A New Synthesis of Chlorins

Jacobi, Peter A.; Lanz, Sandra; Ghosh, Indranath; Leung, Sam H.; Löwer, and Franziska; Pippin, Douglas

doi:10.1021/ol006983m

Cited by 48 publications

(51 citation statements)

References 31 publications

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“…Oxidation of dihydrodipyrrin 1-Me with SeO 2 in 1,4-dioxane at room temperature, a procedure first reported by Jacobi and coworkers, 13,28 gave the corresponding dihydrodipyrrin-carboxaldehyde 1-CHO in 47% yield (Scheme 4). We began the methodology studies with a substrate for which data were in hand concerning synthesis of the dihydrodipyrrin and conversion to a bacteriochlorin.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and photophysical characteristics of 2,3,12,13-tetraalkylbacteriochlorins

et al. 2016

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Bacteriochlorins absorb strongly in the near-infrared spectral region and hence are of great interest across the field of photochemistry. The established de novo self-condensation of a dihydrodipyrrinacetal has afforded stable bacteriochlorins bearing a variety of b-pyrrolic substituents, but the route was incompatible with the presence of two alkyl groups. The lacuna stemmed from the instability of the dialkyl-substituted dihydrodipyrrin-acetal. Here, two dihydrodipyrrin-carboxaldehydes, each bearing a tert-butoxycarbonyl group at the pyrrole a-position, were prepared and found to be stable to routine handling. Each ester-substituted dihydrodipyrrin-carboxaldehyde in acid underwent in situ ester cleavage and ensuing self-condensation to provide the corresponding 2,3,12,13-tetraalkylbacteriochlorin.The alkyl groups examined include methyl and methyl acetate. Such synthetic bacteriochlorins, while previously unknown, provide valuable models of the natural chromophores. The absorption and fluorescence characteristics of the tetraalkylbacteriochlorins are generally typical for this genre of macrocycle. The X-ray structure of the tetramethylbacteriochlorin reveals that the pyrrolinic (reduced) rings are modestly more twisted out-of-plane (torsional angle B111) than those of the nearly planar (torsional angle B11) parent bacteriochlorin that lacks pyrrolic tetraalkyl groups. The resonance Raman spectrum of the tetramethylbacteriochlorin is also far richer in the low-to mid-frequency region than that of the unsubstituted analogue, but like the unsubstituted counterpart, is far sparser in the highfrequency region than that of native bacteriochlorophyll. Access to tetraalkylbacteriochlorins constitutes one step on the path from the most simple, fully unsubstituted bacteriochlorin to the fully decorated, natural bacteriochlorophylls.

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Section: Resultsmentioning

confidence: 99%

Synthesis and photophysical characteristics of 2,3,12,13-tetraalkylbacteriochlorins

et al. 2016

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“…This method is based on a variant of the MacDonald porphyrin synthesis (Arsenault et al 1960) and involves condensation of bis-formyldihydrodipyrrins with symmetrical dihydrodipyrrins (Jacobi et al 2001). By this approach the chlorin chromophore is obtained directly in the proper oxidation state and with no need for subsequent isomerization.…”

Section: Methodsmentioning

confidence: 99%

The binding of analogs of porphyrins and chlorins with elongated side chains to albumin

et al. 2009

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In previous studies, we demonstrated that elongation of side chains of several sensitizers endowed them with higher affinity for artificial and natural membranes and caused their deeper localization in membranes. In the present study, we employed eight hematoporphyrin and protoporphyrin analogs and four groups containing three chlorin analogs each, all synthesized with variable numbers of methylenes in their alkyl carboxylic chains. We show that these tetrapyrroles’ affinity for bovine serum albumin (BSA) and their localization in the binding site are also modulated by chain lengths. The binding constants of the hematoporphyrins and protoporphyrins to BSA increased as the number of methylenes was increased. The binding of the chlorins depended on the substitution at the meso position opposite to the chains. The quenching of the sensitizers’ florescence by external iodide ions decreased as the side chains became longer, indicating to deeper insertion of the molecules into the BSA binding pocket. To corroborate this conclusion, we studied the efficiency of photodamage caused to tryptophan in BSA upon illumination of the bound sensitizers. The efficiency was found to depend on the side-chain lengths of the photosensitizer. We conclude that the protein site that hosts these sensitizers accommodates different analogs at positions that differ slightly from each other. These differences are manifested in the ease of access of iodide from the external aqueous phase, and in the proximity of the photosensitizers to the tryptophan. In the course of this study, we developed the kinetic equations that have to be employed when the sensitizer itself is being destroyed.

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“…Unfortunately, such a limitation prevents large-scale isolation of Chls and to overcome the use of such chromatographic techniques, chemical modifications can be exploited to transform Chls into derivatives which are easier to purify. These included the ring closure of bilanes by Montforts, 56 MacDonald [2 + 2] type cyclizations by Jacobi 57,58 and the extensive work by Battersby 59 and Lindsey 60 towards substituted dipyrrins and subsequent acid-catalyzed and metal-mediated cyclizations to form the chlorin macrocycles. 53 Green biomass represents a good source of natural dyes including Chls but besides the production of "chlorophyllin" (see below) no attempts have ever been made to extract Chl or derivatives thereof on an industrial scale.…”

Section: Fundamentals Of Chlorophyll Chemistrymentioning

confidence: 99%

How green is green chemistry? Chlorophylls as a bioresource from biorefineries and their commercial potential in medicine and photovoltaics

Ryan

Senge

2015

Photochem Photobiol Sci

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As the world strives to create a more sustainable environment, green chemistry has come to the fore in attempts to minimize the use of hazardous materials and shift the focus towards renewable sources. Chlorophylls, being the definitive "green" chemical are rarely used for such purposes and this article focuses on the exploitation of this natural resource, the current applications of chlorophylls and their derivatives whilst also providing a perspective on the commercial potential of large-scale isolation of these pigments from biomass for energy and medicinal applications.

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A New Synthesis of Chlorins

Abstract: A new synthesis of chlorins has been developed, based upon the acid-catalyzed condensation of dialdehydes AB with dipyrromethanes CD.

Cited by 48 publications

References 31 publications

Synthesis and photophysical characteristics of 2,3,12,13-tetraalkylbacteriochlorins

Synthesis and photophysical characteristics of 2,3,12,13-tetraalkylbacteriochlorins

The binding of analogs of porphyrins and chlorins with elongated side chains to albumin

How green is green chemistry? Chlorophylls as a bioresource from biorefineries and their commercial potential in medicine and photovoltaics

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