Medium effects on the dimerization of coproporphyrin-I free base

Morales‐Rojas, Hugo; Yatsimirsky, Anatoly K.

doi:10.1002/(sici)1099-1395(199905)12:5<377::aid-poc137>3.0.co;2-0

Cited by 12 publications

(4 citation statements)

References 46 publications

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“…Another comparison can be made with coproporphyrin, a molecule bearing four negatively charged carboxylate groups distributed around the macrocycle. For this porphyrin, a Kd value of about 1.1 × 10 5 M −1 in 0.15 M NaCl, pH 9.0, is derived from literature data (41), one order of magnitude lower than for DS. Thus, disulfonated deuteroporphyrins display a very important propensity to dimerize, despite their excellent water solubility.…”

Section: Discussionmentioning

confidence: 96%

“…This relation applies well to the interaction of small ions with spherical charge distribution in a range of ionic strengths below 0.15 M. In aqueous solution, the value of A is 0.509 and the product B × d is generally taken as 1, which corresponds to a mean ion diameter of 3 Å. This relation was used quite successfully in the case of porphyrin dimerization, although it constitutes a rough approximation (41,44). The plot of log Kd versus μ 1/2 /(1 +μ 1/2 ) shows good linearity (see Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Increasing the product B × d to 1.5 to better account for the porphyrin size (41) did not affect the plot linearity and yielded charges of 2.8 and 1.2 for DS and DS‐DM, respectively. As generally observed, these values are less than the formal charges on the porphyrins (41,44), a difference that could be because of the formation of ion pairs between the porphyrin and sodium or potassium counterions. However, these data clearly highlight the neutralization of the carboxylic chains upon esterification.…”

Section: Discussionmentioning

confidence: 99%

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Self-association of Disulfonated Deuteroporphyrin and its Esters in Aqueous Solution and Photosensitized Production of Singlet Oxygen by the Dimers¶

Dairou

Vever‐Bizet

Brault

2007

Photochemistry and Photobiology

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Dimerization of free acid and ester forms of disulfonated deuteroporphyrin is investigated in aqueous solution by absorbance and fluorescence spectroscopies. The dimerization equilibrium constant increases with the extent of esterification. In phosphate buffer saline (pH 7.4, 20°C), it ranges from 1.4 × 106M−1 to 7.8 × 107M−1 for the free acid and the diethyl ester forms, respectively. The dimer formation is favored by an increase of ionic strength, as predicted by the Debye–Hückel law. The dimers display a marked shift to the blue of their Soret band. In agreement with the exciton model, a cofacial stacking of the molecules with some offset is postulated. The sulfonate groups on each molecule are likely to stand on opposite directions to reduce repulsion. Both the analysis of porphyrin self‐association and careful examination of the fluorescence excitation spectra show that the dimers of disulfonated deuteroporphyrins do not fluoresce at all. The quantum yield of formation of singlet oxygen by the disulfonated deuteroporphyrins in deuterated methanol is 0.71, a value typical of monomers. In deuterated water, the yield is 0.44 for all the compounds studied though they are dimerized. The fact that nonfluorescent dimers of porphyrins can be efficient photosensitizers is emphasized.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Self-association of Disulfonated Deuteroporphyrin and its Esters in Aqueous Solution and Photosensitized Production of Singlet Oxygen by the Dimers¶

Dairou

Vever‐Bizet

Brault

2007

Photochemistry and Photobiology

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“…By contrast, in N,N-dimethylformamide (DMF) or DMF/H 2 O (9:1), the B band appears at 427 nm and the Q bands are relatively sharp; the spectrum is nearly identical to that of the similarly substituted synthetic compound 2,7,12,8,13, (Kleinspehn et al 1966). Similar behavior in aqueous versus organic media is exhibited by coproporphyrin and other porphyrins that bear four or fewer alkyl carboxy groups (Mauzerall 1965;Brown et al 1976;Morales-Rojas and Yatsimirsky 1999). The broadened, blue-shifted spectrum in aqueous solution is a consequence of aggregation, most likely via hydrophobic stacking to form multimeric assemblies (Brown et al 1976).…”

Section: Porphyrin Structure and Propertiesmentioning

confidence: 99%

Simple Formation of an Abiotic Porphyrinogen in Aqueous Solution

Lindsey

Ptaszek

Taniguchi

2009

Orig Life Evol Biosph

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Porphyrins have long been proposed as key ingredients in the emergence of life yet plausible routes for forming their essential pyrrole precursor have heretofore not been identified. Here we show that the anaerobic reaction of δ-aminolevulinic acid (ALA, 1-5 mM) with the β-ketoester methyl 4-methoxyacetoacetate (2-40 mM) in water (pH5-7) at 70-100°C for >6 h affords the porphyrinogen, which upon chemical oxidation gives the corresponding porphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted pyrrole, which undergoes tetramerization and macrocycle formation under kinetic control. The resulting type-I porphyrin bears four propionic acid and four carbomethoxy groups, is distinct from porphyrins (e.g., uroporphyrin or coproporphyrin) derivable from ALA alone via the extant universal biosynthetic path to tetrapyrroles, and is photoactive upon assembly into cationic micelles in aqueous solution. The simple self-organization of eight acyclic molecules into a tetrapyrrole macrocycle, from which a porphyrin is derived that is photoactive in lipid assemblies, augurs well for the spontaneous origin of catalysts and pigments essential for prebiotic metabolism and proto-photosynthesis.

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Complexation of dicarboxylates and phosphates by a semisynthetic alkaloid‐based cyclophane in water

Lara

Godoy‐Alcántar

Rivera

et al. 2001

J of Physical Organic Chem

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Dicationic N,N′‐dibenzylated cyclophane‐type derivative 1 of a bisisoquinoline macrocyclic alkaloid, S,S‐(+)‐tetrandrine, was prepared and characterized. In aqueous solution 1 undergoes dimerization, which was studied by the concentration dependence of its 1H NMR signals. The salt effect on the dimerization constant was analyzed by using different versions of Debye–Hückel‐type equations. 1H NMR titration of 1 by 10 dicarboxylate anions of different structures revealed strong peak binding selectivity for succinate in the series of α,ω‐dicarboxylates. Aromatic carboxylates have larger binding constants and for o‐phthalate the formation of both 1:1 and 1:2 host–guest complexes is observed. Binding of nucleotides (AMP, ADP and ATP) to 1 is surprisingly insensitive to the guest charge, indicating a major contribution of stacking interactions of the nucleobase with 1. Copyright © 2001 John Wiley & Sons, Ltd.

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Medium effects on the dimerization of coproporphyrin-I free base

Cited by 12 publications

References 46 publications

Self-association of Disulfonated Deuteroporphyrin and its Esters in Aqueous Solution and Photosensitized Production of Singlet Oxygen by the Dimers¶

Self-association of Disulfonated Deuteroporphyrin and its Esters in Aqueous Solution and Photosensitized Production of Singlet Oxygen by the Dimers¶

Simple Formation of an Abiotic Porphyrinogen in Aqueous Solution

Complexation of dicarboxylates and phosphates by a semisynthetic alkaloid‐based cyclophane in water

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