Polymethine cyanines

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... 

Of some importance as textile dyes are aza analogues of polymethine (cyanine) dyes. Azacarbocyanines result when Fischer s aldehyde is heated with primary aromatic amines. Thus Cl Basic Yellow 11 (6.220) is obtained when Fischer s aldehyde is condensed with 2,4-dimethoxyaniline. The equivalent reaction with 2-methylindoline gives Cl Basic Yellow 21 (6.221), which has superior light fastness but has been classified by ETAD as toxic [73]. The tinctorially strong golden yellow diazacarbocyanine dye Cl Basic Yellow 28 (6.222) is prepared by coupling diazotised p-anisidine with Fischer s base (6.223), followed by quaternisation with dimethyl sulphate. Some triazacarbocyanine dyes are also used commercially. 

Because they exhibit excellent fluorescence on excitation, the polymethine cyanine dyes are dealt with in greater detail in Chapter 3 (section 3.5.1.7). They are also used as spectral sensitisers in photography (see section 4.5.3). 

Table VII summarizes the data on longwavelength absorption bands of 138-140 polymethine cyanine dyes (82JOC5235 88MI3).

Polymethine cyanine photochemistry in fluid solution is dominated by trans-cis isomerization as the main Si state decay route. 

Chloro-3,4-dimethylindolenine Polymethine cyanines from pyridines... 

Sanchez-Galvez A, Hunt P, Robb M, Olivucci M, Vreven T, Schlegel H. Ultrafast radiationless deactivation of organic dyes evidence for a two-state two-mode pathway in polymethine cyanines. J Am Chem Soc. 2000 122 2911-2924. 

Polymethine cyanines 27, 426 Polynitriles s. Tetracyano... Polynitro compds., aliphatic... 

There are some exceptions to this, e.g, the spectra in concentrated sulfuric acid of phthalocyanine pigments and certain vat dyes and the charge-resonance spectra of hepta- and higher polymethine-cyanines and of the beta-carotene-antimony trichloride complex [ ], all of which have peaks in the near infrared beyond 800 m/i. 

Matselyukh, B. P Yarmoluk, S. M. Matselyukh, A. B. Kovalska, V. B. Kocheshev, I. O. Kryvorotenko, D. V. Lukashov, S. S. Interaction of cyanine dyes with nucleic acids XXXI. Using of polymethine cyanine dyes for the visualization of DNA in agarose gels. J. Biochem. Biophys. Methods 2003, 57, 35-43. 

The half-wave potentials of a number of benzothi(and selen)azole dyes have been correlated with their electronic spectra. Phosphorus-containing polymethine cyanine dyes of type (103) are accessible by the condensation of 2-alkoxyvinyl (or 4-alkoxybutadienyl)-benzothiazolium and cyanomethylphosphonium salts. ... 

There is agreement that the tram —> cis photoisomerization in polymethine cyanines takes place via the 1 state. The fluorescing fr ns state is populated via the Franck Condon (FC) precursor and decays via the perpendicular state Qperp ) into tram- and ds-isomers (Scheme 1). The potential energies of the ground and exdted singlet states as a function of the angle of rotation about polymethine C-C bonds have a respective maximum and minimum at about Two theoretical models were presented... 

Sibbett, W., Taylor, J.R., and Welford, D., Substituent and environmental effects on the picosecond lifetime of the polymethine cyanine dyes, IEEE J. Quantum Electron., 17,500,1981. 

MomicchioK, R, Baraldi, I., and Berthier, G., Theoretical study of trans-cis photoisomerism in polymethine cyanines. Chem. Phys., 123,103,1988. 

---