- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Stereospecific [2+2]-cross-photocycloaddition in a supramolecular donor–acceptor complex
摘要： A bis(propylammonium) derivative of (E)-4-(4-mercaptostyryl)pyridine, which was synthesized for the first time, forms a highly stable bimolecular complex with a bis(18-crown-6 ether) derivative of (E)-stilbene in solution owing to ditopic coordination via hydrogen bonds. The complex formation results in much faster deactivation of the excited states of both compounds, which is explained by photoinduced electron transfer from the stilbene derivative to the styrylpyridinium dye. Despite this, the complexed olefins undergo [2+2]-cross-photocycloaddition upon selective excitation of the dye to afford solely the syn-cycloadduct. The retro-photocycloaddition occurs readily upon UV irradiation of the cycloadduct and leads to the initial bimolecular complex.
关键词： Photoinduced electron transfer,Donor–acceptor systems,Cross-photocycloaddition,Self-assembly
更新于2025-09-10 09:29:36
-
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
-
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
-
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
-
Tuning Photoinduced Electron Transfer Efficiency of Fluorogenic BODIPY- <i>α</i> -Tocopherol Analogues
摘要： Fluorogenic analogues of α-tocopherol developed by our group have been instrumental in monitoring reactive oxygen species (ROS) within lipid membranes. Prepared as two-segment trap-reporter (chromanol-BODIPY) probes, photoinduced electron transfer (PeT) was utilized to provide these probes with an off/on switch mechanism warranting the necessary sensitivity. Herein we rationalize within the context of Marcus theory of electron transfer how substituents on the BODIPY core and linker length joining the trap and reporter segments, tune PeT efficiency. DFT and electrochemical studies were used to estimate the thermodynamic driving force of PeT in our constructs. By tuning the redox potential over a 400 mV range, we observed over an order of magnitude increase in PeT efficiency. Increasing the linker length between the chromanol and BODIPY by 2.8 angstroms in turn decreased PeT efficiency 2.7-fold. Our results illustrate how substituent and linker choice enable “darkening” the off state of fluorogenic probes based on BODIPY fluorophores, by favoring PeT over radiative emission from the singlet excited state manifold. Ultimately, our work brings light to the sensitivity ceiling one may achieve in developing fluorogenic antioxidants analogues of α-tocopherol. The work provides general guidelines applicable to those developing fluorogenic probes based on PeT.
关键词： electrochemical studies,α-tocopherol,lipid membranes,reactive oxygen species,redox potential,photoinduced electron transfer,Marcus theory,DFT,Fluorogenic analogues,BODIPY
更新于2025-09-09 09:28:46
-
Background-free fluorescence decay time sensing and imaging of pH with highly photostable diazaoxotriangulenium dyes
摘要： Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic receptor groups inducing fluorescence quenching via photoinduced electron transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent pK’a values ~5 and 7.5 for the p,p-dichlorophenol- and the p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetime (17-20 ns), high quantum yield (~60%) and high photostability. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behaviour which makes them suitable for studying 2D pH distribution with help of fluorescence lifetime imaging technique. The lifetime response is particularly pronounced for the sensors with high dye concentration (0.5-1% wt. in respect to the polymer) and is attributed to efficient homo-FRET mechanism.
关键词： pH sensor,photoinduced electron transfer,Decay time,triangulenium,Frequency Domain FLIM,FRET
更新于2025-09-09 09:28:46