Charge Transfer Research Articles

Intramolecular Singlet Fission in Individual Graphene Nanoribbons─Competition with a Charge Transfer.

Graphene nanoribbons (NRs) constitute a versatile platform for developing novel materials, where their structure governs their optical, electronic, and magnetic properties while also shaping their excited-state dynamics. Here, we investigate a set of three twisted N-doped molecular NRs of increasing length, obtained by linearly fusing perylene diimide to pyrene and pyrazino- or thiadiazolo-quinoxaline residues. By employing various temperature-dependent time-resolved spectroscopy techniques, we reveal how the flexible twisted NR geometry promotes the formation of a mixed electronic state with varying contributions from locally excited and charge-transfer (CT) states. The fate of this mixed state is highly sensitive to the molecular geometry, length, and solvent polarity. For the shortest NR, intersystem crossing dominates the deactivation pathway, efficiently generating triplets in low-polarity solvents. In contrast, for the extended NRs, intramolecular singlet fission (SF) takes place within a single nanoribbon. This is enabled by enhanced superexchange coupling due to a pronounced push-pull nature and the existence of multiple localized π-electron states caused by heteroatom doping, thereby circumventing the need for dimeric interactions typically associated with conventional SF systems. In higher-polarity environments, evidence of a (diabatic) CT state emerges. These findings underscore the intricate relationship between geometry, energy levels, and excited-state dynamics in twisted N-doped NRs.

Blue organic long-persistent luminescence via upconversion from charge-transfer to locally excited singlet state

Long-persistent luminescence (LPL) materials have applications from safety signage to bioimaging; however, existing organic LPL (OLPL) systems do not align with human scotopic vision, which is sensitive to blue light. We present a strategy to blueshift the emissions in binary OLPL systems by upconverting the charge-transfer (CT) to a locally excited (LE) singlet state. Through rigorous steady-state and time-resolved photoluminescence spectroscopy and wavelength-resolved thermoluminescence measurements, we provide the direct experimental evidence for this upconversion in OLPL systems featuring small energy offsets between the lowest-energy CT and LE singlet states. These systems exhibited strong room temperature LPL, particularly when extrinsic electron traps are added. Importantly, the developed OLPL system achieved Class A (ISO 17398) LPL, matching well with human scotopic vision. The findings not only elucidate the role of small energy offsets in modulating LPL but also provide potential avenues for enhancing the efficiency and applicability of OLPL materials.

Improving the oxygen evolution performance of iron-manganese oxyhydroxides by Cr doping.

The slow oxygen evolution reaction (OER) dynamics affect the energy efficiency of many electrocatalytic reactions. To accelerate the commercialization of electrolytic water, efficient and economical OER electrocatalysts need to be developed. Here, a series of FeMnMOOH/NF (M = Cr, Ni, Co, Cu, Zn, Sc and Ru) oxyhydroxides are constructed by a hydrothermal method and Cr doping illustrates the optimum oxygen evolution activity with a low overpotential of 241 mV. Cr doping increases the active sites, prevents Fe leaching, accelerates charge transfer, and lowers the energy barrier, thus promoting the OER. In situ Raman spectra indicate that Fe, Mn and Cr sites are all involved in the OER and the cooperative mechanism among them accelerates the reaction.

Synergistic Halogen-Bonding Passivation and Carboxylic Acid Anchoring in Carbazole-Based Hole-Transport Materials Enhance Performance and Stability of p-i-n Perovskite Solar Cells.

Interfaces pose significant challenges to the performance and stability of perovskite solar cells (PSCs), as defects and weak interactions at these boundaries can lead to energy losses and degradation. To address these issues, it is crucial to functionalize hole transport materials (HTMs) to effectively manage interfacial defects and enhance charge transfer. This study introduces a carbazole-based hole transport layer (TC-ICA) that leverages halogen bonding (XB) for enhanced interface passivation with the perovskite layer and carboxylic group anchoring to the indium-doped tin oxide (ITO). By combining these functionalities, the TC-ICA material leads to exceptional device stability (99% shelf stability over 320 days of air storage and a T80-lifetime exceeding 1000 h under light soaking) and enhanced efficiency (15.4%), outperforming single-function materials like TC-CA (14.7%) and TC-I (10.7%). This dual-function strategy marks a significant advancement in the quest for high-performance and long-term stable PSCs.

Rechargeable Cadmium Metal Batteries Enabled by an Aqueous CdSO4 Electrolyte.

Rechargeable aqueous cadmium (Cd) metal batteries enabled by the Cd plating and stripping behaviors of anode show great promise for next-generation energy storage applications due to the superior corrosion resistance, high specific capacity (476.5 mAh g-1), suitable redox potential (-0.4 V vs standard hydrogen electrode), and cost-effectiveness of Cd anode. However, this field is still in its infancy, with limited scientific exploration and numerous unresolved challenges. Therefore, to bridge the existing research gap in the field of Cd metal batteries, this study conducted a comprehensive investigation into the electrochemical performance of the Cd metal, utilizing a stable and low-cost aqueous CdSO4 solution as an electrolyte. It is revealed that the solvation structure of Cd2+ transitions from [Cd(H2O)9]2+ to [Cd(H2O)6(SO4)3]4- as the CdSO4 concentration increases from 0.5 to 3 M. This transition reduces the activity of H2O around Cd2+, promotes charge transfer, and enhances desolvation/solvation kinetics during Cd plating/stripping processes. Consequently, when the concentration of CdSO4 reached nearly saturated 3 M, the Cd anode presents optimal corrosion-resistant and dendrite-free capabilities, reflecting in durable Cd plating/stripping performance for over 2000 h with a high Coulombic efficiency of 99.7%. Furthermore, the Cd//V2O5 full cell achieves an ultralong cycle life, maintaining stable performance for 30,000 cycles with minimal capacity degradation. The high reversibility of the Cd anode and the exceptional performance of the full cell affirm the potential of aqueous CdSO4 electrolyte as a foundation for the future development of Cd metal batteries, offering profound insights and guidance for advancing aqueous energy storage technology.

Intervalence Charge Transfer and Exothermic and Isoenergetic Symmetry Breaking Charge Separation in Far-Red Capturing Zinc Phthalocyanine Dimers.

Orientation and distance-dependent intervalence charge transfer phenomenon is demonstrated in far-red capturing zinc phthalocyanine dimers connected by a bis-acetylene-phenyl π-spacer (ortho, meta, or para positions) upon oxidizing one of the phthalocyanine rings, resulting in split oxidation waves and a new optical transition in the near-infrared region. Optical studies initially probed the symmetry-breaking charge separation events in these dimers wherein solvent polarity-dependent quenching was witnessed. Interestingly, efficient quenching in nonpolar toluene was also seen for the ortho-dimer. Free-energy calculations supported symmetry-breaking charge separation in polar solvents and the ortho-dimer even in nonpolar solvents under isoenergetic (endothermic by ~40 mV) conditions. Molecular electrostatic potential maps generated on DFT-optimized structures revealed quadrupolar charge transfer states, more so in polar media. The time-dependent DFT calculations revealed the conversion of the quadrupolar charge transfer states to bipolar charge-separated states from different singlet-singlet excitations. Femtosecond transient absorption studies covering broad temporal and spatial scales provided evidence for the charge separation process, including that for the ortho-dimer in toluene, where an isoenergetic process was predicted. The charge-separated states lasted for 200-500 ps depending upon dimer linkage. These unprecedented findings reveal the potential applications of the investigated phthalocyanine dimers in energy harvesting, photocatalytic, and pertinent optoelectronic applications.

Selective reagent ion – time-of-flight – mass spectrometric studies of cocaine: investigations of charge and proton transfer reaction processes**We dedicate this paper to Professor Tilmann Märk on the occasion of his 80th birthday.

Abstract Investigations are reported for the reactions of H3O+.(H2O)n (n = 0 and 1), NO+ and O2+• with cocaine (C17H21NO4) using a Selective Reagent Ion-Time-of-Flight-Mass Spectrometer (SRI-ToF-MS) covering a range of DC reduced electric field values (from approximately 60 Td up to about 230 Td), with the electric field strength being determined from the total DC voltage drop across the drift tube. In addition to examining the influence of the reduced electric field value on the reagent ion-cocaine product ion types and distributions, the effects of applying a radio frequency (RF) electric field in the ion funnel region of the drift tube are also reported. Observed reaction pathways without (DC mode) and with (DC + RF mode) the ion funnel operating include non-dissociative and dissociative proton transfer for the reactions involving H3O+.(H2O)n (n = 0 and 1), and non-dissociative and dissociative charge transfer for the reactions involving NO+ and O2+•. Although the dissociative proton transfer pathways leading to product ions with m/z values of 272.129 (C16H18NO3+), 182.118 (C10H16NO2+) and 123045 (C7H7O2+) are highly exoergic, as determined from density functional theory calculations, non-dissociative proton transfer dominates resulting in C17H21NO4.H+ at m/z 304.155. The significance of the lack of dissociative proton transfer is discussed. Non dissociative charge transfer, leading to C17H22NO4+ at m/z 303.155, dominates up to DC drift tube electric field strengths of about 80 V/cm, after which the product ion C5H8N+ becomes the dominant product ion. Other product ions resulting from dissociative charge transfer processes that are common to both NO+ and O2+• reactions with cocaine are C10H16NO2+ and C7H5O+ at m/z 182.118 and 105.036, respectively. The reactions with O2+• lead to a fourth observed fragment ion at m/z 272.129 corresponding to C16H18NO3+.

A multifaceted approach to novel (E)-3-(4-bromobenzylidene)-1,8-naphthyridine-2,4(1H,3H)-dione: synthesis, biological screening, DFT and molecular docking studies

A novel (E)-3-(4-bromobenzylidene)-1,8-naphthyridine-2,4(1H,3H)-dione derivative was synthesized and evaluated for its anticancer potential. The chemical formula and structure of the synthesized derivative was obtained using different spectroscopic techniques. Molecular structure optimization of the synthesized compound was performed using B3LYP/6–311++G (d,p) level of theory. The UV–Vis spectrum showed strong charge transfer transitions (π–π*) with high extinction coefficient (0.9869). The NBO analysis showed orbital overlap between π (C2-N11) and π*(C3-C4) due to the intramolecular charge transfer. The first hyperpolarizability (β0) was found to be 47.074 × 10−30esu, showed that the molecule can be a better option for NLO applications as compared to the standard reference urea. The global reactivity descriptors were also correlated with the biological properties of the compound. The moderate activity against HeLa cell line of the synthesized compound was reflected from its IC50 value (230 μM), QTAIM framework and Reduced Density Gradient were used to describe the nature of various intermolecular interactions and showed two closed-shell interactions (O13 – H18 and O15 – H23) with calculated bond energies of −5.0828 kJ/mol and −6.1495 kJ/mol, respectively. The reactivity sites were identified by mapping the electron density into Molecular Electrostatic Potential (MEP) and indicated that in the molecule the most electrophilic sites are the nitrogen of NH and phenyl ring. Docking studies were performed to examine binding sites of the titled molecule and the total binding energy and inhibition constant of compound were found to be −7.89 Kcal/mol and 1.65 µM exhibiting good binding affinity with the protein HER2 kinase. The bioactivity scores indicated drug-likeness of the synthesized molecule.

Dynamics of vibrationally coupled intersystem crossing in state-of-the-art organic optoelectronic materials

This work investigates intersystem crossing (ISC) induced by spin-orbit coupling (SOC) in state-of-the-art non-fullerene acceptors (NFAs). A quantum chemistry study analyzed SOC in 10 NFAs using the optimized geometry of the ground state (OGGS), revealing the importance of excited-state character (local or charge transfer) in determining SOC. However, ISC rates calculated with Marcus formalism were significantly lower than experimental values, showing that the three-state model (S1, T1, and T2) is insufficient. A simplified method to calculate coupled probabilities was proposed, leveraging a quantum walk on a one-dimensional graph. This approach aligned ISC rates with experimental data and explained Y6’s higher triplet state efficiency compared to ITIC-like NFAs. Further, the dihedral angle (ϕ) in IT-4Cl and Y6 was analyzed. Y6’s unique excited-state potential energy curve (PEC) showed a minimum at ϕ ≈ 90o. Using PECs, ISC rates were refined, showing coupling via ϕ vibrations. Finally, the Wentzel-Kramers-Brillouin (WKB) approximation explained Y6’s photoluminescence at low temperatures, highlighting non-adiabatic phenomena crucial for understanding the photophysics of organic semiconductors. Triplet states act as channels that enhance recombination, reducing the optoelectronic efficiency of semiconductor devices. Therefore, understanding and controlling these states can contribute to improving the efficiency of organic solar cells (OSCs) and organic light-emitting diodes (OLEDs).

Small Twist Angles Accelerate Electron and Hole Transfer in MoSe2/WSe2 Heterostructures.

Van der Waals (vdW) heterostructures host interlayer excitons that act as robust carriers of valley information and sensitive probes of strongly correlated electronic phases. The formation and properties of these interlayer excitons critically depend on efficient charge transfer across the heterointerface. Among the various factors influencing these processes, the twist angle emerges as a key degree of freedom, allowing precise modulation of the stacking configuration and electronic band structure of the heterostructure. In this study, we perform ultrafast pump-probe measurements on MoSe2/WSe2 heterostructures with various twist angles. Counterintuitively, the results show that both electron and hole transfer rates are strongly influenced by twist angles, peaking at 0 and 60° twist angles, respectively. Theoretical calculations indicate that this behavior stems from reduced valley energy offsets and enhanced interlayer hybridization at small twist angles, which collectively promotes more efficient electron and hole transfer. Our findings demonstrate the influence of twist-angle engineering on interfacial carrier dynamics and its impact on the optoelectronic properties of vdW heterostructures.

Interplay of Charge Transfer and Local Triplet States in Donor-Acceptor-Based TADF Compounds.

Donor-acceptor-based thermally activated delayed fluorescence (TADF) emitters have a complicated energy level scheme with multiple singlet and triplet energy levels. Among them, TADF compounds with the lowest-energy charge-transfer triplet state (type III compounds) are especially interesting due to their specific emission properties. We show that type III TADF compounds may show dual phosphorescence at low temperatures as well as weak high-energy emission at room temperature, somewhat resembling the phosphorescence spectrum of the local triplet. Such untypical behavior was demonstrated only in compounds with a low energy gap between the triplet states of different character, imposing efficient communication between them through vibronic coupling.

Viologen Covalent Organic Framework Mediates Near-Infrared Light-Induced Electron Transfer for Catalytic Oxidative Coupling Reactions.

Near-infrared (NIR) light-driven photoreactions are advantageous over visible light-driven ones because NIR photons have lower energy and fewer side reactions, deeper penetration in reaction media, and high abundance in the solar spectrum. However, currently available covalent organic frameworks (COFs) absorb in the UV-vis region and catalyze photoreactions under blue or white light irradiation. Herein, we report a linker-to-linker charge transfer process in a viologen-linked porphyrin COF (Vio-COF), leading to a novel type of hyperporphyrin effect and extending the absorption into the NIR region with an absorption edge at 998 nm. Under NIR irradiation, photoinduced charge separation in Vio-COF generates a viologen radical that efficiently reduces oxygen to form superoxide radicals for catalytic oxidative coupling reactions. The proximity of porphyrin and viologen units within the framework significantly enhances the catalytic performance of Vio-COF, outperforming its homogeneous counterparts in aerobic oxidative amidation and amine coupling reactions. Vio-COF was readily recycled and used in six oxidative coupling reactions.

Trimodal Hierarchical Porous Carbon Nanoplates with Edge Curvature for Faster Mass Transfer and Enhanced Oxygen Reduction.

Although hierarchical porous carbon materials have been widely used for electrocatalysis, the role of curvature in carbon nanostructures during electrochemical reactions remains poorly understood due to a lack of experimental models featuring clearly defined curved geometries and periodic structures. In this study, we fabricate hierarchical porous cobalt- and nitrogen-containing carbon nanoplates with trimodal porosity (macro-, meso-, and micropores) and continuous, homogeneous curved edges (Co/N-CNP-CURV) using a polystyrene-directed templating approach. The Co/N-CNP-CURV catalyst exhibits excellent catalytic activity and stability for the alkaline oxygen reduction reaction, with a half-wave potential of 0.82 V and a minimal potential shift of 8 mV after 5000 cycles. The enhanced electrocatalytic activity is attributed to synergistic combinations of the trimodal porosity, abundant Co-Nx active sites, a high density of curved edges, and graphitic carbon encapsulated with cobalt nanoparticles. Density functional theory calculations reveal that the presence of curvature in Co/N-CNP-CURV is beneficial for enhancing the charge transfer from the catalyst to O2, lowering the adsorption energy of O2, and reducing the activation free energy barrier for the rate-determining step (*O2 + (H+ + e-) → *OOH). The study provides compelling experimental evidence supporting the critical role of the curvature effect in enhancing the electrocatalytic performance of nanoporous metal-containing carbon materials.

Elucidating the Functional Orbital Evolution in Transition Metal-Doped Bi3O4Br Platforms for CO2 Photoreduction.

Frontier orbital hybridization plays a vital role in the initial adsorption and activation process during catalysis. A formidable challenge is the precise determination of active orbitals/sites. Herein, 2D Bi3O4Br nanosheets are adopted as an operable platform for heteroatom doping of various transition metals (Fe, Ni, Zn/Cd). As the atom number of dopants increases, the capability of selective CO2 photoconversion is continuously amplified. The intrinsic nature is the variation of active functional orbital as indicated from band center distance (Δd/p-p) indicators. The calculated charge transfer of various CO2-bound geometries further demonstrates the p-p orbital interaction overwhelms d-p orbital interaction. X-ray photoelectron spectroscopy and X-ray absorption spectroscopy results verify the charged nature of Bi sites with 6p orbitals not fully filled by electrons. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis and Gibbs free energy change profile suggest the rapid emergence of the critical *COOH intermediate in a thermodynamically preferred pathway.

Probing structural defects and X-ray induced persistent luminescence mechanisms on rare earth-doped strontium sulfide materials.

Persistent luminescence is related to the existence of point defects in the crystal structure, which can be induced by the insertion of dopant ions to create trap levels for charge carriers. Strontium sulfide (SrS) is a promising host for X-ray activated phosphors due to its high luminescence yield and X-ray absorption efficiency. While the mechanisms of UV- and visible light-induced luminescence in rare-earth doped SrS have been previously explored, this work focuses on understanding X-ray induced mechanisms using synchrotron radiation techniques. Extended X-ray absorption fine structure (EXAFS) analysis suggested that rare-earth ions incorporate into the SrS lattice primarily as substitutional defects, with structural distortions depending on the differences in ionic radii between Sr2+ and RE2+/3+. X-ray absorption near edge structure (XANES) spectra revealed the mixed-valence nature of Ce in SrS:Ce and SrS:Eu,Ce materials, and also that X-ray irradiation triggers complex charge transfer processes. The X-ray excited optical luminescence (XEOL) results showed that co-doped samples exhibited longer persistent luminescence decay times than their single-doped counterparts due to the increased number of defects. These findings provide new insights into the interplay between crystal defects and persistent luminescence in X-ray-activated phosphors, contributing to the design of more efficient materials for applications such as medical imaging, optical information storage, and industrial sensing.

Ti-MXene/α-Ni(OH)2 nanostructures as high performance electrocatalyst for oxygen evolution reaction.

Herein, the strategy of homogenous inclusion of nanoparticles within the surface and interlayers of 2D MXenes was established to achieve effective OER performance. A greater quantity of ~6 nm sized Ni(OH)2 particles uniformly anchored on multi-layered accordion-like nanosheets of Ti3C2Tx. The strong interconnection of Ni(OH)2 on Ti3C2Tx promoting synergistic effects and improves electron transfer properties alongside the intrinsic OER activity. The Ti3C2Tx-Ni(OH)2-4 demonstrated remarkable OER activity by exhibiting a lower overpotential (235.54 mV at 10 mA/cm2) in alkaline conditions. Increased ECSA (2.925 mF cm-2), lower charge transfer resistance, lowering the reaction barrier and stabilizing/converting essential intermediates via the Ti3C2Tx-Ni(OH)2 electrocatalyst synergistically improve OER activity. The effective interaction between Ti3C2Tx and Ni(OH)2 in Ti3C2Tx-Ni(OH)2 improves stability during long-term operations. Moreover, a Ti3C2Tx-Ni(OH)2-4||Pt/C cell has 1.7V at 10 mA/cm2. It could be deduced that the usage of Ni(OH)2 as an electrocatalyst together with Ti3C2Tx can provide noteworthy water splitting properties.

Molecular tunnel junctions based on mixed SAMs: exponential correlation of the average metal-HOMO coupling with SAM/metal work function.

We report the transport characteristics of molecular tunnel junctions based on binary mixed self-assembled monolayers (SAMs) of aromatic molecules using the conducting probe atomic force microscopy platform. The molecules include terphenyl dithiol and two derivatives, 2',3',5',6'-tetrafluoroterphenyl dithiol and 4,4'-(bicyclo[2.2.2]octane-1,4-diyl)dibenzenethiol, whose junction conductances differ from terphenyl dithiol by factors of 10 and 100, respectively. The junction conductance G varies exponentially with binary SAM composition, not linearly, as might be expected. By employing an analytical model for the off-resonant current-voltage (I-V) behavior, we extract the average electronic density of state parameters for junctions with Au tip and substrate contacts as a function of binary SAM composition. The average HOMO to Fermi level offset εh is weakly dependent on SAM composition, reflecting commonly observed HOMO level pinning. In stark contrast, and in correspondence with the conductance results, the average metal-HOMO coupling Γ depends exponentially on composition, not linearly as simple composition-based averaging predicts. On the other hand, Kelvin probe measurements of binary mixed SAM-metal work functions reveal that work function (or work function change ΔΦ) varies linearly with SAM composition; it is a simple sum of the single component SAM work functions weighted by their relative surface coverages. Thus, G and Γ are both exponentially correlated with ΔΦ; variation of ΔΦ by 360 meV (∼7%) tunes G by >100× and Γ by a factor of 10, with smaller work functions (and larger ΔΦ values) leading to larger G and Γ values. Qualitatively, a correlation between Γ and ΔΦ, which both reflect interfacial charge transfer, appears reasonable, but a fundamental understanding requires a first principles model that can also account for the simultaneous pinning of εh.

Exploring the Mechanisms of Charge Transfer and Identifying Active Sites in the Hydrogen Evolution Reaction Using Hollow C@MoS2-Au@CdS Nanostructures as Photocatalysts.

Plasmonic metal-semiconductor nanocomposites are promising candidates for considerably enhancing the solar-to-hydrogen conversion efficiency of semiconductor-based photocatalysts across the entire solar spectrum. However, the underlying enhancement mechanism remains unclear, and the overall efficiency is still low. Herein, a hollow C@MoS2-Au@CdS nanocomposite photocatalyst is developed to achieve improved photocatalytic hydrogen evolution reaction (HER) across a broad spectral range. Transient absorption spectroscopy experiments and electromagnetic field simulations demonstrate that compared to the treated sample, the untreated sample exhibits a high density of sulfur vacancies. Consequently, under near-field enhancement, photogenerated electrons from CdS and hot electrons generated by intra-band or inter-band transitions of Au nanoparticles are efficiently transferred to the CdS surface, thus significantly improving the HER activity of CdS. Additionally, in situ, Raman spectroscopy provided spectral evidence of S─H intermediate species on the CdS surface during the HER process, which is verified through isotope experiments. Density functional theory simulations identify sulfur atoms in CdS as the catalytic active sites for HER. These findings enhance the understanding of charge transfer mechanisms and HER pathways, offering valuable insights for the design of plasmonic photocatalysts with enhanced efficiency.

10% Conversion of Imine into Thiazole in Covalent Organic Frameworks for Efficient Photocatalytic H2O2 Generation

AbstractThe 5–10 nm exciton diffusion distance for most organic semiconductors is much less than the particle size of 2D covalent organic frameworks (COFs). As a result, the local structure change in a small domain of COFs, rather than the whole particles, could effectively promote the charge transfer for photocatalysis. Herein, three‐component condensation is used to preparing four mixed imine‐ and thiazole‐linked donor‐acceptor (D–A) COFs. In contrast to four 100% imine COFs, four mixed ca. 90% imine‐ and 10% thiazole‐linked materials have 77–95% higher photocatalytic hydrogen peroxide (H2O2) production rate in pure water and O2 due to the more prolonged lifetime for excitation state. In particular, USTB‐10‐S exhibits the H2O2 generation rate to 5041 µmol g−1 h−1. Coupling with benzyl alcohol as sacrificial reagent, its H2O2 production rate is further increased to 16152 µmol g−1 h−1, much superior to most COF‐based photocatalysts. This work illustrates the proof‐of‐concept that the local structure change of COFs in a tiny amount is able to significantly enhance the charge separation and thus the photocatalytic performance, inspiring the development of defect engineering in the field of COFs.

Merging Heterogeneous Graphitic Carbon Nitride Photocatalysis with Cobaloxime Catalysis in Uphill Dehydrogenative Synthesis of Anilines.

Synthesis of substituted anilines upon nucleophilic addition of secondary amines to cyclohexanone derivatives followed by aromatization of the enamine by employing a combination of Ir-polypyridine complex as a photoredox catalyst and cobaloxime as H2-evolution catalyst was developed recently by Leonori et al. In this work, we replace homogeneous photoredox catalyst by heterogeneous mesoporous graphitic carbon nitride (mpg-CN) that is free of rare elements. Substituted aromatic amine and H2 are formed simultaneously. Combination of X-Ray spectroscopies revealed charge transfer from cobaloxime to mpg-CN in the dark. Illumination of the catalytic system with visible light induces electron transfer from mpg-CN to cobaloxime and formation of persistent Co(II) species. The results of DFT modelling suggest that the studied reaction is strongly endothermic and endergonic. Thus, energy of photons is stored in the reaction products - H2 and the aromatic amine.