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

Transformation of chlorins into bile pigment analogues

Treatment of trans-octaethylchlorin (1) with one equivalent of thallium(III) trifluoroacetate affords the corresponding aquo-hydroxide chelate (2) after chromatography on deactivated alumina; with four equivalents of the reagent, the ring opened dihydrobiliverdin (4) is obtained. When zinc trans-octaethylchlorin is treated with one equivalent of thallium(III) trifluoroacetate, the zinc meso-trifluoroacetoxy-trans-octaethylchlorin (12) is produced: hydrolysis of the trifluoroacetoxy-function in (12) in the presence of oxygen furnishes the dihydrobiliverdin (4) in high yield

ChemInform Abstract: BILE PIGMENT STUDIES. PART 4. SOME NOVEL REACTIONS OF METALLOPORPHYRINS WITH THALLIUM(III) AND CERIUM(IV) SALTS. RING CLEAVAGE OF MESO-TETRAPHENYLPORPHYRIN

Treatment of zinc(II) meso-tetraphenylporphyrin (5) with thallium(III) trifluoroacetate or nitrate, or cerium(IV) ammonium nitrate gives a mixture of the 5,15-dihydroxy-5,10,15,20-tetraphenylporphodimethenes (7), the 5-hydroxy-15-methoxy-derivatives (8), and the ring-opened bilinone (10) after acidic demetallation. An extra product when thallium(III) trifluoroacetate is employed is the trifluoroacetyl derivative (12) or (13). When thallium(III) nitrate or cerium(IV) ammonium nitrate are used, the β-nitro-meso-tetraphenylporphyrin (14) is also isolated. Nitration of zinc(II) octa-alkylporphyrins with these two salts is shown to be a general reaction which can be controlled to give mono- or di-nitration at the meso-positions. Mechanistic implications of the ring-cleavage and nitration reactions are discussed

Bile pigment studies. Part 4. Some novel reactions of metalloporphyrins with thallium(III) and cerium(IV) salts. Ring cleavage of meso-tetraphenylporphyrin

Treatment of zinc(II) meso-tetraphenylporphyrin (5) with thallium(III) trifluoroacetate or nitrate, or cerium(IV) ammonium nitrate gives a mixture of the 5,15-dihydroxy-5,10,15,20-tetraphenylporphodimethenes (7), the 5-hydroxy-15-methoxy-derivatives (8), and the ring-opened bilinone (10) after acidic demetallation. An extra product when thallium(III) trifluoroacetate is employed is the trifluoroacetyl derivative (12) or (13). When thallium(III) nitrate or cerium(IV) ammonium nitrate are used, the β-nitro-meso-tetraphenylporphyrin (14) is also isolated. Nitration of zinc(II) octa-alkylporphyrins with these two salts is shown to be a general reaction which can be controlled to give mono- or di-nitration at the meso-positions. Mechanistic implications of the ring-cleavage and nitration reactions are discussed

Biosynthetic intermediates between coproporphyrinogen-III and protoporphyrin-IX

New syntheses of the isomeric tripropionic prophyrins (3a) and (3b) have been carried out, and the feeding of the porphyrinogens (5b) and (5c) (labelled with tritium) to an enzyme system from Euglena gracilis has confirmed the hypothesis that the 2-propionic acid side-chain is modified before the 4-substituent in the biosynthesis of protoporphyrinogen-IX (5d) from coproporphyrinogen-III (5a)

Pyrroles and related compounds. Part XXXII. Biosynthesis of protoporphyrin-IX from coproporphyrinogen-III

New syntheses of 4,6,7-tris-(2-methoxycarbonylethyl)-1,3,5,8-tetramethyl-2-vinylporphyrin (2c) and its 4-vinyl isomer (2d), from pyrromethanes, are reported. These porphyrins and coproporphyrin-III tetramethyl ester (2b) were labelled at the meso-positions with tritium, and incubated in the form of the porphyrinogen carboxylic acids, with a cell-free system from Euglena gracilis. Coproporphyrinogen-III (3b), the standard for the system, was incorporated into protoporphyrin-IX (1a) to the extent of 2.0%, whereas the 2- and 4-vinylporphyrinogens gave incorporations of 3.0 and 0.5%, respectively. These results show conclusively that, in the biosynthesis of protoporphyrin-IX from coproporphyrinogen-III in Euglena gracilis, the 2-propionic acid group is converted into vinyl before the 4-substituent is modified. Further confirmation was obtained by detection of radiochemically labelled 2-vinylporphyrinogen (3c) [by isolation of the corresponding porphyrin (1c) using dilution analysis] as a product of the coproporphyrinogen-III feeding; the isomeric identity of the porphyrin (1c) was established using high-pressure liquid chromatography

Pyrroles and related compounds. Part XXIII. Protoporphyrin-l

The synthesis of protoporphyrin-l dimethyl ester (2) via the b-oxobilane route is reported. Fractional crystallisation was unsuccessful in the separation of the dimethyl esters of protoporphyrin-l and protoporphyrin-IX and also the tetramethyl esters of coproporphyrins -I and -III; the significance of these observations, in relation to biosynthetic investigations, is discussed

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