Bacteriochlorophyll aggregates in positively charged micelles

Gottstein, J.; Scherz, Avigdor; Scheer, Hugo

doi:10.1016/0005-2728(93)90247-d

Cited by 12 publications

(10 citation statements)

References 16 publications

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“…The spectrum of BChl in a micellar solution of the cationic detergent CTAB (0.1% w/v) (Fig. 9c) is that of the monomer but with a blueshifted Q y peak (770 nm), which appears to be characteristic of BChl spectra in cationic detergents (47). The Q x peak at 587 nm is indicative of five‐fold coordination (48,49).…”

Section: Resultsmentioning

confidence: 93%

Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Limantara

Koehler

Wilhelm

et al. 2006

Photochem & Photobiology

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The photostabilities of bacteriochlorophyll a and several of its derivatives, which are of interest as potential sensitizers in photodynamic tumor therapy, were investigated. The pigments were irradiated with light >630 nm in organic solvents (acetone, tetrahydrofuran, pyridine, methanol, ethanol, n-propanol, 2-propanol and toluene) and in aqueous detergent solutions (cetyl-trimethyl-ammonium bromide [CTAB], lauryldimethyl-aminoxide [LDAO] or sodium dodecyl-sulfate [SDS] and Triton X-100 [TX100]). Their stabilities in these different solvents were determined in the presence and absence of an external sensitizer (pyromethyl-pheophorbide a), oxygen, sodium ascorbate and inert gas (Ar) or vacuum. The photodegradation products of bacteriochlorophyll a in acetone solution were isolated, purified by HPLC and analyzed by their absorption spectra and mass spectroscopy. Besides the well-known dehydrogenation products, such as [3-acetyl]-chlorophyll a, which were obtained as by-products, the major products had low absorption in the visible-near infrared spectral range. The spectral signature of the major component of these products was characteristic of linear open-chain tetrapyrroles, but they lacked the characteristic protonation-deprotonation behavior and reactivity of bilins with Zn(++).

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Section: Resultsmentioning

confidence: 93%

Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Limantara

Koehler

Wilhelm

et al. 2006

Photochem & Photobiology

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“…Among amphiphilic tetrapyrrole macrocycles that have been studied in surfactant assemblies, the vast majority contain the porphyrin chromophore (40,41), with substantially fewer chlorins examined (for an overview, see Reference 32). Even fewer studies of bacteriochlorophylls (and derivatives thereof) in micelles have been reported (42)(43)(44)(45)(46)(47)(48), whereas studies of synthetic bacteriochlorins in micelles have only appeared quite recently (32,49). A chief objective of many early studies of tetrapyrroles in surfactant assemblies has been to examine interfacial photoreactions (e.g.…”

Section: Chromophoresmentioning

confidence: 99%

Enhanced Light‐Harvesting Capacity by Micellar Assembly of Free Accessory Chromophores and LH1‐like Antennas

Harris

Sahin

Jiang

et al. 2014

Photochem & Photobiology

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Biohybrid light-harvesting antennas are an emerging platform technology with versatile tailorability for solar-energy conversion. These systems combine the proven peptide scaffold unit utilized for light harvesting by purple photosynthetic bacteria with attached synthetic chromophores to extend solar coverage beyond that of the natural systems. Herein, synthetic unattached chromophores are employed that partition into the organized milieu (e.g. detergent micelles) that house the LH1-like biohybrid architectures. The synthetic chromophores include a hydrophobic boron-dipyrrin dye (A1) and an amphiphilic bacteriochlorin (A2), which transfer energy with reasonable efficiency to the bacteriochlorophyll acceptor array (B875) of the LH1-like cyclic oligomers. The energy-transfer efficiencies are markedly increased upon covalent attachment of a bacteriochlorin (B1 or B2) to the peptide scaffold, where the latter likely acts as an energy-transfer relay site for the (potentially diffusing) free chromophores. The efficiencies are consistent with a Förster (through-space) mechanism for energy transfer. The overall energy-transfer efficiency from the free chromophores via the relay to the target site can approach those obtained previously by relay-assisted energy transfer from chromophores attached at distant sites on the peptides. Thus, the use of free accessory chromophores affords a simple design to enhance the overall light-harvesting capacity of biohybrid LH1-like architectures.

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“…The observations made herein can be compared with the results of prior studies on chlorophyll a and bacteriochlorophyll a and derivatives thereof in micellar media. 16,[62][63][64]79 Those studies utilized surfactants bearing positive, negative, or neutral surfactant head groups, including those used here (CTAB, SDS, TX-100). The studies, by design, generally employed conditions to foster the incorporation of multiple chromophores per micelle and thus inter-chromophore interactions (aggregation).…”

Section: Comparison With Studies Of Natural Photosynthetic Chromophor...mentioning

confidence: 99%

“…An additional motivation was to examine the potential effects of charged head groups of the surfactants to mimic a similar role of ionized amino acids in proteins that had been suggested by theoretical work. [87][88][89] In the case of bacteriochlorophyll a, a new feature bathochromically shied from the monomer position (780 nm) was observed in TX-100 ($850 nm) 79 and CTAB ($970 nm) 64 corresponding to Q y shis of roughly 1000 and 2500 cm À1 , respectively. Additionally shied, broadened or split Soret features were observed.…”

Section: Comparison With Studies Of Natural Photosynthetic Chromophor...mentioning

confidence: 99%

“…The compounds are characterized using static and time-resolved absorption and uorescence spectroscopy in dimethylformamide (DMF) and in aqueous micellar solution containing a neutral, cationic, or anionic surfactant: Triton X-100 (TX-100), cetyl (hexadecyl) trimethylammonium bromide (CTAB), or sodium dodecyl sulfate (SDS); such surfactants have been employed previously with chlorophyll a, 62 chlorophyll derivatives, 16,63 and bacteriochlorophyll a. 64 The studies provide a roadmap of the interplay between spectral and photophysical properties and the specic environment, macrocycle type (chlorin, bacteriochlorin), central metal (zinc, free base), and substituent groups (hydrophobic, hydrophilic). The insights aid the rational design of amphiphilic photosynthetic-chromophore analogues for target environments (proteins, membranes, micelles, etc.)…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Amphiphilic chlorins and bacteriochlorins in micellar environments. Molecular design, de novo synthesis, and photophysical properties

et al. 2013

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The incorporation of amphiphilic tetrapyrrole macrocycles in organized media is of great value for a variety of fundamental photochemical studies, yet work to date has chiefly employed porphyrins rather than chlorins or bacteriochlorins. The latter absorb strongly in the red or near-infrared spectral region, respectively. Here, eight amphiphilic macrocycles (six chlorins and two bacteriochlorins) have been designed, synthesized and characterized; the compounds differ in long wavelength absorption (610-745 nm) and peripheral substituents (type of auxochrome, hydrophobic/hydrophilic groups). A methyl pyridinium or benzoic acid substituent at the 15-position provides a polar "tail" whereas a hydrophobic group distal thereto (in the chlorins) provides a lipophilic "head" for the spontaneous incorporation in organized media. The eight (bacterio)chlorins are characterized by static and time-resolved absorption and fluorescence spectroscopy in N,N-dimethylformamide (DMF) and three micellar environments (TX-100, CTAB, and SDS) as well as ultrafast transient absorption studies in DMF. In most cases, a long-lived excited singlet state was observed [free base chlorins (F f ¼ 0.14-0.20; s S ¼ 7.9-12.1 ns; F isc ¼ 0.5), zinc chlorins (F f ¼ 0.08-0.19; s S ¼ 2.0-3.4 ns; F isc ¼ 0.6-0.8) and free base bacteriochlorins (F f ¼ 0.06-0.16; s S ¼ 1.8-4.6 ns; F isc ¼ 0.4)]. In the case of bacteriochlorins, minimal medium dependence was observed whereas changing the hydrophilic group from methyl pyridinium to benzoic acid increases the fluorescence yield and excited-state lifetime by 50%. In the case of chlorins, the zinc chelate with methyl pyridinium substitution exhibits substantial environmental dependence due to interaction of the solvent with the methyl pyridinium group and the central zinc metal. Collectively, the studies provide valuable information for the design of red or near-infrared absorbing chromophores for incorporation into amphiphilic environments such as micelles, membranes, or proteins.

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Bacteriochlorophyll aggregates in positively charged micelles

Cited by 12 publications

References 16 publications

Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Enhanced Light‐Harvesting Capacity by Micellar Assembly of Free Accessory Chromophores and LH1‐like Antennas

Amphiphilic chlorins and bacteriochlorins in micellar environments. Molecular design, de novo synthesis, and photophysical properties

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