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Peculiar Photoinduced Electron Transfer in Porphyrin-Fullerene Akamptisomers
摘要： Porphyrin-fullerene dyads are promising candidates for organic photovoltaic devices. Electron transfer (ET) properties of the molecular devices depend significantly on the mutual position of the donor and acceptor. Recently, a new type of molecular isomerism (akamptisomerism) has been discovered. In the present study, we explore how photoinduced ET can be modulated by passing from one akamptisomer to another. To this aim, four akamptisomers of quinoxalinoporphyrin–[60]fullerene complex are selected for the computational study. The most striking finding is that, depending on the isomer, the porphyrin unit in the dyad can act as either electron donor or electron acceptor. Thus, the stereoisomeric diversity allows one to change the direction of ET between the porphyrin and fullerene moieties. To understand the effect of akamptisomerism on the photoinduced ET processes a detailed analysis of initial and final states involved in the ET is performed. The computed rate for charge separation is estimated to be in the region of 1-10 ns-1. The formation of a long-living quinoxalinoporphyrin anion-radical species is predicted.
关键词： quinoxalinoporphyrin–[60]fullerene complex,Porphyrin-fullerene dyads,photoinduced electron transfer,organic photovoltaic devices,akamptisomerism
更新于2025-09-10 09:29:36
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Sensitive fluorescence sensor for point-of-care detection of trypsin using glutathione-stabilized gold nanoclusters
摘要： There is an urgent demand for on-site detection of biomarker, particularly in clinical diagnosis and therapeutics applications. Herein, we designed a convenient and sensitive fluorescence nanosensor for point-of-care determination of trypsin (TRY). The fluorescence intensity of gold nanoclusters (AuNCs) can be quenched by cytochrome c (Cyt c) via electron transfer mechanism. TRY specifically catalyzes the hydrolysis of Cyt c to produce small peptide fragments, inducing the significant fluorescence recovery. As a result, the AuNCs-based system processed a sensitive and selective response to TRY with the range 0.2-100 μg mL-1, accompanying a detection limit of 0.08 μg mL-1. Significantly, the sensing assay can be used to construct test strips for rapid and visual recognition of TRY. Combining with smartphone and ImageJ software, we further developed an image processing algorithm for quantitative detection of TRY with highly promising, which validated the potential point-of-care application.
关键词： Gold nanoclusters,Fluorescence,Electron transfer,Trypsin,Test strips
更新于2025-09-10 09:29:36
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Rapid, Specific, and Ultrasensitive Fluorogenic Sensing of Phosgene through an Enhanced PeT Mechanism
摘要： We report the design of an enhanced PeT-based fluorogenic phosgene probe 1-CN comprising a BODIPY fluorescence reporter, and a catechol quencher at the meso-position acting as the phosgene reaction site. The fluorescent catechol-derived probe 1-CN specifically reacts with phosgene to result in a cyclic carbonate ester. The fast (< 3 s) reaction suppresses a reductive PeT quenching process, leading to a fluorescence turn-on signal (up to ca. F/F0 ~ 1300). The high sensitivity (LOD = 24 pM) of the probe is achieved by the precise adjustment of the energy levels of the frontier orbitals involved in the PeT.
关键词： BODIPY,Phosgene,Fluorescent turn-on probe,Photoinduced electron transfer (PeT),Sensing
更新于2025-09-10 09:29:36
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Disentangling the Electron and Hole Dynamics in Janus CdSe/PbSe Nanocrystals through Variable Pump Transient Absorption Spectroscopy
摘要： CdSe/PbSe Janus hetero-nanocrystals (HNCs) represent an interesting system where structurally immiscible CdSe and PbSe co-exist in a single structure with intermixed electronic states. Here, we have investigated the carrier dynamics in Janus CdSe/PbSe HNCs through ultrafast transient absorption spectroscopy by selectively exciting either the CdSe or the PbSe domains. Upon excitation of the CdSe domain sub-picosecond hole transfer to the hybrid interfacial PbSe states were identified. On the other hand, the transfer of hot electron from PbSe to CdSe was evident upon creation of hot electrons in PbSe domain without exciting the CdSe domain. The photo-excited hot hole also gets transferred to the hybrid interfacial states in sub-ps time (~1ps) bleaching the corresponding transition. The decay of the localized hole was found to be much slower compared to the electron which can be beneficial for carrier extraction and multiexciton generation. The finding of hot electron transfer in a single structure and slow decay of holes can thus prove to be advantageous for future design of photovoltaic devices.
关键词： carrier dynamics,ultrafast transient absorption spectroscopy,CdSe/PbSe Janus hetero-nanocrystals,photovoltaic devices,hot electron transfer
更新于2025-09-10 09:29:36
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Highly Stable and Multifunctional Aza-BODIPY-Based Phototherapeutic Agent for Anticancer Treatment
摘要： Phototherapy, as an important class of noninvasive tumor treatment methods, has attracted extensive research interest. Although a large amount of the near-infrared (NIR) phototherapeutic agents have been reported, the low efficiency, complicated structures, tedious synthetic procedures, and poor photostability limit their practical applications. To solve these problems, herein, a donor?acceptor?donor (D?A?D) type organic phototherapeutic agent (B-3) based on NIR aza-boron-dipyrromethene (aza-BODIPY) dye has been constructed, which shows the enhanced photothermal conversion efficiency and high singlet oxygen generation ability by simultaneously utilizing intramolecular photoinduced electron transfer (IPET) mechanism and heavy atom effects. After facile encapsulation of B-3 by amphiphilic DSPE?mPEG5000 and F108, the formed nanoparticles (B-3 NPs) exhibit the excellent photothermal stabilities and reactive oxygen and nitrogen species (RONS) resistance compared with indocyanine green (ICG) proved for theranostic application. Noteworthily, the B-3 NPs can remain outstanding photothermal conversion efficiency (η = 43.0%) as well as continuous singlet oxygen generation ability upon irradiation under a single-wavelength light. Importantly, B-3 NPs can effectively eliminate the tumors with no recurrence via synergistic photothermal/photodynamic therapy under mild condition. The exploration elaborates the photothermal conversion mechanism of small organic compounds and provides a guidance to develop excellent multifunctional NIR phototherapeutic agents for the promising clinical applications.
关键词： heavy atom effects,intramolecular photoinduced electron transfer,donor?acceptor?donor type,NIR phototherapeutic agents,aza-BODIPY
更新于2025-09-10 09:29:36
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Bandgap Engineered Polypyrrole-Polydopamine Hybrid with Intrinsic Raman and Photoacoustic Imaging Contrasts
摘要： Intrinsically multimodal nanomaterials have revealed their great potential as a new class of contrast agents. We herein report a bandgap engineering strategy to develop an intrinsically Raman-photoacoustic (PA) active probe that is based on semiconducting conjugated polymers. This dual modal probe is prepared by doping a semiconducting conjugated polymer with polydopamine (PDA) through a one-pot reaction. When applied in the polypyrrole (PPy), this strategy can enhance Raman scattering and the PA amplitude of PPy-PDA hybrid by 3.2 and 2.4 times, respectively, so that both signals can be further applied in bioimaging. In the hybrid, such a dual-enhancement effect is achieved by infusing these two macromolecules at the nanoscale to reduce the optical bandgap energy. This work not only introduces a dual modal contrast agent but also provides a new method of manipulating semiconducting polymer’s inherent optical features for bioimaging.
关键词： intrinsically multimodal nanomaterials,semiconducting polymers,polydopamine,intermolecular electron transfer
更新于2025-09-10 09:29:36
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Photosensitization and Photocatalysis - Perspectives in Organic Synthesis
摘要： Photochemical sensitization and photocatalysis have very similar definitions and are closely related. Each of the two terms are preferentially used in different scientific communities. Three types of processes are discussed: (1) sensitization involving energy transfer, (2) photocatalysis in which hydrogen abstraction plays a key role and (3) photoredox catalysis in which electron transfer is involved. The processes are discussed in connection with [2+2] photocycloadditions and C-H activation, which are of particular interest for organic synthesis.
关键词： [2+2] Photocycloaddition,Photosensitization,Energy transfer,Hydrogen atom transfer,Electron transfer,C-H activation,Photocatalysis
更新于2025-09-09 09:28:46
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High-Energy Charge-Separated States by Reductive Electron Transfer Followed by Electron Shift in Tetraphenylethylene – Aluminum(III) Porphyrin – Fullerene Triad
摘要： A high potential supramolecular triad (TPE-AlPor?Im-C60) composed of aluminum(III) porphyrin (AlPor), fullerene (C60), and tetraphenylethylene (TPE) has been constructed. The fullerene and tetraphenylethylene units are bound axially to opposite faces of the porphyrin plane via coordination and covalent bonds, respectively. The ground and excited-state properties of the triad and reference dyads are studied using steady-state and time-resolved spectroscopic techniques. The transient data show that photoexcitation results in charge separation (CS) from tetraphenylethylene to the excited singlet state of the porphyrin (1AlPor*), generating high-energy (2.14 eV) charge-separated state, (TPE)?+-(AlPor)?? in toluene. A subsequent electron migration from the AlPor?? to fullerene generates a second high-energy (1.78 eV) charge-separated state (TPE)?+-AlPor?Im-(C60)??. The lifetime of the charge separation persists about 25 ns. The high energy stored in the form of charge-separated states along with its reasonable lifetimes makes these donor-acceptor systems potential electron-transporting catalysts to carry out energy-demanding photochemical reactions, especially in artificial photosynthesis for conversion of solar energy into chemical energy.
关键词： high-energy charge-separated states,aluminum(III) porphyrin,tetraphenylethylene,fullerene,reductive electron transfer,electron shift,triad
更新于2025-09-09 09:28:46
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Influence of Dye-Coordinated Metal Ions on Electron Transfer Dynamics at Dye–Semiconductor Interfaces
摘要： Maximizing regeneration and minimizing recombination rates at dye?semiconductor interfaces is crucial for the realization of efficient dye-sensitized solar and photoelectrosynthesis cells. Previously it has been shown that simply coordinating the metal ion to the nonsurface bound carboxylate groups of a dye molecule can slow recombination rates and increase open-circuit voltages. However, it was unclear if the additional steric effects or charge of the metal ion were the cause of this behavior. Here we use three different redox mediators, (1) I?/I3?, (2) [tris(1,10-phenanthroline)cobalt]3+/2+, and (3) [Co(4,4′,4″-tritert-butyl-2,2′:6′,2″-terpyridine)(NCS)3]0/1? to elucidate the role, if any, of electrostatic interactions between the coordinated metal ion and mediator in dictating these interfacial electron transfer events. Using a combination of spectroscopy, electrochemistry, and solar cell measurements, we demonstrate that while electrostatic interactions may influence dye regeneration rates, for example, increased steric bulk of the metal ion between TiO2(e?) and the oxidized mediator likely has a stronger influence on the overall device performance. Additionally, electrochemical impedance spectroscopy and intensity dependent measurements suggest that the coordination of the metal ion can slow diffusion of the mediators within the mesoporous oxide which could have implications for the use of multilayer assemblies in dye-sensitized devices.
关键词： redox mediator,regeneration,kinetics,dye-sensitized solar cells,electron transfer
更新于2025-09-09 09:28:46
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In-situ XPS Study of Core-levels of ZnO Thin Films at the Interface with Graphene/Cu
摘要： We have investigated core-levels of ZnO thin films at the interface with the graphene on Cu foil using in-situ X-ray Photoelectron Spectroscopy (XPS). Spectral evolution of C 1s, Zn 2p, and O 1s are observed in real time during RF sputtering deposition. We found binding energy (BE) shifts of Zn 2p and ‘Zn?O’ state of O 1s depending on ZnO film thickness. Core-levels BE shifts of ZnO will be discussed on the basis of electron transfer at the interface and it may have an important role in the electronic transport property of the ZnO/graphene-based electronic device.
关键词： In-situ XPS,Electron transfer,Graphene,Thin film,ZnO,Dipole,Interface
更新于2025-09-09 09:28:46