Efficient Electron Transfer Process Research Articles

Visible-light responsive Ag-doped ZnO/InVO4 composite photocatalyst for efficient degradation of tetracycline and Inactivate E. coli

Ternary heterostructured xAg/ZnO/InVO4 (x=2 %,5 %,7 %) composites were synthesized by a simple hydrothermal method. The prepared photocatalyst underwent characterization using a series of techniques, including XRD, BET, SEM, TEM, FTIR, and Raman spectroscopy. The photoluminescence spectra and electrochemical studies indicated that the addition of Ag promotes the effective separation of photogenerated charge carriers. The 5 % Ag/ZnO/InVO4 photocatalysts under visible light irradiation improved tetracycline removal to 88.6 % within 120 min. The highest degradation performance was achieved under the photocatalyst addition of 30 mg and pH 7. Moreover, the 5 % Ag/ZnO/InVO4 exhibited bactericidal activity against E. coli up to 100 %, which was significantly higher than that of the sum of ZnO, InVO4, and ZnO/InVO4. The radical scavengers trapping experiments revealed that ·OH, h+, and e- were generated in the photocatalytic process, and h+ played a major role in tetracycline degradation with a contribution of 72.3 %. According to the results of photochemical characterization and capture experiments, a detailed photocatalytic mechanism was proposed that the heterostructured combination of Ag, ZnO, and InVO4 provided synergistic photocatalytic activity through an efficient electron transfer process. An innovative concept for the process of environmental remediation is presented for the natural solar energy treatment of organic pollutants in bodies of water.

Efficient Visible‐Light‐Driven Aromatic Alcohol Oxidation Using PI‐TiO2 Composite Photocatalyst

AbstractSynthesizing fine chemicals and valuable pharmaceutical intermediates through selective catalytic oxidation of alcohols is indispensable and crucial. However, the conventional methods of alcohol oxidation have inevitable drawbacks, including harsh reaction conditions and environmental pollution. Thus, it is imperative to develop efficient catalytic oxidation systems for alcohols. Herein, we successfully synthesized a 15 wt %PI‐TiO2 composite by a one‐step solid‐state heating polymerization technique. This catalyst exhibits excellent responsiveness to visible light and demonstrates remarkable catalytic activity. Furthermore, TEMPO was introduced as a cocatalyst to construct a PI‐TiO2/TEMPO/O2 system for the catalytic oxidation of alcohols. In comparison to the individual effects of PI or TiO2, this system showcases improved catalytic activity and broader substrate applicability. As a result, the conversion efficiency of benzyl alcohol increases by 3.44 times and 2.26 times, respectively. This research not only introduces a novel approach for preparing visible light‐active PI‐TiO2 catalysts but also indicates the significance of establishing an efficient electron transfer process in alcohol catalytic oxidation.

Synthesis, structural characterisations, electrochemical behavior and antibacterial activities of a chromium(III) resorcinolate complex

The integration and implementation of transition metal complexes as working electrode for surface modifications has become an area of research interest now a days. Based on this, a novel anionic complex having a formula of Na3[Cr(HR)4Cl2] (HR- = resorcinolate) with octahedral geometry, was prepared and characterized by elemental analysis, molar conductance, vibrational spectra. Electropolymerization of the ligand, salt, and complex was done on glassy carbon electrodes with effective surface area 0.15, 0.17, and 0.2 cm2 for poly(NaHR)/GCE, Cr(0)/GCE, and poly(Na3[Cr(HR)4(Cl2)]/GCE respectively. The presence of a redox polymer film on the surface of the electrode was indicated by the experimental changes observed for a solution containing Na3[Cr(HR)4Cl2]. Specifically, the anodic peak currents, which represent the oxidation process, showed significant increases at different potential values compared to the ligand and salt. These potential values were approximately + 114 mV and + 573 mV. Additionally, the cathodic peak current, which is corresponding to the reduction process, exhibited changes at − 230 mV as the scan cycles were increased. These variations strongly suggested the formation of a film composed of a redox polymer on the electrode's surface. Further, the resistance to charge transfer (Rct) of the compound is in the lower voltage compared to the free ligand, CrCl3•6H2O, and the unmodified GCE. This indicates that the modified compound exhibits improved conductivity due to its reduced charge transfer resistance. The antibacterial activity assessed against two Gram-positive bacteria strains (Staphylococcus aureus and Streptococcus epidermis) and two Gram-negative bacteria strains (Escherichia coli and Klebsiella pneumoniae), indicate that the Cr(III) complex exhibit higher antibacterial activity compared to the ligand and the metal salt but lower than the reference. The synthesized is a highly conductive material suitable for potential applications in sensors and catalysis, especially in situations that require efficient and rapid electron transfer process

Straw-sheaf-like AgVO3 nanowires for remarkable Zn2+ storage properties

Zinc-ion batteries (ZIBs) have received considerable attention as promising energy storage devices because of their impressive energy densities and inexpensive cost. However, there are still challenges to be addressed regarding the performance and cycling stability of ZIBs. In this work, a straw-sheaf-like AgVO3 structure assembled from multiple strongly bonded nanowires was successfully synthesized using a one-step hydrothermal route. We investigate the structural advantages offered by the AgVO3 compound for ZIBs. The AgVO3, which is distinguished by one-dimensional nanowires and a straw-sheaf-like architecture, possesses remarkable properties that facilitate efficient zinc ion deintercalation and electron transfer processes. These include the shortened diffusion length caused by the presence of nanowires, which allows for faster ion migration. The tightly bundled nanowires also provide robust structural support, accommodating the significant volume changes caused by repeated electrochemical reactions. Notably, a single crystal structure enables excellent conductivity and electrochemical kinetics. Remarkably, the straw-sheaf-like AgVO3 electrode exhibited excellent reversible capacity (292.3 mAh g−1 at 0.1 A g−1) and long cycling stability. The remarkable electrochemical properties illuminate the potential of AgVO3 as a viable material for ZIBs, paving the way for improved performance and durability in this promising energy storage technology.

Crystal structure, Hirshfeld surface analysis and ionic conduction properties of 4-(diphenylamino)benzaldehyde-4-(methyl)thiosemicarbazone additive with D-π-D molecular arrangement system

A new single crystal of 4-(diphenylamino)benzaldehyde-4-(methyl)thiosemicarbazone, featuring a D-π-D molecular template was synthesized and utilized as an additive in solid biopolymer electrolytes mixed with carboxymethyl cellulose (CMC) and propylene carbonate (PC). The additive was structurally characterized using single-crystal X-ray diffraction. This revealed a triclinic crystal structure belonging to the triclinic space group, P1−. The lattice parameters were determined as follows: a = 6.942(6) Å; b = 11.409(11) Å; c = 12.442(10) Å; α= 91.024(16)°; β= 104.264(12)°; γ= 107.496(12)°; V= 906.4(13)Å3 and Z= 2. Notably, the additive exhibited extensive π-electron delocalization, leading to the formation of infinite chains through C-H-π interactions and intermolecular hydrogen bonding, ultimately resulting in an inverse centrosymmetric dimer in the form of the R22(8) motif. Furthermore, a detailed Hirshfeld surface analysis of the additive revealed significant contributions from C···H/ H···C, H···S/S···H and H···N/ N···H interactions with 20.7%, 11.2% and 3.7% of the total Hirshfeld surface analysis, respectively. These interactions indicate the potential of the additive to facilitate efficient electron transfer processes. The conductivity (σ) of the CMC–PC–additive system determined at ambient temperature was 8.00 ×10−9 Scm−1. The dielectric properties showed that the system follows the non-Debye behavior, in which the conductivity is predominantly due to ion conduction via the hopping mechanism.

Magnetite modified zeolite as an alternative additive to promote methane production from anaerobic digestion of waste activated sludge

Methane recovery from bio-wastes is one promising renewable energy to relieve the energy crisis faced around the world. Zeolite is one of attractive exogenous additives for promoting methane production from anaerobic digestion due to its potentials in regulating microorganism enrichment and anaerobic environment. However, the poor electron mediated ability limited its positive effects. Hence, this study hypothesized that the electron mediated ability of zeolite would be improved by loading magnetite, thereby generating more positive impacts on the performance of sludge anaerobic digestion. Compared to control group, magnetite modified zeolite (MZ) effectively improved methane yield by 37.4%. The reason was that the electron mediated ability and adsorption capacity of zeolite were improved by loading magnetite, facilitating the degradation of refractory organics and the conversion of volatile fatty acids. Moreover, the activities of cytochrome c and F420 increased by 33.3% and 29.8% with MZ additive, contributing to stimulating efficient electron transfer process. In addition, the electro-active genera were enriched, such as Bacteroidetes_vadinHA17, Methanobacterium, and Methanosaeta, and the direct interspecies electron transfer was possibly established for methanogenesis with the help of MZ. This study will provide valuable references for the application of zeolite in anaerobic digestion.

Enhancing the Carrier Transport in Monolayer MoS2 through Interlayer Coupling with 2D Covalent Organic Frameworks.

The coupling of different 2D materials (2DMs) to form van der Waals heterostructures (vdWHs) is a powerful strategy for adjusting the electronic properties of 2D semiconductors, for applications in opto-electronics and quantum computing. 2D molybdenum disulfide (MoS2 ) represents an archetypical semiconducting, monolayer thick versatile platform for the generation of hybrid vdWH with tunable charge transport characteristics through its interfacing with molecules and assemblies thereof. However, the physisorption of (macro)molecules on 2D MoS2 yields hybrids possessing a limited thermal stability, thereby jeopardizing their technological applications. Herein, the rational design and optimized synthesis of 2D covalent organic frameworks (2D-COFs) for the generation of MoS2 /2D-COF vdWHs exhibiting strong interlayer coupling effects are reported. The high crystallinity of the 2D-COF films makes it possible to engineer an ultrastable periodic doping effect on MoS2 , boosting devices' field-effect mobility at room temperature. Such a performance increase can be attributed to the synergistic effect of the efficient interfacial electron transfer process and the pronounced suppression of MoS2 's lattice vibration. This proof-of-concept work validates an unprecedented approach for the efficient modulation of the electronic properties of 2D transition metal dichalcogenides toward high-performance (opto)electronics for CMOS digital circuits.

Meso-aryltellurium-BODIPY-based fluorescence turn-on probe for selective, sensitive and fast glutathione sensing in HepG2 cells

Glutathione (GSH) as one most abundant thiol, acts as important roles in regulating cellular redox activities, and various diseases are closely related with its abnormal levels. Thus, monitoring intracellular GSH levels is essential for understanding cellular metabolism of many related diseases. In this work, we firstly reported a new fluorescence turn-on sensor, which was capable of selectively, sensitively and rapid sensing GSH over other thiols, especially cysteine and homocysteine in solutions and living cells. A meso-aryltellurium boron dipyrromethene (BODIPY) was firstly designed and synthesized, which showed silenced emission due to an efficient photoinduced electron transfer (PET) process from electron-rich Te to BODIPY, and then upon exposure to GSH, the meso-Te-C bond could be rapidly cleaved by the thiol group of GSH, thus resulting in an obvious fluorescence “turn-on” phenomenon through inhibition of the PET effect. This probe exhibited excellent selectivity and sensitivity towards GSH with a short response time of 2 min, showing a remarkable fluorescence enhancement observed at 541 nm with a large fluorescence quantum yield increase from nearly 0 to 0.73 upon excitation at 500 nm in PBS/CH3CN (9/1, v/v). The detection limit towards GSH was further calculated to be 1.7 nM by the linear fluorescence change at 541 nm in the GSH-concentration ranging from 0 to 4 μM. Furthermore, its sensing mechanism was validated by using mass spectrometry, confirming the rapid cleavage of the Te–C bond by GSH. Finally, cell imaging experiments demonstrated that this probe could successfully detect GSH in living cells, highlighting its potential for rapid and sensitive detection of intracellular GSH level changes. Therefore, a new meso-aryltellurium-BODIPY fluorescence turn-on sensor was firstly developed, which could selectively, sensitively and fast detect cellular GSH over other thiols based on the rapid cleavage of the meso Te–C bond.

Mechanochemically synthesized Mn3O4@β-cyclodextrin mediates efficient electron transfer process for peroxymonosulfate activation

The rational surface engineering of heterogeneous catalysts is of great significance in advanced oxidation processes (AOPs) for eliminating refractory contaminants but remains challenging. In this study, β-cyclodextrin modified Mn3O4 (Mn3O4@β-CD) was prepared through a mechanochemical approach for peroxymonosulfate (PMS) activation, which achieved efficient bisphenol A (BPA) removal via electron transfer process (ETP). The reactive PMS* complex with elevated potential was identified to dominate the ETP by withdrawing electrons from BPA with Mn3O4@β-CD working as electron shuttle, as evidenced by spectroscopy and electrochemical techniques. Experimental results and density functional theory (DFT) calculations showed that the β-CD modification enhanced the interfacial accumulation of pollutants and shortened the migration distance between pollutants (electron donor) and catalysts (electron shuttle) to mediate electron transfer more effectively. Benefitting from the improved ETP, the Mn3O4@β-CD/PMS system showed efficient PMS utilization and practical adaptability in actual waterbodies. This study provides a rational approach for modulating the surface structure of heterogeneous catalysts in PMS-based AOPs for environmental remediation.

Non-Conjugated Bis-(Dithienylethene)-Naphthalenediimide as a Dynamic Anti-Counterfeiting Agent: Driving the Wheel of Photoswitching Enactment.

Photochromic fluorescent molecules dramatically extend their fields of applications ranging from optical memories, bioimaging, photoswitches, photonic devices, anti-counterfeiting technology and many more. Here, we have logically designed and synthesized a triazole appended bis-(dithienylethene)-naphthalenediimide based photo-responsive material, 5, which demonstrated fluorescence enhancement property upon photocyclization (ΦF =0.42), with high photocyclization (44 s, ksolution =0.0355 s-1 , ksolid =0.0135 s-1 ) and photocycloreversion (160 s, ksolution =0.0181 s-1 , ksolid =0.0085 s-1 ) rate and decent photoreaction quantum yield (Φo→c =0.93 and Φc→o =0.11). The open isomer almost converted to the closed isomer at photo-stationary state (PSS) with distinct color change from colorless to blue with 92.85 % conversion yield. A reversible noninvasive modulation of fluorescence through efficient photoinduced electron transfer (PET) process was observed both in solution as well as in solid state. The fluorescence modulation through PET process was further corroborated with thermodynamic calculations using the Rehm-Weller equation and quantum chemical studies (DFT). The thermally stable compound 5 exhibits high fatigue resistance property (up to 50 cycles) both in solution and solid state. Furthermore, the compound 5 was successfully applied as erasable ink and in deciphering secret codes (Quick Response/bar code) portending potential promising application in anti-counterfeiting.

3D ZnO hollow spheres-dispersed CsPbBr3 quantum dots S-scheme heterojunctions for high-efficient CO2 photoreduction

Efficient electron transfer process and excellent CO2 adsorption capacity are of great significance for improving CO2 photoreduction efficiency. 3D-0D ZnO/CsPbBr3 S-scheme heterojunction hollow spheres were successfully prepared via a simple self-assembled process for efficient CO2 photoreduction. Photocatalytic CO2 reduction experiments showed that the ZnO/CsPbBr3 had the excellent CO2 photocatalytic conversion activity to CO, which was about 2.61 times higher than that of ZnO hollow micro-spheres and 1.9 times higher than that of pure CsPbBr3 quantum dots (QDs). Photoelectrochemical characterization confirmed that the ZnO/CsPbBr3 composite had good photoelectric conversion ability and carrier transfer ability, which was beneficial to the photocatalytic reaction. The suitable band gap structure and DFT calculation results showed that the formation of built-in electric field at the ZnO/CsPbBr3 interface can greatly improve the S-scheme electron transfer ability, which can foster the CO2 photoreduction. Besides, the introduction of 3D structure can improve the dispersion of CsPbBr3 QDs and effectively enhance the CO2 capture ability of the catalyst, which greatly promoted the CO2 photoreduction reaction. The current work can present a novel S-scheme photocatalyst, which is looked forward to providing a certain perception into the advance of novel highly efficient CsPbBr3 QDs-based photocatalysts for CO2 resource utilization.

Solid-State Luminescence Turn-On Sensing Using MOF-Confined Reporter-Spacer-Receptor Architectures Facilitated by Quencher Displacement.

The reporter-spacer-receptor (RSR) approach is prevalent to develop molecular turn-on sensors. However, the fluorescent RSR sensors barely operate in solid state, which hinders their fabrication into devices for practical applications. Herein, we present a novel strategy to achieve solid-state luminescence turn-on sensing by assembling RSR architectures within MOF frameworks. Unlike the regular RSR systems, the framework-confined fluorophore and receptor are well arranged and separated even in the solid state. This concept is illustrated by a multicomponent MOF (Fc@NU-1000), which contains organic linkers with a highly luminescent pyrene core as the reporter, Zr6 nodes with unsaturated sites as the receptor, and the incorporated Fc molecules as the quencher. The separate incorporation of pyrene core and Fc in the multicomponent MOF favors an efficient pseudointramolecular photoinduced electron transfer (PET) process, resulting in significant luminescence quenching. Interestingly, such PET process can be blocked via the quencher displacement initiated by the phosphate analyte, therefore recovering the solid-state luminescence of MOF microcrystals. We found that Fc@NU-1000 is shown as a sensitive solid-state luminescence turn-on probe for phosphate with the naked-eye response at a low content. What's more, this study is the first example of confining a quencher displacement-based RSR system in the MOF framework for solid-state luminescence turn-on sensing, thus also providing new opportunities for MOF materials to develop luminescence turn-on sensors.

Excellent Nonlinear Optical Limiting Behavior of Tetra (C60) Lanthanum Phthalocyanine in Solid Poly(methyl methacrylate) Films

This work reports on the exceptional optical limiting performance of a novel D–A-type compound, namely, LaPc-4(C60), wherein the lanthanide phthalocyanine is used as a donor and four C60 are used as acceptors. In addition, phenyl ether bonds were introduced into the molecule, making it semirigid and increasing its solubility. At the same time, the phenyl ether bond could act as a π-electron bridge, which increases the electron transfer pathway, expands the π-conjugated system, and reduces the spatial site resistance of the molecule. Furthermore, the uniform poly(methyl methacrylate) (PMMA) composite film (LaPc-4(C60)/PMMA) was prepared by a simple solution casting method. In comparison with individual C60 or LaPc(CHO)4, both LaPc-4(C60) in solution and in the solid PMMA composite film exhibited larger third-order nonlinear absorption coefficients and lower limiting thresholds at 532 nm. In particular, LaPc-4(C60)/PMMA exhibits huger nonlinear absorption coefficient (2900 cm/GW) and larger third-order susceptibility (4.91 × 10–9 esu), which can be attributed to the synergistic effect of the different non-linear absorption mechanisms and efficient photoinduced electron transfer process between C60 and LaPc.

Rational design of bromine-modified Ir(III) photosensitizer for photocatalytic hydrogen generation

The facile design of highly efficient photosensitizers is fundamentally crucial for the construction of efficient photocatalytic H2-evolving systems. In this work, we employed substituted 2-(thiophen-2-yl) pyridine (C^N) and 2,2′-bipyridine (N^N) ligands to afford a series of iridium complexes. Interestingly, by introducing heavy halogen group -Br, the triplet state lifetime of affording photosensitizer was significantly enhanced to 4273 ns, which is 54 times to that of unmodified one (77 ns). While coupling with Ni-substituted polyoxometalate Ni4(SiW9)2 catalyst and triethanolamine electron donor, the bromine-modified photosensitizer can effectively drive hydrogen generation with a turnover number of ∼ 1400 under visible light irradiation. Spectroscopic studies reveal that the -Br modified iridium complex exhibits larger Stern − Volmer constants for both reductive and oxidative quenching processes. Mechanistic analyses demonstrate the advantages of long-lived excited states and good photostability of bromine modified photosensitizer, the efficient electron transfer process, and the well-matched energy levels between all three catalytic components for efficient hydrogen production.

Pivotal role of reversible NiO6 geometric conversion in oxygen evolution.

Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts1-3. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway1-15. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen-oxygen bonding in AEM and deprotonation in LOM1-5,8. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.

Mesoporogen free synthesis of CuO/TiO2 heterojunction for ultra-trace detection of catechol in water samples

Creating mesoporous architecture on the surface of metal oxides without using pore creating agent is significant interest in electrochemical sensors because these materials act as an efficient electron transfer process between the electrode interface and the analytes. Recent advances in mesoporous titanium dioxide (TiO2)-based materials have acquired extraordinary opportunities because of their interconnected porous structure could act as a host for doping with various transition metals or heteroatoms to form a new type of heterojunction. Herein, a simple method is developed to synthesize mesoporous copper oxide (CuO) decorated on TiO2 nanostructures in which homogenous shaped CuO nanocrystals act as dopants decorated on the mesoporous structure of TiO2, resulting in p-n heterojunction nanocomposite. The TiO2 particles exhibit a mesoporous structure with a pore volume of about 0.117 cm3/g is capable to load CuO nanocrystals on the surface. As a result, large pore volume 0.304 cm³/g is obtained for CuO–TiO2 heterojunction nanocomposite with the loading of uniform-shaped CuO nanocrystals on the mesoporous TiO2. The resulting CuO–TiO2 nanocomposite on modified glassy carbon (GC) electrode exhibits good electrochemical performance for oxidation of catechol with the observation of strong enhancement in the anodic peak potential at +0.36 V. The decrease in the overpotential for the oxidation of catechol when compared to TiO2/GC is attributed to the presence of CuO nanocrystals providing a large surface area, resulting in wide linear range 10 nM to 0.57 μM. Moreover, the resultant modified electrode exhibited good sensitivity, selectivity and reproducibility and the sensor could able to determine the presence of catechol in real samples such as lake and river water. Therefore, the obtained CuO–TiO2 nanocomposite on the modified GC delivered good electrochemical sensing performance and which could be able to perform a promising strategy for designing various metal oxide doped nanocomposites for various photochemical and electrocatalytic applications.

Efficient charge transfer in an aggregation-induced nanocavity of Au nanoclusters.

In the last 20 years, extensive research has been reported on the use of plasmonic nanoparticles as a potential photocatalyst. However, the low conversion efficiency has still remained a major concern. Herein, we present a new photocatalytic reaction system based on Au nanoclusters (Au NCs) to enhance the conversion efficiency. Negatively charged Au NCs electrostatically interact with positively charged metal ions and form highly aggregated nanocrystals, which can efficiently capture a chemical substance in the reaction mixture. In such a reaction system, the distance between the electron donor and acceptor can be shortened, resulting in an efficient electron transfer process. We examined the electron transfer behavior in a nanocavity system via resazurin photoreduction and compared the reaction rate with that of a colloidal system, which is a commonly used reaction system. Evidently, the nanocavity system facilitated an enhanced reaction rate compared to that of the colloidal system. Furthermore, this nanocavity reaction system permitted multistep photoreactions and multi-electron transfer processes.

Controlled synthesis of zinc-metal organic framework microflower with high efficiency electrochemiluminescence for miR-21 detection

In this study, as the self-enhanced electrochemiluminescence (ECL) emitter, the dual ligand metal-organic framework microflower was successfully synthesized via a facile one-pot method by integrating 9,10-di(pcarboxyphenyl) anthracene (DPA) ligand and N, N-Diethylethylenediamine (DEAEA) ligand into zinc ions metal node, denoted as Zn-DPA/DEAEA (d-MOF). The DPA ligand was a typical ECL luminophore. The DEAEA ligand not only could be used as an effective co-reactant but also a morphologic regulator. The morphology of d-MOF changed from a thick sheet to a thin sheet and finally a microflower by controlling the dosage of DEAEA. Linking emitter and co-reactant in a MOF structure, the d-MOF exhibited an efficient intramolecular electron transfer process, with a strong and ultra-stable ECL performance without any extra co-reactants compared with the DPA ligand or the Zn-DPA single ligand MOF (s-MOF). Furthermore, an ECL resonance energy transfer (ECL-RET) biosensor was fabricated using d-MOF as donor, and 6-carboxy-4′, 5′-dichloro-2′, 7′-dimethoxyfluorescein (JOE) as accepter for the ultra-sensitive detection of miR-21 without additional co-reactant. And with a detection linear range of miR-21 was 100.0 aM to 10.0 pM, with a detection limit of 61.7 aM. This work offers a new perspective for the future design of stable self-enhanced ECL materials.

Tropane and related alkaloid skeletons via a radical [3+3]-annulation process

Tropanes and related bicyclic alkaloids are highly attractive compounds possessing a broad biological activity. Here we report a mild and simple protocol for the synthesis of N-arylated 8-azabicyclo[3.2.1]octane and 9-azabicyclo[3.3.1]nonane derivatives. It provides these valuable bicyclic alkaloid skeletons in good yields and high levels of diastereoselectivity from simple and readily available starting materials using visible-light photoredox catalysis. These bicyclic aniline derivatives are hardly accessible via the classical Robinson tropane synthesis and represent a particularly attractive scaffold for medicinal chemistry. This unprecedented annulation process takes advantage of the unique reactivity of ethyl 2-(acetoxymethyl)acrylate as a 1,3-bis radical acceptor and of cyclic N,N-dialkylanilines as radical 1,3-bis radical donors. The success of this process relies on efficient electron transfer processes and highly selective deprotonation of aminium radical cations leading to the key α-amino radical intermediates.

Intra-supramolecular electron transfer of the light harvesting porphyrin—phthalocyanine complex in aqueous medium

Report of the construction of the supramolecular light harvesting composed of zinc(II) phthalocyanine tetrasulfonic acid (ZnPcS[Formula: see text], as electron donor, and meso-tetra([Formula: see text]-methyl-4-pyridyl)porphyrin toluene sulfonate (TMPP), as electron acceptor. The steady-state absorption and fluorescence spectra of TMPP in MeOH showed the formation of monomer form ([Formula: see text] = 426 nm and [Formula: see text] = 654 and 715 nm). In water, different spectral features were recorded, suggesting the formation of aggregated forms. The formation of aggregated form in water was confirmed by recording the remarkable decrease of the fluorescence intensities of the singlet excited TMPP with increasing the concentrations of TMPP. In cationic micelle CTAB, both the absorption and fluorescence spectra were significantly decreased with increasing the concentrations of CTAB with a break at critical micelle concentration (CMC) at 6.00 × 10[Formula: see text] M. In an anionic micelle (SDS), the CMC value was found to be 1.00 × 10[Formula: see text] M. Upon interacting with ZnPcS4 in water, the steady state absorption measurement showed clear evidence for the formation of light harvesting porphyrin-phthalocyanine supramolecular complex through [Formula: see text]–[Formula: see text] and ionic interactions. The emission intensity of the singlet TMPP was found to significantly decrease in the presence of ZnPcS4 suggesting the intra-supramolecular electron transfer process from the electron donating ZnPcS4 to the electron deficient TMPP. From the fluorescence lifetime measurements, the rate and quantum yield of electron transfer were found to be 7.67 × 108 s[Formula: see text] and 0.81, respectively. The finding of the examined light-harvesting supramolecular complex ZnPcS4-TMPP shows the ability to absorb the light in a wide range of the solar spectrum (UV-vis-NIR), in addition to the efficient electron transfer process in an aqueous medium, rendering it as a simple model of the artificial photosynthetic reaction center.