首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
A covalently linked BODIPY−fullerene C60 dyad (BDP−C60) was synthesized as a two-segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C60 to inactivate bacteria. The absorption spectrum of BDP−C60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C60. Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 μM BDP−C60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activated photodynamic action of BDP−C60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP−C60 is an interesting photosensitizing structure in which the light-harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria.  相似文献   

2.
Despite significant effort, a majority of heavy-atom-free photosensitizers have short excitation wavelengths, thereby hampering their biomedical applications. Here, we present a facile approach for developing efficient near-infrared (NIR) heavy-atom-free photosensitizers. Based on a series of thiopyrylium-based NIR-II (1000–1700 nm) dyads, we found that the star dyad HD with a sterically bulky and electron-rich moiety exhibited configuration torsion and significantly enhanced intersystem crossing (ISC) compared to the parent dyad. The electron excitation characteristics of HD changed from local excitation (LE) to charge transfer (CT)-domain, contributing to a ≈6-fold reduction in energy gap (ΔEST), a ≈10-fold accelerated ISC process, and a ≈31.49-fold elevated reactive oxygen species (ROS) quantum yield. The optimized SP@HD-PEG2K lung-targeting dots enabled real-time NIR-II lung imaging, which precisely guided rapid pulmonary coronavirus inactivation.  相似文献   

3.
M. Elisa Milanesio 《合成通讯》2013,43(15):2135-2144
A covalently linked porphyrin–fullerene C60 dyad 6 was conveniently synthesized by 1,3‐dipolar cycloaddition using 5‐(4‐carbonylphenyl)‐10,15,20‐tris(4‐methoxylphenyl)porphyrin 5, N‐methylglycine and fullerene C60. Spectroscopic studies show that dyad 6 is a promising architecture with potential application as photoactive organic material.  相似文献   

4.
Few-layer black phosphorus (BP) nanosheets show potential application in biomedicine such as photodynamic therapy (PDT), and are therefore commonly used in anticancer therapy and nanomedicine due to being relatively less invasive. However, they suffer from low ambient stability and poor therapeutic efficacy. Herein, C60 was covalently grafted onto the edges of BP nanosheets, and the resultant BP-C60 hybrid was applied as a novel endocytosing photosensitizer, resulting in not only significantly enhanced PDT efficacy relative to that of the pristine BP nanosheets, but also drastically improved stability in a physiological environment, as confirmed by both in vitro and in vivo studies. Such improved stability was due to shielding effect of the stable hydrophobic C60 molecules. The enhanced PDT efficacy is interpreted from the photoinduced electron transfer from BP to C60, leading to the promoted generation of ˙OH radicals, acting as a reactive oxygen species (ROS) that is effective in killing tumor cells. Furthermore, the BP-C60 hybrid exhibited low systemic toxicity in the major organs of mice. The BP-C60 hybrid represents the first BP-fullerene hybrid nanomaterial fulfilling promoted ROS generation and consequently enhanced PDT efficacy.

Covalently grafting C60 molecules onto black phosphorus (BP) nanosheets improves their tumor inhibition rate from 36.6% to 88.2%.  相似文献   

5.
Novel phenylene-bridged zinc bisporphyrins (1-4), fulleropyrrolidines (C60-m, C60-h) and their N-oxides (C60-mo, C60-ho) were synthesized. The fluorescence quenching processes of bisporphyrins in toluene solution by fulleropyrrolidines and their N-oxides were investigated by steady-state fluorescence spectra. The fluorescence quenching constants proved that the fluorescence quenching ability was decreased as reduction of the pyrrolidine functional groups of fullerene surface: C60-h〉C60-m〉C60, and the fluorescence quenching ability was increased about 1.3-7.4 times by utilizing fulleropyrrolidine N-oxides (C60-mo, C60-ho) compared to fulleropyrrolidine compounds (C60-m, C60-h). The results revealed photoinduced electron transfer (PET) efficiency between bispor-phyrin and fullerene derivatives could be tunable by change of functional groups on fullerene surface.  相似文献   

6.
A coumarin derivative with a malonate unit has been synthesized and used for the preparation of a fullerene–coumarin dyad through the Bingel cyclopropanation method. The newly synthesized dyad is soluble in organic solvents and has been fully characterized with traditional spectroscopic techniques. Electronic interactions between the two components of the dyad were probed with the aid of UV/Vis spectroscopy, fluorescence emission, and electrochemistry measurements. Our studies clearly show the presence of electronic interactions between C60 and modified coumarin in the ground state; efficient electron‐transfer quenching of the singlet excited state of the coumarin moiety by the appended fullerene sphere was also observed. Time‐resolved fluorescence measurements revealed lifetimes for the coumarin–C60 dyad at a maximum of 50 ps, while the quantum yield was reaching unity. Additionally, the redox potentials of the C60–coumarin dyad were determined and the energetics of the electron‐transfer processes were evaluated. Finally, after alkaline treatment of C60–coumarin, which resulted in the deprotection of carboxylate units, the dyad was tested as a metal receptor for divalent metal cations; ion competition studies and fluorescence experiments showed binding selectivity for lead ions.  相似文献   

7.
Water-soluble fullerenes prepared by using solubilizing agents based on natural products are promising photosensitizers for photodynamic therapy. Cyclodextrin, β-1,3-glucan, lysozyme, and liposomes can stably solubilize not only C60 and C70, but also some C60 derivatives in water. To improve the solubilities of fullerenes, specific methods have been developed for each solubilizing agent. Water-soluble C60 and C70 exhibit photoinduced cytotoxicity under near-ultraviolet irradiation, but not at wavelengths over 600 nm, which are the appropriate wavelengths for photodynamic therapy. However, dyad complexes of solubilized C60 derivatives combined with light-harvesting antenna molecules improve the photoinduced cytotoxicities at wavelengths over 600 nm. Furthermore, controlling the fullerene and antenna molecule positions within the solubilizing agents affects the performance of the photosensitizer.  相似文献   

8.
When irradiated, fullerene efficiently generates reactive oxygen species (ROS) and is an attractive photosensitizer for photodynamic therapy (PDT). Ideally, photosensitizers for PDT should be water-soluble and tumor-specific. Because cancer cells endocytose glucose more effectively than normal cells, the characteristics of fullerene as a photosensitizer were improved by combining it with glucose. The cytotoxicity of PDT was studied in several cancer cell lines cultured with C60-(Glc)1 (d -glucose residue pendant fullerene) and C60-(6Glc)1 (a maltohexaose residue pendant fullerene) subsequently irradiated with UVA1. PDT alone induced significant cytotoxicity. In contrast, PDT with the glycoconjugated fullerene exhibited no significant cytotoxicity against normal fibroblasts, indicating that PDT with these compounds targeted cancer cells. To investigate whether the effects of PDT with glycoconjugated fullerene were because of the generation of singlet oxygen (1O2), NaN3 was added to cancer cells during irradiation. NaN3 extensively blocked PDT-induced apoptosis, suggesting that PDT-induced cell death was a result of the generation of 1O2. Finally, to investigate the effect of PDT in vivo, melanoma-bearing mice were injected intratumorally with C60-(Glc)1 and irradiated with UVA1. PDT with C60-(Glc)1 suppressed tumor growth. These findings indicate that PDT with glycoconjugated fullerene exhibits tumor-specific cytotoxicity both in vivo and in vitro via the induction of 1O2.  相似文献   

9.
To develop n-type processable polymeric materials for photovoltaic applications, a series of polymers was synthesized by grafting fullerene C60 onto polystyrene (PS). Grafted polymers were studied and compared with PS:fullerene blends. Electronical and electrical properties were first measured to define the minimal amount of C60 required for solar cells application. Then, thermal properties and rheological behavior of grafted polymers were analyzed to determine whether they could be processed from the melt. A throughout experimental study revealed that C60-grafted polymers exhibit two thresholds. The first threshold at 3–4 vol % (detected by electrical conductivity, electron mobility, and melt viscosity measurements) is associated to the percolation of C60 molecules. The second threshold (evidenced by glass transition and melt viscosity measurements and confirmed by optical and atomic force micrograph observations) at about 12–13 vol % is assumed to be related to the formation of C60 aggregates. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013  相似文献   

10.
A new amide‐linked phthalocyanine‐fullerene dyad ZnPc‐C60 was synthesized and characterized. The photophysical and electrochemical properties of the ZnPc‐C60 dyad were investigated. The fluorescence spectrum and quantum yield in different solvents showed the occurrence of photoinduced electron transfer (PET) from the singlet excited ZnPc to C60, which was further confirmed by nanosecond transient absorption spectra and cyclic voltammetry data. The free energy change for charge separation (ΔGCS) was estimated to be exothermic with ?0.51 eV, which favored the formation of charge‐separation state. The PET from ZnPc to C60 in ZnPc‐C60 made the dyad exhibit stronger reverse saturable absorption performance compared with C60 and the control sample in the Z‐scan experiments, which indicated the synergistic effect of two active moieties in the dyad.  相似文献   

11.
High oxidation potential perfluorinated zinc phthalocyanines (ZnFnPcs) are synthesised and their spectroscopic, redox, and light‐induced electron‐transfer properties investigated systematically by forming donor–acceptor dyads through metal–ligand axial coordination of fullerene (C60) derivatives. Absorption and fluorescence spectral studies reveal efficient binding of the pyridine‐ (Py) and phenylimidazole‐functionalised fullerene (C60Im) derivatives to the zinc centre of the FnPcs. The determined binding constants, K, in o‐dichlorobenzene for the 1:1 complexes are in the order of 104 to 105 M ?1; nearly an order of magnitude higher than that observed for the dyad formed from zinc phthalocyanine (ZnPc) lacking fluorine substituents. The geometry and electronic structure of the dyads are determined by using the B3LYP/6‐31G* method. The HOMO and LUMO levels are located on the Pc and C60 entities, respectively; this suggests the formation of ZnFnPc.+–C60Im.? and ZnFnPc.+–C60Py.? (n=0, 8 or 16) intra‐supramolecular charge‐separated states during electron transfer. Electrochemical studies on the ZnPc–C60 dyads enable accurate determination of their oxidation and reduction potentials and the energy of the charge‐separated states. The energy of the charge‐separated state for dyads composed of ZnFnPc is higher than that of normal ZnPc–C60 dyads and reveals their significance in harvesting higher amounts of light energy. Evidence for charge separation in the dyads is secured from femtosecond transient absorption studies in nonpolar toluene. Kinetic evaluation of the cation and anion radical ion peaks reveals ultrafast charge separation and charge recombination in dyads composed of perfluorinated phthalocyanine and fullerene; this implies their significance in solar‐energy harvesting and optoelectronic device building applications.  相似文献   

12.
Synthesis of Sulfolenobilins and Their Cyclization Directed to Chlorinatozinc‐Fullerene Dyads A novel chlorinatozinc‐fullerene dyad 18 was synthesized to model the photosynthetic reaction center. The synthetic key step for the formation of the dyad 18 is an unusual one‐pot reaction of the (sulfolenobilinato)nickel rac‐ 16a , b with concomitant generation of the chlorin macrocycle and linkage to the [5,6]fullerene‐C60Ih. This one‐pot reaction is a complex cascade of single reaction steps with a total yield of 32% and an average yield of 83% for the individual steps. The chlorinatozinc‐fullerene dyad is so far one of three examples that contain chlorin moieties, the chromophores in naturally occurring photosynthetic systems.  相似文献   

13.
The synthesis of a new azafullerene C59N–phthalocyanine (Pc) dyad is described. The key step for the synthesis of the C59N–Pc dyad was the formation of the C59N‐based carboxylic acid, which was smoothly condensed with hydroxy‐modified Pc. The structure of the C59N–Pc dyad was verified by 1H and 13C NMR spectroscopy, IR spectroscopy, UV/Vis spectroscopy and MS measurements. The photophysical and electrochemical properties of the C59N–Pc dyad were investigated in both polar and non‐polar solvents by steady state and time‐resolved photoluminescence and absorption spectroscopy, as well as by cyclic voltammetry. Different relaxation pathways for the photoexcited C59N–Pc dyad, as a result of changing the solvent polarity, were found, thus giving rise to energy‐transfer phenomena in non‐polar toluene and charge‐transfer processes in polar benzonitrile. Finally, the detailed quenching mechanisms were evaluated and compared with that of a C60–Pc dyad, which revealed that the different excited‐state energies and reduction potentials of the two fullerene spheres (i.e. C59N vs. C60) strongly diverged in the deactivation pathways of the excited states of the corresponding phthalocyanine dyads.  相似文献   

14.
The synthesis of a porphyrin–fullerene dyad with “parachute” topology is reported. To determine whether the dyad is “flexing” at room temperature, low‐temperature NMR experiments were used. Computational modeling has shown the low‐energy conformation of the dyad to be nonsymmetric. Although, 1H NMR spectroscopy at room temperature is consistent with a molecule with C2v symmetry, the spectrum changes on lowering the temperature consistent with “windshield wiper”‐like motion, in which the porphyrin moiety rotates from one side of the C60 sphere to the other. Nanosecond and picosecond fluorescence lifetime experiments show two components contribute to the fluorescence decay, also consistent with the presence of more than one conformer.  相似文献   

15.
By grafting polystyryllithium (PSLi) or polyisoprenyllithium (PILi) onto the fullerene borne by the mono-adduct polystyrene (PS)-C60 (≈90%) obtained upon reacting the fullerene with azide-terminated PS, fairly well-defined palm-tree like polymers PSaC60(PSb)5 and block copolymers PSaC60(PI)5 could be obtained. In these architectures, 5 PS (PI) branches of equal length are connected to a PS trunk through a single fullerene molecule.  相似文献   

16.
The successful synthesis is described for a donor–acceptor rod–coil block copolymer comprising blocks of poly[2,7‐(9,9‐dihexylfluorene)‐alt‐bithiophene] (F6T2) and polystyrene functionalized with fullerene (PS(C60)) (F6T2‐b‐PS(C60)). This new material was obtained by combining Suzuki polycondensation with radical addition fragmentation chain transfer. The block copolymer was characterized by nuclear magnetic resonance, gel permeation chromatography, and optical spectroscopy methods. Photophysical data for (F6T2‐b‐PS(C60)) and a related block copolymer (F6T2‐b‐PS(PCBM)) (PCBM, phenyl‐C61‐butyric acid methyl ester) are reported and their performance as compatibilizers in bulk heterojunction organic solar cells is assessed. It is demonstrated that the addition of the rod–coil block copolymers to the active layer extends the operational stability of organic photovoltaic devices. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 888–903  相似文献   

17.
A high potential donor–acceptor dyad composed of zinc porphyrin bearing three meso‐pentafluorophenyl substituents covalently linked to C60, as a novel dyad capable of generating charge‐separated states of high energy (potential) has been developed. The calculated energy of the charge‐separated state was found to be 1.70 eV, the highest reported for a covalently linked porphyrin–fullerene dyad. Intramolecular photoinduced electron transfer leading to charge‐separated states of appreciable lifetimes in polar and nonpolar solvents has been established from studies involving femto‐ to nanosecond transient absorption techniques. The high energy stored in the form of charge‐separated states along with its persistence of about 50–60 ns makes this dyad a potential electron‐transporting catalyst to carry out energy‐demanding photochemical reactions. This type of high‐energy harvesting dyad is expected to open new research in the areas of artificial photosynthesis especially producing energy (potential) demanding light‐to‐fuel products.  相似文献   

18.
The thermal stability of well‐defined hexa‐adducts (PS)6C60 in solution at temperatures around 100 °C has been studied by multi‐detector Size Exclusion Chromatography. The degradation reaction corresponds to a quantitative release of the polystyrene arms from the fullerene core through thermal cleavage of the PS‐C60 link. From the kinetics of formation of cut arms and the progressive decrease of the stars' functionality, we could establish that the reaction follows a stepwise “breaking” mechanism where a 6‐arm star is first converted to a 5‐arm star, then to a 4‐arm star, and so on down to the ungrafted arm. Furthermore, not only does the thermal stability of the PS? C60 bond increase if the functionality of the star decreases, but the difference is large enough to allow determination of the kinetics constants for the first three steps. The activation energy for the breaking of an arm‐C60 link is about 65 kJ/mol. The stability of (PS)6C60 slightly decreases with an increase of the arm length. MALDI‐TOF mass spectroscopy has shown that both C? C bonds in α and β positions to C60 can be cut, but the breaking of the direct fullerene‐arm bond is favored. We have also found that a polyisoprene? C60 bond is about seven times less stable than a PS‐fullerene link upon heating. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4820–4829, 2004  相似文献   

19.
《Electroanalysis》2006,18(9):841-848
Redox active films have been generated electrochemically by the reduction of dyads consisting of fullerene C60 covalently linked to zinc meso‐tetraphenyloporphyrin, ZnP? C60, and palladium acetate. The films are believed to consist of a polymeric network formed via covalent bonds between the palladium atoms and the fullerene moieties. In these films, the zinc porphyrin moiety is covalently linked to the polymeric chains through the pyrrolidine ring of the fullerene. The ZnP? C60/Pt films are electrochemically active in both positive and negative potential excursions. At positive potentials, two oxidation steps for the zinc porphyrin are observed. In the negative potential range, electron transfer processes involving the zinc porphyrin and the fullerene entities are observed. Film formation is also accompanied by palladium deposition on the electrode surface. The presence of a metallic phase in the film influences its morphology, structure and electrochemical properties.  相似文献   

20.
The role of π‐conjugated molecular bridges in through‐space and through‐bond electron transfer is studied by comparing two porphyrin–fullerene donor–acceptor (D–A) dyads. One dyad, ZnP–Ph–C60 (ZnP=zinc porphyrin), incorporates a phenyl bridge between D and A and behaves very similarly to analogous dyads studied previously. The second dyad, ZnP–EDOTV–C60, introduces an additional 3,4‐ethylenedioxythienylvinylene (EDOTV) unit into the conjugated bridge, which increases the distance between D and A, but, at the same time, provides increased electronic communication between them. Two essential outcomes that result from the introduction of the EDOTV unit in the bridge are as follows: 1) faster charge recombination, which indicates enhanced electronic coupling between the charge‐separated and ground electronic states; and 2) the disappearance of the intramolecular exciplex, which mediates photoinduced charge separation in the ZnP–Ph–C60 dyad. The latter can be interpreted as a gradual decrease in electronic coupling between locally excited singlet states of D and A when introducing the EDOTV unit into the D–A bridge.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号