Cyanine dyes spectral properties

Sato S, Tsunoda M, Suzuki M, Kutsuna M, Takido-uchi K, Shindo M, Mizuguchi H, Obara H, Ohya H (2009) Synthesis and spectral properties of polymethine-cyanine dye-nitroxide radical hybrid compounds for use as fluorescence probes to monitor reducing species and radicals. Spectrochim Acta A 71 2030-2039... 

Organic fluorescent dyes with the appropriate spectral properties also can be paired with lanthanide chelates in FRET systems. For instance, many rhodamine dyes and the cyanine dye Cy5 have ideal excitation wavelengths for receiving energy from a nearby europium chelate. The LeadSeeker assay system from GE Healthcare incorporates various Cy5-labeled antibodies for developing specific analyte assays. In addition, if using a terbium chelate as the donor, then a Cy3 fluorescent dye can be used in assays as the acceptor. 

Cyclocondensation of isatin hydrazones 620 with 621 in strong acid gave thiazolo[3, 4 2,3][l,2,4]triazino[5,6-6]indoles 622, which underwent conventional reaction with 2-methyl-3-ethylbenzothiazolium perchlorate 623 to form unsymmetrical cyanines 624 (83URP1054350 85KGS211). The spectral properties of a series of polymethine dyes were examined (88KGS1547). 

While the covalent attachment of cyanine dyes such as Cy5 or Alexa 647 to proteins does not result in noticeable changes in their spectral properties, squaraine dyes (oxo-squarines and squaraines with substituted squaraine oxygens) behave quite the opposite the absorption and emission maxima of squaraines are in general red-shifted after binding to proteins and the quantum yields and fluorescence lifetimes are manifold increased [68-70]. In general hydrophobic squaraines exhibit more pronounced increases compared to hydrophilic dyes. These effects are even stronger in noncovalent dye-protein complexes. Importantly, the photostability of squaraines also increases after binding to proteins. 

It has been necessary to understand the relationship between molecular fine structure of cyanine dyes and important properties such as colour, dye aggregation, adsorption on silver halide and electrochemical potentials in order to design and prepare sensitizers with optimum performance. For general discussion of these topics and the mechanism of spectral sensitization, the reader is referred to recent surveys on the subject (B-77MI11401, 77HC(30)441). 

The known factors which influence the solution spectra of cyanines have been recently reviewed (14, 46, 73). It will be sufficient to summarize here some of the concentration-dependent spectral properties for the specific case of l,l -diethyl-2,2 -cyanine this cyanine was employed in many of the present experiments. In alcohol as in dilute water solutions this dye, which will be referred to as Pseudocyanine, although it has also been called Pseudoisocyanine, appears to exist only in an extended configuration and has its maximum absorption near 523 n.m. This transition... 

Other studies that have been reported regard spectral and luminescent properties of some pyrylium and thiopyrylium salts (86MI1), emission properties of -y,y -chalcogenopyrylotrimethine cyanine dyes (90JA3845), and the effect of the polymethine chain length on the fluorescence spectra of symmetrical chalcogenopyrylocyanine dyes (92MI3). 

Malicka, J., et al. (2003) Fluorescence spectral properties of cyanine dye-labelled DNA oligomers on surfaces coated with silver particles. Anal Biochem 317 136-46. 

This work explored whether supersensitization of electron transfer could be demonstrated in a monolayer assembly. We also studied the properties of excited cyanine dyes, the class of compound used almost exclusively as photographic spectral sensitizers (26). Kuhn, Mtfbius, and co-workers have demonstrated the detailed information that can be gained on energy and charge-transfer properties through the use of monolayer assemblies of such dyes (23, 27). We emphasized investigations of cyanine dye... 

When the absorption and / or the emission spectra of a fluorophore possess two or more bands, the Stokes shift will be equal to the difference that separates the two most intense bands of the two spectra (Fig. 2.5). Stokes shift is dependent on the structure of the fluorophore itself and on its environment (the solvent where it is dissolved and / or the molecule to which it is bound. For example, the cyanine dye, thiazole orange (TO) absorbs at 500 nm and emits at 535 nm when it is dissolved in solution at low concentrations. These spectral properties are characteristic of that of a monomer. Increasing the concentrations yields to the formation of aggregates that absorb at 473 nm and emit at 635 nm. Thus, aggregates how larger Stokes shift compared to the monomer. The same phenomenon is also observed when TO monomers interact with DNA at high concentration of TO compared to that of DNA. In this case, the Stokes shift is found equal to at least 100 nm (Ogul chansky et al. 2001). 

Another class of long-wavelength dyes are the phthalo-cyanines and naphthalocyanines (Hgure3.19). At presenL foese dyes are less used in biochemistry owing to their lack of water solubility, their tendency to aggregate, and the lack of conjugatable forms. The spectral properties of the NIR dyes have been suimnarized in Refs. 4S, 54, and 55. 

Dye aggregation has been a topic of interest because it is thought to be a key issue in natural and artificial photosynthetic systems as well as in photonic materials such as nonlinear optical materials. The adsorpion of a cationic cyanine dye, l,l -diethyl-2,2 -cyanine (pseudoisocyanine, abbreviated as PIC, whose molecular structure is shown in Fig. 11) on smectites (montmorillonite and saponite) was reported (172,173). It is well known that the spectral properties of cyanine dyes are strongly affected by aggregation (174,175). These aggregates (so-called... 

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