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Special Issue "Tetrapyrrolic Macrocycles: Synthesis, Functionalization and Applications"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: closed (15 January 2016)

Special Issue Editors

Guest Editor
Prof. Dr. M. Graça P. M. S. Neves

Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal
Website | E-Mail
Interests: Organic synthesis; tetrapyrrolic macrocycles; functionalization of porphyrins and analogues via metal-catalyzed processes and cycloaddition reactions; development of molecules with structural features to be considered as sensors, catalysts, dyes for photovoltaic cells and for medicinal and environmental applications
Guest Editor
Prof. Dr. M. Amparo F. Faustino

Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal
Website | E-Mail
Interests: Synthesis, reactivity and caracterization of tetrapyrrolic macrocycles; Functionalization of porphyrin and related derivatives via cycloaddition reactions (Diels-Alder, 1,3-dipolar and 1,5-electrocyclizations); Development of molecules with structural features to be considered in medical and environmental applications, namely photodynamic therapy of neoplastic tissues, microorganism photoinactivation (including antibiotic-resistant strains, viruses, and spores) and water disinfection; Improvement of photochemical techniques to develop environmentally friendly approaches for wastewater treatment

Special Issue Information

Dear Colleagues,

Tetrapyrrolic macrocycles, like porphyrins and analogs, participate in very important biological processes, such as respiration, electron-transfer, and photosynthesis. Additionally, their physicochemical features strongly encourage the application of these molecules in a wide range of fields. These macrocycles are being used as catalysts, advanced biomimetic models for photosynthesis, new electronic materials, sensors, and drugs. For instance, in the biomedical field, porphyrins and related species are being successfully used for the treatment of oncological and non-oncological diseases via photodynamic therapy (PDT). This Special Issue aims to provide a forum for the dissemination of the latest information on the synthesis and functionalization of tetrapyrrolic macrocycles and their potential applications.

Dr. M. Graça P. M. S. Neves
Dr. M. Amparo F. Faustino
Guest Editors

Dr. M. Graça P. M. S. Neves Dr. M. Amparo F. Faustino

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Keywords

  • tetrapyrrolic macrocycles;
  • porphyrins
  • synthesis
  • functionalization
  • application

Published Papers (12 papers)

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Research

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Open AccessArticle Mechanism of the Zn(II)Phthalocyanines’ Photochemical Reactions Depending on the Number of Substituents and Geometry
Molecules 2016, 21(5), 635; doi:10.3390/molecules21050635
Received: 12 March 2016 / Revised: 28 April 2016 / Accepted: 3 May 2016 / Published: 14 May 2016
Cited by 2 | PDF Full-text (1246 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, the synthesis and the nonlinear absorption and population dynamics investigation of a series of zinc phthalocyanines (ZnPcs) dissolved in chloroform are reported. In order to determine the relevant spectroscopic parameters, such as absorption cross-sections of singlet and triplet excited states,
[...] Read more.
In this work, the synthesis and the nonlinear absorption and population dynamics investigation of a series of zinc phthalocyanines (ZnPcs) dissolved in chloroform are reported. In order to determine the relevant spectroscopic parameters, such as absorption cross-sections of singlet and triplet excited states, fluorescence relaxation times, intersystem crossing, radiative decay and internal conversion, different optical and spectroscopic techniques were used. By single pulse and pulse train Z-scan techniques, respectively, singlet and triplet excited states‘ absorption cross-section were determined at 532 nm. Furthermore, the intersystem crossing time was obtained by using both techniques combined with the fluorescence lifetime determined by time-resolved fluorescence. The radiative and internal conversion rates were determined from the fluorescence quantum yield of the samples. Such spectroscopy parameters are fundamental for selecting photosensitizers used in photodynamic therapy, as well as for many other applications. Full article
Open AccessArticle Development of Singlet Oxygen Luminescence Kinetics during the Photodynamic Inactivation of Green Algae
Molecules 2016, 21(4), 485; doi:10.3390/molecules21040485
Received: 6 February 2016 / Revised: 22 March 2016 / Accepted: 7 April 2016 / Published: 13 April 2016
Cited by 1 | PDF Full-text (3380 KB) | HTML Full-text | XML Full-text
Abstract
Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in
[...] Read more.
Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in order to determine optimization parameters. The observation of singlet oxygen luminescence kinetics proved to be a very effective approach towards understanding mechanisms on a cellular level. In this study, the first two-dimensional measurement of singlet oxygen kinetics in phototrophic microorganisms on surfaces during photodynamic inactivation is presented. We established a system of reproducible algae samples on surfaces, incubated with two different cationic, antimicrobial potent photosensitizers. Fluorescence microscopy images indicate that one photosensitizer localizes inside the green algae while the other accumulates along the outer algae cell wall. A newly developed setup allows for the measurement of singlet oxygen luminescence on the green algae sample surfaces over several days. The kinetics of the singlet oxygen luminescence of both photosensitizers show different developments and a distinct change over time, corresponding with the differences in their localization as well as their photosensitization potential. While the complexity of the signal reveals a challenge for the future, this study incontrovertibly marks a crucial, inevitable step in the investigation of photodynamic inactivation of biofilms: it shows the feasibility of using the singlet oxygen luminescence kinetics to investigate photodynamic effects on surfaces and thus opens a field for numerous investigations. Full article
Open AccessArticle Iron(III) Fluorinated Porphyrins: Greener Chemistry from Synthesis to Oxidative Catalysis Reactions
Molecules 2016, 21(4), 481; doi:10.3390/molecules21040481
Received: 23 February 2016 / Revised: 31 March 2016 / Accepted: 5 April 2016 / Published: 12 April 2016
Cited by 3 | PDF Full-text (1925 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Iron(III) fluorinated porphyrins play a central role in the biomimetics of heme enzymes and enable cleaner routes to the oxidation of organic compounds. The present work reports significant improvements in the eco-compatibility of the synthesis of 5,10,15,20-tetrakis-pentafluorophenylporphyrin (H2TPFPP) and
[...] Read more.
Iron(III) fluorinated porphyrins play a central role in the biomimetics of heme enzymes and enable cleaner routes to the oxidation of organic compounds. The present work reports significant improvements in the eco-compatibility of the synthesis of 5,10,15,20-tetrakis-pentafluorophenylporphyrin (H2TPFPP) and the corresponding iron complex [Fe(TPFPP)Cl], and the use of [Fe(TPFPP)Cl] as an oxidation catalyst in green conditions. The preparations of H2TPFPP and [Fe(TPFPP)Cl] typically use toxic solvents and can be made significantly greener and simpler using microwave heating and optimization of the reaction conditions. In the optimized procedure it was possible to eliminate nitrobenzene from the porphyrin synthesis and replace DMF by acetonitrile in the metalation reaction, concomitant with a significant reduction of reaction time and simplification of the purification procedure. The Fe(III)porphyrin is then tested as catalyst in the selective oxidation of aromatics at room temperature using a green oxidant (hydrogen peroxide) and green solvent (ethanol). Efficient epoxidation of indene and selective oxidation of 3,5-dimethylphenol and naphthalene to the corresponding quinones is observed. Full article
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Open AccessArticle Photophysical Characterization and in Vitro Phototoxicity Evaluation of 5,10,15,20-Tetra(quinolin-2-yl)porphyrin as a Potential Sensitizer for Photodynamic Therapy
Molecules 2016, 21(4), 439; doi:10.3390/molecules21040439
Received: 12 January 2016 / Revised: 14 March 2016 / Accepted: 24 March 2016 / Published: 31 March 2016
Cited by 3 | PDF Full-text (1560 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Photodynamic therapy (PDT) is a selective and minimally invasive therapeutic approach, involving the combination of a light-sensitive compound, called a photosensitizer (PS), visible light and molecular oxygen. The interaction of these per se harmless agents results in the production of reactive species. This
[...] Read more.
Photodynamic therapy (PDT) is a selective and minimally invasive therapeutic approach, involving the combination of a light-sensitive compound, called a photosensitizer (PS), visible light and molecular oxygen. The interaction of these per se harmless agents results in the production of reactive species. This triggers a series of cellular events that culminate in the selective destruction of cancer cells, inside which the photosensitizer preferentially accumulates. The search for ideal PDT photosensitizers has been a very active field of research, with a special focus on porphyrins and porphyrin-related macrocycle molecules. The present study describes the photophysical characterization and in vitro phototoxicity evaluation of 5,10,15,20-tetra(quinolin-2-yl)porphyrin (2-TQP) as a potential PDT photosensitizer. Molar absorption coefficients were determined from the corresponding absorption spectrum, the fluorescence quantum yield was calculated using 5,10,15,20-tetraphenylporphyrin (TPP) as a standard and the quantum yield of singlet oxygen generation was determined by direct phosphorescence measurements. Toxicity evaluations (in the presence and absence of irradiation) were performed against HT29 colorectal adenocarcinoma cancer cells. The results from this preliminary study show that the hydrophobic 2-TQP fulfills several critical requirements for a good PDT photosensitizer, namely a high quantum yield of singlet oxygen generation (Φ 0.62), absence of dark toxicity and significant in vitro phototoxicity for concentrations in the micromolar range. Full article
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Open AccessArticle Can Expanded Bacteriochlorins Act as Photosensitizers in Photodynamic Therapy? Good News from Density Functional Theory Computations
Molecules 2016, 21(3), 288; doi:10.3390/molecules21030288
Received: 30 January 2016 / Revised: 19 February 2016 / Accepted: 24 February 2016 / Published: 29 February 2016
Cited by 9 | PDF Full-text (1824 KB) | HTML Full-text | XML Full-text
Abstract
The main photophysical properties of a series of expanded bacteriochlorins, recently synthetized, have been investigated by means of DFT and TD-DFT methods. Absorption spectra computed with different exchange-correlation functionals, B3LYP, M06 and ωB97XD, have been compared with the experimental ones. In good agreement,
[...] Read more.
The main photophysical properties of a series of expanded bacteriochlorins, recently synthetized, have been investigated by means of DFT and TD-DFT methods. Absorption spectra computed with different exchange-correlation functionals, B3LYP, M06 and ωB97XD, have been compared with the experimental ones. In good agreement, all the considered systems show a maximum absorption wavelength that falls in the therapeutic window (600–800 nm). The obtained singlet-triplet energy gaps are large enough to ensure the production of cytotoxic singlet molecular oxygen. The computed spin-orbit matrix elements suggest a good probability of intersystem spin-crossing between singlet and triplet excited states, since they result to be higher than those computed for 5,10,15,20-tetrakis-(m-hydroxyphenyl)chlorin (Foscan©) already used in the photodynamic therapy (PDT) protocol. Because of the investigated properties, these expanded bacteriochlorins can be proposed as PDT agents. Full article
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Open AccessArticle Rhodium Porphyrin Bound to a Merrifield Resin as Heterogeneous Catalyst for the Cyclopropanation Reaction of Olefins
Molecules 2016, 21(3), 278; doi:10.3390/molecules21030278
Received: 4 February 2016 / Revised: 18 February 2016 / Accepted: 24 February 2016 / Published: 27 February 2016
PDF Full-text (412 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyclopropanation reaction is an important tool for obtaining interesting compounds and can be catalyzed by metalloporphyrins with high syn/anti ratio. The catalyst cannot be recycled and is usually lost during chromatographic separation from the two isomeric products. In this paper a meso-tetraphenylporphyrin
[...] Read more.
Cyclopropanation reaction is an important tool for obtaining interesting compounds and can be catalyzed by metalloporphyrins with high syn/anti ratio. The catalyst cannot be recycled and is usually lost during chromatographic separation from the two isomeric products. In this paper a meso-tetraphenylporphyrin rhodium(III) chloride was bound to a Merrifield resin and used to catalyze the cyclopropanation reaction of nine olefins, giving good yields and selectivities of the final products and for the first time, a partial recycling of the catalyst. This new catalytic system will be tested in the future for the synthesis of natural products containing cyclopropyl ring. Full article
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Open AccessArticle Synthesis of 5,10-bis(Trifluoromethyl) Substituted β-Octamethylporphyrins and Central-Metal-Dependent Solvolysis of Their meso-Trifluoromethyl Groups
Molecules 2016, 21(3), 252; doi:10.3390/molecules21030252
Received: 9 January 2016 / Revised: 15 February 2016 / Accepted: 19 February 2016 / Published: 23 February 2016
Cited by 1 | PDF Full-text (951 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
5,10-Bistrifluoromethyl substituted β-octamethylporphyrins were synthesized via a scrambling side reaction of a dipyrromethane precursor in the presence of a large excess of trifluoroacetic acid. Compared with the trans-analogs, the cis-analogs of meso-trifluoromethyl β-octaalkylporphyrin showed more red-shifted absorption bands. These meso
[...] Read more.
5,10-Bistrifluoromethyl substituted β-octamethylporphyrins were synthesized via a scrambling side reaction of a dipyrromethane precursor in the presence of a large excess of trifluoroacetic acid. Compared with the trans-analogs, the cis-analogs of meso-trifluoromethyl β-octaalkylporphyrin showed more red-shifted absorption bands. These meso-trifluoromethyl derivatives of β-octaalkylporphyrins underwent smooth metalation, similar to other common porphyrins, however, the corresponding zinc complexes underwent a type of solvolysis, whereby the trifluoromethyl groups were converted into methoxycarbonyl groups by the methanol used as solvent. UV-visible absorption spectra and X-ray crystal structure analyses revealed that the presence of a methoxycarbonyl substituent did not influence the deformation of the molecular framework and its absorption properties; this is because the methoxycarbonyl has a planar and perpendicular geometry, as opposed to the relatively bulky trifluoromethyl substituent. Full article
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Open AccessArticle Synthesis and Properties of Bis-Porphyrin Molecular Tweezers: Effects of Spacer Flexibility on Binding and Supramolecular Chirogenesis
Molecules 2016, 21(1), 16; doi:10.3390/molecules21010016
Received: 25 October 2015 / Revised: 21 November 2015 / Accepted: 7 December 2015 / Published: 23 December 2015
PDF Full-text (6083 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ditopic binding of various dinitrogen compounds to three bisporphyrin molecular tweezers with spacers of varying conformational rigidity, incorporating the planar enediyne (1), the helical stiff stilbene (2), or the semi-rigid glycoluril motif fused to the porphyrins (3),
[...] Read more.
Ditopic binding of various dinitrogen compounds to three bisporphyrin molecular tweezers with spacers of varying conformational rigidity, incorporating the planar enediyne (1), the helical stiff stilbene (2), or the semi-rigid glycoluril motif fused to the porphyrins (3), are compared. Binding constants Ka = 104–106 M−1 reveal subtle differences between these tweezers, that are discussed in terms of porphyrin dislocation modes. Exciton coupled circular dichroism (ECCD) of complexes with chiral dinitrogen guests provides experimental evidence for the conformational properties of the tweezers. The results are further supported and rationalized by conformational analysis. Full article
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Review

Jump to: Research

Open AccessReview Immobilized Lignin Peroxidase-Like Metalloporphyrins as Reusable Catalysts in Oxidative Bleaching of Industrial Dyes
Molecules 2016, 21(7), 964; doi:10.3390/molecules21070964
Received: 22 June 2016 / Revised: 17 July 2016 / Accepted: 19 July 2016 / Published: 22 July 2016
Cited by 6 | PDF Full-text (6668 KB) | HTML Full-text | XML Full-text
Abstract
Synthetic and bioinspired metalloporphyrins are a class of redox-active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and
[...] Read more.
Synthetic and bioinspired metalloporphyrins are a class of redox-active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and nitroso-compounds, has been deeply investigated. Such a broad substrate specificity has suggested their use also in the bleaching of textile plant wastewaters. In fact, industrial dyes belong to very different chemical classes, being their effective and inexpensive oxidation an important challenge from both economic and environmental perspective. Accordingly, we review here the most widespread synthetic metalloporphyrins, and the most promising formulations for large-scale applications. In particular, we focus on the most convenient approaches for immobilization to conceive economical affordable processes. Then, the molecular routes of catalysis and the reported substrate specificity on the treatment of the most diffused textile dyes are encompassed, including the use of redox mediators and the comparison with the most common biological and enzymatic alternative, in order to depict an updated picture of a very promising field for large-scale applications. Full article
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Open AccessReview Porphyrin Macrocycle Modification: Pyrrole Ring-Contracted or -Expanded Porphyrinoids
Molecules 2016, 21(3), 320; doi:10.3390/molecules21030320
Received: 1 February 2016 / Revised: 24 February 2016 / Accepted: 1 March 2016 / Published: 9 March 2016
Cited by 14 | PDF Full-text (6779 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, several synthetic strategies aiming at the peripheral functionalization of porphyrins were developed. Particularly interesting are those involving the modification of β-pyrrolic positions leading to pyrrole-modified porphyrins containing four-, five-, six- or seven-membered heterocycles. Azeteoporphyrins, porpholactones and morpholinoporphyrins are representative examples
[...] Read more.
In recent years, several synthetic strategies aiming at the peripheral functionalization of porphyrins were developed. Particularly interesting are those involving the modification of β-pyrrolic positions leading to pyrrole-modified porphyrins containing four-, five-, six- or seven-membered heterocycles. Azeteoporphyrins, porpholactones and morpholinoporphyrins are representative examples of such porphyrinoids. These porphyrin derivatives have recently gained an increasing interest due to their potential application in PDT, as multimodal imaging contrast agents, NIR-absorbing dyes, optical sensors for oxygen, cyanide, hypochlorite and pH, and in catalysis. Full article
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Open AccessReview Porphyrins as Catalysts in Scalable Organic Reactions
Molecules 2016, 21(3), 310; doi:10.3390/molecules21030310
Received: 29 January 2016 / Revised: 26 February 2016 / Accepted: 1 March 2016 / Published: 8 March 2016
Cited by 15 | PDF Full-text (7933 KB) | HTML Full-text | XML Full-text
Abstract
Catalysis is a topic of continuous interest since it was discovered in chemistry centuries ago. Aiming at the advance of reactions for efficient processes, a number of approaches have been developed over the last 180 years, and more recently, porphyrins occupy an important
[...] Read more.
Catalysis is a topic of continuous interest since it was discovered in chemistry centuries ago. Aiming at the advance of reactions for efficient processes, a number of approaches have been developed over the last 180 years, and more recently, porphyrins occupy an important role in this field. Porphyrins and metalloporphyrins are fascinating compounds which are involved in a number of synthetic transformations of great interest for industry and academy. The aim of this review is to cover the most recent progress in reactions catalysed by porphyrins in scalable procedures, thus presenting the state of the art in reactions of epoxidation, sulfoxidation, oxidation of alcohols to carbonyl compounds and C–H functionalization. In addition, the use of porphyrins as photocatalysts in continuous flow processes is covered. Full article
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Open AccessReview Recent Advances in Solid Catalysts Obtained by Metalloporphyrins Immobilization on Layered Anionic Exchangers: A Short Review and Some New Catalytic Results
Molecules 2016, 21(3), 291; doi:10.3390/molecules21030291
Received: 13 January 2016 / Revised: 18 February 2016 / Accepted: 24 February 2016 / Published: 29 February 2016
Cited by 8 | PDF Full-text (3531 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Layered materials are a very interesting class of compounds obtained by stacking of two-dimensional layers along the basal axis. A remarkable property of these materials is their capacity to interact with a variety of chemical species, irrespective of their charge (neutral, cationic or
[...] Read more.
Layered materials are a very interesting class of compounds obtained by stacking of two-dimensional layers along the basal axis. A remarkable property of these materials is their capacity to interact with a variety of chemical species, irrespective of their charge (neutral, cationic or anionic). These species can be grafted onto the surface of the layered materials or intercalated between the layers, to expand or contract the interlayer distance. Metalloporphyrins, which are typically soluble oxidation catalysts, are examples of molecules that can interact with layered materials. This work presents a short review of the studies involving metalloporphyrin immobilization on two different anionic exchangers, Layered Double Hydroxides (LDHs) and Layered Hydroxide Salts (LHSs), published over the past year. After immobilization of anionic porphyrins, the resulting solids behave as reusable catalysts for heterogeneous oxidation processes. Although a large number of publications involving metalloporphyrin immobilization on LDHs exist, only a few papers have dealt with LHSs as supports, so metalloporphyrins immobilized on LHSs represent a new and promising research field. This work also describes new results on an anionic manganese porphyrin (MnP) immobilized on Mg/Al-LDH solids with different nominal Mg/Al molar ratios (2:1, 3:1 and 4:1) and intercalated with different anions (CO32− or NO3). The influence of the support composition on the MnP immobilization rates and the catalytic performance of the resulting solid in cyclooctene oxidation reactions will be reported. Full article
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