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1.
Synthesizing 2D metal–organic frameworks (2D MOFs) in high yields and rational tailoring of the properties in a predictable manner for specific applications is extremely challenging. Now, a series of porphyrin‐based 2D lanthanide MOFs (Ln‐TCPP, Ln=Ce, Sm, Eu, Tb, Yb, TCPP=tetrakis(4‐carboxyphenyl) porphyrin) with different thickness were successfully prepared in a household microwave oven. The as‐prepared 2D Ln‐TCPP nanosheets showed thickness‐dependent photocatalytic performances towards photooxidation of 1,5‐dihydroxynaphthalene (1,5‐DHN) to synthesize juglone. Particularly, the Yb‐TCPP displayed outstanding photodynamic activity to generate O2? and 1O2. This work not only provides fundamental insights into structure designing and property tailoring of 2D MOFs nanosheets, but also pave a new way to improve the photocatalytic performance.  相似文献   

2.
The generation of singlet oxygen (1O2) during photodynamic therapy is limited by the precise cooperation of light, photosensitizer, and oxygen, and the therapeutic efficiency is restricted by the elevated glutathione (GSH) levels in cancer cells. Herein, we report that an ultrathin two‐dimensional metal–organic framework of Cu‐TCPP nanosheets (TCPP=tetrakis(4‐carboxyphenyl)porphyrin) can selectively generate 1O2 in a tumor microenvironment. This process is based on the peroxidation of the TCPP ligand by acidic H2O2 followed by reduction to peroxyl radicals under the action of the peroxidase‐like nanosheets and Cu2+, and their spontaneous recombination reaction by the Russell mechanism. In addition, the nanosheets can also deplete GSH. Consequently, the Cu‐TCPP nanosheets can selectively destroy tumor cells with high efficiency, constituting an attractive way to overcome current limitations of photodynamic therapy.  相似文献   

3.
A new phosphorescent dinuclear cationic iridium(III) complex ( Ir1 ) with a donor–acceptor–π‐bridge–acceptor–donor (D? A? π? A? D)‐conjugated oligomer ( L1 ) as a N^N ligand and a triarylboron compound as a C^N ligand has been synthesized. The photophysical and excited‐state properties of Ir1 and L1 were investigated by UV/Vis absorption spectroscopy, photoluminescence spectroscopy, and molecular‐orbital calculations, and they were compared with those of the mononuclear iridium(III) complex [Ir(Bpq)2(bpy)]+PF6? ( Ir0 ). Compared with Ir0 , complex Ir1 shows a more‐intense optical‐absorption capability, especially in the visible‐light region. For example, complex Ir1 shows an intense absorption band that is centered at λ=448 nm with a molar extinction coefficient (ε) of about 104, which is rarely observed for iridium(III) complexes. Complex Ir1 displays highly efficient orange–red phosphorescent emission with an emission wavelength of 606 nm and a quantum efficiency of 0.13 at room temperature. We also investigated the two‐photon‐absorption properties of complexes Ir0 , Ir1 , and L1 . The free ligand ( L1 ) has a relatively small two‐photon absorption cross‐section (δmax=195 GM), but, when complexed with iridium(III) to afford dinuclear complex Ir1 , it exhibits a higher two‐photon‐absorption cross‐section than ligand L1 in the near‐infrared region and an intense two‐photon‐excited phosphorescent emission. The maximum two‐photon‐absorption cross‐section of Ir1 is 481 GM, which is also significantly larger than that of Ir0 . In addition, because the strong B? F interaction between the dimesitylboryl groups and F? ions interrupts the extended π‐conjugation, complex Ir1 can be used as an excellent one‐ and two‐photon‐excited “ON–OFF” phosphorescent probe for F? ions.  相似文献   

4.
A novel luminescent metal–organic framework ( Zn‐TCPP/BPY ) with pillared structure based on 2,3,5,6‐tetrakis(4‐carboxyphenyl)pyrazine (H4TCPP) and 4,4′‐bipyridine (BPY) has been designed and synthesized through a solvothermal reaction. The [Zn2(COO)4] paddlewheel units are linked by TCPP4? ligands to form two‐dimensional layers and further connected by BPY ligands as pillars to construct the twofold interpenetrating three‐dimensional framework. Interestingly, Zn‐TCPP/BPY possesses outstanding stability in organic solvents and water as well as maintains its structural rigidity in aqueous solutions of different pH values (3–12). After activation, Zn‐TCPP/BPY possesses permanent porosity with Brunauer–Emmett–Teller surface area of 630 m2 g–1. Remarkably, Zn‐TCPP/BPY displays excellent fluorescent property in virtue of the aggregation‐induced emission effect of the H4TCPP ligand, which can be highly active and quenched by small amounts of 2,4,6‐trinitrophenol (TNP) and Fe3+ ions. Furthermore, the detection effect of Zn‐TCPP/BPY remains basically the same even after five cycles. The excellent stability, high sensitivity, and recyclability of Zn‐TCPP/BPY make it an outstanding chemical sensor for detecting TNP and Fe3+ ions.  相似文献   

5.
Modular optimization of metal–organic frameworks (MOFs) was realized by incorporation of coordinatively unsaturated single atoms in a MOF matrix. The newly developed MOF can selectively capture and photoreduce CO2 with high efficiency under visible‐light irradiation. Mechanistic investigation reveals that the presence of single Co atoms in the MOF can greatly boost the electron–hole separation efficiency in porphyrin units. Directional migration of photogenerated excitons from porphyrin to catalytic Co centers was witnessed, thereby achieving supply of long‐lived electrons for the reduction of CO2 molecules adsorbed on Co centers. As a direct result, porphyrin MOF comprising atomically dispersed catalytic centers exhibits significantly enhanced photocatalytic conversion of CO2, which is equivalent to a 3.13‐fold improvement in CO evolution rate (200.6 μmol g?1 h?1) and a 5.93‐fold enhancement in CH4 generation rate (36.67 μmol g?1 h?1) compared to the parent MOF.  相似文献   

6.
The stable cationic iridacyclopentenylidene [TpMe2Ir(?CHC(Me)?C(Me)C H2(NCMe)]PF6 ( A ; TpMe2=hydrotris(3,5‐dimethylpyrazolyl)borate) has been obtained by α‐hydride abstraction from the iridacyclopent‐2‐ene [TpMe2Ir(CH2C(Me)?C(Me)C H2)(NCMe)]. Complex A exhibits Brønsted–Lowry acidity at the Ir? CH2 and proximal (relative to Ir? CH2) methyl sites. The coordination of an extra molecule of acetonitrile to the iridium center initiates the reversible isomerization of the chelating carbon chain of A to the monodentate butadienyl ligand of complex [TpMe2Ir(CH?C(Me)C(Me)?CH2)(NCMe)2]PF6, which is capable to engage in a water‐promoted C? C coupling with the MeCN co‐ligands. The product is an aesthetically appealing bicyclic structure that resembles the hydrocarbon barrelene.  相似文献   

7.
A series of phosphorescent cyclometalated iridium complexes with 2,5‐diphenylpyridine‐based ligands has been synthesized and characterized to investigate the effect of the simple ligand modification on photophysics, thermostability and electrochemistry. The complexes have the general structure (CN)2Ir(acac), where CN is a monoanionic cyclometalating ligand [e.g. 2,5‐diphenylpyridyl (dppy), 2,5‐di(4‐methoxyphenyl)pyridyl (dmoppy), 2,5‐di(4‐ethoxyphenyl)pyridyl (deoppy) and 2,5‐di(4‐ethylphenyl)pyridyl (deppy)]. The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The (dppy)2Ir(acac) has been characterized using X‐ray crystallography. Calculation on the electronic ground state of (dppy)2Ir(acac) was carried out using B3LYP density functional theory. The highest occupied molecular orbital (HOMO) level is a mixture of Ir and ligand orbitals, while the lowest occupied molecular orbital (LUMO) is predominantly dppy ligand‐based. Electrochemical studies showed the oxidation potentials of (dmoppy)2Ir(acac), (deoppy)2Ir(acac), (deppy)2Ir(acac) were smaller than that of (ppy)2Ir(acac), while the oxidation potential of (dppy)2Ir(acac) was larger relative to (ppy)2Ir(acac). The 10% weight reduction temperatures of these complexes were above that of (ppy)2Ir(acac). All complexes exhibited intense green photoluminescence, which has been attributed to MLCT triplet emission. The maximum emission wavelengths in CH2Cl2 at room temperature were in the range 531–544 nm, which is more red‐shifted than that of (ppy)2Ir(acac). Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

8.
Cyclometalated IrIII complexes with acetylide ppy and bpy ligands were prepared (ppy=2‐phenylpyridine, bpy=2,2′‐bipyridine) in which naphthal ( Ir‐2 ) and naphthalimide (NI) were attached onto the ppy ( Ir‐3 ) and bpy ligands ( Ir‐4 ) through acetylide bonds. [Ir(ppy)3] ( Ir‐1 ) was also prepared as a model complex. Room‐temperature phosphorescence was observed for the complexes; both neutral and cationic complexes Ir‐3 and Ir‐4 showed strong absorption in the visible range (ε=39600 M ?1 cm?1 at 402 nm and ε=25100 M ?1 cm?1 at 404 nm, respectively), long‐lived triplet excited states (τT=9.30 μs and 16.45 μs) and room‐temperature red emission (λem=640 nm, Φp=1.4 % and λem=627 nm, Φp=0.3 %; cf. Ir‐1 : ε=16600 M ?1 cm?1 at 382 nm, τem=1.16 μs, Φp=72.6 %). Ir‐3 was strongly phosphorescent in non‐polar solvent (i.e., toluene), but the emission was completely quenched in polar solvents (MeCN). Ir‐4 gave an opposite response to the solvent polarity, that is, stronger phosphorescence in polar solvents than in non‐polar solvents. Emission of Ir‐1 and Ir‐2 was not solvent‐polarity‐dependent. The T1 excited states of Ir‐2 , Ir‐3 , and Ir‐4 were identified as mainly intraligand triplet excited states (3IL) by their small thermally induced Stokes shifts (ΔEs), nanosecond time‐resolved transient difference absorption spectroscopy, and spin‐density analysis. The complexes were used as triplet photosensitizers for triplet‐triplet annihilation (TTA) upconversion and quantum yields of 7.1 % and 14.4 % were observed for Ir‐2 and Ir‐3 , respectively, whereas the upconversion was negligible for Ir‐1 and Ir‐4 . These results will be useful for designing visible‐light‐harvesting transition‐metal complexes and for their applications as triplet photosensitizers for photocatalysis, photovoltaics, TTA upconversion, etc.  相似文献   

9.
A series of metal–organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1? Mn?OH?, 2? Mn?SO42?, 3? Mn?bdc2?, 4? Eu?SO42? (H2BpybcCl2=1,1′‐bis(4‐carboxybenzyl)‐4,4′‐bipyridinium dichloride, H2bdc=1,4‐benzenedicarboxylic acid) have been obtained by a self‐assembly process. Single‐crystal X‐ray‐diffraction analysis revealed that all of these compounds contained the same n‐fold 2D→3D Borromean‐entangled topology with irregular butterfly‐like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non‐interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1? Mn?OH? further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π‐conjugated structures.  相似文献   

10.
The Hirsch–Bingel reaction of bis{4‐methyl[1,2,3]triazolyl}malonic ester‐bridged bis(permethyl‐β‐cyclodextrin) 1 with C60 has led to the formation of a new fullerene‐bridged bis(permethyl‐β‐cyclodextrin) 2 , which has been comprehensively characterized by NMR spectroscopy, MALDI‐MS, and elemental analysis. Taking advantage of the high affinity between 2 and 5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphyrin ( 3 ) or [5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphinato]zinc(II) ( 4 ), linear supramolecular architectures with a width of about 2 nm and a length ranging from hundreds of nanometers to micron dimension were conveniently constructed and fully investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Significantly, the photoinduced electron‐transfer (PET) process between porphyrin and C60 moieties takes place within the 2 ? 3 and 2 ? 4 supramolecular architectures under light irradiation, leading to the highly efficient quenching of the porphyrin fluorescence. The PET process and the charge‐separated state were investigated by means of fluorescence spectroscopy, fluorescence decay, cyclic voltammetry, and nanosecond transient absorption measurements.  相似文献   

11.
2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon‐conjugated porphyrin‐based covalent organic framework (Por‐sp2c‐COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light‐emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π‐conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por‐sp2c‐COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por‐sp2c‐COF is pivotal for cooperative photocatalysis with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.  相似文献   

12.
Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh3)3] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph2P)C6H4}2Si(F)2 to afford a silyl complex [{[o‐(iPh2P)C6H4]2(F)Si}Ir(CO)(PPh3)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of Hδ+???Fδ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh3)3] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph2P)C6H4}3Si(F) even at ambient temperature.  相似文献   

13.
Single atoms immobilized on metal–organic frameworks (MOFs) with unique nanostructures have drawn tremendous attention in the application of catalysis but remain a great challenge. Various single noble‐metal atoms have now been successfully anchored on the well‐defined anchoring sites of the zirconium porphyrin MOF hollow nanotubes, which are probed by aberration‐corrected scanning transmission electron microscopy and synchrotron‐radiation‐based X‐ray absorption fine‐structure spectroscopy. Owing to the hollow structure and excellent photoelectrochemical performance, the HNTM‐Ir/Pt exhibits outstanding catalytic activity in the visible‐light photocatalytic H2 evolution via water splitting. The single atom immobilized on MOFs with hollow structures are expected to pave the way to expand the potential applications of MOFs.  相似文献   

14.
A mesomeso‐linked diphenylamine‐fused porphyrin dimer and its methoxy‐substituted analogue were synthesized from a mesomeso‐linked porphyrin dimer by a reaction sequence involving Ir‐catalyzed β‐selective borylation, iodination, meso‐chlorination, and SNAr reactions with diarylamines followed by electron‐transfer‐mediated intramolecular double C?H/C?I coupling. While these dimers commonly display characteristic split Soret bands and small oxidation potentials, they produced different products upon oxidation with tris(4‐bromophenyl)aminium hexachloroantimonate. Namely, the diphenylamine‐fused porphyrin dimer was converted into a dicationic closed‐shell quinonoidal dimer, while the methoxy‐substituted dimer gave a mesomeso, β‐β doubly linked porphyrin dimer.  相似文献   

15.
meso‐Triazolyl‐appended ZnII–porphyrins were readily prepared by CuI‐catalyzed 1,3‐dipolar cycloaddition of benzyl azide to meso‐ethynylated ZnII–porphyrin (click chemistry). In noncoordinating CHCl3 solvent, spontaneous assembly occurred to form tetrameric array ( 3 )2 from mesomeso‐linked diporphyrins 3 , and dodecameric porphyrin squares ( 4 )4 and ( 5 )4 from the L ‐shaped mesomeso‐linked triporphyrins 4 and 5 . The structures of these assemblies were examined by 1H NMR spectra, absorption spectra, and their gel permeation chromatography (GPC) retention time. Furthermore, the structures of the dodecameric porphyrin squares ( 4 )4 and ( 5 )4 were probed by small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) measurements in solution using a synchrotron source. Excitation‐energy migration processes in these assemblies were also investigated in detail by using both steady‐state and time‐resolved spectroscopic methods, which revealed efficient excited‐energy transfer (EET) between the mesomeso‐linked ZnII–porphyrin units that occurred with time constants of 1.5 ps?1 for ( 3 )2 and 8.8 ps?1 for ( 5 )4.  相似文献   

16.
Two examples of heterometallic–organic frameworks (HMOFs) composed of dicarboxyl‐functionalized FeIII‐salen complexes and d10 metals (Zn, Cd), [Zn2(Fe‐L)22‐O)(H2O)2] ? 4 DMF ? 4 H2O ( 1 ) and [Cd2(Fe‐L)22‐O)(H2O)2] ? 2 DMF ? H2O ( 2 ) (H4L=1,2‐cyclohexanediamino‐N,N′‐bis(3‐methyl‐5‐carboxysalicylidene), have been synthesized and structurally characterized. In 1 and 2 , each square‐pyramidal FeIII atom is embedded in the [N2O2] pocket of an L4? anion, and these units are further bridged by a μ2‐O anion to give an (Fe‐L)22‐O) dimer. The two carboxylate groups of each L4? anion bridge ZnII or CdII atoms to afford a 3D porous HMOF. The gas sorption and magnetic properties of 1 and 2 have been studied. Remarkably, 1 and 2 show activity for the photocatalytic degradation of 2‐chlorophenol (2‐CP) under visible‐light irradiation, which, to the best of our knowledge, is the first time that this has been observed for FeIII‐salen‐based HMOFs.  相似文献   

17.
Nanoscaled coordination polymers based on biologically prevalent ions have potential applications in drug delivery and biomedical imaging. Herein, coordination polymer nanoparticles of anionic porphyrins, including meso‐tetra(4‐carboxyphenyl)‐porphyrin (H2TCPP4?) and meso‐tetra(4‐sulfonatophenyl)‐porphyrin (H2TPPS4?), and alkaline or alkaline earth metal cations, such as K+ and Ca2+, were constructed in aqueous solution in the presence of cucurbit[7]uril (CB7) or cucurbit[8]uril (CB8). UV/Vis absorption and fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron spectroscopy (SEM), and atomic force microscopy (AFM) were applied to explore the assembly and particle formation of porphyrin anions and metal cations mediated by CBn. The particle size depends on the kinds of CBn and metal cations and their concentrations. The uptake of H2TPPS4? particles by tumor cells (A549 cells) was found to be more efficient than H2TPPS4? at 37 °C, showing the application potential of such assembled particles in biology and medicine.  相似文献   

18.
A set of novel greenish‐yellow‐, yellow‐, and orange‐light‐emitting polymeric iridium(III) complexes were synthesized with the bridge‐splitting method. The respective dimeric precursor complexes, [Ir(ppy)2‐μ‐Cl]2 (ppy = 2‐phenylpyridine) and [Ir(ppy? CHO)2‐μ‐Cl]2 [ppy? CHO = 4‐(2‐pyridyl)benzaldehyde], were coordinated to 2,2′‐bipyridine carrying poly(ε‐caprolactone) tails. The resulting emissive polymers were characterized with one‐dimensional (1H) and two‐dimensional (1H? 1H correlation spectroscopy) nuclear magnetic resonance and infrared spectroscopy, gel permeation chromatography, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and the successful coordination of the iridium(III) centers to the 2,2′‐bipyridine macroligand was revealed. The thermal behavior was studied with differential scanning calorimetry and correlated with atomic force microscopy. Furthermore, the quantitative coordination was verified by both the photophysical and electrochemical properties of the mononuclear iridium(III) compounds. The photoluminescence spectra showed strong emissions at 535 and 570 nm. The color shifts depended on the substituents of the cyclometallating ligands. Cyclic voltammetry gave oxidation potentials of 1.23 V and 1.46 V. Upon the excitation of the films at 365 nm, yellow light was observed, and this could allow potential applications in light‐emitting devices. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2765–2776, 2005  相似文献   

19.
Two porous porphyrin‐based covalent triazine frameworks (PCTFs), in which porphyrin is incorporated as building block, have been synthesized by the Friedel–Crafts reaction. The copolymer PCTFs show large Brunauer–Emmett–Teller specific surface area of up to 1089 m2 g?1, high CO2 uptake capacity reaching 139.9 mg g?1 at 273 K/1.0 bar, and good selectivity for CO2/CH4 adsorption attaining 6.1 at 273 K/1.0 bar. The resulting porous solids also can be used as matrices for drug delivery of ibuprofen in vitro. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2594–2600  相似文献   

20.
A thiophene‐phenylquinoline‐based homoleptic IrIII complex, [Ir(Th‐PQ)3], has been synthesised by a simple route and utilised as a dopant in solution‐processed phosphorescent organic light‐emitting diodes (PhOLEDs). It shows the current efficiency of approximately 26 cd A?1 and the external quantum efficiency of about 21 %, which are the highest values reported to date for PhOLEDs prepared by solution‐process.  相似文献   

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