Cyanines during the 1990s:  A Review

Mishra, Amaresh; Behera, Ratikanta; Behera, Pradipta Kumar; Mishra, Bijaya Kumar; Behera, G. B.

doi:10.1021/cr990402t

Cited by 1,469 publications

(1,205 citation statements)

References 381 publications

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“…1 These authors contributed equally to this work vitro screens involving surfactant inducers include thiacarbocyanine dyes such as N744 [8][9][10]. Cyanines are highly prone to self-association reactions that form dimers and higher order aggregates, leading to shifts in absorbance spectra relative to dye monomer [11]. Blue (hypsochromic) and red (bathochromic) shifted transitions are termed H-bands and J-bands, respectively.…”

Section: Introductionmentioning

confidence: 99%

Potent inhibition of tau fibrillization with a multivalent ligand

Honson

Jensen

Darby

et al. 2007

Biochemical and Biophysical Research Communications

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Small-molecule inhibitors of tau fibrillization are under investigation as tools for interrogating the tau aggregation pathway and as potential therapeutic agents for Alzheimer's disease. Established inhibitors include thiacarbocyanine dyes, which can inhibit recombinant tau fibrillization in the presence of anionic surfactant aggregation inducers. In an effort to increase inhibitory potency, a cyclic bis-thiacarbocyanine molecule containing two thiacarbocyanine moieties was synthesized and characterized with respect to tau fibrillization inhibitory activity by electron microscopy and ligand aggregation state by absorbance spectroscopy. Results showed that the inhibitory activity of the bisthiacarbocyanine was qualitatively similar to a monomeric cyanine dye, but was more potent with 50% inhibition achieved at ~80 nM concentration. At all concentrations tested in aqueous solution, the bis-thiacarbocyanine collapsed to form a closed clamshell structure. However, the presence of tau protein selectively stabilized the open conformation. These results suggest that the inhibitory activity of bis-thiacarbocyanine results from multivalency, and reveal a route to more potent tau aggregation inhibitors.

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Section: Introductionmentioning

confidence: 99%

Potent inhibition of tau fibrillization with a multivalent ligand

Honson

Jensen

Darby

et al. 2007

Biochemical and Biophysical Research Communications

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“…One of the widely known classes of photochromic molecules is the stilbene-like molecule [3]. Introducing a crown ether moiety into the stilbene-like molecules gives substances that respond optically to the presence of metal cations or amines in solutions.…”

Section: Introductionmentioning

confidence: 99%

Cation‐Dependent Photochromic Properties of Novel Ditopic Receptors

et al. 2003

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Novel crown-containing 2-styrylbenzothiazoles were prepared to obtain optical ditopic receptors that can bind alkaline-earth metal cations by a crown ether fragment and could serve as host for the heavy metal cations and proton owing to the presence of the heterocyclic part. Photochemical transformations of the ditopic receptors depend on the type of metal cations present in solution. They include trans-cis-isomerization, [2+2]-cycloaddition, and electrocyclic reaction.

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“…This induces a bathochromic shift of the polymer p-p* transition larger than the aggregation-induced wavelength change. The strong tendency of cyanines to aggregate 27 explains the increase in absorption wavelength with increasing dye concentration.…”

Section: Discussionmentioning

confidence: 99%

Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

Castro

Benmansour

Moser

et al. 2009

Phys. Chem. Chem. Phys.

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Power-conversion efficiencies of organic heterojunction solar cells can be increased by using semiconducting donor-acceptor materials with complementary absorption spectra extending to the near-infrared region. Here, we used continuous wave fluorescence and absorption, as well as nanosecond transient absorption spectroscopy to study the initial charge transfer step for blends of a donor poly(p-phenylenevinylene) derivative and low-band gap cyanine dyes serving as electron acceptors. Electron transfer is the dominant relaxation process after photoexcitation of the donor. Hole transfer after cyanine photoexcitation occurs with an efficiency close to unity up to dye concentrations of B30 wt%. Cyanines present an efficient self-quenching mechanism of their fluorescence, and for higher dye loadings in the blend, or pure cyanine films, this process effectively reduces the hole transfer. Comparison between dye emission in an inert polystyrene matrix and the donor matrix allowed us to separate the influence of self-quenching and charge transfer mechanisms. Favorable photovoltaic bilayer performance, including high open-circuit voltages of B1 V confirmed the results from optical experiments. The characteristics of solar cells using different dyes also highlighted the need for balanced adjustment of the energy levels and their offsets at the heterojunction when using low-bandgap materials, and accentuated important effects of interface interactions and solid-state packing on charge generation and transport. IntroductionThe potential of cheap photovoltaics is fueling the interest in organic semiconductors. [1][2][3][4] State-of-the-art devices are made from a combination of electron-donor and electron-acceptor (D-A) materials, sandwiched between metallic electrodes. 5 Photoexcitation of either of the two components leads to an exciton that can dissociate into free charge carriers at the D-A interface. 6 After charge separation, electrons and holes are transported via drift and diffusion processes to the electrodes, where they are collected, giving rise to an electric current. 2 Device efficiency is determined by the short-circuit current (J sc ), the open-circuit voltage (V oc ), and the fill factor (FF) via Z = (J sc V oc FF)/P, where P is the incident optical power. The FF is a measure of the ability to transport and extract charges when the applied voltage approaches V oc ; J sc is determined by the fraction of absorbed photons from the incident sunlight as well as by the ability to create charges via exciton dissociation at the D-A interface. Consensus has now been reached that V oc correlates with the energy difference (E D ) between the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor. [7][8][9] It follows that both J sc and V oc depend on the donor and acceptor energy levels and their offsets at the heterojunction (for illustration, see Fig. 1c). A high V oc requires a high E D . However, this implies that the HOMO-HOMO (E HH ) and LUMO-LUMO (E...

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Cyanines during the 1990s: A Review

Cited by 1,469 publications

References 381 publications

Potent inhibition of tau fibrillization with a multivalent ligand

Potent inhibition of tau fibrillization with a multivalent ligand

Cation‐Dependent Photochromic Properties of Novel Ditopic Receptors

Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

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