Boosting Photoredox Catalysis Using a Two-Dimensional Electride as a Persistent Electron Donor

Abstract

Electrides, which have excess anionic electrons, are solid-state sources of solvated electrons that can be used as powerful reducing agents for organic syntheses. However, the abrupt decomposition of electrides in organic solvents makes controlling the transfer inefficient, thereby limiting the utilization of their superior electron-donating ability. Here, we demonstrate the efficient reductive transformation strategy which combines the stable two-dimensional [Gd2C]2+·2e– electride electron donor and cyclometalated Pt­(II) complex photocatalysts. Strongly localized anionic electrons at the interlayer space in the [Gd2C]2+·2e– electride are released via moderate alcoholysis in 2,2,2-trifluoroethanol, enabling persistent electron donation. The Pt­(II) complexes are adsorbed onto the surface of the [Gd2C]2+·2e– electride and rapidly capture the released electrons at a rate of 107 s–1 upon photoexcitation. The one-electron-reduced Pt complex is electrochemically stable enough to deliver the electron to substrates in the bulk, which completes the photoredox cycle. The key benefit of this system is the suppression of undesirable charge recombination because back electron transfer is prohibited due to the irreversible disruption of the electride after the electron transfer. These desirable properties collectively serve as the photoredox catalysis principle for the reductive generation of the benzyl radical from benzyl halide, which is the key intermediate for dehalogenated or homocoupled products.

Interlayer Charge Transfer Regulates Single-Atom Catalytic Activity on Electride/Graphene 2D Heterojunctions

“…Interface engineering can regulate the catalytic performance of SACs via proximity effects, such as charge transfer, strain, and interface hybridization. − Layered electrides possess loosely bound electrons, enabling colossal electron transfer to active catalytic sites. , A typical example is the graphene/Ca 2 N heterojunction, whose surface Van Hove singularity could serve as an electron bath to promote O 2 adsorption and subsequent CO oxidation with low energy barriers . Another important instance is observed in an Ru-loaded C12A7:e – electride, where extra orbital electrons enhance the catalytic efficiency for the nitrogen reduction reaction (NRR). , 2D electride/graphene-based heterostructure (EGH) SACs are promising candidates to control the electron coordination environment of metal atoms through interlayer charge transfer, resulting in SACs with high catalytic activity and low activation energy.…”

“…25−28 Layered electrides possess loosely bound electrons, enabling colossal electron transfer to active catalytic sites. 29,30 A typical example is the graphene/ Ca 2 N heterojunction, whose surface Van Hove singularity could serve as an electron bath to promote O 2 adsorption and subsequent CO oxidation with low energy barriers. 31 Another important instance is observed in an Ru-loaded C12A7:e − electride, where extra orbital electrons enhance the catalytic efficiency for the nitrogen reduction reaction (NRR).…”

Tuning the Magnetic Properties of Two-Dimensional Electride Gd2C via Halogenation

“…8 These interstitial AEs with their own magnetic moments (∼0.5 μ B /AE) promote the exchange interactions between gadolinium ions, giving rise to roomtemperature ferromagnetism in the Gd 2 C electride with highdensity magnetization. Furthermore, the interstitial AEs with considerably high mobility and low work function present compelling physical and chemical properties, such as ferromagnetic Weyl fermions, 9 pure quantum electron liquid phase, 10 persistent electron donor to boost photoredox catalysis, 11 spin-polarized electronic states, 8,12 and large intrinsic anomalous Hall conductivity. 13 Interestingly, the ferromagnetism of Gd 2 C transforms to antiferromagnetism if the AEs are passivated by chlorine or hydrogen.…”

Photoredox Selective Homocoupling of Propargyl Bromides

“…The Wurtz reaction of alkyl halides with sodium metal (later Ag, Li, Mg, Mn, Fe, Ni, and Zn) for homocoupled dimer synthesis could also be modified to photoredox Csp 3 –Csp 3 radical–radical homocoupling (Scheme a). Benzyl and allyl bromides have been reduced to generate benzyl and allyl radical intermediates, respectively, and their radical–radical homocoupling selectively provided the corresponding dimers. , Despite the high and similar reactivity of propargyl radicals compared to allyl and benzyl radicals, a photoredox Wurtz-type reaction of propargyl bromides has not yet been developed. Since the alkynyl moiety is one of the most versatile synthons for many other functional groups, Wurtz-type products of propargyl bromides, namely, 1,5-diynes ( B ), would be valuable building blocks for the synthesis of complex functional molecules (Scheme b) …”