Transfer Step Research Articles

Epitaxial Growth of 1D Te/2D MoSe2 Mixed‐Dimensional Heterostructures for High‐Efficient Self‐Powered Photodetector

AbstractMixed‐dimensional heterostructures provide additional freedom to construct diverse functional electronic and optoelectronic devices, gaining significant interest. Herein, highly‐aligned pseudo‐1D tellurium is epitaxially grown on 2D monolayer transition metal dichalcogenides (TMDs), including MoSe2, MoS2, and WS2. A one‐pot chemical vapor deposition (CVD) technique eliminates the normally required transfer steps, thereby producing mixed‐dimensional heterostructures with an ultraclean interface. The controllable epitaxial growth of Te/TMD heterostructures are verified by Raman, scanning probe microscopy (SPM), and transmission electron microscopy (TEM) observation. The photoluminescence results indicate that the emission from TMDs is quenched in the heterostructure, confirming the efficient transfer of photogenerated carriers from TMDs to Te. Additionally, the mixed‐dimensional p‐n Te/MoSe2 heterojunction photodetector presents self‐driven behavior with high responsivity (328 mA W−1), external quantum efficiency (79%), and specific detectivity (8.2 × 109 Jones). The modified facile synthesis strategy and proposed growth mechanism in this study shed light on synthesizing mixed‐dimensional heterojunctions. This opens avenues for fabricating functional devices with reduced sizes and high densities, further enabling miniaturization and integration opportunities.

Copper(I) Complexes of Amide Functionalized Bisphosphine: Proximity Enhanced Metal-Ligand Cooperativity and Its Catalytic Advantage in C(sp3)-H Bond Activation of Unactivated Cycloalkanes in Dehydrogenative Carboxylation Reactions.

The reactions of amide functionalized bisphosphine, o-Ph2PC6H4C-(O)N(H)C6H4PPh2-o (1) (BalaHariPhos), with copper salts is described. Treatment of 1 with CuX in a 1:1 molar ratio yielded chelate complexes of the type [CuX{(o-Ph2PC6H4C(O)N(H)C6H4PPh2-o)}-κ2-P,P] (X = Cl, 2; Br, 3; and I, 4), which on subsequent treatment with KOtBu resulted in a dimeric complex [Cu(o-Ph2PC6H4C(O)(N)C6H4PPh2-o)]2 (5). Interestingly, complexes 2-4 showed weak N-H···Cu interactions. These weak H-bonding interactions are studied in detail both experimentally and computationally. Also, CuI complexes 2-5 were employed in the oxidative dehydrogenative carboxylation (ODC) of unactivated cycloalkanes in the presence of carboxylic acids to form the corresponding allylic esters. Among complexes 2-5, halide-free dimeric CuI complex 5 showed excellent metal-ligand cooperativity in the oxidative dehydrogenative carboxylation (ODC) in the presence of carboxylic acids to form the corresponding allylic esters through C(sp3)-H bond activation of unactivated cycloalkanes. Mechanistic details of the catalytic process were established by isolating the precatalyst [Cu{(o-Ph2PC6H4C(O)(NH)C6H4PPh2-o)-κ2-P,P}(OOCPh)] (6) and fully characterized by mass spectrometry, NMR data, and single-crystal X-ray analysis. Density functional theory-based calculations further provided a quantitative understanding of the energetics of a series of H atom transfer steps occurring in the catalytic cycle.

Nanoporous Substrates to Advance CAR-T Cell Production for Advanced Cell Therapies

Background: CAR-T cell therapy has transformed blood cancer treatment with promising clinical trial outcomes. However, access to this therapy has been limited due lengthy and complex CAR-T cell production process, resulting in a very costly therapy. To enhance patient welfare, establishment of innovative point-of-care solutions with a simplified and shortened manufacturing processes is crucial to ensure higher cell quality and a shorter vein to vein time. immUni technology, a novel nano-engineered substrate will allow to combine and enhance key steps of the CAR-T production - from T cell activation, gene transfer to expansion. immUni platform integrates a unique combination of biochemical and physical stimulation. The biophysical activation is achieved without the need for a TCR agonist, resulting in a striking balance between robust T cell activation and proliferation as well as T cell effector function and a less differentiated phenotype required for CAR-T cell therapy. immUni technology is an easy-to-use platform that minimizes benchwork. Aims: To provide a novel technology to produce optimal CAR-T cell therapies. Methods: Human naïve pan T cells isolated from healthy donors were used for the following experiments. After 24h Il-2 secretion was measured using an ELISA assay and CD69 expression via flowcytometry as a readout for activation. The gene transfer of the CD19-specific 2 nd generation CAR construct was conducted 48 hours after activation, employing both lentiviral transduction and non-viral CRISPR/Cas9 gene editing into the TRAC locus. For T cell culture and expansion, the medium was supplemented with IL-7 and IL-15. CAR expression was measured 6 days post activation. The T cell phenotype was identified and quantified after 10 days of expansion with markers against CD95, CD45RA, CCR7 as well as CD4, CD8 and CD3. Results: For a head-to-head comparison between immUni substrates and established activation methods for CAR-T production, we benchmarked our solely aCD28-antibody coated immUni surface, against Dynabeads TM (Thermo Fisher Scientific) and against aCD3/aCD28 antibodies immobilized on flat surfaces When measuring CD69 expression after activation on immUni substrates, T cells showed high percentages of CD69 expressing cells (>80%) while maintaining lower MFI values compared to the two other activation methods. In contrast, Il-2 secretion was significantly enhanced on immUni substrates (120%, Fig. 1A). Furthermore, we conducted T cell expansion and differentiation experiments, which demonstrated a remarkable 3x higher fold expansion after 10 days when activated on immUni substrates compared to activation via Dynabeads TM. On top of their outstanding effector functions, 80% of the T cells maintain a less differentiated CCR7 positive phenotype (Fig. 1B). This outcome holds great promise for long-term tumor control. To further validate this novel activation method for CAR-T cell production, we measured gene transfer efficiency using lentiviral transduction and non-viral CRISPR/Cas9 gene editing via electroporation. Lentiviral transduction resulted in at least 90% more CD19 CAR-positive CAR-T cells after 6 days post activation (n=2) compared to Dynabeads TM and flat substrates. CRISPR/Cas9 knock-in to the TRAC locus resulted in an improvement of 50% when compared to antibody-coated flat substrates (n=2), holding a great promise in further combining activation and gene transfer steps. Conclusion: Our preliminary data strongly supports the potential of our innovative immUni technology to enhance CAR-T cell production. Comparative studies against Dynabeads TM demonstrate that our technology outperforms current methods with abbreviated T cell activation time, enhanced gene transfer, and robust cytokine production. The accelerated expansion of CAR-T cells, coupled with the retention of a memory-related phenotype, holds great promise for effective tumor eradication, currently under preclinical validation. immUni user-friendly, off-the-shelf product is ready for R&D use in this field. A seamless integration into existing production lines, enhancing accessibility and adoption is currently under development.

Uncovering the Mechanisms of Triplet-Triplet Annihilation Upconversion Enhancement via Plasmonic Nanocavity Tuning.

The nonlinear conversion of photons from lower to higher energy is important for a wide range of applications, from quantum communications and optoelectronics to solar energy conversion and medicine. Triplet-triplet annihilation upconversion (TTA UC), which utilizes an absorber/emitter molecular pair, is a promising tool for upconversion applications requiring low intensity light such as photovoltaics, photocatalysis, and bioimaging. Despite demonstrations of efficient TTA UC in solution, practical applications have proven difficult, as thin films retard the necessary energy transfer steps and result in low emission yields. In this work, TTA UC emission from a thin film is greatly enhanced through integration into plasmonic nanogap cavities consisting of a silver mirror, a nanometer-scale polymer spacer containing a TTA molecular pair, and colloidally synthesized silver nanocubes. Mechanistic studies performed by varying the nanocube side length (45-150 nm) to tune the nanogap cavity resonance paired with simulations reveal absorption rate enhancement to be the primary operative mechanism in overall TTA UC emission enhancement. This absorption enhancement decreases the TTA UC threshold intensity by an order of magnitude and allows TTA UC emission to be excited with light up to 120 nm redder than the usable wavelength range for the control samples. Further, combined nanogap cavities composed of two distinct nanocube sizes result in surfaces which simultaneously enhance the absorption rate and emission rate. These dual-size nanogap cavities result in 45-fold TTA UC emission enhancement. In total, these studies present TTA UC emission enhancement, illustrate how the usable portion of the spectrum can be expanded for a given sensitizer-emitter pair, and develop both mechanistic understanding and design rules for TTA UC emission enhancement by plasmonic nanostructures.

Insight into the island-sea effect of Cu−N−C for enhanced CO2 eletroreduction selectively towards C2H4

The electrochemical reduction of CO2 into C2H4 with a high energy density and added value is a promising and desirable strategy for addressing carbon neutrality and energy shortage. However, the intricate peculiarity of the reaction limits the selectivity of atomically dispersed copper catalysts (ADCCs) towards C2H4, primarily due to the excessive number of electron transfer steps and the singular reactivity resulting from the presence of isolated single atoms or atom clusters. Herein, the Cu−N − C catalyst with a precisely controlled Island-sea structure (Island of atom cluster surrounded by the Sea with single atoms, namely CuSA/AC−C3N4) delivered outstanding C2H4 selectivity of up to 80.35 % (carbonaceous product ratio exceeding 99.4 %) and enhanced activity (a 56-fold increase in current density). Experimental and theoretical investigation further unveiled that the crucial intermediate *CHO was generated at the Sea of single-atoms and then transferred to the Island of atom cluster with high reductive activity via the electron bridge, facilitating subsequent C−C coupling and deep reduction towards C2H4. Importantly, the Island-sea effect not only coupled the electron transfer processes but also facilitated the synergistic functionalization reactions involving the supply of *H and C−C bond formation. This study provides novel insights and avenues for the development of enhanced M−N − C catalysts.

Tracking the first electron transfer step at the donor side of oxygen-evolving photosystem II by time-resolved infrared spectroscopy.

In oxygen-evolving photosystem II (PSII), the multi-phasic electron transfer from a redox-active tyrosine residue (TyrZ) to a chlorophyll cation radical (P680+) precedes the water-oxidation chemistry of the S-state cycle of the Mn4Ca cluster. Here we investigate these early events, observable within about 10ns to 10ms after laser-flash excitation, by time-resolved single-frequency infrared (IR) spectroscopy in the spectral range of 1310-1890cm-1 for oxygen-evolving PSII membrane particles from spinach. Comparing the IR difference spectra at 80ns, 500ns, and 10µs allowed for the identification of quinone, P680 and TyrZ contributions. A broad electronic absorption band assignable P680+ was used to trace largely specifically the P680+ reduction kinetics. The experimental time resolution was taken into account in least-square fits of P680+ transients with a sum of four exponentials, revealing two nanosecond phases (30-46ns and 690-1110ns) and two microsecond phases (4.5-8.3µs and 42µs), which mostly exhibit a clear S-state dependence, in agreement with results obtained by other methods. Our investigation paves the road for further insight in the early events associated with TyrZ oxidation and their role in the preparing the PSII donor side for the subsequent water oxidation chemistry.

Can HOCl be superficially stabilized on an electrocatalyst as proposed in the active chlorine mechanism involving •OH radicals?: Beyond the Cl2 evolution

According to Comninellis’ proposal on water oxidation, anodes physisorbing active oxygen readily form •OH radicals to develop electrocombustion processes, while electrode surfaces forming the so-called higher oxide MO x+1 chemisorb active oxygen, being more prone to perform the O2 evolution reaction (OER). Here, we adopt a similar premise to account for the active chlorine mechanism (ACM), assuming that the capacity of an electrocatalyst to physisorb/chemisorb active oxygen determines the type of chlorine species formed and stabilized. Density Functional Theory (DFT) calculations are conducted to evaluate the stability of HOCl, OCl and OCl --H+ species oxidant species on Boron Doped Diamond (BDD), and rutile-type surfaces (110 plane) of SnO2, TiO2, PbO2, RuO2, and IrO2, in the absence and presence of H2O molecules. The computed relaxed models reveal that SnO2 and PbO2 physisorbing active oxygen are only able to stabilize OCl-ads species on pentacoordinated transition metal atoms (M5c); whereas RuO2, and IrO2 chemisorbing active oxygen produce Clads- on an adjacent M5c active site. The BDD surface is the only surface able to maintain the HOCl stability with and without H2O solvation. Thus, it is proposed that BDD and TiO2, physisorbing active oxygen, preferentially adopt a 2-electron transfer step to generate (HOCl)ads; while SnO2 and PbO2, with moderate physisorption, also follow a 2-electron transfer step but produced (OCl-)ads and (H+)ads, thus dissociating (HOCl)ads. RuO2 and IrO2, preferentially forming the so-called higher oxide MOx+1, adopt a 3-electron transfer step to either produce (OCl)ads, or (O)ads + (Cl)ads, where there is a more equal competition towards the oxygen evolution.

Theoretical Insights into the Generation Mechanism of the Tyr122 Radical Catalyzed by Intermediate X in Class Ia Ribonucleotide Reductase.

Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides in all organisms. There is an ∼35 Å long-range electron-hole transfer pathway during the catalytic process of class Ia RNR, which can be described as Tyr122β ↔ [Trp48β]? ↔ Tyr356β ↔ Tyr731α ↔ Tyr730α ↔ Cys439α. The formation of the Y122• radical initiates this long-range radical transfer process. However, the generation mechanism of Y122• is not yet clear due to confusion over the intermediate X structures. Based on the two reported X structures, we examined the possible mechanisms of Y122• generation by density functional theory (DFT) calculations. Our examinations revealed that the generation of the Y122• radical from the two different core structures of X was via a similar two-step reaction, with the first step of proton transfer for the formation of the proton receptor of Y122 and the second step of a proton-coupled long-range electron transfer reaction with the proton transfer from the Y122 hydroxyl group to the terminal hydroxide ligand of Fe1III and simultaneously electron transfer from the side chain of Y122 to Fe2IV. These findings provide an insight into the formation mechanism of Y122• catalyzed by the double-iron center of the β subunit of class Ia RNR.

Mechanism of stepwise electron transfer in six-transmembrane epithelial antigen of the prostate (STEAP) 1 and 2.

Six transmembrane epithelial antigen of the prostate (STEAP) 1-4 are membrane-embedded hemoproteins that chelate a heme prosthetic group in a transmembrane domain (TMD). STEAP2-4, but not STEAP1, have an intracellular oxidoreductase domain (OxRD) and can mediate cross-membrane electron transfer from NADPH via FAD and heme. However, it is unknown whether STEAP1 can establish a physiologically relevant electron transfer chain. Here, we show that STEAP1 can be reduced by reduced FAD or soluble cytochrome b5 reductase that serves as a surrogate OxRD, providing the first evidence that STEAP1 can support a cross-membrane electron transfer chain. It is not clear whether FAD, which relays electrons from NADPH in OxRD to heme in TMD, remains constantly bound to the STEAPs. We found that FAD reduced by STEAP2 can be utilized by STEAP1, suggesting that FAD is diffusible rather than staying bound to STEAP2. We determined the structure of human STEAP2 in complex with NADP+ and FAD to an overall resolution of 3.2 Å by cryo-electron microscopy and found that the two cofactors bind STEAP2 similarly as in STEAP4, suggesting that a diffusible FAD is a general feature of the electron transfer mechanism in the STEAPs. We also demonstrated that STEAP2 reduces ferric nitrilotriacetic acid (Fe3+-NTA) significantly slower than STEAP1 and proposed that the slower reduction is due to the poor Fe3+-NTA binding to the highly flexible extracellular region in STEAP2. These results establish a solid foundation for understanding the function and mechanisms of the STEAPs.

Iridium-Catalyzed Hydrogenation of a Phenoxy Radical to the Phenol: Overcoming Catalyst Deactivation with Visible Light Irradiation.

Piano-stool iridium hydride complexes bearing phenylpyridine ligands are effective precatalysts for promoting the formation of element-hydrogen bonds using H2 as the stoichiometric H-atom source. Irradiation with blue light resulted in a profound enhancement of catalyst turnover for the iridium-catalyzed hydrogenation of the aryloxyl radical 2,4,6-tBu3-C6H2O• to the corresponding phenol. Monitoring the progress of the reaction revealed the formation of an iridium 3,3-dimethyl-2,3-dihydrobenzofuranyl compound arising from two C-H activation events following the proton-coupled electron transfer (PCET) step. Under thermal conditions, this compound was inactive for catalytic aryloxide hydrogenation, representing a deactivation pathway. Irradiation with blue light under H2 released the free heterocycle and regenerated the piano-stool iridium hydride precatalyst, establishing a pathway for catalyst recovery and overall enhanced turnover.

Metal-Free C(sp3)-H Bond Arylation of 3-Methylindole Derivatives via 3-Indole Imine Methides.

Direct arylation of the benzylic C(sp3)-H bond is one of the most straightforward strategies for the construction of multi-aryl methanes, owing to the extraordinary step and atom economy. In this paper, we developed the first metal-free arylation of the C(sp3)-H bond in 3-methylindoles, thereby providing rapid access to a range of diaryl- and triarylmethanes with two indole rings. Mechanistically, 3-indole imine methide serves as the key intermediate. Water plays a crucial role in this process, likely serving as a proton shuttle to facilitate the key 1,3-proton transfer step in this reaction and, thus, enhance the reaction efficiency.

Unravelling the Effect of Acid-Driven Electron Transfer in High-Valent FeIV =O/MnIV =O Species and Its Implications for Reactivity.

The electron transfer (ET) step is one of the crucial processes in biochemical redox reactions that occur in nature and has been established as a key step in dictating the reactivity of high-valent metal-oxo species. Although metalloenzymes possessing metal-oxo units at their active site are typically associated with outer-sphere electron transfer (OSET) processes, biomimetic models, in contrast, have been found to manifest either an inner-sphere electron transfer (ISET) or OSET mechanism. This distinction is clearly illustrated through the behaviour of [(N4Py)MnIV (O)]2+ (1) and [(N4Py)FeIV (O)]2+ (2) complexes, where complex 1 showcases an OSET mechanism, while complex 2 exhibits an ISET mechanism, especially evident in their reactions involving C-H bond activation and oxygen atom transfer reactions in the presence of a Lewis/Bronsted acid. However, the precise reason for this puzzling difference remains elusive. This work unveils the origin of the perplexing inner-sphere vs outer-sphere electron transfer process (ISET vs OSET) in [(N4Py)MnIV (O)]2+ (1) and [(N4Py)FeIV (O)]2+ (2) species in the presence of Bronsted acid. The calculations indicate that when the substrate (toluene) approaches both 1 and 2 that is hydrogen bonded with two HOTf molecules (denoted as 1-HOTf and 2-HOTf, respectively), proton transfer from one of the HOTf molecules to the metal-oxo unit is triggered and a simultaneous electron transfer occurs from toluene to the metal centre. Interestingly, the preference for OSET by 1-HOTf is found to originate from the choice of MnIV =O centre to abstract spin-down (β) electron from toluene to its δ(dxy ) orbital. On the other hand, in 2-HOTf, a spin state inversion from triplet to quintet state takes place during the proton (from HOTf) coupled electron transfer (from toluene) preferring a spin-up (α) electron abstraction to its σ* (dz 2 ) orbital mediated by HOTf giving rise to ISET. In addition, 2-HOTf was calculated to possess a larger reorganisation energy, which facilitates the ISET process via the acid. The absence of spin-inversion and smaller reorganisation energy switch the mechanism to OSET for 1-HOTf. Therefore, for the first time, the significance of spin-state and spin-inversion in the electron transfer process has been identified and demonstrated within the realm of high-valent metal-oxo chemistry. This discovery holds implications for the potential involvement of high-valent Mn-oxo species in performing similar transformative processes within Photosystem II.

Magic angle spinning effects on longitudinal NMR relaxation: 15N in L-histidine

Solid-state magnetic resonance is a unique technique that can reveal the dynamics of complex biological systems with atomic resolution. Longitudinal relaxation is a mechanism that returns longitudinal nuclear magnetization to its thermal equilibrium by incoherent processes. The measured longitudinal relaxation rate constant however represents the combination of both incoherent and coherent contributions to the change of nuclear magnetization. This work demonstrates the effect of magic angle spinning rate on the longitudinal relaxation rate constant in two model compounds: L-histidine hydrochloride monohydrate and glycine serving as proxies for isotopically-enriched biological materials. Most notably, it is demonstrated that the longitudinal N15 relaxation of the two nitrogen nuclei in the imidazole ring in histidine is reduced by almost three orders of magnitude at the condition of rotational resonance with the amine, while the amine relaxation rate constant is increased at these conditions. The observed phenomenon may have radical implications for the solid-state magnetic resonance in biophysics and materials, especially in the proper measurement of dynamics and as a selective serial transfer step in dynamic nuclear polarization.

Chalcogen Bond Catalysis with Telluronium Cations for Bromination Reaction: Importance of Electrostatic and Polarization Effects.

Recently, chalcogen bond catalysts with telluronium cations have garnered considerable attention in organic reactions. In this work, chalcogen bond catalysis on the bromination reaction of anisole with N-bromosuccinimide (NBS) with the telluronium cationic catalysts has been explored with density functional theory (DFT). The catalytic reaction is divided into two stages: the bromine transfer step and the proton transfer step. Based on the computational results, one can find the rate-determining step is the bromine transfer step. Moreover, the present study elucidates that a stronger chalcogen bond between catalysts and NBS will give better catalytic performance. Additionally, this work also clarified the importance of the electrostatic and polarization effects in the chalcogen bond between the oxygen atom of NBS and the Te atom of the catalyst in this bromination reaction. The electrostatic and polarization effects are significantly influenced by the electron-withdrawing ability of the substitution groups on the catalysts. Moreover, the structure-property relationship between the strength of chalcogen bond, electrostatic effect, polarization effect and catalytic performance are established for the design of more efficient chalcogen bond catalysts.

Unraveling the mechanism and kinetics of aerobic Baeyer–Villiger oxidation of cyclohexanone

AbstractThis study explores the aerobic Baeyer–Villiger oxidation of cyclohexanone into ε‐caprolactone using metalloporphyrin and benzaldehyde, a greener process to replace hazardous concentrated peroxyacid. The reaction mechanism involves a series of free radical reactions, identified through in situ EPR. In this complex three‐component reaction, we developed an intrinsic kinetic model based on the proposed mechanism. Utilizing a hyperbolic equation, the model well fits experimental data, describing biomimetic catalytic behavior of the aerobic Baeyer–Villiger oxidation. The reaction orders for the three reactants corroborate the kinetic model, with the activation energy of oxygen (130.27 kJ/mol) surpassing cyclohexanone (94.85 kJ/mol) and benzaldehyde (40.73 kJ/mol), implying slow initial oxygen activation while rapid subsequent benzaldehyde oxidation, making oxygen transfer and activation key steps. This unified approach to elementary reaction, mechanism, and intrinsic kinetics provides robust forecasts and lays the groundwork for additional studies, such as side reactions control and mass transfer enhancement and reactor design.

Revealing the role of double-layer microenvironments in pH-dependent oxygen reduction activity over metal-nitrogen-carbon catalysts

A standing puzzle in electrochemistry is that why the metal-nitrogen-carbon catalysts generally exhibit dramatic activity drop for oxygen reduction when traversing from alkaline to acid. Here, taking FeCo-N6-C double-atom catalyst as a model system and combining the ab initio molecular dynamics simulation and in situ surface-enhanced infrared absorption spectroscopy, we show that it is the significantly distinct interfacial double-layer structures, rather than the energetics of multiple reaction steps, that cause the pH-dependent oxygen reduction activity on metal-nitrogen-carbon catalysts. Specifically, the greatly disparate charge densities on electrode surfaces render different orientations of interfacial water under alkaline and acid oxygen reduction conditions, thereby affecting the formation of hydrogen bonds between the surface oxygenated intermediates and the interfacial water molecules, eventually controlling the kinetics of the proton-coupled electron transfer steps. The present findings may open new and feasible avenues for the design of advanced metal-nitrogen-carbon catalysts for proton exchange membrane fuel cells.

Density functional theory study of the styrylbenzoquinoline dyad and the related dibenzoquinolylcyclobutane formed in the [2 + 2] photocycloaddition reaction

AbstractThe structure and electronic properties of the biphotochromic dyad with two styrylbenzo[f]quinoline photochromes, as well as the corresponding cyclobutane with two benzo[f]quinoline (BQ) substituents, are studied by DFT at the M06‐2X/6‐31G* level, the cyclobutane being a product of the [2 + 2] photocycloaddition (PCA) reaction of the dyad. According to calculations, the dyad forms π‐stacked folded conformers, which, when excited, can form excimers that are precursors of cyclobutane. TD DFT calculations and natural transition orbital (NTO) analysis indicated that the lowest singlet excited S1 state in the dyad is localized on the SBQ photochrome, including the ethylene group that undergoes PCA. Thus, the conditions for concerted electrocyclic reactions are satisfied, and the direct PCA follows the Woodward–Hoffmann rules. In contrast, in cyclobutane, the S1 state is localized on the BQ substituent rather than on the cyclobutane core. Therefore, the reverse ring‐opening (retro‐PCA) reaction cannot follow the Woodward‐Hoffmann rules and inevitably involves a step of excitation energy transfer from BQ to cyclobutane, which means the predissociation mechanism.

2D High-Temperature Superconductor Integration in Contact Printed Circuit Boards.

Inherent properties of superconducting Bi2Sr2CaCu2O8+x films, such as the high superconducting transition temperature Tc, efficient Josephson coupling between neighboring CuO layers, and fast quasiparticle relaxation dynamics, make them a promising platform for advances in quantum computing and communication technologies. However, preserving two-dimensional superconductivity during device fabrication is an outstanding experimental challenge because of the fast degradation of the superconducting properties of two-dimensional flakes when they are exposed to moisture, organic solvents, and heat. Herein, to realize superconducting devices utilizing two-dimensional (2D) superconducting films, we develop a novel fabrication technique relying on the cryogenic dry transfer of printable circuits embedded into a silicon nitride membrane. This approach separates the circuit fabrication stage requiring chemically reactive substances and ionizing physical processes from the creation of the thin superconducting structures. Apart from providing electrical contacts in a single transfer step, the membrane encapsulates the surface of the crystal, shielding it from the environment. The fabricated atomically thin Bi2Sr2CaCu2O8+x-based devices show a high superconducting transition temperature of Tc ≃ 91 K close to that of the bulk crystal and demonstrate stable superconducting properties.

Ecofriendly Transfer Printing for Biodegradable Electronics Using Adhesion Controllable Self‐Assembled Monolayers

AbstractThe biodegradable electronics are on the rise, not just due to their role in medical implants, but also because of their eco‐friendly attributes. A variety of methods, including transfer printing, have been employed to integrate inorganic electronics onto biodegradable polymer substrates. However, the use of expensive materials, multiple intermediary steps, and labor‐intensive procedures can undermine their environment‐friendly benefits. Here, a straightforward yet efficient fabrication method is introduced for creating high‐performance biodegradable electronic devices. This method leverages the controlled adhesion between the biodegradable device and substrate using self‐assembled monolayers of octadecyltrichlorosilane. Mechanical and thermal analyses based on scratch tests and time‐domain thermoreflectance quantify the adhesion by adjusting the packing density of octadecyltrichlorosilane. Controlled adhesion allows the photolithography process without delamination while facilitating easy delamination during transfer printing. The authors demonstrate the direct fabrication of electronics consisted of inorganic materials (Mg, Zn, SiO2, Si nanomembrane) on wafers and transfer‐printing onto polymer substrates via a single transfer step. This streamlined approach enables wafer‐scale fabrication of biodegradable electronics, highlighting its potential for mass manufacturing. Pilot conceptual demonstration of mass‐produced edible hydration sensors and their application in salivation measurement through in vivo model show the potential capability of proposed fabrication method in the use of practical level.

Revealing electron transfer mechanisms of microelectrolysis for pollutant degradation by a dual electrode approach

Microelectrolysis has been proven to be a practical technology for the catalytic elimination of pollutants in wastewater. This study presents a research method focusing on the demonstration of electron transfer in microelectrolysis through a dual-electrode unit. 2,4-Dichlorophenol, sodium isobutyl xanthate and sodium diethyldithiocarbamate were taken as the typical pollutants for degradation. The results of electrochemical tests and quantum chemical calculations indicated that the ΔG among electron transfer steps proceeding on cathodes is the internal factor deciding the electron flow kinetics between the anode and cathode. The electron transfer rate is influenced by the electron transfer step with a ΔGmax in the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) of the cathode process and is restricted by the number of active sites on the cathode surface. Organics that react with intermediates formed in electrochemical chain reactions promote the entire electron transfer process between the poles, while organics that increase cathode electronegativity have the opposite effect. The cathode products of ·OH, ⋅H, ⋅OOH/⋅O2—, and H2O2, which are derived from the ORR and HER processes, are important for pollutant degradation. Catalysts can be selected and designed based on the required active substance and solution chemical environment for the degradation of targeted contaminants. This study elucidates the electrode kinetics of microelectrolysis, which can be the inspirational basis for catalyst design and technology application.