Exploring the reactivity of formylporphyrins with 3-(diethylamino)phenol. Synthesis, spectroscopic properties and singlet oxygen generation of a new porphyrin–rosamine conjugate

The design of novel molecular structures with tunable photophysical properties is an important research field for many applications including optoelectronics, sensing and bioimaging. Porphyrin and rhodamine/rosamine derivatives are among the most studied and relevant chemosensors and imaging probes due to their attractive photophysical properties, such as high absorption coefficients and long emission wavelengths. In this work, we present the synthesis and the structural characterization of a new porphyrin–rosamine conjugate H2P3 and its related triarylmethane precursors H2P1 and H2P2. The photophysical properties of H2P1, H2P2 and H2P3, and their ability to chelate iron(III) and copper(II) ions, were evaluated by absorption and emission spectroscopy. The formation of copper(II) complexes was confirmed by electron paramagnetic resonance (EPR), which also allowed the detection of an intense and stable radical signal for the free-base H2P3. Further studies involving the addition of the 2,2,6,6-tetramethylpiperidine spin trap to derivatives H2P1, H2P2 and H2P3, showed that only H2P3 gives rise to an EPR detectable signal due to a strong generation of singlet oxygen.publishe

New triazine bridged triads based on BODIPY-porphyrin systems: extended absorption, efficient energy transfer and upconverted emission

Two novel triads connecting a BODIPY to ethylenediamine substituted porphyrins via triazine linker have been synthesized and characterized. One of the triads is a linear D-A structure with one BODIPY (D) and one porphyrin (A) bridged by the triazine linker and the other one is a branched A-D4 structure with the porphyrin core linked to four BODIPY units. The triads show extended absorption in the visible region with contributions from both porphyrin (Soret band centred at 410–430 nm) and BODIPY units (strong absorption at ≈ 502 nm) in good agreement with the expected molar ratio. Both triads exhibit linear and nonlinear optical properties featuring an efficient energy transfer from the BODIPY donor to the porphyrin acceptor. The nonlinear upconverted emission properties of the triads were studied by two-photon excitation in the Near-infrared (NIR, 710–930 nm). The maximum two-photon absorption cross-section values for the triads (40–70 GM) are larger than those typically reported in this wavelength range for porphyrins and BODIPY. Both the green emission of BODIPY (≈514 nm) and the red emission of porphyrins (650–750 nm) were observed under NIR excitation at 930 nm. The distinct features of triads, namely i) an extended absorption; ii) an efficient energy transfer and iii) the nonlinear upconverted emission featuring a large separation between the excitation and emission wavelengths could be beneficial for application in sensing and imaging procedures.publishe

Cancer, Photodynamic Therapy and Porphyrin-Type Derivatives

ABSTRACT This review has two parts. The first one gives an approach to interdisciplinary studies against cancer carried out by many scientists using porphyrin-type substrates as photosensitizers in PDT. Intensive studies were performed for almost six decades. The successes really started in 1993 with the first formulation patented under the trade name Photofrin, which was immediately approved in several countries to treat certain types of cancer. Photofrin is still used although certain negative features soon became well known. That has motivated the search for better new photosensitizers. Several ones were developed, evaluated and a few of them had clinical approval. This group includes porphyrin derivatives and pro-drugs (aminolevulinic acid and its alkyl esters). Oncological, dermatological and ophthalmic applications are now taking place for the benefit of mankind. The second part of this review is related with the work carried out in Aveiro at the authors University on the synthesis and biological evaluation of several potential PDT photosensitizers. Not only new synthetic methodologies mainly for porphyrins and chlorins were developed but also other related macrocycles of the phthalocyanine and corrole types have entered in the same “pipeline”. In vivo and in vitro biological evaluations also took place under interdisciplinary studies

Diels-Alder reactions of Ni(II) β-vinyl-meso-tetraarylporphyrins

The cycloaddition reactions of nickel(II) β-vinyl-meso-tetraphenylporphyrins with tetracyanoethylene (TCNE) in chloroform, afford [2+2] adducts containing a cyclobutane ring and [4+2] adducts. The [2+2] adducts can also be produced by rearrangement of the [4+2] chlorins

New naphthochlorins from the intramolecular cyclization of β-vinyl-meso-tetraarylporphyrins

Treatment of nickel(II) β-vinyl-meso-tetraphenylporphyrins with a dilute solution of sulfuric acid affords new naphthochlorins that result from an intramolecular cyclization involving the vinyl group and the ortho position of the adjacent phenyl ring. These naphthochlorins are very stable compounds and exhibit strong absorptions in the 670 nm region of the visible spectrum. © 1995

Electrochemical and spectroscopic properties of C(II)beta;-nitro meso-tetra(pentafluorophenyl)porphyrins

Some electrochemical and spectroscopic properties of the copper(II) derivatives of β-unsubstituted, β-mono-, β-di-and β-tri-substituted meso-tetra(pentafluorophenyl)porphyrins are presented. The red-shirt observed on the bands of the optical spectra, and the value of the first and second reduction potentials of these compounds depend on the number of nitro substituents on the porphyrin macrocycle

Cancer, Photodynamic Therapy and Porphyrin-Type Derivatives

<div><p>ABSTRACT This review has two parts. The first one gives an approach to interdisciplinary studies against cancer carried out by many scientists using porphyrin-type substrates as photosensitizers in PDT. Intensive studies were performed for almost six decades. The successes really started in 1993 with the first formulation patented under the trade name Photofrin, which was immediately approved in several countries to treat certain types of cancer. Photofrin is still used although certain negative features soon became well known. That has motivated the search for better new photosensitizers. Several ones were developed, evaluated and a few of them had clinical approval. This group includes porphyrin derivatives and pro-drugs (aminolevulinic acid and its alkyl esters). Oncological, dermatological and ophthalmic applications are now taking place for the benefit of mankind. The second part of this review is related with the work carried out in Aveiro at the authors University on the synthesis and biological evaluation of several potential PDT photosensitizers. Not only new synthetic methodologies mainly for porphyrins and chlorins were developed but also other related macrocycles of the phthalocyanine and corrole types have entered in the same “pipeline”. In vivo and in vitro biological evaluations also took place under interdisciplinary studies.</p></div

Oxidation of natural compounds catalyzed by Mn(III) porphyrin complexes

The oxidation of 1,8-cineole (1) and methyl dehydroabietate (8b) by hydrogen peroxide, catalysed by Mn(III) porphyrin complexes, is reported. Five oxygenated products (2-6) have been obtained from reactions at positions 2 and 3 of 1,8-cineole and three oxygenated products (9-11) from the reaction at position 7 of methyl dehydroabietate

Meso-Tetraphenylporphyrin Dimer Derivative as a Potential Photosensitizer in Photodynamic Therapy

Studies on the synthesis, preliminary in vivo biological activity, singlet oxygen and fluorescence yields of a climeric porphyrin (D1) are described. The pharmacokinetic behavior and photodynamic properties of the dimer D1 were examined in Balb/c mice bearing an MS-2 fibrosarcoma. Compound D1 shows a high selectivity for tumor localization (tumor/peritumoral tissue ratios of dye concentration ranging between ca 100 and 140 at 24 h after drug administration of 5.0-1.0 mg kg-1 into DL-α-dipalmitoylphosphatidylcholine liposomes). The phototherapeutic efficiency of dimer D1 was evaluated by following the growth curves of fibrosarcoma irradiated with red light (600-700 nm) with a total dose of 400 J cm-2, at 24 h after intravenous injection. Photodynamic therapy-treated tumors showed a significant delay in growth as compared to untreated control mice. The results obtained suggest that the porphyrin dimer D1 may be a promising candidate for further use in PDT experiments

A facile and effective synthesis of 4-imino-3-(arylidene)- azetidine-2-thiones via phosphorus pentasulfide

<div><p>A new and an efficient synthesis of 4-imino-3-(arylidene)-azetidine-2-thiones is reported. The reaction of arylidenemalononitriles with phosphorus pentasulfide and ethanol affords the title products in good yields. Elemental analysis, infrared, ¹H NMR, ¹³C NMR and mass spectral data elucidated structure of newly synthesized compounds.</p></div