Bibliographies thématiques / Extended porphyrin

Littérature scientifique sur le sujet « Extended porphyrin »

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Publié le 4 mai 2024

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Articles de revues sur le sujet "Extended porphyrin"

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Yan, Jia Ying, Ya Qing Feng, Fang Qun Zhou, Yi Wen Chang et Bao Zhang. « Studies on Sonogashira Coupling Reaction of Dibenzoporphyrin ». Advanced Materials Research 581-582 (octobre 2012) : 317–21. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.317.

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Changing the proportion of NBS and porphyrin, dibromination of β, β’- π-extended porphyrins was found to selectively occur to the β and β’ position of the porphyrins which is antipotal to the fused aromatic ring. Subsequent Sonogashira coupling of the resultant dibromoporphyrin introduced a carboxylphenylethynyl group to the π-extended porphyrin and the π conjugation was thus further elongated. The coupling products have shown a broadening and a red-shift of the Soret band and Q bands in the UV-Vis absorption spectra compared with the π-extended porphyrin starting materials and the original unmodified porphyrins.
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Cheprakov, Andrei V., et Mikhail A. Filatov. « The dihydroisoindole approach to linearly annelated π-extended porphyrins ». Journal of Porphyrins and Phthalocyanines 13, no 03 (mars 2009) : 291–303. http://dx.doi.org/10.1142/s1088424609000383.

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The dihydroisoindole strategy for the synthesis of linearly annelated π-extended porphyrins is a common approach to tetrabenzo-, tetranaphtho-, and tetraanthraporphyrins with variable functionality and substitution patterns. This method implies the use of a common type of precursors involving the 4,7-dihydroisoindole moiety, which are the closest possible stable relatives of the unstable isoindole, benzoisoindole and naphthoisoindole. A key feature of this strategy is the unprecedented mildness of the final oxidative aromatization step, which accounts for synthetic versatility, better functional group tolerance and high purity of the products. Many new linearly annelated π-extended porphyrins of the tetrabenzo-, tetranaphtho-, and tetraanthraporphyrin families were produced and characterized for the first time, including soluble planar and highly emissive 5,15-diaryl derivatives. The double bond of the dihydroisoindole fragment can also be useful for further modification of the porphyrin by means of addition of cycloaddition reactions, leading to new, previously inaccessible porphyins bearing multiple halide, hydroxy, or acetoxy groups at the periphery.
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Brewer, Ashley, Matthew Lacey, John R. Owen, Iris Nandhakumar et Eugen Stulz. « Supramolecular hetero-porphyrin SWNT complexes ». Journal of Porphyrins and Phthalocyanines 15, no 04 (avril 2011) : 257–63. http://dx.doi.org/10.1142/s1088424611003227.

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The complexation of single walled carbon nanotubes (SWNTs) with neutral, anionic and cationic porphyrins has been investigated under identical complex forming conditions. The determination of the porphyrin loading reveals large differences depending on the nature of the porphyrin used. Combinations of different porphyrins to form mixed hetero-porphyrin complexes shows that the mixture of a cationic and anionic porphyrin results in loading which is an order of magnitude larger than in all other complexes. This complex also exhibits high adsorption and emission intensities and can be regarded as an extended co-operative binary ionic (CBI) solid. The complexes were further studied using Raman spectroscopy, elemental analysis, AFM and cyclic voltammetry.
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Wang, Hong, Yi Hu, Michael Thomas, Ajyal Alsaleh et Francis D'Souza. « (Invited) Pi-Extended Porphyrins : Synthesis, Functionalization and Applications in Dye-Sensitized Solar Cells ». ECS Meeting Abstracts MA2022-01, no 13 (7 juillet 2022) : 903. http://dx.doi.org/10.1149/ma2022-0113903mtgabs.

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pi-Extended porphyrins are of broad interest due to their unique combination of photophysical, optoelectronic, and physicochemical properties, and their potential applications in many areas ranging from biomedicine to organic electronics.1,2 In this talk, three series of beta-functionalized push-pull pi-extended porphyrins as sensitizers for dye-sensitized solar cells will be presented.3-5 Our studies show significant push-pull effects for these porphyrins. DFT calculations suggest that the inclusion of ethynylphenyl bridge between the donating group and the porphyrin core significantly segregate the frontier orbitals. It has also been found that dimethylaminophenyl group cause dye decomposition on solar cells. To solve the dye degradation problem, porphyrin dyes with tertiary arylamine groups serving as the donor groups were prepared. Our studies show that tertiary arylamine groups are able to stabilize the dyes adsorbed on the solar cells. Their photovoltaic performances were tested in dye-sensitized solar cells. In this talk, the synthesis and characterization of pentacene-fused (linearly conjugated) and pentaquinone-fused (cross-conjugated) porphyrin oligomers will also be presented.6 These pentacene-fused porphyrins are much more stable than their corresponding pentacene derivatives. The electronic absorption spectra and transit spectroscopy of these porphyrins indicate highly interactive multiple p-systems. The electronic and optical properties of these p-extended porphyrins were measured using UV-Vis spectroscopy, life-time and steady state fluorescence spectroscopy, and cyclic voltammetry. DFT calculations were also performed for these porphyrins.
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de Torres, Miriam, Sergey Semin, Ilya Razdolski, Jialiang Xu, Johannes A. A. W. Elemans, Theo Rasing, Alan E. Rowan et Roeland J. M. Nolte. « Extended π-conjugated ruthenium zinc–porphyrin complexes with enhanced nonlinear-optical properties ». Chemical Communications 51, no 14 (2015) : 2855–58. http://dx.doi.org/10.1039/c4cc09592h.

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Chevrier, Michèle, Sébastien Richeter, Olivier Coulembier, Mathieu Surin, Ahmad Mehdi, Roberto Lazzaroni, Rachel C. Evans, Philippe Dubois et Sébastien Clément. « Expanding the light absorption of poly(3-hexylthiophene) by end-functionalization with π-extended porphyrins ». Chemical Communications 52, no 1 (2016) : 171–74. http://dx.doi.org/10.1039/c5cc06290j.

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Thomas, Michael B., R. G. Waruna Jindasa, Yi Hu, Benjamin Schmitz, Hong Wang et Francis D’Souza. « Investigation of the push–pull effects on β-functionalized zinc porphyrin coordinated to C60 donor–acceptor conjugates ». Canadian Journal of Chemistry 96, no 9 (septembre 2018) : 881–89. http://dx.doi.org/10.1139/cjc-2017-0416.

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Two novel β-functionalized push–pull zinc porphyrins with amine or phenyl push-groups and cyclic imide or carboxylic esters pull-groups have been newly synthesized for light energy harvesting applications. The ethynylphenyl spacers extended the conjugation of the porphyrin π-systems, as reflected by their red-shifted absorbance and fluorescence spectra. Computational studies performed at the B3LYP/6-31G* level indicated no steric hindrance between the porphyrin π-system and the substituents. The calculated HOMO and LUMO orbitals displayed significant delocalization in 1, where the electron density in the HOMO was localized over the push groups, whereas the LUMO was extended over the porphyrin π- and pull-groups. On the other hand, 2 did not display significant orbital segregation, which is attributed to its weaker push–pull character. Electrochemical studies revealed smaller HOMO–LUMO gaps for the push–pull zinc porphyrins. As a consequence of the push–pull effects, reduction in fluorescence intensity and lifetime was observed. Femtosecond transient absorption spectral studies revealed successful formation of singlet excited state in both of the push–pull porphyrins. Donor–acceptor conjugates were subsequently built and characterized by coordinating an electron acceptor, C60Im, via metal–ligand axial coordination. Efficient photo-induced charge separation in both donor–acceptor conjugates was witnessed wherein the charge-separated states persisted tens of nanoseconds prior returning to the ground state.
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Warrener, Ronald N., Hongsui Sun et Martin R. Johnston. « Position-Addressable Nano-Scaffolds. II. The Introduction of One, Two, or Three Addressable Succinimide Linkage Points onto the Under-Surface of ‘Southern’ Cavity Bis-Porphyrins ». Australian Journal of Chemistry 56, no 4 (2003) : 269. http://dx.doi.org/10.1071/ch02219.

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Cavity bis-porphyrins containing up to three addressable succinimide rings on the underface are reported for the first time. This is achieved by site-selective addition of o-chloranil to the 7-oxanorbornene π-bond of O-bridged sesquinorbornadienosuccinimide (1a) to form a scaffold α-dione, followed by condensation with porphyrindiamine (12) to produce a porphyrin-containing norbornene BLOCK (13) incorporated a succinimide ring fused to the underside. Dual 1,3-dipolar coupling of (13) with alicyclic bis-epoxides (15) formed the cavity bis-porphyrins (16) containing two succinimide rings while similar 1,3-dipolar coupling with succinimide-containing bis-epoxide (17) gave the extended cavity bis-porphyrin (18) having three succinimide rings within the cavity section. A similar cycloaddition/condensation strategy provides the shortest route to cavity bis-porphyrins containing a single succinimide ring yet reported.
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Hamer, Mariana, Rolando M. Caraballo, Peter J. Eaton et Craig Medforth. « Nanoparticles as template for porphyrin nanostructure growth ». Journal of Porphyrins and Phthalocyanines 23, no 04n05 (avril 2019) : 526–33. http://dx.doi.org/10.1142/s1088424619500469.

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Porphyrins and metalloporphyrins are one of the most widely studied platforms for the construction of supramolecular structures. These compounds have an extended aromatic system that allows [Formula: see text]–[Formula: see text] stacking interactions which, together with hydrogen bonds, electrostatic forces and the formation of inter-metallic complexes arising from peripheral groups, offer a versatile platform to control the self-assembly mechanism. In this work, we present the study of nanostructures formed by self-assembly of the water-soluble porphyrins meso-tetra([Formula: see text]-methyl-4-pyridyl)porphyrin (TMPyP) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) in the presence of hard nanotemplates. Different nanoparticles (silica, gold, and polystyrene), concentrations and synthetic procedures were explored. The obtained materials were characterized by SEM and AFM microscopies, UV-vis absorption spectroscopy and dynamic light scattering measurements. A clear modification of the SiO2 NP surface roughness using one-pot synthesis was observed. The results were variable depending on the porphyrin–surface interactions and concentrations used. At lower porphyrin concentrations, a shift of the Soret band was observed, while at higher concentrations, free NS were formed. This reflects a competition between surface and solution directed self-assembly.
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Vannelli, Tommaso A., et Timothy B. Karpishin. « Neocuproine-Extended Porphyrin Coordination Complexes ». Inorganic Chemistry 38, no 10 (mai 1999) : 2246–47. http://dx.doi.org/10.1021/ic9812914.

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Thèses sur le sujet "Extended porphyrin"

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Mori, Hirotaka. « Studies on Novel π-Extended Porphyrins ». 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215337.

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Hu, Yi. « Synthesis and Characterization of β-Functionalized π-Extended Porphyrins ». Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609167/.

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Porphyrins with extended π-electronic networks are promising candidates for a wide range of applications from medicine to nanotechnology owing to their unique optical and electronic properties. This dissertation is focused on synthesis, characterization and application of β-functionalized π-extended porphyrins. This dissertation is comprised of seven chapters. Chapter 1 focuses on the importance and objective of this work. Chapter 2 gives brief introduction to porphyrins and π-extended porphyrins. In chapter 3, a class of β-functionalized linear push-pull zinc dibenzoporphyrins YH1-YH3 were designed, synthesized, and utilized as light harvesters for DSSCs. In chapter 4, in order to further enhance the photovoltaic performance of β-functionalized benzoporphyrin dyes based DSSCs, a new class of push-pull dibenzoporphyrins YH4-YH7 bearing the phenylethynyl bridge was designed, synthesized and utilized as light harvesters for DSSCs. In chapter 5, in order to solve the photodegradation problem associated with YH7, a new series of push-pull dibenzoporphyrins YH8-YH10 bearing different diarylamino push groups was designed and synthesized. This class of push-pull porphyrins shows improved photostability and enhanced DSSC performance. In chapter 6, a new pentacene-fused diporphyrin with high stability and solubility was prepared and characterized. Chapter 7 includes the summary of this dissertation and describes possible future work.
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Altundas, Abdullah Bilal. « Synthesis of XZH-5 Derivatives as Inhibitors of Signal Transducer and Activator of Transcription 3 (STAT3) and Synthesis of π-Extended Tetraphenylporphyrins ». Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1473201129.

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Jiang, Lin. « Functionalized pi-Extended Porphyrins ». Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1373974099.

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Fukui, Norihito. « Development of Novel π-Extended Porphyrins ». Kyoto University, 2018. http://hdl.handle.net/2433/232280.

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Kumar, Siddhartha. « Synthesis and Characterization of π-Extended Benzoporphyrins ». Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505216/.

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Porphyrins offer a very synthetically flexible template which can be modified in numerous ways to synthesize molecules with very useful properties applicable in areas such as non-linear optical properties, photodynamic therapy, dye-sensitized solar cells, chemical sensors and organic electronic devices. β-Substituted π-extended porphyrins offer unique capabilities in tuning the properties of the molecule towards practical applications. Increased π-conjugation allows the HOMO-LUMO gap to decrease and hence to redshift the absorption into the near-IR region. β-Fused benzoporphyrins offer additional benefits in which the benzene ring itself can be further modified using electron donating substituents and electron donating substituents to electronically tune these porphyrins for various uses. The goal of the research pursued in this dissertation was to develop new methods for the development of β-Substituted π-extended porphyrins and to study their optical and electronic properties. To accomplish this goal, we developed new method to synthesize A2B2 type tetrabenzoporphyrins and we studied the electron transfer in such systems. We also studied the effectiveness of such systems in dye sensitized solar cells. A new method to synthesize functionalized naphthalene fused porphyrins was also developed and we were also able to use this method to synthesize a push-pull naphthalene fused porphyrin.
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Iordache, Adriana. « Activation par transfert d'électron : applications aux systèmes commutables et à l'ingénierie moléculaire ». Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENV056.

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Ce mémoire s'articule autour de deux aspects complémentaires des processus qui accompagnent le transfert d'électron. Le cœur de ce projet concerne la valorisation de l'électrochimie moléculaire comme technique d'activation dans deux directions : activation de processus mécaniques ou de mouvements moléculaires dans des architectures commutables pour lesquelles un transfert d'électron fournit l'impulsion tout en permettant le contrôle et la lecture de l'état d'un système dynamique, et activation de processus chimiques pour lesquels l'électrochimie est exploitée en ingénierie moléculaire pour élaborer des molécules complexes et proposer une alternative efficace aux méthodes classiques de la synthèse organique. Le fil conducteur « activation électrochimique » est déroulé autour deux grandes classes de composés : les -dimères de dérivés du viologène et les macrocycles conjugués à base de pyrrole. Dans la première partie de ce mémoire, nous présenterons nos résultats en matière de systèmes moléculaires commutables dont les mouvements intramoléculaires et les propriétés sont activés et contrôlés par simple transfert d'électron tandis que la deuxième partie est centrée sur l'ingénierie électrochimique de porphyrines étendues
One of the most important key to the development of nanosciences lies in our ability to monitor, modify or control nanometric materials. The addition or removal of electrons to or from given molecular objects can find useful applications in numerous arena of nanosciences: as signal transcription of interactions processes, as impulse to trigger conformational, configurational or directional mechanical changes at the molecular level or even as a way to control and activate the reactivity of molecular building blocks in organic synthesis. This work deals with two complementary processes associated to electron transfer: molecular movements in switchable architectures and activation of molecular building blocks to form conjugated macrocyclic structures The first part of this research work is devoted to the synthesis of porphyrin-based molecular tweezers and of ferrocene-based molecular pivots. The dynamic properties of these switchable molecular objects; relying on reversible π-dimerization processes, have been investigated by spectroscopic, electrochemical and spectroelectrochemical methods. In the second part of this manuscript we show few examples of electrochemically driven synthetic procedures for preparation of expanded porphyrins. Unlike chemical oxidants, which must often be tested empirically for a given transformation, under electrochemical conditions, one has the opportunity to tune the reactivity of the pyrrole-based reagent via the choice of anodic voltage. We especially established that the use of bipyrrole allows for the clean and high-yield production of cyclo[8]pyrrole; the requisite electrochemically-induced cyclization of four bipyrrole building blocks likely involving an electrolyte-based templating effect. The success of this approach leads us to propose that analogous electrochemical oxidation processes could be used to generate a range of new expanded porphyrin products
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Roznyatovskiy, Vladimir. « From old porphyrins to novel materials ». Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-4050.

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The fascinating role that porphyrins play in natural processes such as photosynthesis and respiration, continues to provide a compelling motivation to study these chromophores and to design new analogues with improved functions. This dissertation describes the interdisciplinary study of several classes of compounds that include π-extended porphyrins, expanded porphyrins, porphycenes, polypyrroles and porphyrins. Dictated by the need to capture efficiently red and near-infrared light, the so-called π-extension approach has been established as a powerful tool in the synthesis of large aromatic chromophores. Many of these artificial systems demonstrate properties similar to natural porphyrins. Often, however, a reduced bandgap is seen due to a greater π-system. Synthetic challenges associated with the preparation of the linearly annulated porphyrins have long been recognized. Many of these have now beed overcome as the result of a newly developed synthetic protocol described in Chapter 1. This protocol allows for the synthesis of a pyrrolic building block under milder conditions. As a continuation of this work, naphthobipyrroles were obtained via the π-extension strategy applied to a benzobipyrrole. The utility of this new building block was demonstrated with the syntheses of an electrochromic polynaphthobipyrrolic polymer (Chapter 3) and a dinaphthoporphycene (Chapter 2), a chromophore isomeric to porphyrin. Chapter 4 describes a different approach to porphyrin functionalization. Here, the goal was to effect substitution at the so-called β pyrrolic positions with using two bithiophene groups. Although, the resulting product is not completely rigid, enhancement in the sensitizing properties of the basic porphyrin chromophore was seen in a dye sensitized solar cell (DSSC) assembly, as studied by scanning electrochemical microscopy (SECM). The synthetic contributions concerning this work, carried in collaboration with Bard group, are expected to lay the groundwork for the development future photovoltaic materials. Expanded porphyrins are the more diverse group of porphyrinic derivatives. In effort to develop new conjugated expanded porphyrin systems and to understand their spectroscopic behavior in greater detail, a set of expanded porphyrins, based on the direct electrochemical oxidation of terpyrrole-like fragments, was developed in conjunction with the Bucher group (Grenoble, France). This effort is described in Chapter 5. Specifically it is shown that trithiacyclo[9]pyrrole may be prepared by means of an electrochemical synthesis.
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Lin, Rong-Shin, et 林榮新. « The synthesis of the fully conjugated of extended bimetal-porphyrin and application ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/57214063528479044596.

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碩士
臺灣大學
化學研究所
95
To synthesize a conjugation system of porphyrins and to study their properties with metal ions are the major work of this thesis. With the assists of microwave technology, the target molecule was easily achieved. In the presence of the diketone porphyrin with 5,6-diamino-1,l0-phenanthroline in a co-solvent system (CH2Cl2:Et2O: MeOH:H2O) proceeded smoothly to yield the p-diketoone prophyrin (A9). Complexation of A9 with various metal ions were investigated. In a typical example, reaction of CoCl2 with A9 in the DMF, produced a metal-prophyrin species C1. This cobalt prophyrin complex can be used as a catalyst in oxidation olefin, benzaldehydes and sulfides under mild conditions.
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Kung, Hsiang-Ho, et 孔祥禾. « Synthesis of Various π-Extended Push-Pull Porphyrin Dimers for Dye-Sensitized Solar Cells ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34772354196540897275.

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碩士
國立中興大學
化學系所
101
Energy is the prime need of human being but their sources is limited in nature. So, the development of alternative clean and renewable energy sources is a priority in the research field to solve the problem of energy shortages and green house effect. Among numbers of alternative energy, infinite and inexhaustible solar energy is a good candidate to meet a rapidly increasing global demand for energy. Recently, the development of solar cells especially to the third generation solar cells is dye-sensitized solar cells (DSSC). DSCC are currently attracting considerable attention because of their high light-to-electricity conversion efficiencies, ease of fabrication, and low production costs. However, we focused on application of DSCC especially for dye design that is based on porphyrin structure. In addition of porphyrin monomers as dyes, we have synthesized a series of porphyrin dimers due to their wider Soret band and Q band caused by exciton coupling. Moreover, the increasing of extinction coefficient and bathochromic shift in absorption spectrum is also notable application for porphyrin dimers. We expect these advantages are useful in DSCC. Therefore, we designed and successfully synthesized various of π-extended push-pull porphyrin dimers by single bond or ethynyl group as linker to combine two porphyrin monomers. In addition, we are also committed to study device for dye-sensitized solar cells, hope that we can get achievements well in the future.
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Chapitres de livres sur le sujet "Extended porphyrin"

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Vinogradov, Sergei A., et David F. Wilson. « Extended Porphyrins ». Dans Advances in Experimental Medicine and Biology, 597–603. Boston, MA : Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-5865-1_74.

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Crow, John P. « Administration of Mn Porphyrin and Mn Texaphyrin at Symptom Onset Extends Survival of ALS Mice ». Dans ACS Symposium Series, 295–318. Washington, DC : American Chemical Society, 2005. http://dx.doi.org/10.1021/bk-2005-0903.ch017.

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Cheprakov, Andrei V. « 58 The Synthesis of π-Extended Porphyrins ». Dans Handbook of Porphyrin Science, 1–149. World Scientific Publishing Company, 2011. http://dx.doi.org/10.1142/9789814322386_0010.

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« Metal Complexes Containing Redox-active Ligands ». Dans Inorganic Electrochemistry Theory, Practice and Application, 335–401. 2e éd. The Royal Society of Chemistry, 2011. http://dx.doi.org/10.1039/bk9781849730716-00335.

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Chapter 7 extends the discussion of Chapter 6 to metal complexes containing redox-active ligands such as ferrocenes, fullerenes, dioxolenes, dithiolenes, porphyrins and other less well-known ligands. The object is to show how the electron transfer activity of the metal centre coupled to that of the ligand itself leads to quite extended redox activity, which can be exploited to set up materials having well-defined electronic properties for potentially innovative applications.
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Taber, Douglass. « Construction of Alkenes, Alkynes and Allenes ». Dans Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0020.

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Products such as 3 and 6 are usually prepared by phosphonate condensation. J. S. Yadav of the Indian Institute of Technology, Hyderabad found (Tetrahedron Lett. 2008, 49, 4498) that the cation-exchange resin Amberlyst-15 in CH2Cl2 mediated the condensation of a terminal alkyne such as 1 with an aldehyde to give the enone 3. Similarly, Teruaki Mukaiyama of Kitasato University showed (Chemistry Lett. 2008, 37, 704) that tetrabutylammonium acetate mediated the condensation of 5 with an aldehyde such as 4 to give the ester 6. David M. Hodgson of the University of Oxford described (J. Am. Chem. Soc. 2008, 130, 16500) the optimization of the Schlosser protocol for the condensation of a phosphorane with an aldehyde 7 followed by deprotonation and halogenation, to deliver the alkenyl halide 9 with good geometric control. Jun Terao of Kyoyo University and Nobuaki Kambe of Osaka University accomplished (Chem. Commun. 2008, 5836) the homologation of a halide such as 10 to the corresponding allylic Grignard reagent 12. Primary, secondary and tertiary halides worked well. Jennifer Love of the University of British Columbia developed (Organic Lett. 2008, 10, 3941) a Rh catalyst for the addition of thiols to terminal alkynes such as 13, and found that the product thioether 14 coupled smoothly with Grignard reagents to deliver the 1,1-disubstituted alkene 15. Glenn C. Micalizio, now at Scripps Florida, established (J. Am. Chem. Soc. 2008, 130, 16870) what appears to be a general method for the construction of Z-trisubstituted alkenes such as 18. The Ohira protocol has become the method of choice for converting an aldehyde 19 to the alkyne 21. We have found (Tetrahedron Lett. 2008, 49, 6904) that the reagent 20 offers advantages in price, preparation and handling. Bo Xu and Gerald B. Hammond of the University of Louisville observed (Organic Lett. 2008, 10, 3713) that an allene ester such as 22 is readily homologated to the alkyne 23. Ashton C. Partridge of Massey University extended (Tetrahedron Lett. 2008, 49, 5632) condensation with the aryl phosphonate 25 to porphyrin aldehydes, leading to alkynes such as 26.
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Leys, Clyde, Adam Schwarz, Mark Cloos, Sugeng Widodo, J. Richard Kyle et Julius Sirait. « Chapter 29 : Grasberg Copper-Gold-(Molybdenum) Deposit : Product of Two Overlapping Porphyry Systems ». Dans Geology of the World’s Major Gold Deposits and Provinces, 599–620. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.29.

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Abstract The supergiant Grasberg porphyry deposit in Papua, Indonesia (5.26 Gt @ 0.61% Cu and 0.57 g/t Au, with no cutoff applied) is hosted by the Grasberg Igneous Complex that fills an upward-flared diatreme ~1,800 m wide at the 4,250-m surface elevation. The Grasberg Igneous Complex is emplaced into folded and strike-slip faulted Tertiary and older sediments and comprises 3.6 to 3.3 Ma Dalam monzodiorite intrusions and subordinate volcanic rocks occupying much of the pipe, the central 3.2 Ma Main Grasberg intrusion, and the NW-SE-trending 3.2 to 3.0 Ma Kali dikes. The Grasberg Igneous Complex contains two porphyry systems: Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold. The Gajah Tidur intrusion belongs to the Dalam igneous group and is a 3.4 Ma porphyritic monzonite with its top at a 2,750-m elevation; it is overprinted by an extensive, domal, quartz stockwork, with a low-grade and intensely phyllic-altered core, surrounded by molybdenite-bearing veins, with a pre-Main Grasberg Re-Os age, as well as chalcopyrite and overprinting pyrite-covellite veins. The strongly potassic-altered, Main Grasberg monzodiorite porphyry extends from surface to the 2,700-m elevation and is overprinted by a cylindrical, ~1-km-diameter, intense quartz-magnetite stockwork cut by abundant chalcopyrite-bornite veins with rare molybdenite dated at 3.09 Ma. A 700-m-wide annulus of chalcopyrite overprinted by pyrite-covellite-mineralized phyllic alteration surrounds the stockwork. Altered and mineralized Main Grasberg and surrounding Dalam rocks were subsequently wedged apart by the largely unmineralized Kali dikes. Gold is predominantly associated with the Main Grasberg porphyry system where it occurs as 1- to 150-µm (avg ~15 µm) native gold inclusions within chalcopyrite and bornite. Melt and fluid inclusions from Main Grasberg stockwork quartz veins, which exhibit crack-seal textures, comprise K-feldspar-rich silicate melt, sulfide melt, virtually water-free salt melt, and coexisting hypersaline and vapor-rich fluids. Factors important in forming the Grasberg deposit include the following: (1) generation of highly oxidized fertile magma in a postsubduction tectonic setting; (2) efficient extraction of metals from the parental magma chamber; (3) prolonged maintenance of a fluid-accumulating cupola in a strike-slip structural setting that delivered multiple overlapping discharges of metal-rich fluid; (4) highly focused fluid flow into a narrow, permeable stockwork zone in which a steep temperature gradient enabled highly efficient copper and gold precipitation and led to high ore grades; (5) limited dilution by postmineral intrusions; (6) the youthfulness of the deposit minimized erosion and resulted in preservation of nearly all the high-grade Main Grasberg porphyry orebody; and (7) the proximity of the two porphyry centers enables them to be mined as a single, large deposit. The Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold porphyry centers overlap in space and formed within ~250,000 years of one another. However, their distinct metal endowment, depth of emplacement, and geometry indicate that they formed under different magmatic, hydrothermal, and structural conditions, which are the subject of ongoing research.
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LaZella, Andrew. « The Real Concept of Being ». Dans The Singular Voice of Being, 41–60. Fordham University Press, 2019. http://dx.doi.org/10.5422/fordham/9780823284573.003.0003.

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Chapter 2 continues the discussion of the previous chapter by examining Scotus’s claim that being is a real concept. The chapter asks: How is being a real concept (i.e., a concept about things, not about concepts) without corresponding to a real common element shared between God and creatures and between each of the categories? The first section begins with an examination of what Scotus means by real concepts, in addition to several related factors. These include: conceptual simplicity and complexity; simple-simplicity and non-simple simplicity; distinct and confused cognition; and abstraction and division. The second section shows how Scotus expands the more limited Porphyrian scope of quid and quale to include being as transcendental quid and ultimate differences as transcendental qualia. With these factors in play, the third section turns to the issue of the double primacy of being and resolves the ever so important question of how univocal being relates to ultimate difference. That is, they are not beings, but they are not nothing. The fourth section shows how Scotus solves the various problems surrounding univocity raised in the previous chapter. The extent to which ultimate differences avoid vain repetition leads into a more extended discussion of these transcendental principles.
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Turner, Stephen J., Graeme Reynolds et Steffen G. Hagemann. « Chapter 13 : Boddington : An Enigmatic Giant Archean Gold-Copper (Molybdenum-Silver) Deposit in the Southwest Yilgarn Craton, Western Australia ». Dans Geology of the World’s Major Gold Deposits and Provinces, 275–88. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.13.

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Abstract Boddington is a giant, enigmatic, and atypical Archean Au-Cu deposit hosted in a small, remnant greenstone belt within granite-gneiss and migmatite of the Southwest terrane of the Yilgarn craton, Western Australia. Primary Au and Cu (and Mo) mineralization consists of a network of thin fractures and veins, controlled by shear zones, and dominantly hosted by early dioritic intrusions and their immediate wall rocks, which comprise felsic to intermediate-composition volcanic and volcaniclastic rocks. The pre-~2714 Ma host rocks are typically steeply dipping and strongly deformed, with early ductile and overprinting brittle-ductile fabrics, and have been metamorphosed at mid- to upper greenschist facies. Features consistent with porphyry-style mineralization, classic orogenic shear zones, and intrusion-related Au-Cu-Bi mineralization are all recognized, giving rise to a variety of genetic interpretations. It is clear that Boddington does not fit any classic Archean orogenic gold deposit model, having a general lack of quartz veins and iron carbonate alteration, a Cu (Mo and Bi) association, zoned geochemical anomalism, and evidence of high-temperature, saline ore-forming fluids. Detailed petrographic, geochemical, and melt inclusion studies suggest a late-stage ~2612 Ma, monzogranite intrusion as one of the principal sources of the mineralizing fluids. However, there is also local evidence for older, perhaps protore, porphyry-style Cu (±Au) in the dioritic intrusions and patchy, locally high-grade, orogenic-style gold mineralization associated with enclosing shear zones and brittle-style deformation, which was focused on the relatively competent dioritic intrusions. The relative contributions of metals from these components to the system may not be resolvable. It appears that the Boddington deposit has been a locus for multiple episodes of intrusion, alteration, and mineralization over an extended period of time, as has been demonstrated in a number of other large Canadian and Australian gold deposits, including the Golden Mile near Kalgoorlie.
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Dromundo, Omar, Sigfrido Robles, Thomas Bissig, Claudio Flores, Maria del Carmen Alfaro et Lorenzo Cardona. « Chapter 19 : The Peñasquito Gold-(Silver-Lead-Zinc) Deposit, Zacatecas, Mexico ». Dans Geology of the World’s Major Gold Deposits and Provinces, 399–414. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.19.

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Abstract Peñasquito is an Au-Ag-Zn-Pb deposit and currently the principal Au-producing mine in Mexico. It is the most recent major discovery in the historically important Concepción del Oro mining district. Current Au reserves plus historic production at Peñasquito stand at 12.67 Moz, in addition to 527 Moz Ag, 3,600 lb Pb, and 8,000 lb Zn in remaining proven and probable reserves. Mineralization is centered on the Peñasco and Brecha Azul diatreme breccias, which cut an Upper Jurassic to Upper Cretaceous marine carbonate-dominated sedimentary sequence, which underwent folding during the Laramide orogeny. The diatreme breccias and associated mineralization are associated with early Oligocene quartz-feldspar porphyries dated at 34.4 ± 0.4 to 33.7 ± 0.4 Ma and thus 3 to 10 m.y. younger than the other skarn and polymetallic deposits known in the district. The Peñasco diatreme is about 1 km in diameter and hosts epithermal-style disseminated mineralization, whereas the contiguous Cretaceous carbonaceous and calcareous siltstone and interbedded sandstone of the Caracol Formation is the principal host for stockwork and manto-type, massive base metal sulfide mineralization. Skarn-type mineralization is Cu-Zn rich, extends to the current depth of drilling some 2 km below the premine surface, and is hosted by the Jurassic-Cretaceous sequence beneath the Caracol Formation. In addition, weakly developed stockwork Mo (±Cu) mineralization has also been intersected by drilling at depths of nearly 2 km.
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Hayes, Timothy S., James G. Brown, Stephen J. Sutley et Joseph F. Whelan. « Geology and Rock-Water Geochemistry of Exotic Copper Deposits, Ferricretes, and Manganocretes Associated with Porphyry Copper Deposits in Arizona, New Mexico, and Sonora (Extended Abstract) ». Dans Supergene Environments, Processes, and Products. Society of Economic Geologists, 2009. http://dx.doi.org/10.5382/sp.14.13.

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Actes de conférences sur le sujet "Extended porphyrin"

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Avramenko, Aleksandr G., et Aaron S. Rury. « Dynamics of Cavity Multipolaritons formed from Quasi-degenerate Porphyrin Excitons ». Dans Laser Science. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/ls.2022.lw6f.3.

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Multipolaritons are hybrid light-matter states formed from the ultrafast exchange of energy between a cavity photon and resonant excitons. We show evidence that multipolariton formation in extended cavities enables dynamical averaging of excitonic energetic disorder and delays polariton-mediated energy transfer.
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Drobizhev, M., A. Karotki, H. L. Anderson et A. Rebane. « Very efficient multi-photon absorption in porphyrins with extended /spl pi/-conjugation ». Dans Quantum Electronics and Laser Science (QELS). Postconference Digest. IEEE, 2003. http://dx.doi.org/10.1109/qels.2003.237846.

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Alfano, Robert F., G. C. Tang, Asima Pradhan, D. J. Choy et E. Opher. « Fluorescence spectra from cancerous and normal human breast and lung tissues ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.thq3.

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Laser spectroscopy provides a unique and sensitive approach to reveal changes in the physical and chemical properties that occur in healthy and abnormal cells in tissues. There are well-known intrinsic fluorophors, flavins, and porphyrins bound to proteins within cells that fluoresce in the visible spectral region. These native fluorophors display well-defined spectral features that characterize the local environment and state of the cells. Recently, Alfano and co-workers1,2 established that the fluorescence spectroscopy and relaxation times from malignant and normal rat tissues were different. The differences were attributed to the transformation of the local environment surrounding the fluorophors assigned to be flavins and porphyrins in the normal and cancerous rat tissues. We extended our past fluorescence work1-3 to human breast and lung tissues. We show that there exist differences in the spectral profiles measured for normal and malignant tissues. The assignments of the fluorescence peaks at ~520 and 600 nm are consistent with our past assignments in rat kidney tissues.1-3 The fluorescence profile for the cancer tissues exhibit smoother spectral profiles than the normal tissues. The 600-nm peaks in the cancer tissue are reduced compared to normal tissues.
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Rapports d'organisations sur le sujet "Extended porphyrin"

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Wang, Hong, et Lei Kerr. Pi-Extended Porphyrins : Functionalization and applications in DSSC. SC0010800-Final. Office of Scientific and Technical Information (OSTI), août 2018. http://dx.doi.org/10.2172/1417036.

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Israel, Alvaro, et John Merrill. Production of Seed Stocks for Sustainable Tank Cultivation of the Red Edible Seaweed Porphyra. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7696527.bard.

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Porphyra species (commonly known as ‘nori’ or ‘purple laver’) are edible red seaweeds rich in proteins, vitamins and other highly valued biogenic compounds. For years Porphyra has been cultured using seeded nets extended in the open sea, and its biomass consumed primarily in the Far East. While demands for international markets have increased steadily at an average of 20% per year, supplies are on the verge and not expected to meet future demands. Alternatively, land-based cultivation of seaweed has become attractive in the mariculture industry since (1) important growth parameters can be controlled, (2) is environmentally friendly and (3) perfectly matches with integrated aquaculture leading to sustainable, high quality products. During the last few years a tank cultivation technology for Porphyra has been developed at the Israeli institution. This technology is based on indoor production of asexual spores and their subsequent growth to 1-2 mm seedlings. The seedlings are then transferred to outdoor tanks and ponds when seawater temperatures drop to 20 °C, or below, and days become shorter during winter time. However, the current technology efficiently serves only about 100 m2 of ponds during one growth season. In order to produce seedlings in sufficient amounts, it is critical to address both technical and biological aspects of seedling production, securing optimal up-scale to commercial-size cultivation farms. We hypothesize that massive production of spores is related to thalli origin, thalli age and sporulation triggers, and that seedling survival and their subsequent growth potential is determined by the seawater quality and overall indoor growth conditions imposed. A series of bio-reactors were constructed and tested in which spore release and spore growth were separately studied. The main assessment criteria for optimal viability of the seedlings will be by determining their electron transport rate using PAM fluorometry and by subsequent growth and biomass yields in outdoor ponds. Altogether the project showed (1), controlled sporulation is possible in big outdoor/growth chamber settings provided initial stock material (small frozen seedlings) is at hand, (2), contamination problems can be almost completely avoided if stock material is properly handled (clean as possible and partially dehydrated prior to freezing), (3), spore release can significantly be enhance using high nutrient levels during thawing for P. yezoensis and P. haitanensis, but not for P. rosengurttii, (4), PAM fluorometry is an efficient tool to estimate growth capacity in both seedlings and juvenile thalli. The BARD funding also served to explore other aspects of Porphyra biology and cultivation. For example, the taxonomical status of Porphyra strains used in this study was defined (see appendix), and the potential use of this seaweed in bioremediation was well substantiated. In addition, BARD funding supported a number of opportunities and activities in the Israeli lab, direct or indirectly related to the initial objectives of the project such as: additional molecular work in other seaweeds, description of at least 2 new species for the Israeli Mediterranean, and continuous support for the writing of a book on Global Change and applied aspects of seaweeds. The technology for Porphyra cultivation in land-based ponds is readily available. This study corroborated previous know-how of Porphyra growth in tanks and ponds, and yet offers important improvements regarding seedling production and their handling for successful cultivation. This study supported various other activities opening additional important issues in the biology/cultivation/use of Porphyra and other seaweeds.
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