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Electron transfer from photoexcited naphthalene-1,4:5,8-bis(dicarboximide) radical anion to Mn(bpy)(CO)3X and Re(bpy)(CO)3X CO2 reduction catalysts linked via a saturated methylene bridge
摘要： Supramolecular systems that connect a naphthalene-1,4:5,8-bis(dicarboximide) (NDI) radical anion donor to Mn(bpy)(CO)3Br or Re(bpy)(CO)3Cl CO2 reduction catalysts via a methylene bridge have been synthesized and studied by femtosecond transient visible, near-infrared and mid-infrared spectroscopy. The use of the methylene bridge to link NDI to the complexes does not affect the reduction potentials of the metal complexes. Selective photoexcitation of NDI?? to 2*NDI?? results in ultrafast reduction of the bipyridine (bpy) ligands on both the Mn and Re complexes to form Mn(I)(bpy??)(CO)3X and Re(I)(bpy??)(CO)3X in near unity quantum yield, respectively. The initial formation of Mn(I)(bpy??)(CO)3X is unexpected based on previous electrochemical data that indicates the Mn(I) center is reduced at a more positive potential than the bpy ligand. Moreover, the rate of forward electron transfer in the Mn complex was found to be faster than in the Re complex, while the rate of the back electron transfer in the Re complex was faster than in the Mn complex.
关键词： Electrochemistry,CO2 reduction,Electron transfer,Radical anions,Femtosecond spectroscopy,Solar energy
更新于2025-09-23 15:23:52
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Polydopamine-Based Tumor-Targeted Multifunctional Reagents for Computer Tomography/Fluorescence Dual-Mode Bioimaging-Guided Photothermal Therapy
摘要： Development of multifunctional diagnosis and treatment reagents is very meaningful in clinical application. Herein, we developed a polydopamine-based (PDA-based) tumor targeted multifunctional reagent by surface-initiated atom transfer radical polymerization (ATRP) strategy. First, the targeted PDA nanoparticles were prepared via combining with folic acid (FA) and dopamine. Then ATRP technology was used to graft the europium(III) complexes onto PDA surface (defined as FEDA). A series of detections revealed that the FEDA nanoparticles had been successfully prepared and exhibited a bright X-ray computer tomography (CT) and photoluminescence (PL) dual-mode imaging efficiency and an excellent photothermal therapy (PTT) effect in vivo/in vitro.
关键词： europium(III) complexes,polydopamine,dual-mode imaging-guided photothermal therapy,folic acid targeted,atom transfer radical polymerization
更新于2025-09-23 15:23:52
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Removal of Polymers for KrF and ArF Photoresist Using Hydrogen Radicals Containing a Small Amount of Oxidizing Radicals
摘要： Photoresist removal method using hydrogen radicals, which are produced on a tungsten hot-wire catalyst, is effective to resolve some environmental and industrial problems in conventional methods for the fabrication of electronic devices. However, its removal rate is not as good as that of the conventional ones. We have previously described that the removal rate of a positive-tone novolac photoresist is enhanced by the addition of a small amount of oxygen gas to the atmosphere, in which hydrogen radicals are produced. Oxidizing radicals, such as OH and O radicals, can be produced together with H radicals. In present study, we examined the effects of oxygen addition on base polymers of KrF and ArF photoresists: the former is poly(vinyl phenol) (PVP), and the latter is poly(methyl methacrylate) (PMMA). Effects of oxygen addition on PVP was confirmed, as was found for the novolac photoresist. On the other hand, the effects on PMMA were different from the cases of the novolac photoresist and PVP. Results were ascribed to the presence or absence of benzene rings, the properties of polymers and the reactivity of oxidizing radicals.
关键词： Oxygen addition,Environment,Removal,Photoresist,Hydrogen radical
更新于2025-09-23 15:23:52
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Night-Time Oxidation of a Monolayer Model for the Air–Water Interface of Marine Aerosols—A Study by Simultaneous Neutron Reflectometry and in Situ Infra-Red Reflection Absorption Spectroscopy (IRRAS)
摘要： This paper describes experiments on the ageing of a monolayer model for the air–water interface of marine aerosols composed of a typical glycolipid, galactocerebroside (GCB). Lipopolysaccharides have been observed in marine aerosols, and GCB is used as a proxy for these more complex lipopolysaccharides. GCB monolayers are investigated as pure films, as mixed films with palmitic acid, which is abundant in marine aerosols and forms a stable attractively mixed film with GCB, particularly with divalent salts present in the subphase, and as mixed films with palmitoleic acid, an unsaturated analogue of palmitic acid. Such mixed films are more realistic models of atmospheric aerosols than simpler single-component systems. Neutron reflectometry (NR) has been combined in situ with Fourier transform infra-red reflection absorption spectroscopy (IRRAS) in a pioneering analysis and reaction setup designed by us specifically to study mixed organic monolayers at the air–water interface. The two techniques in combination allow for more sophisticated observation of multi-component monolayers than has previously been possible. The structure at the air–water interface was also investigated by complementary Brewster angle microscopy (BAM). This study looks specifically at the oxidation of the organic films by nitrate radicals (NO3?), the key atmospheric oxidant present at night. We conclude that NO3? oxidation cannot fully remove a cerebroside monolayer from the surface on atmospherically relevant timescales, leaving its saturated tail at the interface. This is true for pure and salt water subphases, as well as for single- and two-component films. The behaviour of the unsaturated tail section of the molecule is more variable and is affected by interactions with co-deposited species. Most surprisingly, we found that the presence of CaCl2 in the subphase extends the lifetime of the unsaturated tail substantially—a new explanation for longer residence times of materials in the atmosphere compared to lifetimes based on laboratory studies of simplified model systems. It is thus likely that aerosols produced from the sea-surface microlayer at night will remain covered in surfactant molecules on atmospherically relevant timescales with impact on the droplet’s surface tension and on the transport of chemical species across the air–water interface.
关键词： palmitic acid,monolayer,neutron,nitrate radical,palmitoleic acid,reflectivity,aerosol,infra-red,cerebroside,Brewster angle microscopy
更新于2025-09-23 15:23:52
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UV-activated persulfate oxidation of 17β-estradiol: Implications for discharge water remediation
摘要： The female sexual hormone, 17β-estradiol (E2), was chosen as a model emerging contaminant to study its degradation kinetics using UV-activated persulfate (UV/PS). Our objective was to quantify the effectiveness of UV/PS coupled with slow-release technology to degrade E2 in real wastewater using a systematic design flow-through system. This was accomplished by quantifying the effects on E2 degradation rates of the initial PS or E2 concentration, initial pH, constituent ions, turbidity, humic acids, and real wastewater. The results showed that the E2 degradation rates increased with increasing PS concentration. The presence of other constituent ions (NO3–, Cl–, HCO3–) resulted in varying degradation rates due to the formation of active and less reactive radicals. Humic acid had higher significant impact on the rates than did turbidity. In addition, the observed degradation rates (0.140 min-1) in Deionized water were much higher than those observed in real wastewater matrix (0.001 min-1). Biodegradable soywax was the best binding agent that provided sustained delivery of PS thus resulting in better E2 removal than with other waxes. But treating E2 with PS soywax in a wastewater matrix, our flow-through system was able to maintain the E2 concentration below 50% in the contact tank (~150 min) and able to continually remove E2 up to 65% (~240 min) in the effluent reservoir. The overall results supported the use of UV-activated slow-release PS to treat discharge water in animal farming.
关键词： influencing factor,slow-release oxidant,17β-estradiol,UV activation,persulfate oxidation,sulfate radical
更新于2025-09-23 15:22:29
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Anti-Markovnikov Hydroazidation of Alkenes by Visible Light Photoredox Catalysis
摘要： The anti-Markovnikov hydroazidation of alkenes has been accomplished using [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 as photocatalyst and trimethylsilyl azide as azidating agent. The reactions were greatly facilitated by water, whose beneficial effect can be attributed to its participation in the reaction as the hydrogen donor, as indicated by deuterium isotope experiments. The reactions can be effected under solvent free conditions in the presence of water. 4-Dimethylaminopyridine also exhibited a beneficial effect on the reactions. The present method enabled hydroazidation of several types of unactivated alkenes with good yield and high regionselectivity.
关键词： hydroazidation,water,trimethylsilyl azide,radical reactions,photoredox catalysis
更新于2025-09-23 15:22:29
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Photocatalytic Degradation of Estriol Using Iron-Doped TiO2 under High and Low UV Irradiation
摘要： Iron-doped TiO2 nanoparticles (Fe-TiO2) were synthesized and photocatalitically investigated under high and low ?uence values of UV radiation. The Fe-TiO2 physical characterization was performed using X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Diffuse Re?ectance Spectroscopy (DRS), and X-ray Photoelectron Spectroscopy (XPS). The XPS evidenced that the ferric ion (Fe3+) was in the TiO2 lattice and unintentionally added co-dopants were also present because of the precursors of the synthetic method. The Fe3+ concentration played a key role in the photocatalytic generation of hydroxyl radicals (?OH) and estriol (E3) degradation. Fe-TiO2 accomplished E3 degradation, and it was found that the catalyst with 0.3 at.% content of Fe (0.3 Fe-TiO2) enhanced the photocatalytic activity under low UV irradiation compared with TiO2 without intentionally added Fe (zero-iron TiO2) and Aeroxide? TiO2 P25. Furthermore, the enhanced photocatalytic activity of 0.3 Fe-TiO2 under low UV irradiation may have applications when radiation intensity must be controlled, as in medical applications, or when strong UV absorbing species are present in water.
关键词： hydroxyl radical,estriol,iron-doped TiO2,photocatalytic activity,low UV irradiation
更新于2025-09-23 15:22:29
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Technical notes Integrated image navigation system using head-mounted display in “RoboSurgeon” endoscopic radical prostatectomy
摘要： The safety and efficacy of minimally invasive surgery relies on visual information. We aimed to develop an integrated image navigation system (RoboSurgeon System) that combines head-mounted displays (HMDs) with multiple image modalities, and assessed its feasibility in 5 prostate cancer patients who underwent gasless single-port endoscopic radical prostatectomy. A robotically manipulated transrectal ultrasound (TRUS) system was used. In all cases, preoperative magnetic resonance (MR) images and intraoperative real-time images of an endoscope, TRUS, and HMD-mounted camera were integrated and displayed synchronously on each HMD in a four-split screen mode during the entire process. The TRUS helped identify the boundary with the adjacent structures endoscopically in reference to MR images. There were no negative incidents in intraoperative or postoperative courses. Integrated image navigation using HMDs as individualized monitors is feasible in the natural ergonomic position and may be beneficial to identify correct dissection planes. The efficacy of the RoboSurgeon System deserves further evaluation.
关键词： image navigation,prostate cancer,head-mounted display,minimally invasive surgery,transrectal ultrasound,radical prostatectomy
更新于2025-09-23 15:22:29
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Effect of Electron-Nuclear Hyperfine Interactions on Multiple Quantum Coherences in Photogenerated Covalent Radical (Qubit) Pairs
摘要： Ultrafast photo-driven electron transfer reactions starting from an excited singlet state in an organic donor-acceptor molecule can generate a spin-correlated radical pair (RP) with an initially entangled spin state that may prove useful as a two-qubit pair in quantum information protocols. Here we investigate the effects of modulating electron-nuclear hyperfine coupling by rapidly transferring an electron between two equivalent sites comprising the reduced acceptor of the RP. A covalent electron donor-acceptor molecule including a tetrathiafulvalene (TTF) donor, a 4-aminonaphthalene-1,8-imide (ANI) chromophoric primary acceptor, and a m-xylene bridged cyclophane having two equivalent pyromellitimides (PI2), TTF-ANI-PI2, as a secondary acceptor was synthesized along with the analogous molecule having one pyromellitimide (PI) acceptor, TTF-ANI-PI. Photoexcitation of ANI within each molecule results in sub-nanosecond formation of TTF+?-ANI-PI-? and TTF+?-ANI-PI2 -?. The effect of reducing electron-nuclear hyperfine interactions in TTF+?-ANI-PI2 -? relative to TTF+?-ANI-PI-? on decoherence of multiple-quantum coherences has been measured by pulse-EPR spectroscopy. This contribution is especially relevant in the absence of modulation of exchange or dipolar interactions, as with the RP at a fixed distance in the molecules in this work. The theoretical prediction of the contribution from an ensemble of hyperfine interactions to decoherence in these RPs is shown to be less than the full width at half maximum of the quantum beat frequencies measured experimentally. Pulse bandwidth and off-resonant excitation by square microwave pulses are proposed as larger contributors to decoherence in these molecules than the hyperfine interactions, and specific pulse shapes relevant to arbitrary waveform generation are introduced.
关键词： pulse-EPR spectroscopy,photogenerated covalent radical pairs,electron-nuclear hyperfine interactions,multiple quantum coherences,quantum information protocols
更新于2025-09-23 15:21:21
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3-Hydroxyflavone and N-phenylglycine in High Performance Photoinitiating Systems for 3D Printing and Photocomposites Synthesis
摘要： In this work, we propose to use 3-hydroxyflavone as a versatile high performance visible light photoinitiator (PIs) in combination with an amino acid (N-phenylglycine) for the free radical polymerization (FRP) of methacrylates in thick samples or composites upon visible light exposure (Light-Emitting Diode LED@405 nm or LED@477 nm). The high originality of this approach is the use of safer compounds in photoinitiating systems (flavone derivative/amino acid). 3-Hydroxyflavone can also be used in three-component systems with an iodonium salt and an amine for the cationic polymerization of epoxides upon exposure to near UV light LED@385 nm. Also interestingly, a charge transfer complex CTC between N-phenylglycine NPG and iodonium salt gives also remarkable initiating performance for free radical polymerization of methacrylates upon mild light irradiation conditions (LED@405 nm). High polymerization initiating abilities are found and high final reactive function conversions are obtained. The use of the new proposed initiating systems as materials for laser write or 3D printing experiments was also especially carried out with the formation of printed green fluorescent photopolymers. This green fluorescence obtained with naturally occurring 3-hydroxyflavone compound can be ascribed to the excited state intramolecular proton transfer ESIPT character. A full picture of the included photochemical mechanisms is given. Remarkably, 3-hydroxyflavone is also very efficient for photocomposites synthesis with glass fibers (thick samples with good depth of cure) using UV or LED@395 nm conveyor.
关键词： 3D printing,Cationic polymerization,Light-Emitting Diodes (LEDs),Free radical polymerization,photoinitiators,composites
更新于2025-09-23 15:21:21