Chiral J-Aggregates Formed by Achiral Cyanine Dyes

Kirstein, Stefan; Berlepsch, Hans von; Böttcher, Christoph; Bürger, Christian; Ouart, Andrè; Reck, G.; Dähne, S.

doi:10.1002/1439-7641(20001103)1:3<146::aid-cphc146>3.3.co;2-p

Cited by 43 publications

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“…One enantiomer has angles b between 0°and 90°, the other one between 90°a nd 180°. It is assumed that the single strands of the large superhelices also consist of such rings that are stacked up to cylinders [15,19]. As can be seen in Fig.…”

Section: Theory Of Spectral Behavior Of Cylindrical Jaggregatesmentioning

confidence: 99%

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Polarized absorption and anomalous temperature dependence of fluorescence depolarization in cylindrical J-aggregates

et al. 2002

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Polarized absorption and anomalous temperature dependence of fluorescence depolarization in cylindrical J-aggregates Spitz, C.; Knoester, J.; Ouart, A.; Daehne, S. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractWe study chiral J-aggregates of the amphiphilic dye 1A that are spontaneously and asymmetrically generated from achiral dye monomers. These aggregates occur in two types. One type possesses a threefold split J-absorption band and forms micrometer-sized superhelices. The other type has a twofold split J-absorption band and forms smaller nanoparticles. We show that the analysis of optical experiments with polarized light in terms of an exciton model yields strong indications that the smaller aggregates have a cylindrical structure as well; the lower exciton band is polarized along the cylinder axis, while the higher band is polarized perpendicular to it. Our analysis allows for an estimate of the number of molecules around the circumference of the cylinder. Fluorescence-polarization excitation spectra at room temperature confirm the cylinder model. At low temperature, these spectra reveal a surprising loss of fluorescence polarization upon excitation in the higher exciton band. Possible explanations for this observation are discussed. Ó

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Section: Theory Of Spectral Behavior Of Cylindrical Jaggregatesmentioning

confidence: 99%

“…2 Although the presumed rectangular shape of the molecules does not permit an optimal intermolecular overlapping, which is necessary for strong coupling, the real overlap might be much better due to an intramolecular twist of the chromophores by 17°around their trimethine chain, like it happens in crystals [19].…”

Section: Absorption Spectramentioning

confidence: 99%

Polarized absorption and anomalous temperature dependence of fluorescence depolarization in cylindrical J-aggregates

et al. 2002

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“…Recently, it was shown by Dähne et al that amphiphilic cyanine dyes are able to form very regular and well-defined structures in aqueous solutions already at low concentrations [20][21][22][23][24]. These dyes consist of a 5, 5 -6, 6 -tetrachlorobenzimidacarbocyanine chromophor [20] to which alkyl chains at the 1, 1 position of the nitrogen atoms and different acidoor sulfoalkyl substituents at the 3, 3 position (cf.…”

Section: Introductionmentioning

confidence: 99%

Photo‐induced reduction of Noble metal ions to metal nanoparticles on tubular J‐aggregates

Kirstein

Berlepsch

Böttcher

2006

International Journal of Photoenergy

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Palladium and silver nanoparticles are formed on the surface of tubular J-aggregates of an amphiphilic tetrachlorobenzimidacarbocyanine dye by reduction of the respective metal cations in aqueous solution. Upon addition of the palladium complex Na 2 PdCl 4 to the aggregate solution, the absorption spectrum shows significant changes which is explained by partial destruction of the aggregates. Cryogenic transmission electron microscopy (cryo-TEM) images show that the tubular J-aggregates are randomly covered by well-separated Pd nanoparticles of approximately 1-3 nm size. Larger particles and higher particle density along the aggregates are obtained when an auxiliary reducing agent is added to the solution. The presence of the metallic particles leads to efficient fluorescence quenching giving clear evidence for super quenching. In similar experiments using AgNO 3 , silver nanoparticles are grown which are larger in size but less dense distributed along the aggregates. At least in the case of the silver particles, the spontaneous formation of metal nanoparticles is assumed to be initiated by a photo-induced electron transfer process (PET).

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“…1-3 There are many achiral molecules reported to show chirality induced by certain chiral templates, [4][5][6][7] in which the chirality of achiral molecules can be induced through the interactions of achiral molecules with the chiral templates and the chirality of achiral molecules usually follows the chirality of the templates.…”

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Induced Circular Dichroism of Anionic Porphyrin TPPS Aggregates in DNA Solutions

Liao

Liu

et al. 2009

Polym. J.

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Induced circular dichroism (CD) of achiral anionic tetrakis (4-sulfonatophenyl) porphine (TPPS) in polyanionic DNA solutions was investigated. Induced CD signals of the anionic TPPS aggregates in both cholesteric liquid crystal DNA solutions and isotropic DNA solutions are all observed within an appropriate pH range. When the pH value is less than 5, the induced CD signals of TPPS are split in the isotropic DNA solutions, which should result from the helical arrangement of TPPS molecules within the TPPS aggregates with L-or D-type helix. The induced CD signals without splitting of TPPS aggregates in the cholesteric liquid crystal DNA solutions should result from the helical arrangement of the aggregates like molecule screwing along the cholesteric helix axis. When the pH value is higher than 5.2, no induced CD can be observed in the isotropic solutions and the cholesteric liquid crystal DNA solutions, because the electrostatic repulsion force between the non-protonated TPPS molecules and the bases on DNA chains prevents the chiral induction. The mechanism of the different induced CD signals of TPPS aggregates in the DNA solutions is discussed.KEY WORDS: Porphyrin / DNA / Chirality / Induced chirality from achiral components is an attractive field in recent years.1-3 There are many achiral molecules reported to show chirality induced by certain chiral templates, [4][5][6][7] in which the chirality of achiral molecules can be induced through the interactions of achiral molecules with the chiral templates and the chirality of achiral molecules usually follows the chirality of the templates.In cholesteric liquid crystals, the local orientation direction of the molecules is perpendicular to the helix axis and is regularly rotated with a constant twist angle. Therefore, the cholesteric liquid crystal structure is believed to be a good chiral template, which can precisely control the molecular orientation through intermolecular interactions. Many achiral dye molecules can be arranged helically in the cholesteric liquid crystals and show induced CD signals, [8][9][10][11][12][13][14] that is liquid crystal induced CD.DNA is a chiral molecule, which is used as a chiral template to induce many achiral dyes to show induced CD signals. [15][16][17][18][19][20][21] DNA aqueous solution can form cholesteric liquid crystal structure when the concentration is higher than the critical value 22 and can induce the chirality of achiral dye molecules, such as Ethidium bromide, Bisbenzimide, etc. 23Tetrakis(4-sulfonatophenyl) porphine (TPPS) is a achiral dye. It can form stable J-aggregate or H-aggregate, which depends on the pH value and ionic strength in the system. TPPS aggregates can be easily induced to show chirality by many cationic chiral and achiral templates, such as L-(or D-) Trp film, 24 gemini-Type Amphiphiles, 25 polylutamic acid 26 and polylysine, 27 chitosan, 28 etc. Usually, these templates are just cationic, which can be directly interacted with the anionic TPPS. However, there are few reports about induced chiralit...

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Chiral J-Aggregates Formed by Achiral Cyanine Dyes

Cited by 43 publications

References 0 publications

Polarized absorption and anomalous temperature dependence of fluorescence depolarization in cylindrical J-aggregates

Polarized absorption and anomalous temperature dependence of fluorescence depolarization in cylindrical J-aggregates

Photo‐induced reduction of Noble metal ions to metal nanoparticles on tubular J‐aggregates

Induced Circular Dichroism of Anionic Porphyrin TPPS Aggregates in DNA Solutions

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