Search

Electrocatalytic reduction of biomass-derived furan compounds provides a green and sustainable approach to produce value-added fuels and chemicals. Despite the achievements in unimolecular transformation, C–C coupling which holds great promise to yield precursors for high-density fuels has not received extensive attention. Herein, we report a Cu2O-derived nanowire array material with switchable selectivity to electrocatalytic reduction of furfural depending on the electrolyte pH. Besides a high selectivity of 98.4% to furfuryl alcohol via hydrogenation at pH 9.5, the Cu2O-derived array structure also exhibits a high selectivity of 83.5% to hydrofuroin via C–C coupling at pH 14. Upon control experiments and detailed characterization of the electrodes, the array architecture is proposed to decrease the diffusion of ketyl radicals which are the key intermediates for C–C coupling. The confined diffusion results in a high local concentration of the radicals in the array and facilitates their collision for enhancing the formation of hydrofuroin. [ABSTRACT FROM AUTHOR]

Transmissive-to-black switching electrochromic (EC) polymers have attracted considerable attention toward the development of low-cost, low-energy-demand passive displays. However, most reported transmissive-to-black switching EC polymers have high applied potential and low cycling stability, which significantly restrict their practical application. To address this issue, we propose a new structure design concept from the perspective of molecular structural changes by systematically investigating three different types of tetraphenylethylene (TPE)-based π-bridges connected with a diphenylamine (DPA) electroactive unit (pendant-grouped, straight-chained, and hyperbranched). The structural changes of the TPE-based π-bridge during electrochemical redox and the EC performance of polyimides are studied. All the designed polyimides (PG-TPE-PI, ST-TPE-PI, and HB-TPE-PI) exhibit overall transmissive-to-black EC performance. In particular, PG-TPE-PI presents a high response speed (2.29 s/2.51 s), excellent open circuit stability (over 24 h/72 h), and high coloration efficiency (566 cm2 C−1), as well as first-class cycling stability for a transmissive-to-black polymer material (3000 cycles in an open system), thereby showing excellent application potential. [ABSTRACT FROM AUTHOR]

With new detection methods for hazards in food being created, it is essential to build an evaluation model of these methods in order to improve the level and efficiency of food safety related detection. Back propagation neural network (BPNN), classification and regression tree (CART), support vector regression (SVR) and random forest regression (RFR) are the supervised machine learning methods used to build the model. In this study, we used these four approaches to evaluate hazard detection methods. First, the factors that affect the test (considering the accuracy, efficiency and cost of the methods) were considered, and 8 indices were selected to establish an evaluation index system for chemical hazards and biological hazards respectively. Then, 727 methods related to the detection of chemical hazards and 91 methods related to the detection of biological hazards in food were analyzed, and experts were invited to score each method as machine learning training data. Then, four machine learning models were used for training and verification. It turns out that for the detection methods of chemical hazards, the BPNN, CART and SVR models require a shorter period of time to adjust parameters, perform better on the test set with great fitting ability and lower mean square error, and the goodness of fit is 0.969, 0.962 and 0.988, respectively. While for the detection methods of biological hazards, BPNN and SVR models fit better with goodness of fit values of 0.988 and 0.999, respectively, and give more accurate prediction. It can be concluded that BPNN and SVR models perform well for both chemical and biological hazards detection methods, which can be used as a reference for artificial selection before testing. [ABSTRACT FROM AUTHOR]

The synthesis of furan-based platform chemicals from abundant and renewable biomass-based hexoses plays an important role in the development and utilization of biomass energy. The electrochemical 5-hydroxymethylfurfural oxidation reaction (HMFOR) represents a promising route for synthesizing the 2,5-furandicarboxylic acid (FDCA) product which is a high value-added biomass-based monomer. Interface engineering is an effective strategy to adjust the electronic structure, optimize the adsorption of intermediates, and expose more active sites, thus attracting extensive attention for designing efficient HMFOR electrocatalysts. Herein, a NiO/CeO2@NF heterostructure with an abundant interface is designed for boosting the HMFOR performance under alkaline conditions. At 1.475 V vs. RHE, the conversion of HMF is nearly 100%, the selectivity of FDCA is 99.0%, and the faradaic efficiency is as high as 98.96%. The NiO/CeO2@NF electrocatalyst also exhibits robust stability for HMFOR for 10 cycles. When coupled with the cathode hydrogen evolution reaction (HER) in alkaline medium, the yields of FDCA and hydrogen production are 197.92 and 600 μmol cm−2 h−1, respectively. The NiO/CeO2@NF catalyst is also suitable for the electrocatalytic oxidation of other biomass-derived platform compounds. The abundant interface between NiO and CeO2, which can regulate the electronic properties of Ce and Ni atoms, improve the oxidation state of Ni species, regulate intermediate adsorption, and promote electron/charge transfer, makes the most contribution to high HMFOR performance. This work will provide a simple route for the design of heterostructured materials and reveal the application prospect of interface engineering for promoting the upgrading of biomass derivatives. [ABSTRACT FROM AUTHOR]

In this work, a new "off–on" fluorescence strategy for the determination of Ag+ and S2O32− is presented. Nitrogen-doped carbon dots (N-CDs) were synthesized using oxalic acid dihydrate and anhydrous ethylenediamine via a one-pot hydrothermal treatment without further chemical modification. The surface structure and optical properties of the synthesized N-CDs were characterized. The N-CDs emitted bright blue fluorescence with a high quantum yield of 26.01%. Ag+ could selectively quench the fluorescence of N-CDs due to the formation of a N-CDs-Ag+ complex on the surface. The quenching effect demonstrated a linear relationship in the range of 0–14 and 14–80 μM with a low detection limit (LOD) of 150 nM. Furthermore, S2O32− could combine with Ag+ to generate a more stable Ag+–S2O32− complex, and thus the fluorescence of the N-CDs-Ag+ system could be restored by adding S2O32−. The N-CDs-Ag+ solution behaved as a secondary fluorescent probe to detect S2O32− in the range of 0–50 nM with an extremely low LOD of 1.5 nM. The N-CDs were successfully applied to analyze Ag+ and S2O32− in real samples with satisfactory recoveries (99.04–103.20% and 97.11–99.84%, respectively), implying good applicability in practical analysis. [ABSTRACT FROM AUTHOR]

In this work, a new "off–on" fluorescence strategy for the determination of Ag+ and S2O32− is presented. Nitrogen-doped carbon dots (N-CDs) were synthesized using oxalic acid dihydrate and anhydrous ethylenediamine via a one-pot hydrothermal treatment without further chemical modification. The surface structure and optical properties of the synthesized N-CDs were characterized. The N-CDs emitted bright blue fluorescence with a high quantum yield of 26.01%. Ag+ could selectively quench the fluorescence of N-CDs due to the formation of a N-CDs-Ag+ complex on the surface. The quenching effect demonstrated a linear relationship in the range of 0–14 and 14–80 μM with a low detection limit (LOD) of 150 nM. Furthermore, S2O32− could combine with Ag+ to generate a more stable Ag+–S2O32− complex, and thus the fluorescence of the N-CDs-Ag+ system could be restored by adding S2O32−. The N-CDs-Ag+ solution behaved as a secondary fluorescent probe to detect S2O32− in the range of 0–50 nM with an extremely low LOD of 1.5 nM. The N-CDs were successfully applied to analyze Ag+ and S2O32− in real samples with satisfactory recoveries (99.04–103.20% and 97.11–99.84%, respectively), implying good applicability in practical analysis. [ABSTRACT FROM AUTHOR]

The emergence and progress of metal–organic frameworks (MOFs) with high stability, large surface area, and abundant unsaturated active sites, once again promote the development of nanozymes, making nanozymes more advantageous to replace natural enzymes and will increase the applications of chemiluminescence immunoassay. In this study, a flow injection chemiluminescence immunoassay based on Ni/Co metal–organic framework (Ni/Co-MOF) nanozymes was developed, which can quickly and highly sensitively detect florfenicol (FF) in animal-derived food residues. Ni/Co-MOF0.75 nanospheres can not only form stable immune probes with antibodies but also act as nanozymes to efficiently catalyze H2O2 for amplifying the chemiluminescence signal of the luminol–H2O2 system. In addition, due to good biocompatibility and large specific surface area, carboxyl-modified resin beads are used as a suitable material for loading more coating antigens. Based on the principle of competitive immunity, FF standard solution will compete with coating antigen loaded on the carboxyl resin beads for the limited binding sites on the FF antibody. Under the best experimental conditions, the detection range of FF is 0.0001–1000 ng mL−1, and the detection limit (LOD) is 0.033 pg mL−1 (S/N = 3). Furthermore, this method has been successfully applied to the analysis of actual samples with satisfactory results, which will provide a certain reference for the detection of small molecules in food and environmental analysis. [ABSTRACT FROM AUTHOR]

Vascularized bone tissue engineering is regarded as one of the optimal treatment options for large bone defects. The lack of angiogenic properties and unsatisfactory physicochemical performance restricts calcium phosphate cement (CPC) from application in vascularized bone tissue engineering. Our previous studies have developed a starch and BaSO4 incorporated calcium phosphate hybrid cement (CPHC) with improved mechanical strength and handling properties. However, the bioactivity—especially the angiogenic ability—is still absent and requires further improvement. Herein, based on the reported CPHC and the osteogenic and angiogenic properties of strontium (Sr) ions, a strontium-enhanced calcium phosphate hybrid cement (Sr–CPHC) was developed to improve both biological and physicochemical properties of CPC. Compared to CPC, the initial setting time of Sr–CPHC was prolonged from 2.2 min to 20.7 min. The compressive strength of Sr–CPHC improved from 11.21 MPa to 45.52 MPa compared with CPC as well. Sr–CPHC was biocompatible and showed promotion of alkaline phosphatase (ALP) activity, calcium nodule formation and osteogenic relative gene expression, suggesting high osteogenic-inductivity. Sr–CPHC also facilitated the migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro and up-regulated the expression of the vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1). In vivo evaluation showed marked new bone formation in a rat calvarial defect model with Sr-CPHC implanted. Sr–CPHC also exhibited enhancement of neovascularization in subcutaneous connective tissue in a rat subcutaneous implantation model. Thus, the Sr–CPHC with the dual effects of osteogenesis and angiogenesis shows great potential for clinical applications such as the repair of ischemic osteonecrosis and critical-size bone defects. [ABSTRACT FROM AUTHOR]

A general method was elaborately developed for the synthesis of pit-rich metal oxide (TiO2, ZrO2 and HfO2) nanocrystals with metallocene dichlorides as precursors. Benefiting from the synergies in numerous pits, Schottky junctions and nitrogen doping, the hybrid nanostructures of pit-rich TiO2 nanocrystals with Ru loading and N doping exhibited enhanced solar water splitting. [ABSTRACT FROM AUTHOR]

The design of efficient mixed Mn–Co oxides as oxygen reduction reaction (ORR) electrocatalysts in alkaline media has been boosted nowadays. Recently, multivariant MOFs have been demonstrated as versatile precursors to construct these mixed metal oxides. Herein, we synthesized four mixed Mn–Co oxide samples via simply annealing their MIL-53 precursors with different Co/Mn molar ratios. These four samples were dominated by three kinds of Mn–Co spinel phases. The mixed Mn–Co oxides showed enhanced ORR performances compared with the single metal counterparts in alkaline media. In particular, the sample containing a pure MnCo2O4 phase exhibited the highest activity with a half-wave potential of 0.772 V (vs. RHE), only 40 mV negative compared with that of commercial Pt/C. The H2O2 yield was calculated to be below 12.1%, corresponding to the high diffusion-limited current density along with the high electron transfer number. The surface defects, active Mn4+/Mn3+ and electrochemically active surface area together affected the ORR performances of these mixed Mn–Co oxides. The present work highlights the facile controllability of divalent MIL-53 analogues for highly efficient mixed Mn–Co oxides in ORR electrocatalysis. [ABSTRACT FROM AUTHOR]

A complete reaction mechanism for interconversion between hydrogen and formic acid catalyzed by [C,N] cyclometallated organoiridium complex [IrIII(Cp*)(4-(1H-pyrazol-1-yl-κN2)benzoic acid-κC3)(H2O)]2·SO4, i.e. [Ir-1]2·SO4, has been revealed by density functional theory (DFT) calculations. For both the hydrogen storage catalytic cycle I and hydrogen evolution catalytic cycle II, the detailed reaction profiles with the key transition states and intermediates are revealed. Catalytic cycle I shows that the dihydrogen heterolysis facilitated by OH− gives the considerable stable iridium hydride intermediate M-4, followed by an outer-sphere hydrogen transfer to afford a metal–formate complex M-6. Upon the increasing of pH, catalytic cycle II occurs via the generation of the metal–formate complex M-7, followed by the outer-sphere β-H elimination to form a metal–hydride complex M-9, which is subsequently protonated by the hydrated proton H3O+ to afford dihydrogen. The decomposition of bicarbonate and the β-hydride elimination of formate are believed to be the rate-determining steps for cycle I and II, respectively. The acid–base equilibrium between the hydroxy and oxyanion form on the catalyst [C,N] ligand has a considerable influence on the catalytic hydrogen transfer. Our studies are in good agreement with experimental results. Remarkably, the new theoretically designed low-cost cobalt(iii) complex, as a promising catalyst, exhibits catalytic activity for the interconversion between hydrogen and formic acid. [ABSTRACT FROM AUTHOR]

The triplet δ-mechanism different from the previously reported ones, i.e., the π-channel with the unoccupied πSTACKABOVE*/ABOVEBELOWxz/yz/BELOW/STACK (FeO) orbital and the σ-channel involving the unoccupied α-spin Fe-σSTACKABOVE*/ABOVEBELOWz2/BELOW/STACK orbital, has been theoretically described for the methane hydroxylation by [FeIV = O(TMC)(SR)]+ and its derivative [FeIV = O(TMC)(OH)]+ complex for the first time, and we have undertaken a detailed DFT study on the nature of this state by probing its geometry, electronic property and reactivity in comparison to all other possibilities. DFT calculations indicate that the electron transfer for the 3δ-channel from the σC–H orbital of the substrate to the final acceptor σSTACKABOVE*/ABOVEBELOWx2−y2/BELOW/STACK orbital of the catalyst occurs through a complex mechanism, which is initiated by the original α-spin electron transfer from the π* orbital of the catalyst to the σSTACKABOVE*/ABOVEBELOWx2−y2/BELOW/STACK orbital, where the α-spin electron from the σC–H orbital of the substrate shifts to the just empty α-spin π* orbital of the catalyst via the O-px/y based πSTACKABOVE*/ABOVEBELOWxz/yz/BELOW/STACK-orbital concomitantly. It is also found that the electron-donating ability of the axial ligand could influence the reaction channels, evident by the distinction that the electron-deficient F− and CF3CO2− ligands react via the 3σ-channel, whereas the electron-rich SR− and OH− ligands proceed by the 3δ-channel. With respect to reactivity, the 3δ-pathway has a comparable barrier to the 3π and 5π-pathways, which may offer a new approach for the specific control of C–H bond activation by the iron(iv)-oxo species. [ABSTRACT FROM AUTHOR]

A novel 3-5-dichlorosalicylaldehyde Schiff base chemodosimeter (compound 1) for water is designed and synthesized, and it works based on a water-triggered reaction of a Schiff base. Addition of trace amounts of water into 1 in various organic solvents leads to a fluorescence turn-on response and a simultaneous dual-channel signal modulation (both in the fluorescence and absorption spectra). Especially, 1 is found to be an outstanding fluorescence enhancement water sensor in methanol with an extremely low detection limit of 22 ppm. Consequently this probe can be utilized to detect trace water in commercial methanol. The quantitative detection of a wide range of water content is enhanced in THF and acetonitrile (0–35% v/v for THF and 0–20% v/v for acetonitrile), where the fluorescence peak intensity is nearly proportional to the amount of water added. Moreover, 1 can be used for monitoring pH through a novel ON–OFF–ON type signal modulation both in fluorescence and absorption spectra within a wide pH detection range. Thus, the chemodosimeter can not only be utilized to monitor the intracellular pH fluctuations, but also to accomplish simultaneous in situ staining of the cytosol and acidic organelles in two different channels, respectively. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of biomass-derived furan compounds provides a green and sustainable approach to produce value-added fuels and chemicals. Despite the achievements in unimolecular transformation, C-C coupling which holds great promise to yield precursors for high-density fuels has not received extensive attention. Herein, we report a Cu 2 O-derived nanowire array material with switchable selectivity to electrocatalytic reduction of furfural depending on the electrolyte pH. Besides a high selectivity of 98.4% to furfuryl alcohol via hydrogenation at pH 9.5, the Cu 2 O-derived array structure also exhibits a high selectivity of 83.5% to hydrofuroin via C-C coupling at pH 14. Upon control experiments and detailed characterization of the electrodes, the array architecture is proposed to decrease the diffusion of ketyl radicals which are the key intermediates for C-C coupling. The confined diffusion results in a high local concentration of the radicals in the array and facilitates their collision for enhancing the formation of hydrofuroin.

The synthesis of furan-based platform chemicals from abundant and renewable biomass-based hexoses plays an important role in the development and utilization of biomass energy. The electrochemical 5-hydroxymethylfurfural oxidation reaction (HMFOR) represents a promising route for synthesizing the 2,5-furandicarboxylic acid (FDCA) product which is a high value-added biomass-based monomer. Interface engineering is an effective strategy to adjust the electronic structure, optimize the adsorption of intermediates, and expose more active sites, thus attracting extensive attention for designing efficient HMFOR electrocatalysts. Herein, a NiO/CeO 2 @NF heterostructure with an abundant interface is designed for boosting the HMFOR performance under alkaline conditions. At 1.475 V vs. RHE, the conversion of HMF is nearly 100%, the selectivity of FDCA is 99.0%, and the faradaic efficiency is as high as 98.96%. The NiO/CeO 2 @NF electrocatalyst also exhibits robust stability for HMFOR for 10 cycles. When coupled with the cathode hydrogen evolution reaction (HER) in alkaline medium, the yields of FDCA and hydrogen production are 197.92 and 600 μmol cm -2 h -1 , respectively. The NiO/CeO 2 @NF catalyst is also suitable for the electrocatalytic oxidation of other biomass-derived platform compounds. The abundant interface between NiO and CeO 2 , which can regulate the electronic properties of Ce and Ni atoms, improve the oxidation state of Ni species, regulate intermediate adsorption, and promote electron/charge transfer, makes the most contribution to high HMFOR performance. This work will provide a simple route for the design of heterostructured materials and reveal the application prospect of interface engineering for promoting the upgrading of biomass derivatives.

Biomass is regarded as an excellent candidate for the preparation of carbon nanomaterials. A pH sensor was established based on carbon dots synthesized from black fungus, and possesses good fluorescence response and reversibility for pH detection. Meanwhile, the CDs can also be applied to intra-cellular bioimaging, showing potential for bioimaging., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, a novel type oxygen reduction reaction (ORR) electrocatalyst is explored using density functional theory (DFT); the catalyst consists of transition metal M and heteroatom N 4 co-doped in vacancy fullerene (M-N 4 -C 64 , M = Fe, Co, and Ni). Mulliken charge analysis shows that the metal center is the reaction site of ORR. PDOS analysis indicates that in M-N 4 -C 64 , the interaction between Fe-N 4 -C 64 and the adsorbate is the strongest, followed by Co-N 4 -C 64 and Ni-N 4 -C 64 . This is consistent with the calculated adsorption energies. By analyzing and comparing the adsorption energies of ORR intermediates and activation energies and reaction energies of all elemental reactions in M-N 4 -C 64 (M = Fe, Co, and Ni), two favorable ORR electrocatalysts, Fe-N 4 -C 64 and Co-N 4 -C 64 , are selected. Both exhibited conduction through the more efficient 4e - reduction pathway. Moreover, PES diagrams indicate that the whole reaction energy variation in the favorable ORR pathways of Fe-N 4 -C 64 and Co-N 4 -C 64 is degressive, which is conducive to positive-going reactions. This study offers worthwhile information for the improvement of cathode materials for fuel cells., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A general method was elaborately developed for the synthesis of pit-rich metal oxide (TiO2, ZrO2 and HfO2) nanocrystals with metallocene dichlorides as precursors. Benefiting from the synergies in numerous pits, Schottky junctions and nitrogen doping, the hybrid nanostructures of pit-rich TiO2 nanocrystals with Ru loading and N doping exhibited enhanced solar water splitting.

An ascorbic acid/Fe 0 composite (H 2 A/Fe 0 )-activated persulfate (PS) process was provided for rhodamine B (RhB) removal. Experimental results demonstrated that the H 2 A/Fe 0 -PS system exhibits a rapid and continuous oxidation of organic contaminants, and shows great advantages over the conventional Fe 0 -PS system by significantly improving removal efficiency. This H 2 A induced dramatic enhancement for RhB degradation could be attributed to both the reduction and chelating ability of H 2 A. The H 2 A/Fe 0 composites were characterized using TEM, FE-SEM, FTIR and XPS, indicating that the obtained H 2 A/Fe 0 composites were prepared successfully. Key factors affecting the treatment were determined for the H 2 A/Fe 0 -PS system, including H 2 A/Fe 0 dosage, PS dosage, initial solution pH and temperature. Moreover, radical quenching tests revealed that sulfate radicals (SO 4 ˙ - ), hydroxyl radicals (˙OH) and superoxide radicals (O 2 ˙ - ) were generated in the H 2 A/Fe 0 -PS system, and SO 4 ˙ - was the main radical species responsible for RhB degradation. Finally, possible degradation pathways are proposed. These findings prove that the H 2 A/Fe 0 -PS system may provide a simple and effective technology for improving the degradation of refractory organic pollutants., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The design of efficient mixed Mn-Co oxides as oxygen reduction reaction (ORR) electrocatalysts in alkaline media has been boosted nowadays. Recently, multivariant MOFs have been demonstrated as versatile precursors to construct these mixed metal oxides. Herein, we synthesized four mixed Mn-Co oxide samples via simply annealing their MIL-53 precursors with different Co/Mn molar ratios. These four samples were dominated by three kinds of Mn-Co spinel phases. The mixed Mn-Co oxides showed enhanced ORR performances compared with the single metal counterparts in alkaline media. In particular, the sample containing a pure MnCo 2 O 4 phase exhibited the highest activity with a half-wave potential of 0.772 V (vs. RHE), only 40 mV negative compared with that of commercial Pt/C. The H 2 O 2 yield was calculated to be below 12.1%, corresponding to the high diffusion-limited current density along with the high electron transfer number. The surface defects, active Mn 4+ /Mn 3+ and electrochemically active surface area together affected the ORR performances of these mixed Mn-Co oxides. The present work highlights the facile controllability of divalent MIL-53 analogues for highly efficient mixed Mn-Co oxides in ORR electrocatalysis.

The triplet δ-mechanism different from the previously reported ones, i.e., the π-channel with the unoccupied π(xz/yz)* (FeO) orbital and the σ-channel involving the unoccupied α-spin Fe(z2)*-σ orbital, has been theoretically described for the methane hydroxylation by [Fe(IV) = O(TMC)(SR)](+) and its derivative [Fe(IV) = O(TMC)(OH)](+) complex for the first time, and we have undertaken a detailed DFT study on the nature of this state by probing its geometry, electronic property and reactivity in comparison to all other possibilities. DFT calculations indicate that the electron transfer for the (3)δ-channel from the σ(C-H) orbital of the substrate to the final acceptor σ(x2-y2)* orbital of the catalyst occurs through a complex mechanism, which is initiated by the original α-spin electron transfer from the π* orbital of the catalyst to the σ(x2-y2)* orbital, where the α-spin electron from the σ(C-H) orbital of the substrate shifts to the just empty α-spin π* orbital of the catalyst via the O-p(x/y) based π(xz/yz)*-orbital concomitantly. It is also found that the electron-donating ability of the axial ligand could influence the reaction channels, evident by the distinction that the electron-deficient F(-) and CF3CO2(-) ligands react via the (3)σ-channel, whereas the electron-rich SR(-) and OH(-) ligands proceed by the (3)δ-channel. With respect to reactivity, the (3)δ-pathway has a comparable barrier to the (3)π and (5)π-pathways, which may offer a new approach for the specific control of C-H bond activation by the iron(IV)-oxo species.

Comprehensive density functional theory computations on substrate hydroxylation by a range of nonheme iron(IV)-oxo model systems [Fe(IV)(O)(NH(3))(4)L](+) (where L = CF(3)CO(2)(-), F(-), Cl(-), N(3)(-), NCS(-), NC(-), OH(-)) have been investigated to establish the effects of axial ligands with different degrees of electron donor ability on the reactivity of the distinct reaction channels. The results show that the electron-pushing capability of the axial ligand can exert a considerable influence on the different reaction channels. The σ-pathway reactivity decreases as the electron-donating ability of the axial ligand strengthens, while the π-pathway reactivity follows an opposite trend. Moreover, the apparently antielectrophilic trend observed for the energy gap between the triplet π- and quintet σ-channel (ΔG(T-Q)) stems from the fact that the reaction reactivity can be fine-controlled by the interplay between the exchange-stabilization benefiting from the (5)TS(H) relative to the (3)TS(H) by most nonheme enzymes and the destabilization effect of the orbital by the anionic axial ligand. When the former counteracts the latter, the quintet σ-pathway will be more effective than the other alternatives. Nevertheless, when the dramatic destabilization effect of the orbital by a strong binding axial σ-donor ligand like OH(-) counteracts but does not override the exchange-stabilization, the barrier in the quintet σ-pathway will remain identical to the triplet π-pathway barrier. Indeed, the axial ligand does not change the intrinsic reaction mechanism in its respective pathway; however, it can affect the energy barriers of different reaction channels for C-H activation. As such, the tuning of the reactivity of the different reaction channels can be realised by increasing/decreasing the electron pushing ability.