- 标题
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Versatile and Switchable Responsive Properties of a Lanthanide-Viologen Metal-Organic Framework
摘要： Metal–organic frameworks (MOFs) provide intriguing platforms for the design of responsive materials. It is challenging to mobilize as many components as possible of a MOF to collaboratively accomplish multiple responsive properties. Here, reversible photochromism, piezochromism, hydrochromism, ionochromism, and luminescence modulation of an ionic Eu(III) MOF is reported furnished by cationic electron-deficient viologen units and exchangeable guest anions. Mechanistically, the extraordinarily versatile responsive properties are owed to electron transfer (ET), charge transfer (CT), and energy transfer, involving viologen as electron acceptor, anion as electron donor, luminescing Eu(III) as energy donor, and anion-viologen CT complex or ET-generated radical as energy acceptor (luminescence quencher). Moreover, guest anions and waters provide flexible handles to control the ET-based responsive properties. Water release/reuptake or exchange with organic solvents can switch on/off the response to light, while reversible anion exchange can disenable or awaken the responses to pressure, light, and water release/reuptake. The impacts of water and anions on ET are justified by the high polarity and hydrogen-bonding capability of water, the different electron donor strength of anions, and the strong I?-viologen CT interactions. The rich responsive behaviors have great implications for applications such as pressure sensors, iodide detection, and chemical logic gates.
关键词： metal–organic frameworks,electron transfer,charge transfer,luminescence switches,piezochromism
更新于2025-09-23 15:23:52
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Towards the Development of Photo‐Reactive Ruthenium(II) Complexes Targeting Telomeric G‐Quadruplex DNA
摘要： The design and characterization of new ruthenium(II) complexes aimed at targeting G-quadruplex DNA is reported. Importantly, these complexes are based on oxidizing 1,4,5,8-tetraazaphenanthrene (TAP) ancillary ligands known to favour photo-induced electron transfer (PET) with DNA. The photochemistry of complexes 1–4 has been studied by classical methods, which revealed two of them to be capable of photo-abstracting an electron from guanine. From studies of the interactions with DNA through luminescence, circular dichroism, bio-layer interferometry, and surface plasmon resonance experiments, we have demonstrated the selectivity of these complexes for telomeric G-quadruplex DNA over duplex DNA. Preliminary biological studies of these complexes have been performed: two of them showed remarkable photo-cytotoxicity towards telomerase-negative U2OS osteosarcoma cells, whereas very low mortality was observed in the dark at the same photo-drug concentration.
关键词： ruthenium complexes,photo-electron transfer,photocytotoxicity,G-quadruplexes,DNA structures
更新于2025-09-23 15:23:52
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Photonics of tetramethoxy-1,4-distyrylbenzene
摘要： Photonics of tetramethoxy-1,4-distyrylbenzene in MeCN was studied by absorption, luminescence, and laser kinetic spectroscopies. Photoinduced transformations of the compound in question involve cis—trans-isomerization, intersystem crossing, fast and delayed fluorescence, and electron transfer. The ground-state structure and vibrational spectrum, as well as the energies and structures of excited singlet and triplet states were calculated by the DFT/PBE and TDDFT/PBE0 methods. The assignment of vibronic bands in the absorption spectra was made and the energies of corresponding transitions were calculated.
关键词： triplet state,trans—cis-photoisomerization,electron transfer,delayed fluorescence
更新于2025-09-23 15:23:52
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[Zn(OOCH)2(4,4′-bipyridine)] : A metal-organic-framework (MOF) with x-ray-induced photochromic behaviour at room temperature
摘要： Materials that may show photochromism under X-rays have higher spatial resolution for visual low-energy X-rays detection over the commercial instruments and greater X-ray sensitivity than silver salt-based radiographic films. In this work, we discovered that the known MOF, [Zn(OOCH)2(Bpy)]n (Bpy = 4,4′-bipyridine), showed rare photochromic behaviour upon irradiation of hard and soft X-rays at room temperature.
关键词： Metalloviologen,MOF,Photochromic,Radical,X-ray detection,Electron transfer
更新于2025-09-23 15:23:52
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Excited State Dynamics of [Ru(bpy)3]2+ Thin Films on Sensitized TiO2 and ZrO2
摘要： The excited state dynamics of Tris(2,2'-bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy)3(PF6)2], was investigated on the surface of bare and sensitized TiO2 and ZrO2 films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern-Volmer plot of LEG4-sensitized TiO2 substrates with a spin-coated [Ru(bpy)3(PF6)2] layer on top shows considerable quenching of the emission of the latter. Time-resolved emission spectroscopy interestingly reveals the presence of a fast-decay time component (25±5 ns), which is absent when the anatase TiO2 semiconductor is replaced by ZrO2. It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy)3(PF6)2] ground state into the oxidized sensitizer. Therefore, we speculate that the fast-decaying time component observed may be identified with excited-state electron transfer from [Ru(bpy)3(PF6)2] to the oxidized sensitizer. Solid-state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy)3(PF6)2] employed as a hole-transporting material (HTM), exhibit 1.2% and 1.1% power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited-state electron transfer.
关键词： Photochemistry,Excited-state electron transfer,DSSCs,Ru(bpy)3,Solid state
更新于2025-09-23 15:23:52
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Enhanced oxytetracycline removal coupling with increased power generation using a self-sustained photo-bioelectrochemical fuel cell
摘要： Photo-bioelectrochemical fuel cell (PBFC) represents a promising technology for enhancing removal of antibiotic pollutants while simultaneously sustainable transformation of organic wastes and solar energy into electricity. In this study, simultaneous antibiotic removal and bioelectricity generation were investigated in a PBFC with daily light/dark cycle using oxytetracycline (OTC) as a model compound of antibiotic. The specific OTC removal rate increased by 61% at an external resistance of 50 U compared to that in the open-circuit control, which was attributed to bioelectrochemically enhanced co-metabolic degradation in the presence of the bioanode. The OTC removal was obviously accelerated during illumination of cathode in contrast with a dark cathode due to the higher driving force for anodic bioelectrochemical reaction by using photosynthetic oxygen as cathodic electron acceptor during illumination than that using nitrate in dark. The bioelectrocatalytic activity of anodic biofilm was continuously enhanced even at an initial OTC concentration of up to 50 mg L?1. The degradation products of OTC can function as mediators to facilitate the electron transfer from bacteria to the anode, resulting in 1.2, 1.76 and 1.8 fold increase in maximum power output when 10, 30 and 50 mg L?1 OTC was fed to the bioanode, compared to the OTC-free bioanode, respectively. The OTC feeding selective enriched OTC-tolerant bacterial community capable of degrading complex organic compounds and producing electricity. The occurrence of ARGs during bioelectrochemical degradation of OTC was affected more greatly by the succession of the anodic bacterial community than the initial OTC concentration.
关键词： Bioanode,Electron transfer,Oxytetracycline removal,Photo-bioelectrochemical fuel cell
更新于2025-09-23 15:23:52
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Merging Photoredox PCET with Ni-Catalyzed Cross-Coupling: Cascade Amidoarylation of Unactivated Olefins
摘要： A rapid, highly diastereoselective amidoarylation of unactivated olefins was achieved to render medicinally privileged pyrrolidinone structures. Taking advantage of a photoredox proton-coupled electron transfer process, amidyl radicals were obtained from non-prefunctionalized N–H bonds under mild conditions, which were subsequently trapped by pendant olefins, delivering alkyl radicals for nickel-catalyzed cross-coupling. Mechanistic studies revealed the key balance between thermodynamically-driven radical generation and kinetically-driven cyclization, which led to expanding the scope toward urea and carbamate substrates.
关键词： urea,nickel catalysis,carbamate,unactivated olefins,proton-coupled electron transfer,amidoarylation,photoredox catalysis,pyrrolidinone
更新于2025-09-23 15:23:52
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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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Photoinduced electron transfer kinetics of linked Ru-Co photocatalyst dyads
摘要： Two new supramolecular photocatalyst dyads based on the [Ru(2,2′-bipyridine)3]2+ photosensitizer linked to a macrocyclic Co(II)tetra(pyridyl) catalyst for proton reduction are reported. The dyads differ primarily in the bridging ligand which links the molecular modules; the first being a short and flexible linker, and the second a longer and electronically conjugated linker. Ultrafast transient optical spectroscopy was used to monitor the photoinduced kinetics of the dyads following visible excitation of the photosensitizer module. Direct comparison of transient spectra and kinetics indicates that there are indeed substantial differences between the ultrafast transient optical spectroscopy of the dyads, but there is no indication of oxidative quenching of the photosensitizer module by the catalyst module. These initial design and characterization studies of the linked Ru(II)—Co(II) dyads provide an important foundation for advanced designs of systems for efficient solar energy conversion by molecular architectures.
关键词： Ruthenium,Cobalt,Photoinduced electron transfer,Modular assembly,Photocatalyst dyads
更新于2025-09-23 15:22:29
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Synthesis and Properties of Novel Fluorescence Probe Based on 1,8-Naphthalimide for Detection of Hydrogen Sulfide
摘要： Two fluorescence-enhanced probes, 4-(2,4-dinitrophenoxy)-N-(2-hydroxyethyl)-1,8-naphthalimide(NTE-1) and 4-(2,4-dinitrophenoxy)-N-(4-(2,4-dinitrophenoxy)phenyl)-1,8-naphthalimide(NTE-2), have been designed and synthesized for detection of H2S. 4-Hydroxy-1,8-naphthalimide as fluorophore in combination with 2,4-dinitrophenyl ether as H2S response site constructed the fluorescence probes. The consequences showed that both NTE-1 and NTE-2 displayed large red-shift(excess 100 nm) in absorption spectra and more than 30-fold fluorescence enhancement in response to H2S. Moreover, the dual site probe, NTE-2, displayed wider linear range between fluorescence intensity and concentration of H2S(0—40 μmol/L) compared with single site probe, which can be applied to quantitative detection of high concentration of H2S. The photoinduced electron transfer(PET) response mechanism of probe was further studied by analyzing the distributions of molecular orbital. Importantly, the probes have potential practical applications in detection of H2S.
关键词： 2,4-Dinitrophenyl ether,Photoinduced electron transfer,Gaussian,Dual site
更新于2025-09-23 15:22:29