time-resolved ESI-MS, revealed that both synzymes possess catalytic activity. Toxicological experiments using the Galleria mellonella larval model demonstrated the compounds' innocuous nature towards higher eukaryotic organisms, while cytotoxicity assays confirmed their selective efficacy against lung cancer cells. Additional cytological assays, such as the thiobarbituric acid reactive substances assay and caspase-3 activity and p53 expression analysis, reported that C1 and C2 induce cytotoxicity against cancer cells via apoptosis rather than necrosis and behave very differently towards redox substances and ROS-regulating enzymes in vivo. These findings suggest that the structural differences between C1 and C2 lead to distinct redox properties and biological activities, highlighting the potential of these novel Mn(III)-based synzymes as therapeutic agents for the treatment of oxidative stress-related diseases, particularly lung cancer. Further studies are warranted to elucidate the underlying mechanisms of action and explore their clinical applications.

Increasing the CO‐Release Photosensitivity of Mn(I) Carbonyl Complexes Towards Longer Wavelengths by Electronically Tuning Their Schiff Base Ligands

ABSTRACTFive novel manganese (I) tricarbonyl complexes were synthesized by the reaction of Mn (CO)5Br with quinoline‐2‐carboxaldehyde and different anilines. The IR, UV, and myoglobin results indicate that these complexes can be used as photoCORMs (photo photoinduced carbon monoxide releasing molecules) activated by red light. The visible range spectra display strong charge transfer (CT) bands, the maxima of which are sensitive to the ligand substituents. Density functional theory (DFT) and time‐dependent density functional theory (TDDFT) computations show that these CT transitions are admixtures of metal‐to‐ligand and aniline‐to‐quinoline charge transfers and that increasing the electron‐donating ability on the aniline functionality can lead to shifts in the absorption bands of the corresponding compounds to longer wavelengths and to enhanced band intensities, thus enhancing their photoactivity. Photolysis of these complexes in aerobic solution leads to CO photodissociation followed by oxidation of the Mn(I) center to Mn(II).

Second-Shell Coordination Environment Modulation for MnN4 Active Sites by Oxygen Doping to Boost Oxygen Reduction Performance.

As a category of transition metal-nitrogen-carbon (M-N-C) catalysts, Mn-based single-atom catalysts (SACs) are considered as promising non-precious metal catalysts for stable oxygen reduction reaction (ORR) due to their Fenton-inactive character (versus Fe) and more abundant earth reserves (versus Ni, Co). However, their ORR activity is unsatisfactory. Besides, the structure-activity relationship via tuning the coordination environment of the second coordination shell for transition metal single sites is still elusive. Here, a Mn SAC with O doping in the second-shell of atomically dispersed Mn centers (MnSAC-O/C) as highly efficient and stable ORR catalyst is developed. X-ray absorption spectroscopy combined with theoretical calculations verifies the O doping in the second-shell of Mn center, and reveals the distortion of local environment of Mn center in the MnSAC-O/C. The MnSAC-O/C exhibits high ORR performance with a half-wave potential of 0.898 V, superior to MnSAC-C, commercial Pt/C and most reported non-noble metal-based SACs. More importantly, MnSAC-O/C based zinc-air batteries (ZABs) deliver outstanding durability with stable operation exceeding 930 h. Theoretical calculations confirm that O doping breaks the symmetry of charge distribution of MnN4 active center and facilitates OH* desorption, thus attributing to the promoted ORR activity.

Design, Synthesis, Magnetic Properties, and Hydrogen Evolution Reaction of a Butterfly-like Heterometallic Trinuclear [CuII2MnII] Cluster.

A novel heterometallic trinuclear cluster [CuII2MnII(cpdp)(NO3)2(Cl)] (1) has been designed and synthesized by employing a molecular library approach that uses CuCl2·2H2O and Mn(NO3)2·4H2O as inorganic metal salts and H3cpdp as a multifunctional organic scaffold (H3cpdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol). This heterometallic cluster has emerged as an unusual ferromagnetic material and promising electrocatalyst for hydrogen evolution reaction (HER) in the domain of inorganic and materials chemistry. Crystal structure analysis establishes the structural arrangement of 1, revealing a butterfly-like topology with an unusual seven-coordinated Mn(II) center. Formation of this cluster is accomplished by a self-assembly process through functionalization of 1 with one μ2:η1:η1-nitrate and two μ2:η2:η1-benzoate groups via the CuII(μ2-NO3)CuII} and {CuII(μ2-O2CC6H5)MnII} linkages, respectively. Variable-temperature SQUID magnetometry revealed the coexistence of ferromagnetic and antiferromagnetic interactions in 1. The observed magnetic behavior in 1 is unexpected because of a large Cu-O-Mn angle with a value of 132.05°, indicating that the correlation between coupling constants and the structural parameters is a multifactor problem. This cluster shows excellent electrocatalytic performance for the HER attaining a current density of 10 mA/cm2 with a Tafel slope of 183 mV dec-1 at a 310 mV overpotential value. Essentially, cluster 1 shows exceptional electrochemical stability at ambient temperature, accompanied by minimal degradation of the current density as examined by chronoamperometric studies. Density functional theory calculations establish the mechanistic insight into the HER process, indicating that the CuII-OCO-MnII site is the active site for formation of molecular hydrogen.

Nature‐Inspired N, O Co‐Coordinated Manganese Single‐Atom Catalyst for Efficient Hydrogen Peroxide Electrosynthesis

AbstractThe two‐electron oxygen reduction reaction (2e− ORR) is a pivotal pathway for the distributed production of hydrogen peroxide (H2O2). In nature, enzymes containing manganese (Mn) centers can convert reactive oxygen species into H2O2. However, Mn‐based heterogeneous catalysts for 2e− ORR are scarcely reported. Herein, we developed a nature‐inspired single‐atom electrocatalyst comprising N, O co‐coordinated Mn sites, utilizing carbon dots as the modulation platform (Mn CD/C). As‐synthesized Mn CD/C exhibited exceptional 2e− ORR activity with an onset potential of 0.786 V and a maximum H2O2 selectivity of 95.8 %. Impressively, Mn CD/C continuously produced 0.1 M H2O2 solution at 200 mA/cm2 for 50 h in the flow cell, with negligible loss in activity and H2O2 faradaic efficiency, demonstrating practical application potential. The enhanced activity was attributed to the incorporation of Mn atomic sites into the carbon dots. Theoretical calculations revealed that the N, O co‐coordinated structure, combined with abundant oxygen‐containing functional groups on the carbon dots, optimized the binding strength of intermediate *OOH at the Mn sites to the apex of the catalytic activity volcano. This work illustrates that carbon dots can serve as a versatile platform for modulating the microenvironment of single‐atom catalysts and for the rational design of nature‐inspired catalysts.

Nature-Inspired N, O Co-Coordinated Manganese Single-Atom Catalyst for Efficient Hydrogen Peroxide Electrosynthesis.

The two-electron oxygen reduction reaction (2e- ORR) is a pivotal pathway for the distributed production of hydrogen peroxide (H2O2). In nature, enzymes containing manganese (Mn) centers can convert reactive oxygen species into H2O2. However, Mn-based heterogeneous catalysts for 2e- ORR are scarcely reported. Herein, we developed a nature-inspired single-atom electrocatalyst comprising N, O co-coordinated Mn sites, utilizing carbon dots as the modulation platform (Mn CD/C). As-synthesized Mn CD/C exhibited exceptional 2e- ORR activity with an onset potential of 0.786 V and a maximum H2O2 selectivity of 95.8 %. Impressively, Mn CD/C continuously produced 0.1 M H2O2 solution at 200 mA/cm2 for 50 h in the flow cell, with negligible loss in activity and H2O2 faradaic efficiency, demonstrating practical application potential. The enhanced activity was attributed to the incorporation of Mn atomic sites into the carbon dots. Theoretical calculations revealed that the N, O co-coordinated structure, combined with abundant oxygen-containing functional groups on the carbon dots, optimized the binding strength of intermediate *OOH at the Mn sites to the apex of the catalytic activity volcano. This work illustrates that carbon dots can serve as a versatile platform for modulating the microenvironment of single-atom catalysts and for the rational design of nature-inspired catalysts.

Activating the Mn Single Atomic Center for an Efficient Actual Active Site of the Oxygen Reduction Reaction by Spin-State Regulation.

The ligand engineering for single-atom catalysts (SACs) is considered a cutting-edge strategy to tailor their electrocatalytic activity. However, the fundamental reasons underlying the reaction mechanism and the contemplation for which the actual active site for the catalytic reaction depends on the pyrrolic and pyridinic N ligand structure remain to be fully understood. Herein, we first reveal the relationship between the oxygen reduction reaction (ORR) activity and the N ligand structure for the manganese (Mn) single atomic site by the precisely regulated pyrrolic and pyridinic N4 coordination environment. Experimental and theoretical analyses reveal that the long Mn-N distance in Mn-pyrrolic N4 enables a high spin state of the Mn center, which is beneficial to reduce the adsorption strength of oxygen intermediates by the high filling state in antibond orbitals, thereby activating the Mn single atomic site to achieve a half-wave potential of 0.896 V vs RHE with outstanding stability in acidic media. This work provides a new fundamental insight into understanding the ORR catalytic origin of Mn SACs and the rational design strategy of SACs for various electrocatalytic reactions.

Engineering bimetallic cluster architectures: harnessing unique “remote synergy effect” between Mn and Y for enhanced electrocatalytic oxygen reduction reaction

Integrating single atoms and clusters into a unified catalytic system represents a novel strategy for enhancing catalytic performance. Compared to single-atom catalysts, those incorporating both single atoms and clusters exhibit superior catalytic activity. However, the co-construction of these systems and the mechanisms of their catalytic efficacy remain challenging and poorly understood. In this study, we synthesized a Mn–N–C catalyst featuring MnY clusters and Mn single atoms via a straightforward two-step sintering method. Y doping facilitated the formation of Mn clusters and optimized the d-band center of Mn through a unique synergy effect, thereby reducing energy barriers and enhancing the reaction kinetics. Additionally, the electron-donating ability of Y single atoms promoted the formation of unsaturated Mn–N₃ coordination structures, resulting in excellent oxygen reduction reaction (ORR) performance. Consequently, the MnY/NC catalyst demonstrated a half-wave potential (E₁/₂) of 0.90 V and maintained stability in 0.1 M KOH, outperforming both Mn/NC and Pt/C. This work underscores the potential of rare earth metal doping in transition metals to create stable single-atom and cluster systems, effectively leveraging their synergy effect for superior catalytic performance and validating the concept of the “remote synergy effect” in heterogeneous catalysis.

From [2Mn2S] Diamond Cores to Butterfly Rhombs: Transformations That Highlight Alternating Peptide Binding Sites.

Thiocarboxamide chelates are known to assemble [2Mn2S] diamond core complexes via μ-S bridges that connect two MnI(CO)3 fragments. These can exist as syn- and anti-isomers and interconvert via 16-electron, monomeric intermediates. Herein, we demonstrate that reduction of such Mn2 derivatives leads to a loss of one thiocarboxamide ligand and a switch of ligand binding mode from an O- to N-donor of the amide group, yielding a dianionic butterfly rhomb with a short Mn0-Mn0 distance, 2.52 Å. Structural and chemical analyses suggest that reduction of the Mn(I) centers is dependent on the protonation state of the amide-H, as total deprotonation followed by reduction does not result in the reduction of the Mn2 core. Partial deprotonation followed by reduction suggests a pathway that involves monomeric Mn(CO)3(S-O) and Mn(CO)3(S-N) intermediates. Ligand modifications to tertiary amides that remove the possibility of amide-H reduction led to complexes that preserve the [2Mn2S] diamond core during chemical reduction. Further comparison with the tethered system, linking the Mn(CO)3(S-O) sites together, suggests that dimer dissociation is necessary for the overall reductive transformation. These results highlight organomanganese carbonyl chemistry to establish illustrations of peptide fragment binding modes in the uptake of low-valent metal carbonyls related to binuclear active sites of biocatalysts.

Manganese diluted TlInS2 layered semiconductor: Optical, electronic and magnetic properties

Manganese–doped TlInS2 (TlInS2+Mn) layered semiconductors with different doping concentrations of about 0.1 and 0.3 at. percent were investigated. Photo–induced current transient spectroscopy (PICTS) measurements in the temperature range of 80 and 300 K have been made for identifying energy levels related to Mn dopant within the electronic bandgap of TlInS2+Mn crystal. Optical absorption spectra in the photon energy range of ∼1.8–3.1 eV have been extracted by fitting the transmittance spectra of TlInS2+Mn recorded at the temperatures varied from ∼40–300 K. A redshift trend of the absorption edge with increasing of temperature was observed. On the other hand, a blue shift in the absorption edge with Mn doping was observed in the absorption spectra. The Mn dopant induced photoluminescence (PL) was also investigated in the visible region ranging from 320 to 960 nm. Seven peaks were observed in the PL spectra of Mn doped TlInS2 crystal in the regions both ∼960–620 nm (∼1.3–2 eV) and ∼620–320 nm (∼2–3.8 eV) due to the electronic states of Mn ions. Laser–induced breakdown spectroscopy (LIBS) technique was applied to establish of the elemental chemical composition and to confirm presence of each constituent element in TlInS2:Mn. The dc magnetization measurements of TlInS2+Mn performed in a wide temperature range of ∼5 and ∼300 K revealed different (diamagnetic and paramagnetic states) magnetic phases inside the studied temperature range. The X–band electron paramagnetic resonance (ESR) experiments were carried out in the low–temperature phase of TlInS2+Mn to probe the structure of Mn centers in TlInS2. The measurements revealed that the ESR spectrum changes drastically in the low–temperature phase of TlInS2+Mn bulk sample. Finally, a detailed density functional theory (DFT) based computational investigation of electronic band structures, density of states and optical properties of TlInS2+Mn compound has been performed. The results of ab–initio calculations are discussed for three possible states when the manganese atom was doped by replacing either the Tl, In or S atoms in the unit cell of TlInS2. Additionally, the effect of interstitial Mn dopant on the electronic structure and optical properties of TlInS2 material has been simulated.

Polymeric Manganese(II) Acetate Derivatives: Syntheses, Crystal Structures and Magnetic Properties

AbstractThree novel polymeric Mn(II) acetate derivatives, identified as {[Mn2.5(OH)(CH3COO)4] ⋅ 0.5CH3OH ⋅ 0.5CH3CN}n (1), {[Mn3(CH3CO O)6] ⋅ 0.5CH3CN}n (2) and {Mn1.5K(CH3COO)4}n (3), have been successfully prepared by systematically adjusting the ratio of reactants and using the 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (Hmmt) as the template agent. These three complexes can be regarded as the different crystalline forms of Mn(CH3COO)2 under different reaction conditions. Single‐crystal X‐ray diffraction analyses revealed that 1 and 2 feature the unique three‐dimensional (3D) framework. For 3, it displays a 2D structure, which is further assembled to form a 3D extended network via the weak hydrogen bond interactions. Magnetic studies confirmed that 1 and 2 show antiferromagnetic interactions, and 1 displays a long‐range ordering phase below the critical temperature (Tc) of 7.8 K. In addition, magnetisation data collected for 1–2 yield low magnetic entropy changes, which can be attributed to the strong antiferromagnetic interactions among the Mn(II) centres.

Regulating Manganese-Site Electronic Structure via Reconstituting Nitrogen Coordination for Efficient Non-Oxygen-Dependent Sonocatalytic Therapy against Orthotopic Breast Cancer.

Sonocatalytic therapy (SCT) has emerged as a promising noninvasive modality for tumor treatment but is hindered by the insufficient generation of ultrasound-induced reactive oxygen species (ROS) and the hypoxic tumor microenvironments. Herein, we fabricated a carbon nanoframe-confined N-coordinated manganese single-atom sonocatalyst with a five-coordinated structure (MnN5 SA/CNF) using a phthalocyanine-mediated pyrolysis strategy. The precise coordination structure was identified by synchrotron X-ray absorption fine structure analyses. The MnN5 SA/CNF exhibits superior and nonoxygen-dependent sonocatalytic activity owing to the optimized coordination structure and cavitation effect enhanced by defects. Additionally, density functional theory studies reveal that the five-coordination structure downshifts the d-band center of Mn from -0.547 to -0.829 eV and enhances the desorption capacity for oxygen-containing intermediates, thus accelerating the catalytic process. Finally, the as-synthesized MnN5 SA/CNF demonstrates a significantly enhanced antitumor effect through mitochondrial apoptosis in an orthotopic breast cancer mouse model. This work explores the potential of SAzymes-supported biomedical interventions by leveraging enzymatic activity with sonocatalytic properties.

Experimentally Assessing the Electronic Structure and Spin-State Energetics in MnFe Dimers Using 1s3p Resonant Inelastic X-ray Scattering.

The synergistic interaction between Mn and Fe centers is investigated via a comprehensive analysis of full 1s3p resonant inelastic X-ray scattering (RIXS) planes at both the Fe and Mn K-edges in a series of homo- and heterometallic molecular systems. Deconvolution of the experimental two-dimensional 1s3p RIXS maps provides insights into the modulation of metal-ligand covalency and variations in the metal multiplet structure induced by subtle electronic structural differences imposed by the presence of the second metal. These modulations in the electronic structure are key toward understanding the reactivity of biological systems with active sites that require heterometallic centers, including MnFe purple acid phosphatases and MnFe ribonucleotide reductases. Herein, we demonstrate the capabilities of 1s3p RIXS to provide information on the excited state energetics in both element- and spin-selective fashion. The contributing excited states are identified and isolated by their multiplicity and π- and σ-contributions, building a conceptual bridge between the electronic structures of metal centers and their reactivity. The ability of the presented 1s3p RIXS methodology to address fundamental questions in transition metal catalysis reactivity is highlighted.

Enhancing Photoreduction of Cr(VI) through a Multivalent Manganese(II)-Organic Framework Incorporating Anthracene Moieties.

Exploiting a photocatalyst with high stability and excellent activity for Cr(VI) reduction under mild conditions is crucial yet challenging. Herein, the rigid aromatic multicarboxylate ligand with chromophore anthracene was selected to coordinate with multivalent metal ion manganese and to obtain a stable two-dimensional (2D) Mn-based metal-organic framework (MOF), LCUH-120, which can efficiently and quickly convert Cr(VI) into Cr(III) under light without the need for any additional photosensitizer. The efficient photosensitive anthracene group serves as a photosensitizer center and multivalent Mn(II) ion as a photocatalyst center in LCUH-120, and the conversion of Cr(VI) to Cr(III) can be realized completely in just 40 min. Specifically, the rate constant (k) and reduction rate of the Cr(VI) photocatalytic reaction can be high up to 0.134 min-1 and 2.50 mgCr(VI) g-1cata min-1 in an acidic environment (pH = 2), respectively. Compared to our previously reported three-dimensional (3D) Sm-MOF, LCUH-120 exhibits a significantly higher catalytic reaction rate, which might be ascribed to the fact that the photocatalyst center Mn node can improve the rate of electron transfer and promote the separation of holes and photogenerated electrons. In an acidic environment, the reaction mechanism can be verified through various contrast experiments and theoretical simulations.

A New Azide-Bridged Polymeric Manganese (III) Schiff Base Complex with an Allylamine-Derived Ligand: Structural Characterization and Activity Spectra

This paper reports the synthesis and structural characterization of a novel azide-bridged polymeric manganese (III) Schiff base complex, using 2-((allylimino)methyl)-6-ethoxyphenol as a ligand. The crystal structure of the synthesized compound, elucidated by single-crystal X-ray diffraction analysis, indicates that it crystallizes in the monoclinic space group P21/c. The complex is found to display an octahedral geometry in which the central manganese Mn(III) coordinates with two bidentate donor Schiff base ligands via oxygen and nitrogen atoms. In addition, the metallic centers are linked together to form a one-dimensional chain bridged by end-to-end azide ligands. To offer a more thorough characterization of the synthesized compound, the study incorporates experimental data from FT-IR, UV-Vis, and cyclic voltammetry, alongside computational results from Hirshfeld surface analysis and DFT calculations conducted for both the ligand and complex. The computational analyses provided valuable insights into the intrachain and interchain interactions within the crystal structure, clarified the conformational characteristics of the isolated ligand molecule, and aided in the interpretation of the experimental IR spectra. Furthermore, an assessment of the compound’s drug-like properties was conducted using activity spectra for substances (PASS) predictions, revealing potential pharmacological activities.

Chiral Ca–Mn-frameworks with double helical chains and one-dimensional channels constructed from enantiomorphous lactate synthons

Under solvothermal synthetic condition, lactate derivatives (R)-5-(1- carboxyethoxy)isophthalic acid ((R)-H3CIA) and (S)-5-(1-carboxyethoxy)isophthalic acid ((S)–H3CIA) assembled with Ca(Ⅱ) and Mn(Ⅱ) ions to obtain enantiomers {[MnCa0.5((R)-CIA)(H2O)]·((CH3)2NH2CH3CO2)0.5(H2O)}n (HU21-R) and {[MnCa0.5((S)-CIA)(H2O)]·((CH3)2NH2CH3CO2)0.5(H2O)}n (HU21–S), respectively. Complexes HU21-R and HU21–S belong to orthorhombic crystal system with chiral space group I212121. Single crystal X-ray diffraction analysis revealed that all oxygen atoms of synthons (R)-CIA3- and (S)-CIA3- participated in the coordination with metal ions. Thus, semi-rigid (R)-CIA3- and (S)-CIA3- anions become rigid linkers in HU21-R and HU21–S. Fragments of (R)-CIA3- anion are connected by Ca(Ⅱ) ions to build right-handed double helical chains in HU21-R, while the enantiomeric left-handed double helixes are constructed by (S)-CIA3- fragments and Ca(Ⅱ) ions in HU21–S. Additionally, Mn(Ⅱ) centers and CIA3− anions resulted in a rare 4,4,4-connected net with point symbol of (42.62.82)3(42.64). Ca(Ⅱ) ions were further filed into Mn-CIA-framework to form a three dimensional structure with one dimensional channel. Moreover, magnetic test indicates that the framework has a canted antiferromagnetic behavior.

(Digital Presentation) New Earth-Abundant Photoelectrocatalyst and Pathway for CO2 Electroreduction

The rising levels of carbon dioxide (CO2) in the atmosphere is among the most alarming issues in today’s world: harming the environment, health, and economics of all nations on the planet. CO2 capture and its photochemical and/or photoelectrochemical reduction to fuels are promising methodologies to reduce atmospheric CO2. This is a photochemistry, electrochemistry, and catalysis problem. Transition metal complexes that can be tailored to a desired function utilizing a wide range of ligands, play a crucial role in solar fuels chemistry by reducing the activation energy for catalytic CO2 reduction to fuels. In the last decade, Mn-based complexes have sparked a significant interest owing to their abundance in Earth’s crust and lower prices compared to other transition metals. However, a catalyst that operates with high activity and turnover numbers at low overpotential is still required. We report the synthesis, characterization, and activity toward CO2 electrochemical reduction of Mn complexes containing the photoactive, electron-donating 1-imidazole-2,4,6-tri(carbazole-9-yl)-3,5-dicyanobenzene ligand (3CzImIPN). UV-vis and photoluminescence spectra of the Mn complex containing 3CzImIPN will be reported that investigate its photophysical properties under visible light. Cyclic Voltammetry (CV) studies under nitrogen and CO2 will be reported that investigate the electron transfer between the ligand and the Mn centre, as well as the electrochemical reduction of CO2. Evidence will be presented for a new, low overpotential pathway for the electroreduction of CO2 by these types of complexes. Figure 1