An enzyme-mimic single Fe-N ₃ atom catalyst for the oxidative synthesis of nitriles via C─C bond cleavage strategy

Abstract

The cleavage and functionalization of recalcitrant carbon─carbon bonds is highly challenging but represents a very powerful tool for value-added transformation of feedstock chemicals. Here, an enzyme-mimic iron single-atom catalyst (SAC) bearing iron (III) nitride (FeN 3 ) motifs was prepared and found to be robust for cleavage and cyanation of carbon–carbon bonds in secondary alcohols and ketones. High nitrile yields are obtained with a wide variety of functional groups. The prepared FeN 3 -SAC exhibits high enzyme-like activity and is capable of generating a dioxygen-to-superoxide radical at room temperature, while the commonly reported FeN 4 -SAC bearing FeN 4 motifs was inactive. Density functional theory (DFT) calculation reveals that the activation energy of dioxygen activation and the activation energy of the rate-determining step of nitrile formation are lower over FeN 3 -SAC than FeN 4 -SAC. In addition, DFT calculation also explains the catalyst’s high selectivity for nitriles.

Biomass-Derived Single Zn Atom Catalysts: The Multiple Roles of Single Zn Atoms in the Oxidative Cleavage of C–N Bonds

“…As depicted in Figure 6 f, the EPR signal displayed the characteristic fingerprint of spin adducts as a result of ·O 2 – , further confirming that the reactive oxygen species was ·O 2 – . 40 , 41 …”

“…Furthermore, the reactive oxygen species were explored during the oxidative transformation of N -ethylaniline into aniline over the ZnN 4 -SAC catalyst by radical inhibition experiments (Figure e and Table S9). , The conversion greatly decreased from 56% under the standard conditions to 10% in the presence of a radical scavenger of 2,6-di- tert -butyl-4-methylphenol (BHT), suggesting that the reaction should proceed via the radical reaction process. The presence of superoxide radical (·O 2 – ) scavengers (PBQ; 1,4-benzoquinone) greatly inhibited the reaction, while the addition of singlet oxygen (1O 2 ) scavengers (FA; furfuryl alcohol) and hydroxyl radical (·OH) scavengers (IPA; iso-propyl alcohol) showed no significant influence.…”

“…Next, we used the electron paramagnetic resonance (EPR) technique with 5,5-dimethyl-1-pyrroline N -oxide (DMPO) as the spin trap at room temperature. As depicted in Figure f, the EPR signal displayed the characteristic fingerprint of spin adducts as a result of ·O 2 – , further confirming that the reactive oxygen species was ·O 2 – . , …”

“…As depicted in Figure 6f, the EPR signal displayed the characteristic fingerprint of spin adducts as a result of •O 2 − , further confirming that the reactive oxygen species was •O 2 − . 40,41 After the identification of the reactive oxygen species, the plausible mechanism of oxidative cleavage of C−N bonds in Nalkylanilines and N,N-dialkylanilines was studied by GC−MS. First, the oxidative transformation of N-benzyl-N-ethylaniline was performed at 150 °C and 10 bar O 2 (Figure S10a).…”

Axial N Ligand‐Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single‐Atoms Nanozymes

“…Recently, some research revealed that single‐atoms catalysts (SACs) [ 23 , 24 , 25 , 26 , 27 , 28 ] are the ideal candidate for the nanozymes because the atomically dispersed metal centers in SACs exhibit a high catalytic activity via maximized atomic utilization efficiency and active sites density. [ 29 , 30 ] Furthermore, the homogenous structure of metal atoms in SACs is an excellent platform to deeply understand the structure–activity relationships at the atomic level. The previous study [ 31 ] developed single iron atoms nanozymes (SANs) and proved their effectiveness for the O 2 activation in biosensing and biomedical.…”