- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Long-lived triplet excited state in a platinum( <scp>ii</scp> ) perylene monoimide complex
摘要： We report the synthesis and solution based photophysical properties of a new Pt(II)-terpyridine complex coupled to a perylene monoimide (PMI) chromophoric unit through an acetylene linkage. This structural arrangement resulted in quantitative quenching of the highly fluorescent PMI chromophore by introducing metal character into the lowest energy singlet state, thereby leading to the formation of a long-lived PMI-ligand localized triplet excited state (τ = 8.4 μs). Even though the phosphorescence from this triplet state was not observed, highly efficient quenching of this excited state by dissolved oxygen and the observation of singlet oxygen photoluminescence in the near-IR at 1270 nm initially pointed towards triplet excited state character. Additionally, the coincidence of the excited state absorbance difference spectra from the sensitized PMI ligand using a triplet donor and the Pt-PMI complex provided strong evidence for this triplet state assignment, which was further supported by TD-DFT calculations.
关键词： singlet oxygen,perylene monoimide,photophysics,platinum(II) complex,triplet excited state
更新于2025-11-19 16:56:42
-
Dendrimeric nanoparticles for two-photon photodynamic therapy and imaging: synthesis, photophysical properties and cytotoxicity under two-photon irradiation in the NIR
摘要： The synthesis and the photophysical properties of a new class of fully organic monodisperse nanoparticles for combined two-photon imaging and photodynamic therapy are described. The design of such nanoparticle is based on the covalent immobilization of a dedicated quadrupolar dye - which combine large two-photon absorbing (2PA) properties, fluorescence and singlet oxygen generation ability - in a phosphorous-based dendrimeric architecture. Firstly, a bifunctional quadrupolar dye bearing two different grafting moieties, a phenol function and an aldehyde function, was synthesized. It was then covalently grafted through its phenol function to a phosphorus-based dendrimer scaffold of generation 1. The remaining aldehyde functions were then used to carry on the dendrimer synthesis up to generation 2 introducing finally at its periphery 24 water-solubilizing triethyleneglycol chains. A dendrimer confining 12 photoactive quadrupolar units in its inner scaffold and showing water solubility was thus obtained. Interestingly, the G1 and G2 dendrimers retain some fluorescence as well as significant singlet oxygen production efficiencies while they were found to show very high 2PA cross-sections in a broad range of the NIR biological spectral window. Hydrophilic dendrimer G2 was tested in vitro on breast cancer cells, first in one- and two-photon microscopy, which allowed for visualization of their cell internalization, then in two-photon photodynamic therapy. While being non-toxic in the dark and, more importantly, under daylight exposition, dendrimer G2 proved to be very efficient cell death inducer only under two-photon irradiation in the NIR.
关键词： photophysics,photodynamic therapy,dendrimers,imaging,fluorescence
更新于2025-09-23 15:23:52
-
Role of solvent H-bonding and polarity on photophysical properties of a benzothiazole-based ratiometric amyloid fibril sensor
摘要： Detailed photophysical properties of 2-[2′-Me,4′-(dimethylamino)-phenyl]benzothiazole (2Me-DABT), a potential ratiometric amyloid fibril sensor, have been investigated in different solvents and solvent mixtures using steady state and time-resolved spectroscopic techniques. Our studies show that emission properties of 2Me-DABT are significantly modulated by polarity of solvent media. Extent of solvatochromism (3585 cm?1) shown by 2Me-DABT is quite large and can be used to monitor micropolarity of different complex media. Further, Stokes’ shift (> 10,000 cm?1) shown by 2Me-DABT in all studied solvents is also much larger than most common molecular probes. It has also been shown that hydrogen bonding with solvent molecules results in large modulation in photophysical properties of 2Me-DABT. The H-bonding with water molecules induces a large change (39°) in the dihedral angle between benzothiazole and aniline moieties resulting large changes in photophysical properties of 2Me-DABT in polar protic solvents. Photophysical properties reported herein are used to explain observed amyloid sensing behaviour of 2Me-DABT. Detailed quantum chemical calculations are performed to support the experimental results.
关键词： Amyloid sensor,H-bonding,Photophysics,Time-resolved spectroscopy,Fluorescence
更新于2025-09-23 15:23:52
-
Photophysicochemical properties and photodynamic therapy activity of chloroindium(III) tetraarylporphyrins and their gold nanoparticle conjugates
摘要： Novel chloroindium(III) complexes of tetra(4-methylthiophenyl)porphyrin (2a) and tetra-2-thienylporphyrin (2b) dyes have been synthesized and characterized. The main goal of the project was to identify fully symmetric porphyrin dyes with Q-band regions that lie partially in the therapeutic window that are suitable for use in photodynamic therapy (PDT). 2a and 2b were found to have fluorescence quantum yield values ≤ 0.01 and moderately high singlet oxygen quantum yields (0.54?0.73) due to heavy atom effects associated with the sulfur and indium atoms. The dark toxicity and PDT activity against epithelial breast cancer cells (MCF-7) were investigated over a dose range of 3.0?40 mg . mL-1. The in vitro dark cytotoxicity of 2a is significantly lower than that of 2b at ≤ 40 mg . mL-1. 2a was conjugated with gold nanoparticles (AuNPs) to form a nanoconjugate (2a-AuNPs), which exhibited a higher singlet oxygen quantum yield (FD) value and PDT activity than was observed for 2a alone. The results suggest that the AuNPs nanoconjugates of readily synthesized fully symmetric porphyrin dyes are potentially suitable for PDT applications, if meso-aryl substituents that provide scope for nanoparticle conjugation can be introduced that shift the Q bands into the therapeutic window.
关键词： porphyrins,photophysics,dark toxicity,singlet oxygen,gold nanoparticles,photodynamic therapy
更新于2025-09-23 15:22:29
-
Photonics of boron(III) and zinc(II) dipyrromethenates as active media for modern optical devices
摘要： Photonics of complexes of p- and d-elements with dipyrromethenates is investigated. The role of substituents (their type and localization in the ligand) and of the medium in which dipyrromethenates are placed (solvents, gas mixtures, or solid matrices) is discussed as well as the effect of complexing agents on photonics of the examined complexes. The possibilities for dipyrromethenates application as liquid and solid state laser active media, sensor media for determining the oxygen concentration in a gas mixture, and photosensitizers for singlet oxygen generation in optical devices are presented.
关键词： Photochemistry,Dipyrromethenates,Sensorics,Photophysics,Lasing,Photosensitization
更新于2025-09-23 15:22:29
-
Heteroleptic Ir(III)N6 Complexes with Long-Lived Triplet Excited States and In Vitro Photobiological Activities
摘要： A series of cationic heteroleptic iridium(III) complexes bearing tris-diimine ligands [Ir(phen)2(R-phen)]3+ (R-phen = phenanthroline (1), 3,8-diphenylphenanthroline (2), 3,8-dipyrenylphenanthroline (3), 3-phenylphenanthroline (4), 3-pyrenylphenanthroline (5), and 3,8-diphenylethynylphenanthroline (6)) were synthesized and characterized. These complexes possessed phen ligand-localized 1π,π* transitions below 300 nm, and charge transfer (1CT) and/or 1π,π* transitions between 300 and 520 nm. In 1, 2, 4, and 6, the low-energy bands were mixed 1CT/1π,π*. However, the increased π-donating ability of the pyrenyl substituent(s) in 3 and 5 split the low-energy bands into a pyrene-based 1π,π* transition at 300-380 nm and an intraligand charge transfer (1ILCT) transition at 380-520 nm. All complexes were emissive at room temperature in CH3CN, but the parentage of the emitting state varied depending on the R substituent(s). Complex 1 exhibited predominantly phen ligand-localized 3π,π* emission mixed with metal-to-ligand charge transfer (3MLCT) character, while the emission of 2, 4, and 6 was predominantly from the excited-state with 3π,π*/3ILCT/3MLCT character. The emission from 3 and 5 was dominated by pyrene-based 3π,π* states mixed with 3ILCT character. The different natures of the lowest triplet excited states were also reflected by the different spectral features and lifetimes of the triplet transient absorption of these complexes. Complexes 3 and 5 had singlet oxygen quantum yields as high as 81 and 72%, respectively. Both gave submicromolar phototoxicities toward cancer cells (SK-MEL-28 human melanoma) and bacteria (S. aureus and S. mutans) with visible light activation (and marginal to no photobiological activity with red light). Their visible-light phototherapeutic indices (PIs) toward SK-MEL-28 cells were 248 for 3 and >435 for 5; PIs were lower in bacteria (≤62) due to their inherent antimicrobial activities. Both complexes were shown to produce substantial amounts of intracellular reactive oxygen species (ROS), which may account for their photobiological activities.
关键词： photophysics,photodynamic therapy,long-lived triplet excited state,antimicrobial,photobiological activities,reactive oxygen species,heteroleptic Ir(III) trisdiimine complexes
更新于2025-09-23 15:22:29
-
The impact of replacement of nitrogen with phosphorus atom in the pyromellitic diimides on their photophysical and electrochemical properties
摘要： Exploration of optoelectronic properties of novel phosphorus-embedded π-conjugated compounds would provide us with fundamental information about the design of hitherto unknown electroactive organic materials. Herein, detailed photophysical and electrochemical profiles of a series of benzene-cored diketophosphanyl compounds were investigated with steady- and time-resolved spectroscopic and spectroelectrochemical techniques. The comparative studies revealed the impact of phosphorus and nitrogen atoms on their triplet energies and on the behaviour of electrochemical processes to form radical species.
关键词： photophysics,phosphorus heterocycles,π-conjugated compounds,radical,electrochemistry
更新于2025-09-23 15:21:21
-
Quantifying the Oligomeric States of Membrane Proteins in Cells through Super-Resolution Localizations
摘要： Transitions between different oligomeric states of membrane proteins are essential for proper cellular functions. However, the quantification of their oligomeric states in cells is technically challenging. Here we developed a new method to quantify oligomeric state(s) of highly-expressed membrane proteins using the probability density function of molecule density (PDFMD) calculated from super-resolution localizations. We provided the theoretical model of PDFMD, discussed the effects of protein concentration, cell geometry and photophysics of fluorescent proteins on PDFMD, and provided experimental criteria for proper quantification of oligomeric states. This method was further validated using simulated single-molecule fluorescent movies, and applied to two membrane proteins, UhpT and SbmA in E. coli. The study shows that PDFMD is useful in quantifying oligomeric states of membrane proteins in cells that can help in understanding cellular tasks. Potential applications to proteins with higher oligomeric states under high concentration and limitation of our methodology were also discussed.
关键词： PALM,Photophysics,Protein concentration,Cell geometry,Single molecule
更新于2025-09-23 15:21:01
-
Synthesis, Photophysics, and Switchable Luminescence Properties of a New Class of Ruthenium(II)–Terpyridine Complexes Containing Photoisomerizable Styrylbenzene Units
摘要： We report here the synthesis and structural characterization of a new class of homoleptic terpyridine complexes of Ru(II) containing styrylbenzene moieties to improve room-temperature luminescence properties. Solid-state structure determination of 2 was done through single-crystal X-ray diffraction. Tuning of photophysical properties was done by incorporating both electron-donating and electron-withdrawing substituents in the ligand. The complexes exhibit strong emission having lifetimes in the range of 10.0?158.5 ns, dependent on the substituent and the solvent. Good correlations were also observed between Hammett σ p parameters with the lifetimes of the complexes. Styrylbenzene moieties in the complexes induce trans?trans to trans?cis isomerization accompanied by huge alteration of their spectral profiles upon treating with UV light. Reversal of trans?cis to trans?trans forms was also achieved on interacting with visible light. Change from trans?trans to the corresponding trans?cis form leads to emission quenching, whereas trans?cis to the corresponding trans?trans form leads to restoration of emission. In essence, “on?off” and “off?on” photoswitching of luminescence was observed. Calculations involving density functional theory (DFT) and time-dependent-DFT methods were performed to understand the electronic structures as well as for appropriate assignment of the absorption and emission bands.
关键词： Ruthenium(II)?Terpyridine Complexes,Photophysics,Switchable Luminescence,Styrylbenzene Units,Photoisomerization
更新于2025-09-23 15:21:01
-
MEH-PPV photophysics: insights from the influence of a nearby 2D quencher
摘要： The effect of 2D quenching on single chain photophysics was investigated by spin coating 13 nm thick films of polystyrene lightly doped with MEH-PPV onto CVD grown graphene and observing the changes in several photoluminescent (PL) observables. With 99% of the PL quenched, we found a 60% drop in the PL lifetime, along with a significant blue-shift of the PL emission due to the preferential quenching of emission at longer wavelengths. During photo-bleaching, the blue spectral shift observed for isolated polymers was eliminated in the presence of the quencher up until 70% of the polymer was photo-bleached. Results were interpreted using a static disorder induced conjugation length distribution model. The quencher, by opening up a new non-radiative decay channel, ensures that excitons do not have sufficient time to migrate to nearby lower energy chromophores. The reduction of energy transfer into the lowest-energy chromophores thus reduces their rate of photo-bleaching. Finally, the difference between the quenched and non-quenched spectra allows the rate of energy transfer along the polymer backbone to be estimated at ～2 ns?1.
关键词： fluorescence lifetime,photo-bleaching,photophysics,conjugated polymers,fluorescence quenching,single molecules,graphene
更新于2025-09-23 15:19:57