Bibliografie tematiche / Porphyrins

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Letteratura scientifica selezionata sul tema "Porphyrins"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 31 luglio 2024

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Articoli di riviste sul tema "Porphyrins"

1

Hindmarsh, J. Thomas, Linda Oliveras e Donald C. Greenway. "Plasma Porphyrins in the Porphyrias". Clinical Chemistry 45, n. 7 (1 luglio 1999): 1070–76. http://dx.doi.org/10.1093/clinchem/45.7.1070.

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Abstract Background: As an aid in the diagnosis and management of porphyria we have developed a method to fractionate and quantify plasma porphyrins and have evaluated its use in various porphyrias. Methods: We used HPLC with fluorometric detection to measure plasma concentrations of uroporphyrin I and III, heptacarboxyl III, hexacarboxyl III, pentacarboxyl III, and coproporphyrin I and III. We studied 245 healthy subjects, 32 patients with classical porphyria cutanea tarda (PCT), 12 patients with PCT of renal failure, 13 patients with renal failure, 8 patients with pseudoporphyria of renal failure, 3 patients with acute intermittent porphyria, 5 patients with variegate porphyria, 5 patients with hereditary coproporphyria, and 4 patients with erythropoietic protoporphyria. Results: Between-run CVs were 5.4–13%. The recoveries of porphyrins added to plasma were 71–114% except for protoporphyrin, which could not be reliably measured with this technique. Plasma porphyrin patterns clearly identified PCT, and its clinical sensitivity equaled that of urine porphyrin fractionation. The patterns also allowed differentiation of PCT of renal failure from pseudoporphyria of renal failure. Conclusions: The assay of plasma porphyrins identifies patients with PCT and appears particularly useful for differentiating PCT of renal failure from pseudoporphyria of renal failure.
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2

Puzikova, А. I., Е. А. Litvin, D. А. Kildyushkin e А. Е. Druy. "Application of high-performance liquid chromatography in porphyrias diagnostics". Pediatric Hematology/Oncology and Immunopathology 20, n. 3 (8 ottobre 2021): 140–44. http://dx.doi.org/10.24287/1726-1708-2021-20-3-140-144.

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Abstract (sommario):
Porphyrias are distinguished by the stage of heme synthesis at which a failure occurs, leading to the accumulation of intermediate products – porphyrins. Due to the low specificity of clinical manifestations of porphyria and the latent course of the disease, their timely diagnosis is difficult. This article substantiates the effectiveness of high-performance liquid chromatography method in the determination of porphyrins. The method is suitable for porphyrin determination in urine, blood and feces of patients. Examples of its work are shown.
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3

Stölzel, Ulrich, Thomas Stauch e Ilja Kubisch. "Porphyrien". Der Internist 62, n. 9 (29 giugno 2021): 937–51. http://dx.doi.org/10.1007/s00108-021-01066-1.

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Abstract (sommario):
ZusammenfassungPorphyrien werden durch Enzymdefekte der Hämbiosynthese hervorgerufen und anhand spezifischer biochemischer Muster von Porphyrinen und deren Vorläufern in Urin, Stuhl und Blut diagnostiziert. Das jeweilige Muster der akkumulierten Porphyrine, Vorläufer und Derivate ist verbunden mit der klinischen Ausprägung, die abdominale, neurologische, psychiatrische, endokrine, kardiovaskuläre Symptome, Leberschaden und/oder Lichtempfindlichkeit der Haut umfassen kann. Klinisch werden akute und nichtakute Porphyrien unterschieden. Bei symptomatischen (klinisch aktiven), akuten hepatischen Porphyrien – hierzu gehören akute intermittierende Porphyrie, Porphyria variegata, hereditäre Koproporphyrie und Doss-Porphyrie – kommt es aufgrund einer Regulationsstörung zur Kumulation der Porphyrinvorläufer 5‑Aminolävulinsäure und Porphobilinogen. Bei den nichtakuten Formen – u. a. Porphyria cutanea tarda, erythropoetische und X‑chromosomale Protoporphyrie sowie kongenitale erythropoetische Porphyrie – führen akkumulierte Porphyrine zu Lichtempfindlichkeit (Fotodermatose) und mitunter auch zu schweren Leberschäden. Zur Therapie der Porphyrien stehen sowohl bewährte und sichere als auch innovative Optionen zur Verfügung.
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4

Hindmarsh, J. T. "The porphyrias: recent advances." Clinical Chemistry 32, n. 7 (1 luglio 1986): 1255–63. http://dx.doi.org/10.1093/clinchem/32.7.1255.

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Abstract (sommario):
Abstract Recent research has elucidated several of the hitherto poorly understood steps in heme synthesis. This review describes this metabolic pathway and pinpoints the enzymatic blockages in the various porphyrias. Recent advances in the understanding of the etiology of porphyria cutanea tarda are discussed, as are the abnormalities of porphyrin metabolism seen in chronic renal failure and in lead poisoning. An outline is given of the clinical and biochemical abnormalities seen in the porphyrias. Included is an algorithm to aid in the differential diagnosis of these diseases, and a brief review of the new analytical techniques available for the identification and quantification of porphyrins and their precursors in body fluids.
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5

Carson, R. W., E. J. Dunnigan, T. D. DuBose, D. E. Goeger e K. E. Anderson. "Removal of plasma porphyrins with high-flux hemodialysis in porphyria cutanea tarda associated with end-stage renal disease." Journal of the American Society of Nephrology 2, n. 9 (marzo 1992): 1445–50. http://dx.doi.org/10.1681/asn.v291445.

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Abstract (sommario):
Plasma porphyrin levels are markedly increased in patients with porphyria cutanea tarda (PCT) associated with end-stage renal disease. Conventional hemodialysis (CHD) with lower blood flow rates (less than 250 mL/min) and cuprophan or cellulose acetate membranes is ineffective in removing significant amounts of porphyrins in this condition. Changes in plasma porphyrin levels and porphyrin clearances during hemodialysis with higher blood flow rates and more-permeable, high-efficiency cellulose acetate and high-flux polysulfone dialyzers were evaluated in a chronic hemodialysis patient with PCT and markedly elevated plasma porphyrins. The polysulfone membrane achieved significantly better fractional porphyrin removal (P = 0.02) and porphyrin clearances (P less than 0.01) than did the high-efficiency cellulose acetate membrane. After conversion from maintenance CHD with a standard cellulose acetate dialyzer to a 4-wk period of high-flux hemodialysis (HFHD) with a polysulfone dialyzer, predialysis plasma porphyrins fell by 37%. After returning to CHD, plasma porphyrins returned to the higher prestudy levels. These observations suggest that HFHD with more permeable membranes and higher blood flow rates removes porphyrins more effectively than does CHD. HFHD may be a useful adjunct to other measures used in treating dialysis patients with PCT.
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6

Sooambar, Chloé, Vincent Troiani, Hongjin Qiu, Sunichi Fukuzumi, Lucia Flamigni, Régis Rein e Nathalie Solladié. "Chirality and spatially pre-organized multi-porphyrinoids". Journal of Porphyrins and Phthalocyanines 22, n. 04 (aprile 2018): 291–302. http://dx.doi.org/10.1142/s1088424618500396.

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Abstract (sommario):
We report herein that chiral and enantiopure compounds such nucleosides and peptides can pre-organize multi-porphyrinic systems and influence their properties. The first example given concerns star-shaped mutli-porphyrins with chiral and enantiopure nucleosidic linkers. If the configuration is indeed a star-shaped nanomolecule, it appears that the induced conformation is nothing as expected. The four peripheral Zn(II) porphyrins collapse over the free-base central one, inducing totally different photo-physical properties. Despite a minor expected light energy harvesting behavior, the principal capability of this system is to quench the collected light energy and convert it from radiative to non-radiative de-activation. The second example concerns polypeptides with pendant porphyrins. The peptidic backbone confers to the systems, after a certain degree of oligomerization, a 3[Formula: see text] right handed helical conformation which induces cavities within the multi-porphyrinc architecture, ready to welcome guests and render, for example, the complexation of C[Formula: see text] much easier. We thus have constructed novel organic photovoltaic systems using supramolecular complexes of porphyrin–peptide oligomers with fullerene clusters. The composite cluster OTE/SnO[Formula: see text] electrode prepared with (P(ZnP)[Formula: see text] C[Formula: see text], exhibits an impressive incident photon-to-photocurrent efficiency (IPCE) with values reaching as high as 56%. The power conversion efficiency of the (P(H[Formula: see text]P)[Formula: see text] C[Formula: see text] modified electrode reaches 1.6%, which is 40 times higher than the value (0.043%) of the porphyrin monomer (P(H[Formula: see text]P)[Formula: see text] [Formula: see text] C[Formula: see text] modified electrode. Thus, the organization approach between porphyrins and fullerenes with polypeptide structures is promising, and may make it possible to further improve the light energy conversion properties by using a larger number of porphyrins in a polypeptide unit.
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7

Schoenfeld, N., e R. Mamet. "Interference of ofloxacin with determination of urinary porphyrins". Clinical Chemistry 40, n. 3 (1 marzo 1994): 417–19. http://dx.doi.org/10.1093/clinchem/40.3.417.

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Abstract (sommario):
Abstract The second-generation quinolone ofloxacin interferes with the screening test of porphyrins. We observed a 20-fold increase in the porphyrin concentration measured in urine of an ofloxacin-treated patient, compared with drug-free normal urine. Two other fluorinated 4-quinolones tested, norfloxacin and ciprofloxacin, had a less marked effect (a twofold increase), whereas the first-generation quinolone, nalidixic acid, did not affect the measured porphyrin concentration at all. The interference is probably due to the overlap in the emission fluorescence spectra of ofloxacin and urinary porphyrins at approximately 600 nm. To avoid a false-positive diagnosis of porphyria, we suggest using HPLC to separate ofloxacin (10-min retention time) from urinary porphyrins (which only start to elute at 12 min). Nonetheless, given a threefold increase in urinary porphyrins observed in the urine of an ofloxacin-treated patient, we also discuss a possible interference of the drug with the metabolism of porphyrins.
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8

Wenceslau, Adriana C., Guilherme L. Q. C. Ferreira, Noboru Hioka e Wilker Caetano. "Spectroscopic studies of pyridil and methoxyphenyl porphyrins in homogeneous and Pluronic®-based nanostructured systems". Journal of Porphyrins and Phthalocyanines 19, n. 11 (novembre 2015): 1168–76. http://dx.doi.org/10.1142/s1088424615500996.

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Abstract (sommario):
Spectroscopic properties of Porphyrins TPyP (tetra(4-pyridil)porphyrin), TMPP (tetrakis(4-methoxypheny) porphyrin) and its zinc metaled derivatives porphyrins Zn-TPyP and Zn-TMPP respectively, were studied in homogeneous and micro heterogeneous systems, comprising nanostructured Pluronic® copolymeric micellar systems, as a promising drug delivery systems for the porphyrins investigated. Physico-chemical properties such as, hydrophobicity degree, self- aggregation in solvents of different polarities and water/ethanol mixtures (monofasic binary), as well as kinetics profile and isotherm binding, molecular organization, [Formula: see text] and relative localization in neutral micellar systems. The hydrophobic character was the key to relative drug location in the micellar systems. In homogenous solvents systems the porphyrins presented relatively high values of molar absorptivity and low values of [Formula: see text]. The K[Formula: see text] values obtained are modulated by the structure of porphyrins, state of aggregation, as well as, structure and macro molecular self-organization of copolymers. Fluorescence quenching studies have shown that porphyrins in F-127 are located in a less hydrophobic region than the porphyrins in P-123, which are located preferentially in a deeper micellar microenvironment. The zinc porphyrins showed high values of K[Formula: see text]. Thus, the association of the porphyrins with specific binding sites of micellar systems is strongly modulated by the presence of the metal coordinated to the porphyrinic ring.
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9

Woolf, Jacqueline, Joanne T. Marsden, Timothy Degg, Sharon Whatley, Paul Reed, Nadia Brazil, M. Felicity Stewart e Michael Badminton. "Best practice guidelines on first-line laboratory testing for porphyria". Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 54, n. 2 (19 gennaio 2017): 188–98. http://dx.doi.org/10.1177/0004563216667965.

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Abstract (sommario):
The porphyrias are disorders of haem biosynthesis which present with acute neurovisceral attacks or disorders of sun-exposed skin. Acute attacks occur mainly in adults and comprise severe abdominal pain, nausea, vomiting, autonomic disturbance, central nervous system involvement and peripheral motor neuropathy. Cutaneous porphyrias can be acute or chronic presenting at various ages. Timely diagnosis depends on clinical suspicion leading to referral of appropriate samples for screening by reliable biochemical methods. All samples should be protected from light. Investigation for an acute attack: • Porphobilinogen (PBG) quantitation in a random urine sample collected during symptoms. Urine concentration must be assessed by measuring creatinine, and a repeat requested if urine creatinine <2 mmol/L. • Urgent porphobilinogen testing should be available within 24 h of sample receipt at the local laboratory. Urine porphyrin excretion (TUP) should subsequently be measured on this urine. • Urine porphobilinogen should be measured using a validated quantitative ion-exchange resin-based method or LC-MS. • Increased urine porphobilinogen excretion requires confirmatory testing and clinical advice from the National Acute Porphyria Service. • Identification of individual acute porphyrias requires analysis of urine, plasma and faecal porphyrins. Investigation for cutaneous porphyria: • An EDTA blood sample for plasma porphyrin fluorescence emission spectroscopy and random urine sample for TUP. • Whole blood for porphyrin analysis is essential to identify protoporphyria. • Faeces need only be collected, if first-line tests are positive or if clinical symptoms persist. Investigation for latent porphyria or family history: • Contact a specialist porphyria laboratory for advice. Clinical, family details are usually required.
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10

Perkins, S. L., e P. M. Johnson. "Loss of porphyrins from solution during analysis: effect of sample pH and matrix on porphyrin quantification in urine by "high-performance" liquid chromatography." Clinical Chemistry 35, n. 7 (1 luglio 1989): 1508–12. http://dx.doi.org/10.1093/clinchem/35.7.1508.

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Abstract (sommario):
Abstract We report the effect of sample matrix and pH on quantification of porphyrins by HPLC with fluorimetric detection. For aqueous solutions of pH less than 2.5, HPLC peak heights of the porphyrins increased with decreasing pH, reaching a plateau at pH less than 1.0. This loss of porphyrins from solutions with pH greater than 1.0 appeared to be due to a combination of microprecipitation and aggregation effects. No such "pH effect" was observed for urine samples supplemented with mixed-porphyrin standards. Addition of trace amounts of albumin to aqueous solutions also decreased these pH-related losses. These findings suggest a porphyrin-protein interaction that prevents microprecipitation and aggregation processes. We conclude that standard solutions of porphyrins for HPLC analysis should be prepared in a urine matrix. If aqueous solutions are used, then the pH must be adjusted to less than 1.0. Urine samples from normal individuals require only adjustment of pH to less than 2 before analysis; however, porphyric urines requiring dilution should be prepared with porphyrin-free urine diluent.
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Più fonti

Tesi sul tema "Porphyrins"

1

Lefley, Colin Richard. "Raman spectroscopic studies of porphyrins and porphyrin-protein complexes". Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239782.

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2

Krivokapic, Alexander. "Porphyrins and expanded porphyrins for optical limiting". Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270203.

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3

Mori, Goro. "Exploration of Porphyrins and Expanded Porphyrins with Novel Properties". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/124357.

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4

Sek, Sau Yin. "The synthesis of haematoporphyrin derivative III and other novel porphyrins /". Title page, table of contents and abstract only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phs4622.pdf.

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5

Meshkov, Ivan. "Control of molecular movement based on porphyrins". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF006/document.

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Abstract (sommario):
Les travaux décrits dans ce manuscrit s’intéressent au contrôle du mouvement moléculaire. Après une introduction dédiée à l’état de l’art des machines moléculaires, le premier chapitre s’intéresse à la conception de tourniquets moléculaires à base de complexes porphyriniques de P(V). Le mouvement moléculaire a pu être contrôlé de manière réversible soit par l’utilisation des sites de coordination présents à la périphérie du système soit par des variations de pH. Le deuxième chapitre s’intéresse aux propriétés photophysiques des porphyrines de P(V) obtenues et plus particulièrement à leur capacité à générer de l’oxygène singulet avec une application potentielle en Thérapie Photodynamique (PDT).Le troisième chapitre concerne l’élaboration d’un complexe contenant deux porphyrines de Zn(II) dont le mouvement relatif a pu être bloqué réversiblement par l’utilisation des positions axiales des cations métalliques
The manuscript focuses on molecular machines and the control of their movement. Two different devices have been designed, synthetized and characterized. Moreover, a series of new potential photosensitizer was obtained.The introduction gives a general overview on molecular machines, reported during the past 20 years. The first chapter describes the synthesis of molecular turnstiles based on P(V) porphyrins. The molecular motion was controlled reversibly using either coordination chemistry or by changing the pH. The second part is dedicated to the study of the photophysical properties of P(V) porphyrins and especially their capacity to generate singlet oxygen under irradiation., making them potential photosensitizers that can be use in Photodynamic Therapy (PDT) or as catalyst. The third chapter is devoted to the study of a molecular break based on a Zn (II) porphyrin dimer. The control of the movement was performed using the coordination of a bidentate ligand in the axial position of the metal cations
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6

Burgess, Robert Marshall. "Ambient gas effects on thin film porphyrins and on Al/Porphyrin/Ag electroluminescent and electrochemical devices /". Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/11579.

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7

Davis, Nicola Kathleen Sybille. "Anthracene-fused porphyrins". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:86b0efea-d33a-42e2-9304-82d94e8f895a.

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Abstract (sommario):
This thesis describes the synthesis of a novel family of porphyrins fused to anthracenes, together with investigations into their optical and electrochemical properties, as well as exploring their potential for application in dye-sensitised solar cells. Chapter 1 gives an overview of the structure-property relationships of large planar pi- systems for organic electronic applications. Porphyrins are introduced as suitable building blocks for such systems, and approaches for extending the pi-conjugation of these macrocycles are presented. A literature review of porphyrins fused to aromatic units is presented in Chapter 2, with a focus on the influence of structure on the optoelectronic properties of such systems. The chapter concludes with a summary of my previous work on the synthesis of anthracene-fused porphyrins, and the aims of this project are stated. Chapter 3 describes the syntheses of fully and partially fused bis-anthracene porphyrin monomers and dimers. By varying peripheral substituents, it was possible to solve problems of aggregation encountered for these systems. Fusion of anthracene units to a porphyrin core was found to result in systems displaying strong absorption in the near-IR, small HOMO-LUMO gaps, and low oxidation potentials. Chapter 4 explores the synthesis, crystal structure and optoelectronic properties of a porphyrin fused to four anthracenes, revealing this system to exhibit the longest wavelength absorption of any porphyrin monomer. The synthesis of a liquid crystalline tetra-anthracene-fused porphyrin was proposed, and attempts to synthesise the necessary anthracene precursors were undertaken. Chapter 5 describes the molecular design and synthetic pathway to a mono-anthracene fused porphyrin, and its unfused analogue, for use in liquid electrolyte dye-sensitised solar cells. By varying the metal oxide layer or lithium ion concentration of the device, it was possible to achieve incident photon to current conversion efficiency (IPCE) responses at wavelengths beyond 1050 nm. Chapter 6 details the experimental synthetic procedures and characterisation data for all the compounds synthesised during this project.
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8

Locos, Oliver Brett. "Synthesis and investigations of novel alkenylporphyrins and bis(porphyrins)". Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16409/1/Oliver_Locos_Thesis.pdf.

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Abstract (sommario):
Twelve porphyrin dyads linked by an ethene bridge were synthesised as model systems for conjugated polymers. The extent of interporphyrin interaction was investigated for meso-meso and meso-β linked homo- and heterobimetallo-porphyrin dyads. To complement these dyads, model monomers with alkenyl substituents were also studied. Once the synthesis of these compounds was achieved, the extent of interaction was studied using UV-visible and fluorescence spectroscopy and molecular modelling. In order to gain a true indication of the extent of interaction in a dyad, the effect of the bridge as a substituent must be accounted for. This was achieved by studying the series of monomers by UV-visible and fluorescence spectroscopy. The increased conjugation resulting from mono- and bis-alkenyl substituents results in a red shift of the origin of transition energies in the absorption spectrum which is accompanied by a broadened and less intense Soret band and an increase in the intensity of the Q bands. The emission of these compounds also displays an increase in Stokes shift and a loss of vibronic coupling due to the increased conjugation. The serendipitous synthesis of three asymmetric meso-β ethene-linked porphyrin dyads was achieved by the use of palladium-catalysed Heck coupling of mesoethenyl- with meso-bromoporphyrins. A possible mechanism for this meso to β rearrangement was proposed. A series of nine meso-meso ethene-linked dyads was synthesised by palladium-catalysed Suzuki coupling of meso-(2-iodoethenyl)- with meso-borolanylporphyrins. All of these dyads were characterised by 1D and 2D NMR as well as MS analysis. The absorption spectra of ethene-linked dyads exhibit a split Soret band and a red-shifted and intensified HOMO-LUMO band. In the meso-β dyads, the degree of splitting in the Soret band is sufficient only to generate a shoulder on the red edge, whereas in the meso-meso dyads two separate bands appear. The extent of splitting is believed to be an indication of the amount of porphyrin-porphyrin interaction. The fluorescence profiles of the dyads change dramatically depending upon the central substituents in the porphyrins and the wavelength used for irradiation, which suggests that different conformations of these compounds give rise to different parts of their absorption and emission profiles. The fluorescence profiles of the dyads also do not reflect their absorption profiles, and therefore the excitation of the dyad is believed to be accompanied also by a change in geometry. All ethene-linked dyads exhibited an anti-Stokes shift, and the excitation spectra of the different parts of the fluorescence envelope also support the possibility of different conformers contributing to the fluorescence spectra. Molecular mechanics and time-dependent quantum mechanical calculations were performed on seven ethene-linked porphyrin dyads. These calculations further support the proposal of different conformations contributing to the physical properties of ethene-linked dyads. Electronic structure calculations also show considerable electron density on the alkene for the meso-meso ethene-linked dyads, which highlights the important influence of this bridge upon the electronic nature of these conjugated diporphyrins.
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9

Locos, Oliver Brett. "Synthesis and investigations of novel alkenylporphyrins and bis(porphyrins)". Queensland University of Technology, 2006. http://eprints.qut.edu.au/16409/.

Testo completo
Abstract (sommario):
Twelve porphyrin dyads linked by an ethene bridge were synthesised as model systems for conjugated polymers. The extent of interporphyrin interaction was investigated for meso-meso and meso-β linked homo- and heterobimetallo-porphyrin dyads. To complement these dyads, model monomers with alkenyl substituents were also studied. Once the synthesis of these compounds was achieved, the extent of interaction was studied using UV-visible and fluorescence spectroscopy and molecular modelling. In order to gain a true indication of the extent of interaction in a dyad, the effect of the bridge as a substituent must be accounted for. This was achieved by studying the series of monomers by UV-visible and fluorescence spectroscopy. The increased conjugation resulting from mono- and bis-alkenyl substituents results in a red shift of the origin of transition energies in the absorption spectrum which is accompanied by a broadened and less intense Soret band and an increase in the intensity of the Q bands. The emission of these compounds also displays an increase in Stokes shift and a loss of vibronic coupling due to the increased conjugation. The serendipitous synthesis of three asymmetric meso-β ethene-linked porphyrin dyads was achieved by the use of palladium-catalysed Heck coupling of mesoethenyl- with meso-bromoporphyrins. A possible mechanism for this meso to β rearrangement was proposed. A series of nine meso-meso ethene-linked dyads was synthesised by palladium-catalysed Suzuki coupling of meso-(2-iodoethenyl)- with meso-borolanylporphyrins. All of these dyads were characterised by 1D and 2D NMR as well as MS analysis. The absorption spectra of ethene-linked dyads exhibit a split Soret band and a red-shifted and intensified HOMO-LUMO band. In the meso-β dyads, the degree of splitting in the Soret band is sufficient only to generate a shoulder on the red edge, whereas in the meso-meso dyads two separate bands appear. The extent of splitting is believed to be an indication of the amount of porphyrin-porphyrin interaction. The fluorescence profiles of the dyads change dramatically depending upon the central substituents in the porphyrins and the wavelength used for irradiation, which suggests that different conformations of these compounds give rise to different parts of their absorption and emission profiles. The fluorescence profiles of the dyads also do not reflect their absorption profiles, and therefore the excitation of the dyad is believed to be accompanied also by a change in geometry. All ethene-linked dyads exhibited an anti-Stokes shift, and the excitation spectra of the different parts of the fluorescence envelope also support the possibility of different conformers contributing to the fluorescence spectra. Molecular mechanics and time-dependent quantum mechanical calculations were performed on seven ethene-linked porphyrin dyads. These calculations further support the proposal of different conformations contributing to the physical properties of ethene-linked dyads. Electronic structure calculations also show considerable electron density on the alkene for the meso-meso ethene-linked dyads, which highlights the important influence of this bridge upon the electronic nature of these conjugated diporphyrins.
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10

Hames, Tim. "Playing Tetris with porphyrins : the synthesis of porphyrinic materials for self-sssembly studies". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37990/.

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This thesis focuses on the synthesis of porphyrinic materials for self-assembly studies. It begins with the synthesis of a large number of ‘building block’ molecules, terminated with bromo-, alkyne- and TMS- groups. These molecular building blocks are combined to form porphyrin compounds also terminated with bromo- alkyne- and TMS- groups at carefully selected positions. A series of porphyrin arrays inspired by the computer game Tetris was designed to be synthesised from these porphyrin units. The Tetris compounds are comprised of four square-like tetraphenylporphyrin (TPP) units, linked together with alkyne bridges to create arrays shaped like the T, I, L/J, S/Z and O Tetriminos. The NMR spectroscopy of the Tetris compounds is thoroughly explored to highlight the slight structural differences between the molecules. The synthesis of two bromoaryl-terminated porphyrin dimers for ultimate incorporation into covalent organic frameworks (COFs) is also described. The X-ray diffraction data collected showed that crystals grown were of trifluoroacetic acid (TFA) salts of the target compounds. The presence of the TFA anions resulted in significant distortion of the porphyrin ring which is described in full. Finally, the synthesis of a series of poly(acetylene) anthracene dimer compounds that have potential use in the field of organic electronics has also been explored. The electrochemical and fluorescence properties of the molecules across the series are investigated and the crystal structures are described.
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Libri sul tema "Porphyrins"

1

International, Congress on Porphyrins and Porphyrias (2nd 1985 Paris France). Porphyrins and porphyrias: Proceedings of the Second International Congress on Porphyrins and Porphyrias held in Paris (France) 19-22 June, 1985 = Porphyrines et porphyries. Paris, France: Editions INSERM, 1986.

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International Congress on Porphyrins and Porphyrias (2nd 1985 Paris, France). Porphyrins and porphyrias =: Porphyrines et porphyries : proceedings of the Second International Congress on Porphyrins and Porphyrias held in Paris (France), 19-22 June, 1985. London: J. Libbey, 1986.

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3

Dobhal, M. P. Porphyrins - Spectral Data of Porphyrin Isomers and Expanded Porphyrins. A cura di V. Gupta, M. D. Lechner e R. Gupta. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47224-8.

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Gouterman, Martin, Peter M. Rentzepis e Karl D. Straub, a cura di. Porphyrins. Washington, DC: American Chemical Society, 1986. http://dx.doi.org/10.1021/bk-1986-0321.

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Gupta, R. Porphyrins. A cura di V. Gupta, M. D. Lechner e R. Gupta. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-41556-2.

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Gupta, V., M. D. Lechner e R. Gupta, a cura di. Porphyrins. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41561-6.

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Gupta, R. Porphyrins. A cura di V. Gupta, M. D. Lechner e R. Gupta. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49340-3.

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Dobhal, M. P. Porphyrins. A cura di V. Gupta, M. D. Lechner e R. Gupta. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-41605-7.

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A, Radi͡u︡shkina K., e Bogdanovskai͡a︡ V. A, a cura di. Ėlektrokhimii͡a︡ porfirinov. Moskva: "Nauka", 1991.

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J, Weghorn Steven, a cura di. Expanded, contracted & isomeric porphyrins. Oxford, U.K: Pergamon, 1997.

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Capitoli di libri sul tema "Porphyrins"

1

William Louda, J. "Porphyrins". In Encyclopedia of Earth Sciences Series, 1–7. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39193-9_190-1.

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William Louda, J. "Porphyrins". In Encyclopedia of Earth Sciences Series, 1247–53. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-39312-4_190.

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Milgrom, L. R., e F. O’Neill. "Porphyrins". In The Chemistry of Natural Products, 329–81. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2144-6_8.

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Briggs, Thomas. "Porphyrins". In Oklahoma Notes, 104–12. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-4200-0_6.

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Briggs, Thomas. "Porphyrins". In Oklahoma Notes, 100–104. New York, NY: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-0294-0_6.

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Briggs, Thomas. "Porphyrins". In Oklahoma Notes, 100–105. New York, NY: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4684-0437-1_6.

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Loboda, Oleksandr. "Porphyrins". In Carbon Nanostructures, 1–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31845-0_1.

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Ahluwalia, V. K. "Porphyrins". In Biomolecules, 357–84. London: CRC Press, 2024. http://dx.doi.org/10.1201/9781003494553-12.

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Dobhal, M. P. "An Introduction to porphyrins". In Porphyrins - Spectral Data of Porphyrin Isomers and Expanded Porphyrins, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47224-8_1.

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Gupta, V., e R. Gupta. "An Introduction to porphyrins". In Porphyrins, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-41605-7_1.

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Atti di convegni sul tema "Porphyrins"

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Kamitani, K., M. Uo, H. Inoue, A. Makishima, T. Suzuki e K. Horie. "Synthesis and Spectroscopy of TPP Derivative-Doped Silica Gels by Sol-Gel Process". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.wd56.

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We have reported the incorporation of the photochemical hole-burning (PHB) dyes to the silica gels and the observation of spectral holes [1-3]. The porphyrins are well-known PHB dyes. However, in acidic solutions, many porphyrins change their forms into dication which is inactive in PHB [4]. So we have developed two-step sol-gel processes from the hydrolysis of TMOS with NaOH, and successfully incorporated free-base TPPS, a kind of porphyrin, in the silica gels [5].
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Ahmed, Md Soif, Chinmoy Biswas, Dipanjan Banerjee, Botta Bhavani, S. Prasanthkumar, Lingamallu Giribabu, Venugopal Rao Soma e Sai Santosh Kumar Raavi. "Ultrafast Photoexcited Molecular Dynamics of Metalated Porphyrin – Napthalimide Based Donor-Acceptor Systems". In CLEO: Applications and Technology. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_at.2022.jw3b.4.

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Ultrafast excited state molecular relaxation dynamics of two porphyrin-napthalimide molecular systems in donor–acceptor configuration, have been studied using femtosecond transient absorption measurements upon pumping the Soret bands of the porphyrins with 400 nm excitation.
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Morrow, D. I. J., e R. F. Donnelly. "Novel drug delivery strategies for porphyrins and porphyrin precursors". In 12th World Congress of the International Photodynamic Association, a cura di David H. Kessel. SPIE, 2009. http://dx.doi.org/10.1117/12.822673.

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Eom, Hyo Soon, Cheon Min Kim, Sae Chae Jeoung e Dongho Kim. "Ultrafast Vibrational Relaxation and Ligand Photodissociation/Photoassociation Processes of Nickel(II) Porphyrins". In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fe.54.

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The nickel(II) porphyrins have been well suited for an ideal system for investigating electronic decay, axial ligand photodissociation and photoassociation dynamics.1Of great significance in governing photophysics of the four- and six-coordinate nickel(II) complexes is the presence of a low-lying metal excited (dz2,dx2−y2) state having ~250 ps lifetme below porphyrin ring (π,π*) states.1 The (d,d) excited state shows characteristic sharply featured absorption difference spectra, compared to the broader featured more diffuse spectra of the ring (π,π*) and metal⇔ring charge transfer excited states. This favorable properties of the nickel(II) complexes provide a good opportunity for examining the deactivation dynamics in the porphyrin and its interaction with environment that may accompany a transition from an electronic excited state of the macrocycle to an electronic excited state of the metal.
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Harrison, R. J., G. S. Beddard, J. A. Cowan e J. K. M. Sanders. "Detection of the inverted region in photo-induced intramolecular electron transfer". In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/up.1986.mc8.

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Photo-induced electron transfer causes the rapid quenching of the excited singlet state of a number of capped porphyrins. The porphyrin donates an electron to an acceptor such as a quinone as shown in the following scheme We have observed a marked decrease in the rate of charge recombination at high -ΔG, in the so called “inverted” region, as predicted by both classical1 and quantum theories2 of electron transfer.
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Faraon, Victor, Rodica-Mariana Ion, Simona-Florentina Pop, Raluca Van-Staden e Jacobus-Frederick Van-Staden. "Porphyrins as molecular nanomaterials". In Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies, a cura di Paul Schiopu e George Caruntu. SPIE, 2010. http://dx.doi.org/10.1117/12.882110.

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Nasri, Habib. "Porphyrins and Metalloporphyrins : An Overview". In 2020 IEEE International Conference on Design & Test of Integrated Micro & Nano-Systems (DTS). IEEE, 2020. http://dx.doi.org/10.1109/dts48731.2020.9196129.

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Tang, Nansheng, Weigie Su, Thomas M. Cooper, W. Wade Adams, Donna M. Brandelik, Mark C. Brant, Daniel G. McLean e Richard L. Sutherland. "Nonlinear absorption in modified porphyrins". In SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, a cura di Christopher M. Lawson. SPIE, 1996. http://dx.doi.org/10.1117/12.253470.

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Rack, Jeffrey. "Porphyrins for magneto-optical materials". In Organic Photonic Materials and Devices XXVI, a cura di Ileana Rau, Okihiro Sugihara e William M. Shensky. SPIE, 2024. http://dx.doi.org/10.1117/12.3001115.

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Neumann, Laurie. "Synthesis of 5,15-A2BC-Type Porphyrins to Modify a Field-Effect Transistor for Detection of Gram-Negative Bacteria". In SurfCoat Korea and Graphene Korea 2021 International Joint Virtual Conferences. Setcor Conferences and Events, 2021. http://dx.doi.org/10.26799/cp-surfcoat-graphene-korea-2021/2.

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Current biological sensing technologies of bacteria are time consuming, labor intensive and thus expensive. Furthermore, their accuracy and reproducibility could be improved. Conventional electrical measurement methods might combine high sensitive sensing systems with biological requirements. A promising approach is the trapping of bacteria on the surface of the gate-electrode of a modified field-effect transistor (FET) using porphyin based self-assembled monolayers (SAMs). 5,15-A2BC-type porphyrins were synthesized originating from a 5,15-diphenylporphyrin with the functionality to connect to a gold surface. The SAM formation on the surface of the gold electrode was proven by well-established analytical methods. In this work a synthesis route is presented for a linker which is attached to a peptide or cysteine group for trapping of Gram-negative bacteria. Fluorescence lifetime imaging microscopy (FLIM) measurements of porphyrin-stained bacteria were performed to verify the linkage ability.
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Rapporti di organizzazioni sul tema "Porphyrins"

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Day, Nicholas. Polymeric Porphyrins as Solar Photocatalysts. Portland State University Library, gennaio 2000. http://dx.doi.org/10.15760/etd.2621.

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van Willigen, H. Magnetic resonance studies of photosynthetic reaction centers and porphyrins. Office of Scientific and Technical Information (OSTI), novembre 1989. http://dx.doi.org/10.2172/6551500.

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

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Wang, Chenyi. Spectroscopy, NMR, and Electrochemistry Studies of Protonated Aminophenyl/Pyridyl Porphyrins and Their Application in Hydrogen Evolution. Portland State University Library, gennaio 2000. http://dx.doi.org/10.15760/etd.2220.

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C. Saulle, Carolina, Alexandre Claus, Letícia De A. Sales, Alan G. Gonçalves, Diogo R. B. Ducatti, Miguel D. Noseda e Louise L. May De Mio. Photoinactivation of Colletotrichum truncatum, Corynespora cassiicola, Sclerotinia sclerotiorum and Rhizoctonia solani in soybean seeds by cationic porphyrins. Peeref, giugno 2023. http://dx.doi.org/10.54985/peeref.2306p7813370.

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Detty, Michael R. Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells. Fort Belvoir, VA: Defense Technical Information Center, aprile 2008. http://dx.doi.org/10.21236/ada484873.

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You, Youngiee. Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells. Fort Belvoir, VA: Defense Technical Information Center, aprile 2006. http://dx.doi.org/10.21236/ada455268.

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You, Youngjae. Structure Optimization of 21, 23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells. Fort Belvoir, VA: Defense Technical Information Center, aprile 2005. http://dx.doi.org/10.21236/ada435286.

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Michl, J. Pyridinium-Coupled Porphyrin-Based Molecular Grid Membrane. Fort Belvoir, VA: Defense Technical Information Center, luglio 2001. http://dx.doi.org/10.21236/ada395522.

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Braden, Dale. Synthesis and Characterization of a Porphyrin Dyad. Portland State University Library, gennaio 2000. http://dx.doi.org/10.15760/etd.6852.

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