Radical Cation Research Articles

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Ultramarine blue containing paint layers: Further study of the photo-catalytic degradation of binding media

Photo-catalytic degradation of a linseed oil binder by natural ultramarine (Lapis Lazuli or Lazurite) and Sodalite in paint layers was studied. Both pigments degrade the binder under xenon arc exposure, leading to erosion of the binder at the surface, increased roughness, light scattering and desaturation of the color. Both pigments behave similarly to synthetic ultramarine blue studied earlier. The results for Sodalite provide further proof that the zeolitic nature of the aluminosilicate cage causes the catalytic degradation and that the enclathrated polysulfur radical anions S2-. and S3-. trapped inside the cage are not responsible for the catalytic action. Relatively stable synthetic binders are less affected by the presence of synthetic ultramarine blue. The paints were aged in a xenon arc apparatus using a simulated indoor environment (radiation > ca. 320 nm). The samples were analyzed using diffuse reflectance spectroscopy in the UV–vis and short wavelength infrared (SWIR) ranges, Raman spectroscopy, field-emission gun scanning electron microscopy (FEG-SEM) and FTIR.

Structural characteristics of Lacticaseibacillus rhamnosus ACS5 exopolysaccharide in association with its antioxidant and antidiabetic activity in vitro

A novel structure of exopolysaccharide from the Lactic Acid Bacteria (LAB) Lacticaseibacillus rhamnosus ACS5, isolated from home-made Turkish cheese, is described. After lyophilization, the L-EPS-ACS5 was characterized in production and functional activities in vitro, including antioxidant and antidiabetic activities. The physicochemical characterizations of the L-EPS-ACS5 were determined through molecular weight, UV, FTIR, SEM, TGA, HPLC, NMR, methylation, and GC–MS analysis. Strong antioxidant activities of L-EPS-ACS5 were confirmed from the results obtained in the hydroxyl radical, DPPH, ABTS, FRAP, superoxide anion radical, total antioxidant activity, and DNA damage protective effect, and also the L-EPS-ACS5 exhibited high antidiabetic activity (60 %). This study isolated L-EPS-ACS5 from a home-made cheese L. rhamnosus strain, demonstrating its novel and enhanced functionalities compared to existing strains. This opens exciting avenues for its development in the fields of biomedicine and pharmaceuticals.

Electron-deficient Indenofluorene-based Systems: Multicolor and Visible-to-near-infrared (NIR) Electrochromism and OFF-OFF-ON Electrofluorochromism.

Here, we report the synthesis and multi-functional electrochromic behaviour (multi-colour modulation, visible-to-near IR absorption switching, and electrofluorochromism) of electron-deficient indenofluorene-based systems. The compounds (IF1-IF5) have been obtained via Knoevenagel condensation of indenofluorenone (IFK) with various nucleophiles (malononitrile, benzylcyanide, dimethyl malonate, methyl cyanoacetate, benzothiazole-2-acetonitrile). IF1-IF5 possess strong colours and absorb in the visible region (λmax = 295-388 nm). These compounds are electroactive and exhibit two reversible reduction waves (-0.35 ̶ -0.88 V and -0.65 ̶ -1.30V vs Ag/AgCl), generating radical anion and dianion systems. For the electrochromic studies, upon applying the one-electron reduction potential (-0.35 V vs Ag/AgCl), the absorption maximum of IF1 redshift from 382 nm to 1240 nm (IF1-•), which subsequently blueshifts to 466 & 745 nm (IF12-•) upon increasing to two-electron reduction potential (-0.65 V vs Ag/AgCl). The color of the solution was switched from green to dark blue and further to light orange. The electrochromic behaviour is highly reversible and cycling. In addition, unlike the non-fluorescent (IF1 and IF1-•), the two-electron reduced system (IF12-•) is red-emissive (λem = 630 nm) due to the combination of radicals leading to the formation of antiaromatic quinoidal π-conjugated system (IF12-).

Taming CO2•- via Synergistic Triple Catalysis in Anti-Markovnikov Hydrocarboxylation of Alkenes.

The direct utilization of carbon dioxide as an ideal one-carbon source in value-added chemical synthesis has garnered significant attention from the standpoint of global sustainability. In this regard, the photo/electrochemical reduction of CO2 into useful fuels and chemical feedstocks could offer a great promise for the transition to a carbon-neutral economy. However, challenges in product selectivity continue to limit the practical application of these systems. A robust and general method for the conversion of CO2 to the polarity-reversed carbon dioxide radical anion, a C1 synthon, is critical for the successful valorization of CO2 to selective carboxylation reactions. We demonstrate herein a hydride and hydrogen atom transfer synergy driven general catalytic platform involving CO2•- for highly selective anti-Markovnikov hydrocarboxylation of alkenes via triple photoredox, hydride, and hydrogen atom transfer catalysis. Mechanistic studies suggest that the synergistic operation of the triple catalytic cycle ensures a low-steady-state concentration of CO2•- in the reaction medium. This method using a renewable light energy source is mild, robust, selective, and capable of accommodating a wide range of activated and unactivated alkenes. The highly selective nature of the transformation has been revealed through the synthesis of hydrocarboxylic acids from the substrates bearing a hydrogen atom available for intramolecular 1,n-HAT process as well as diastereoselective synthesis. This technology represents a general strategy for the merger of in situ formate generation with a synergistic photoredox and HAA catalytic cycle to provide CO2•- for selective chemical transformations.

Bioinspired Photothermal Metal-Organic Framework Cocrystal with Ultra-Fast Water Transporting Channels for Solar-Driven Interfacial Water Evaporation.

Herein, a bioinspired metal-organic framework (MOF) cocrystal produced from the co-assembly of a MOF [Ni3(hexaiminobenzene)2, Ni3(HIB)2] and p-chloranils (CHLs) is reported. Because of the 2D conjugation nature and the formation of persistent anion radicals, this cocrystal shows an excellent photothermal property, and is further used as an absorber in solar-driven interfacial water evaporation. The solar-driven interfacial water evaporation rate (4.04 kg m-2 h-1) is among the best compared with those of previously reported photothermal materials. Molecular dynamics simulation results suggested that the rotating of the CHL molecules relative to the MOF planes tuned the pore size to enable the ultra-fast water transporting, and thus ultra-high water transporting rates (1.11 × 1011 and 3.21 × 1011 H2O s-1 channel-1 at 298.2 and 323.0 K, respectively) for layered cocrystal structures, that are much higher than that of aquaporins (≈1.1 × 1010 H2O s-1 channel-1 at 298.2 K), are observed. The superior solar-driven water evaporation performance is thus attributed to the synergistic effect of the ultra-fast water transporting pores together with the excellent photothermal property of the cocrystal. This research provided a biomimetic strategy of rational design and production of charge transfer cocrystals to modulate their pores and photothermal properties for solar-driven interfacial water evaporation.

Utilizing Zn(Cu/Cr)Al-Layered Double Hydroxide-Based Photocatalysts for Effective Photodegradation of Environmental Pollutants

Layered double hydroxides (LDHs) and their derived mixed oxides are emerging as a promising class of biocompatible inorganic lamellar nanomaterials. The detailed structure and textural characteristics of the synthesized LDH-based materials were examined using X-ray diffraction, Fourier transform infrared spectroscopy, and N2 adsorption/desorption isotherm. This study explored the removal efficiency of pharmaceutical tolperisone hydrochloride (TLP), as well as the herbicides quinmerac (QUI) and clomazone (CLO) from water, using dried and calcined LDH-based photocatalysts under simulated solar irradiation and UV irradiation. A higher removal efficiency was observed using UV irradiation, for all substrates. The most effective removal was achieved using ZnAl photocatalysts thermally treated at 100 °C (ZnAl 100) and 500 °C (ZnAl 500). The highest removal rates were observed in the TLP/ZnAl 100 and QUI/ZnAl 100 systems, achieving ~79% and ~86% removal after 75 min of treatment under UV. In contrast, the CLO/ZnAl 100 and CLO/ZnAl 500 systems achieved ~47% removal of CLO. Furthermore, this study investigated the role of reactive species to elucidate the mechanisms of photodegradation under UV. It was found that in the degradation of TLP and QUI in the presence of ZnAl 100 and ZnAl 500, the superoxide anion radical played the most important role.

Possibility of identifying 1H-indolylaminium trifluoroacetates with antimicrobial activity by mass spectrometry

The present study proposes a convenient approach to identify a series of novel substituted 1H-indol-5-,6-ylaminium trifluoroacetates with antimicrobial activity based on mass spectral data obtained using direct injection into an ion source at an elevated temperature when the salts decompose with the release of counterions: acids and organic bases – substituted 1H-indolylamines. By the presence of ions with m/z 69, 45, 28, 17 in the spectra, it is judged that the salts are formed by trifluoroacetic acid. Using the available literature data on the mass spectrometry of substituted indoles, aromatic amines, and carboxylic acids, substantiated schemes for the decomposition of molecular ions of organic bases, 1H-indolylamines, are compiled and discussed, in which the mechanism of formation and the structure of fragment ions arising under electron ionization conditions are given. The revealed general, as well as individual for individual representatives with a certain character and place of substitution in the indole bicycle, patterns of behavior of 1H-indolylamine radical ions under conditions of high-temperature mass spectral imaging make it possible to judge their structure and, in general, the structure of 1H-indolylamine trifluoroacetates. The approach used in this work can also be used to prove compounds of a similar group based on the analysis of their mass spectra.

Synthesis of Dibenzoazulene Derivatives via Pd‐Catalyzed (3+2) Alkyne Annulation of Dibenzosuberenone

AbstractNon‐benzenoid PAHs with pentagon/heptagon pairs have unique electronic structures and promising opto‐electronic properties. However, the construction of pentagon/heptagon pair units in these PAHs is challenging. Herein, we developed a Pd‐catalyzed (3+2) alkyne annulation reaction of heptagons, and constructed heptagon/pentagon pairs. The substrate scope is wide and the yield is good to moderate. A series of dibenzoauzlene derivatives were synthesized and their opto‐electronic properties were systematically studied by UV‐vis absorption and cyclic voltammetry. In addition, the dibenzoazulene derivative was further transformed to tropylium cation and tropyl radical, which showed bathochromic shifted absorption and switched aromaticity.

Asymmetric Counteranion‐Directed Electrocatalysis for Enantioselective Control of Radical Cation

AbstractThe control of enantioselectivity in radical cation reactions presents long‐standing challenges, despite a few successful examples. We introduce a novel strategy of asymmetric counteranion‐directed electrocatalysis to address enantioselectivity in radical cation chemistry. This concept has been successfully demonstrated in two reactions: an asymmetric dehydrogenative indole‐phenol [3+2] coupling and an atroposelective C−H/N−H dehydrogenative coupling. These reactions have enabled the synthesis of benzofuroindolines and C−N axially chiral indoles with high yields and excellent enantiomeric excesses. Detailed mechanistic studies confirmed a radical‐radical coupling mechanism. Moreover, density functional theory (DFT) calculations supported the indole radical cation as the pivotal intermediate, rather than a neutral indolyl radical, shedding new light on the underlying processes driving these reactions.

Probing the Molecular Interactions of Electrochemically Reduced Vitamin B2 with CO2.

The electrochemical reduction of riboflavin (vitamin B2) in a dimethyl sulfoxide solvent was examined under a CO2 atmosphere and compared with results under an argon atmosphere. Variable-scan-rate cyclic voltammetry combined with controlled potential electrolysis (CPE) and analysis by UV-vis and EPR spectroscopies provided insights into the nature of interactions of reduced flavins with dissolved CO2. Reductive exhaustive CPE experiments under CO2 indicated an overall two-electron stoichiometry, compared to one-electron reduction under an argon atmosphere, due to the lowering of the formal one-electron reduction potential of the flavin radical anion to form the dianion, which can be rationalized by riboflavin-CO2 molecular interactions. UV-vis spectroscopic measurements confirmed complete chemical reversibility of the redox transformations over extended time scales. Digital simulation modeling of the voltammetric data enabled extraction of thermodynamic and kinetic parameters for the proposed mechanism, comprising multiple proton-coupled electron transfer steps, diamagnetic anions, radical anions, and neutral radical intermediates enroute to the fully reduced state, as well as evidence of a long-lived solution phase complex of the reduced riboflavin with CO2.

The Photodynamic Agent Designed by Involvement of Hydrogen Atom Transferfor Enhancing Photodynamic Therapy.

Although Type-I photodynamic therapy has attracted increasingly growing interest due to its reduced dependence on oxygen, the design of effective Type-I photosensitizers remains a challenge. In this work, we report a design strategy for Type-I photosensitizers by the involvement of hydrogen atom transfer (HAT). As a proof of concept, a HAT-involved Type-I PS, which simultaneously generates superoxide and carbon-centered radicals under light-irradiation, was synthesized. This photosensitizer is comprised of a fluorene-substituted BODIPY unit as an electron acceptor covalently linked with a triphenylamine moiety as an electron donor. Under light-irradiation, photo-induced intramolecular electron transfer occurs to generate the BODIPY anion radical and triphenylamine cation radical. The former transfers electrons to oxygen to generate O2-•, while the latter loses a proton to produce a benzyl carbon-centered radical which is well characterized. The resulting carbon-centered radicals efficiently oxidize NADH by HAT reaction. This photosensitizer demonstrates remarkable photocytotoxicity even under hypoxic conditions, along with outstanding in vivo antitumor efficacy in mouse models bearing HeLa tumors. This work offers a novel strategy for the design of Type-I photosensitizers by involvement of HAT.

Experimental Characterization of the Isomer-Selective Generation of the Astrochemically Relevant Hydroxymethylene Radical Cation (HCOH•+/DCOH•+).

Interest in the observation and characterization of organic isomers in astronomical environments has grown rapidly with an increase in the sensitivity of detection techniques. Accurate modeling and interpretation of these environments require experimental isomer-specific reactivity and spectroscopic measurements. Given the abundance of formaldehyde (H2CO) in various astrophysical objects, the properties and reactivities of its cation isomers H2CO•+ and HCOH•+ are of significant interest. However, for the hydroxymethylene radical cation HCOH•+ (and its isotopologue DCOH•+), detailed reactivity studies have been limited by the lack of suitable experimental methods to generate this isomer with high purity. Here, potential approaches to the isomer-selective generation of HCOH•+ and DCOH•+ are characterized through differential reactivity measurements. While the dissociative photoionization of cyclopropanol (c-CH2CH2CHOH) is determined to be unsuitable, the dissociation of methanol-d3 (CD3OH) allows for the formation of DCOH•+ with a fractional abundance of >99% at photon energies below 14.8 eV. These results will allow future spectroscopic and reactivity measurements of HCOH•+/DCOH•+ to be conducted, laying the groundwork for future detection and incorporation into models of the interstellar medium.

Improved Charge‐Transfer Doping in Crystalline Polymer for Efficient and Stable Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs) have significant potential for next‐generation photovoltaic technology applications. However, the instability of hole transport layers (HTLs) becomes the major obstacle to long‐term operational devices, which are affected by the intrinsic thermal instability and loose structure of hole transport materials, as well as the hygroscopicity and migration of dopants. Here, poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) is used as a model crystalline polymer to thoroughly investigate effective p‐type doping strategies and the underlying mechanism. According to Hard–Soft‐Acid–Base theory, the soft base P3HT is more likely to form a stable Lewis acid–base adduct with the reactive soft acid radical, resulting in a strong charge‐transfer interaction, thereby enhancing conductivity and regulating the energy band of the HTL. Meanwhile, the radical cation salt can promote pre‐nucleation to optimize the crystallization orientation of P3HT. The resulting PSCs exhibited the efficiency of 25.16%, which is the highest efficiency reported so far based on doped P3HT. In addition, the resulting devices demonstrated excellent stability, maintaining 96.5%, 96%, and 91% of their initial efficiency after aging under continuous illumination for 2028 h, at 85 °C for 1080 h, and at maximum power point (MPP) tracking under continuous 1 Sun illumination at 85 °C for 528 h, respectively.

Infrared Spectroscopy of CH5+ Cations in Helium Nanodroplets.

The methanium CH5+ is a prototypical fluxional ion whose infrared spectra remain unassigned. Here we report on the infrared spectra of CH5+ cations and its deuterated isotopomer, CH4D+, in helium droplets at a low temperature of 0.38 K. The ions were produced upon protonation of CH4 molecules, a technique that was developed in this work. The spectra of CH5+ around 3000 cm-1 show two strong and broad infrared bands and a weak shoulder, reflecting its highly fluxional nature. The spectrum of CH4D+ shows a much sharper infrared band, indicating a partial quenching of the exchange of H/D atoms. This work also reports on the infrared spectrum of the methane dimer radical cations (CH4)2+.

A Structural and Functional Mimic of P680+

One or multiple chlorophyll molecules are employed in the reaction center of photosystem II's main electron donor (defined as P680). We have a poor understanding of how the reaction center facilitates water oxidation and the roles that mono‐ and/or multimeric chlorophyll groups play when P680 oxidizes a neighboring tyrosine in order to drive water oxidation at the oxygen evolving complex. We have prepared a dimeric MgII‐porphyrin complex [Mg2(BTPP)] (1, H4‐BTPP = 1,2‐bis‐(10,15,20‐triphenylporphyrin‐5‐yl)‐benzene) as a structural and functional mimic of the dimeric core of P680. 1 was oxidized by one‐electron to the corresponding π‐cation radical complex 2. The radical cation was characterized by UV‐Vis‐NIR, FT‐IR, and EPR spectroscopic techniques. 2 was shown to be reactive towards phenols to give the corresponding phenoxyl radicals, mimicking the reactivity of the P680 cation radical which oxidizes tyrosine to tyrosyl radical. Critically, the dimeric π‐cation radical showed markedly higher rates of proton coupled electron transfer oxidation (PCET) of phenols when compared to its monomeric counterpart [Mg(TPP)] (TPP = 5,10,15,20‐tetraphenylporphyrin). Our findings demonstrate that MgII‐porphyrin complexes are reliable mimics of photosynthetic PCET processes and suggest that photosynthetic reaction centers with multiple π‐conjugated complexes likely lower the barrier to PCET oxidation by π‐cation radical species.

A Structural and Functional Mimic of P680.

One or multiple chlorophyll molecules are employed in the reaction center of photosystem II's main electron donor (defined as P680). We have a poor understanding of how the reaction center facilitates water oxidation and the roles that mono- and/or multimeric chlorophyll groups play when P680 oxidizes a neighboring tyrosine in order to drive water oxidation at the oxygen evolving complex. We have prepared a dimeric MgII-porphyrin complex [Mg2(BTPP)] (1, H4-BTPP = 1,2-bis-(10,15,20-triphenylporphyrin-5-yl)-benzene) as a structural and functional mimic of the dimeric core of P680. 1 was oxidized by one-electron to the corresponding π-cation radical complex 2. The radical cation was characterized by UV-Vis-NIR, FT-IR, and EPR spectroscopic techniques. 2 was shown to be reactive towards phenols to give the corresponding phenoxyl radicals, mimicking the reactivity of the P680 cation radical which oxidizes tyrosine to tyrosyl radical. Critically, the dimeric π-cation radical showed markedly higher rates of proton coupled electron transfer oxidation (PCET) of phenols when compared to its monomeric counterpart [Mg(TPP)] (TPP = 5,10,15,20-tetraphenylporphyrin). Our findings demonstrate that MgII-porphyrin complexes are reliable mimics of photosynthetic PCET processes and suggest that photosynthetic reaction centers with multiple π-conjugated complexes likely lower the barrier to PCET oxidation by π-cation radical species.

Antioxidant effect and inhibitory effect on nitric oxide production of sea mustard fractions from Busan, Korea

We investigated the chemical characteristics and nitric oxide (NO) production and antioxidant effects of sea mustard (Undaria pinnatifida) fractions obtained from Taejongdae in Busan, Korea. Dried sea mustard was extracted using different solvents, and antioxidant effects was evaluated based on the radical scavenging and DNA oxidation assays and the effect on reactive oxygen species (ROS) production. Total phenolic content was significantly higher in the 85% aq. MeOH fraction than that in the other factions. The 85% aq. MeOH fraction was more effective in scavenging free radicals than other fractions, as assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2.2'-azino-bis (3-ethylbenothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS) assays (P<0.05). All sea mustard fractions decreased H2O2-induced cellular ROS production compared to the control (P<0.05), however, the 85% aq. MeOH fraction exhibited the greatest inhibitory effect on ROS production among all fractions. Moreover, the 85% aq. MeOH fraction significantly inhibited genomic DNA oxidation. In addition, we measured NO levels to determine the potential anti-inflammatory effects of fractions from sea mustard and observed the highest level of activity in case of the 85% aq. MeOH fraction. These results indicated that the antioxidant effects of sea mustard are associated with its higher phenol content. This study proposes that processed food products supplemented with sea mustard can be developed into functional foods to promote the health of the local populations.

Nickel Bis(dithiolene) Complexes and Tetrathiafulvalenes from Sterically Hindered Di‐ and Tetra‐substituted Dithiine‐dithiolo‐thione Precursors

Three variants of 5,6‐dihydro‐1,4‐dithiin‐2,3‐(1’,3’‐dithiole‐2’‐thione) (dddt) bearing up to four substituents on the ethylene bridge have been obtained by hetero‐Diels‐Alder reaction. The substituted dddt derivatives have the advantage of providing modulation of the steric hindrance and stereogenic centres, and represent valuable intermediates for both tetrathiafulvalene (TTF) and metal‐dithiolene complexes. Within this work, disubstituted and tetrasubstituted dddt derivatives have been used for the synthesis of Ni(II) monoanionic and neutral complexes, as well as for tetra‐ and octa‐methylated EDT‐TTF and BEDT‐TTF (EDT = ethylenedithio, BEDT = bis(ethylenedithio)) derivatives. While the influence of the bulkiness and number of the substituents is observed in the solid state packing of both types of materials (complexes and TTF), the absence of the counterion in the case of the neutral complexes translated into increased intermolecular interactions between the donors and the formation of 1D and 2D layers. The two examples of tetrasubstituted TTF radical cation salts reported in here show semiconducting behaviour due to the formation of dimers and lateral interactions through the S atoms. Our findings highlight the importance of substitution on these type of dddt precursors and their potential for electroactive molecular materials.

Photocatalytic generation of alkyl carbanions from aryl alkenes

AbstractOrganometallic reagents are routinely used as fundamental building blocks in organic chemistry to rapidly diversify molecular fragments via carbanion intermediates. However, the catalytic generation of carbanion equivalents, particularly from sp3-hybridized alkyl scaffolds, remains an underdeveloped goal in chemical synthesis. Here we disclose an approach for the generation of alkyl carbanions via single-electron reduction of aryl alkenes, enabled by multi-photon photoredox catalysis. We demonstrate that photocatalytically induced alkyl carbanions engage in intermolecular C–C bond-forming reactions with carbonyl electrophiles. Central to this method is the controlled formation of an alkene distonic radical anion intermediate that undergoes nucleophilic addition, followed by a kinetically favoured reductive polar crossover to produce a second carbanion available for further diversification. The versatility of this protocol was illustrated by the development of four distinct intermolecular C–C bond-forming reactions with aromatic alkenes (hydroalkoxylation, hydroamidation, aminoalkylation and carboxyaminoalkylation) to generate a range of valuable and complex scaffolds.