Effect of substituents in directing the formation of benzochlorins and isobacteriochlorins in porphyrin and chlorin systems

[formula: see text] A first synthesis of free-base fluorinated benzochlorins by acid-catalyzed cyclization of 20-(2-trisiloxy-trifluoromethylvinyl)octaethylporphyrin++ + is achieved. Under similar reaction conditions, the purpurin-18-N-hexylimide analogues produced the corresponding fluorinated and nonfluorinated ethylidene-substituted isobacteriochlorins and fluorinated chlorin, respectively. The structure of the porphyrin based fluorinated benzochlorin was also confirmed by X-ray analysis.     

Synthesis and Optical Properties of Dendronized Porphyrin Polymers

Summary: A novel kind of dendronized porphyrin polymers was synthesized by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized macromonomers bearing Fréchet‐type dendrons. The encapsulation of red‐light‐emitting porphyrin‐containing conjugated backbones into dendronized polymers can not only reduce the aggregation of polymer backbones and the self‐quenching of their fluorescence but also endow the porphyrin polymers with good solubility. We also report the optical and electrochemical properties of the porphyrin‐containing dendronized polymers.

Synthesis of a novel kind of dendronized porphyrin polymers by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized dendritic macromonomers.     

含氟卟啉的研究进展

综述了近几年国内外含氟卟啉的合成及其研究进展. 含氟卟啉合成方法分为直接氟化法和间接氟化法. 直接法主要采用无机氟化试剂直接对卟啉环进行氟化; 间接法主要采用含氟砌块法引入氟基团. 由于合成卟啉环比较复杂, 目前氟化学家主要采用间接氟化法合成含氟卟啉化合物.     

Self-organization of a new fluorous porphyrin and C60 films on indium-tin-oxide electrode

The highly fluorinated alkyl moieties of a new porphyrin drive the self-organization of thin films with C(60) on ITO electrodes.     

Selective oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins with molecular oxygen

This paper reported the oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins under mild conditions without any additives.The results showed that the cobalt(Ⅱ)(5,10,15,20-tetrakis(pentafluorophenyl))porphyrin was the best catalyst among the fluorinated metalloporphyrins.The conversion of ethylbenzene reached 38.6%,the selectivity to acetophenone reached 94.0%,and the turnover number is 2719 under the optimal conditions.     

Photocatalytic Hydrogen Evolution Based on Efficient Energy and Electron Transfers in Donor–Bridge–Acceptor Multibranched‐Porphyrin‐Functionalized Platinum Nanocomposites

Two donor–bridge–acceptor conjugates (5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso‐position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched‐porphyrin‐functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light‐harvesting photosensitizer. The occurrence of photoinduced electron‐transfer processes was confirmed by time‐resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H₂, the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor–bridge–acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.     

Self-assembly of discotic liquid crystal porphyrin into more controllable ordered nanostructure mediated by fluorophobic effect

The novel nanoscale discotic liquid crystal porphyrin with partial chain perfluorination, which has the same basic structure as the best photoreceptor in nature (chlorophyll), shows an exceptionally enhanced tendency to self-assemble into ordered nanostructure. Defect-free homeotropically aligned fluorinated porphyrin thin films were, for the first time, fabricated and characterised. The ability to self-assemble large π-conjugated discotic molecules into highly ordered nanostructure via partial chain perfluorination provides new insight for the bottom-up nanofabrication of molecular devices. The controllable ordered porphyrin nanostructure with directed molecular arrangement holds great promise for use in high-performance electronic devices.     

Comparing Structural and Electrical Properties of Fluorinated Graphene,Graphene Oxide,and Graphene Films Functionalized with N-Methylpyrrolidone

The article presents comparison of structural and electrical properties of fluorinated graphene (FG), graphene oxide (GO), and graphene films functionalized with N-methylpyrrolidone (G-NMP). The obtained functionalized graphene films were continuous, having no ruptures, their thickness was 20–50 nm. Fluorinated films are formed from fluorinated areas and corrugated graphene islets. The size and shape of microstructures on G-NMP surfaces depend on the duration of NMP treatment. GO films demonstrate a rippled surface morphology. The resistance of all films of functionalized graphene exceeds that of pristine graphene films (several kilohms). GO and FG films exhibit dielectric properties. Current-voltage characteristics of FG demonstrate two features: stepwise current increase and negative differential resistance (NDR). Functionalized graphene can be used in flexible electronics, particularly in planar printing technologies.     

Electron transfer switching in supramolecular porphyrin-fullerene conjugates held by alkylammonium cation-crown ether binding

Reversible switching between intra- to intermolecular electron transfer paths has been accomplished by adding and extracting potassium ions to the supramolecular porphyrin-fullerene conjugates formed by complexing porphyrin functionalized with a benzo-18-crown-6 entity and fullerene functionalized with an alkylammonium cation entity.     

Ruthenium porphyrin functionalized single-walled carbon nanotube arrays--a step toward light harvesting antenna and multibit information storage

Ruthenium porphyrin functionalized single-walled carbon nanotube arrays have been prepared using coordination of the axial position of the metal ion onto 4-aminopyridine preassembled single-walled carbon nanotubes directly anchored to a silicon(100) surface (SWCNTs-Si). The formation of these ruthenium porphyrin functionalized single-walled carbon nanotube array electrodes (RuTPP-SWCNTs-Si) has been monitored using infrared spectroscopy (IR), differential pulse voltammetry (DPV), atomic force microscopy (AFM), laser desorption time-of-flight mass spectroscopy (LDI-TOF-MS), UV-vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. Electrochemical results show two successive one-electron reversible redox waves. The surface concentration of the ruthenium porphyrin molecules is 3.44 x 10 (-8) mol cm (-2). Optical results indicate that the immobilization of ruthenium porphyrin enhances the light absorption of SWCNTs-Si surfaces in the visible light region. Moreover mixed assembly of ferrocene/porphyrin onto carbon nanotube arrays has been achieved by altering the ratio of two redox-active species in the deposition solution. These results suggest the ruthenium porphyrin modified electrodes are excellent candidates for molecular memory devices and light harvesting antennae.     

Optoelectronic and Self‐assembly Properties of Porphyrin Derivatives with Click Chemistry Modification

A series of functionalized porphyrin molecules containing electron‐rich alkynes, synthesized by means of the Sonogashira coupling reaction were further modified by reacting the ethynyl groups with click reagent through a formal [2+2] click reaction. The photophysical and electrochemical properties of the porphyrin derivatives were studied by UV/Vis spectroscopy and cyclic voltammetry. We show that the optoelectronic properties are affected by the click reagent groups and central metal ions. The functionalized porphyrin molecules show strong charge‐transfer (CT) bands in the visible region (near‐IR region) and potent redox activities. Through a phase‐exchange self‐assembly method, the highly organized morphologies were observed by scanning electron microscopy (SEM). The functionalized porphyrin molecules represent an interesting set of candidates for optoelectronic device components. The effect of the metal ions or click reagent groups on the self‐assembly properties were also studied by the UV/Vis spectroscopic titration experiments.     

A high-performance and simple method for rapid and simultaneous determination of dihydroxybenzene isomers

A novel idea on the basis of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (THPP) functionalized carbon nanotubes (CNTs) film was developed to simulate the chromatographic separation, which was able to rapidly and simultaneously detect dihydroxybenzene isomers based on their different oxidation potentials and corresponding currents. The mechanism involved in the recognition and isolation of the dihydroxybenzene isomers was explored and confirmed by UV spectra and density functional theory. It was proven that the current method for simultaneously detecting and isolating dihydroxybenzene isomers was ascribed to the priority of porphyrin film to induce oxidation of the three kinds of isomers, and the priority depends to a large extent on the different tendencies of dihydroxybenzene to interact with the peripheral hydroxyl group and with the extended π-conjugated ring of porphyrin. Most important of all, porphyrin functionalized CNTs film allows for the formation of well-defined interface and provides an advantageous and high-performance platform for the simultaneous determination and isolation of dihydroxybenzene isomers.     

Photocatalytic hydrogen evolution based on efficient energy and electron transfers in donor-bridge-acceptor multibranched-porphyrin-functionalized platinum nanocomposites

Two donor-bridge-acceptor conjugates (5,10,15,20-tetrakis[4-(N,N-diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20-tetrakis[4-(N,N-diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso-position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched-porphyrin-functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light-harvesting photosensitizer. The occurrence of photoinduced electron-transfer processes was confirmed by time-resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H(2), the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor-bridge-acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.     

Simultaneous hydrogen bonding and π-stacking interactions between flavin/porphyrin host-guest systems

In this Letter, we describe the formation of complexes between flavin and diamidopyridine functionalized porphyrin systems via hydrogen bonding and π-stacking interactions.     

Determination of explosives based on novel type of sensor using porphyrin functionalized carbon nanotubes

The hydroxide of meso-tetraphenylporphyrin derivatives functionalized carbon nanotubes (CNTs) was fabricated in our research to explore the interaction between porphyrin and explosive. It was turned out that in the formation of grid porphyrin film, carbon nanotubes as a cruciul base materials promoted the electron transfer rate. Most of important, the results also showed that the electrochemical response was enhanced through increasing the number of -OH substitution in porphyrin. Such information provides the platform for a practical strategy for rational design of the sensor of explosives.     

Design, syntheses, and studies of supramolecular porphyrin-fullerene conjugates, using bis-18-crown-6 appended porphyrins and pyridine or alkyl ammonium functionalized fullerenes

Photoinduced electron-transfer processes in cis and trans functionalized bis-18-crown-6 porphyrin self-assembled with fullerene functionalized with pyridine or alkylammonium cation entities are reported. The structural integrity of the newly formed supramolecular conjugates was accomplished by optical absorption and emission, electron spray ionization mass, electrochemistry, and semiempirical PM3 calculations. A 1:2 stoichiometry of the supramolecular porphyrin:fullerene conjugates was deduced from these studies. The conjugates revealed stable "two-point"' binding involving metal-ligand coordination and alkylammonium cation-crown ether binding or only the latter type of binding depending upon the functionality of the fullerene and metal ion in the porphyrin cavity. The effect of the variation on free energy changes of charge separation and the charge recombination was achieved by varying the metal ion in the porphyrin cavity. The charge-separation rates (k(CS)) determined from the picosecond time-resolved emission studies were generally higher for the cis bis-crown functionalized porphyrins than those of the corresponding trans ones. A comparison of the k(CS) values reported earlier for 1:1 porphyrin-fullerene conjugates with a similar self-assembly mechanism suggested that employing a higher number of acceptor entities improves the electron-transfer rates. The calculated charge-recombination rates (k(CR)) were 2-3 orders of magnitude smaller than the k(CS) values, suggesting the occurrence of the charge recombination process in the Marcus inverted region. The lifetimes of the radical ion pair (tau(RIP)) ranged between 46 and 233 ns indicating charge stabilization in the studied conjugates.     

One-flask synthesis of mono- and trifunctionalized 21-thia and 21-oxaporphyrin building blocks and their application in the synthesis of covalent and noncovalent unsymmetrical porphyrin arrays

A rapid synthetic route has been developed to synthesize mono- and trifunctionalized 21-thia and 21-oxaporphyrin systems using simple precursors such as 2[alpha-(aryl)-alpha-hydroxymethyl] thiophene (thiophene mono-ol) and 2[alpha-(aryl)-alpha-hydroxymethyl] furan (furan mono-ol), respectively. Condensation of one equivalent of thiophene or furan mono-ol with two equivalents of aryl aldehyde and three equivalents of pyrrole under porphyrin forming conditions followed by column chromatography resulted in functionalized 21-thia or 21-oxaporphyrins. To synthesize monofunctionalized porphyrins, the mono-ol containing the functionalized aryl group was used. The functionalized aldehydes were used to synthesize trifunctionalized porphyrins. The mono-ol method is versatile and applicable to synthesize mono- and trifunctionalized 21-thia and 21-oxaporphyrins containing functional groups such as iodophenyl, ethynylphenyl, hydroxyphenyl, bromophenyl, and pyridyl groups. The monofunctionalized porphyrin building blocks containing iodophenyl and ethynylphenyl groups were used further to synthesize four unsymmetrical covalent porphyrin dimers containing two different porphyrin cores such as N3S-N4, N3O-N4, and N3S-N3O bridged via diaryl ethyne group and one symmetrical phenylethyne bridged dimer containing two N3S cores. A preliminary photophysical study on these dimers indicated a possibility of energy transfer from one subunit to another. We also demonstrated the use of trifunctionalized porphyrins in the synthesis of two noncovalent unsymmetrical porphyrin tetramers containing one N3S and three N4 porphyrin subunits.     

卟啉和酞菁修饰的单壁碳纳米管的合成及光谱性质

利用5-(4-氨基苯基)-10,15,20-三(3,5-二辛氧基苯基)卟啉和2,9,16-三叔丁基-23-氨基锌(Ⅱ)酞菁通过酰胺键连接方式同时对单壁碳纳米管进行共价修饰, 通过红外光谱、拉曼光谱、X射线光电子能谱和透射电镜对所得碳纳米管复合物进行了表征, 证实了其结构. 紫外-可见吸收光谱和荧光光谱分析表明, 光活性分子卟啉和酞菁均与单壁碳纳米管之间存在较强的电子效应. 经卟啉和酞菁共同修饰的单壁碳纳米管复合物比卟啉和酞菁单独修饰的碳纳米管复合物的吸光范围更宽, 而且分散性较好(309 mg/L), 是潜在的光电转换材料.     

Fluorinated photosensitizers: synthesis, photophysical, electrochemical, intracellular localization, in vitro photosensitizing efficacy and determination of tumor-uptake by F in vivo NMR spectroscopy

For in vivo NMR studies, starting from pyrroles, a series of fluorinated porphyrins were synthesized by following the MacDonald reaction conditions. Upon reaction with osmium tetroxide, a fluorinated porphyrin containing four trifluoromethyl groups (12 fluorine units) was converted into the related chlorin and bacteriochlorin which exhibited long-wavelength absorptions at 652 and 720 nm, respectively. All compounds produced good singlet oxygen production efficiency. A comparative study of nine porphyrins with and without fluorine substituents indicated no adverse effects of the presence of fluorinated groups in the photophysical properties of the porphyrins, chlorins or bacteriochlorins. The first and second one-electron reduction potentials (vs SCE) of the investigated compounds range between −1.29 and −1.49 V and between −1.66 and −1.84 V in PhCN containing 0.1 M TBAP. UV-visible spectroelectrochemical data suggested the formation of π-anion and π-cation radicals upon the first reduction and first oxidation. The in vivo ¹⁹F MR study of a representative fluorine labeled compound with twelve equivalent fluorines confirmed the presence of the fluorine labeled sensitizer in mouse (C3H/HeJ) implanted with RIF tumors on mouse foot dorsum by inoculating 2×10⁵ cells (the studies were repeated on four tumored mice to confirm the feasibility and reproducibility). All fluorinated compounds were found to be quite effective in vitro. In a comparative intracellular localization study with Rhodamine-123 in RIF tumor cells, the most soluble porphyrin containing two propionic ester side chains was found to localize in mitochondria as well as the related chlorin and bacteriochlorin.     

Further study on the synthesis of F-containing porphyrins and their catalytic activity on oxidation of cyclohexene

Reaction of tetrakis(p-allyloxyphenyl)porphyrin and perfluoroalkanesulfonyl bromides givestetrakis(p-polyfluoroalkoxylphenyl)substituted porphyrins.The yields are over 90%.The synthesis ofthe metal ion complexes of these F-containing porphyrins is also reported.Preliminary results on thestudy of the catalytic activity of the manganese(Ⅲ)complexes of various fluorinated porphyrins onoxidation of cyclohexene indicate that the introduction of R_F group into porphyrin contributes to thestability of the catalysts.