1,1 -Diethyl-2,2 -cyanine

Table 6.8. Spectral Shifts of Aggregated States of 1,1 -Diethyl-2,2 -cyanine Bromide in Ethylene Glycol-Water Matrix at 173°Ka...

In this respect adsorption of dyes has been popular, especially because their colour allows rapid and accurate spectroscopic detection in the supernatant. However, caveats (i) and (il) above also apply to these adsorbates. For a discussion the reader may consult the proceedings of a symposium devoted to surface area determination in general containing a contribution by Padday in which the outcome of a comparative survey over 19 different laboratories was reported, dealing with the adsorption of the dye 1,1 - diethyl-2,2 cyanine on silver bromide and a few other adsorbents. Giles et al. have given a list of recommended a -values ... 

C23H23IN2, 1,1 -Diethyl-2,2 -cyanine iodide, 43B, 348 C23H25CIN2O, N,N -Diethylpseudoisocyanin chloride monohydrate, 37B, 143... 

Ogawa (1998a) CJACI Adsorption on calcined film Cationic dyes Methylene Blue, 1,1 -diethyl-2,2 -cyanine, tetrakis(N-methyl-4-pvfidino)porphyrln Transparent colored films, dye loading depended on concentration of solution and reoction period... 

Jelley EE. 1937. Molecular, nematic and crystal states of l,l -diethyl- /-cyanine chloride. Nature 139 631-632. 

Because of the basic nitrogen atom, alkyl-selenazoles form quaternary salts. 2,4-Dimethyl-3-ethylselenazolium iodide (mp 157-158 0) was prepared by Brooker et al in 87% yield as colorless crystals by heating of 2,4-dimethylselenazole in excess ethyl iodide for 2 days. By reaction with the corresponding quaternary salts, the following cyanine dyes (8) were prepared" l 3-diethyl-4-methylselenazolo-2 -... 

Figure 6.18. Absorption and fluorescence spectra of l,r-diethyl-2,2 -cyanine bromide at 298 and 77°K. Fluorescence excitation at 498 nm and 565 nm, as indicated by arrows/941 Reprinted by permission of Chemical Physics Letters.

Farrens and Song<40) have replaced the original spark source with a picosecond diode laser in a multiplexed dual wavelength T-formatfluorometer.(41)With an overall instrumental response width of ca. 300 psec full-width half-maximum (FWHM), near-IR fluorescence lifetimes as low as 75 psec in the case of l,l -diethyl-4,4 carbo-cyanine iodide (DCI) (excitation 660 nm) and decay components as low as 48 psec in the case of 124 kDa oat phytochrome (excitation 752 nm) were reported. 

Fig. 14. The increase in absorbance at 238 nm (Ae 2750 M cm ) on DEPC (diethyl pyrocarbonate) modification of A. variabilis plasto-cyanin. Spectra were recorded at 5 min intervals [50]...

The cyanine dye, 3,3 -diethyl-9-methylthiacarbocyanine chloride, had a much greater effect than gelatin in decreasing the reaction rate of the silver chloride. The rate of reduction of silver chloride varied linearly with the amount of silver chloride surface not covered by the dye, and the rate attained at complete coverage was of the order of one-thousandth that for the undyed precipitate. The dye exerted scarcely any effect upon the reduction of silver ions from silver sulfite complex solution. 

Treatment of the pyrazolium[4,3-r/][l,2,3]oxadiazolium diiodide 124 with -hydroxy- or /)-dimethylaminobenzalde-hyde yielded the pyrazolo[4,3-r/][l,2,3]oxadiazole styryl and azastyryl cyanines 83a and 83b in modest yields. Parallel reaction with -nitrosophenol furnished 83c. Reaction of 124 with 1-ethylquinolinium iodide afforded 84a directly. However, 3-anilinocarbomylmethyl-2,4-diethyl-(N-phenylcarbomylmethyl)pyrazolium(4,3-r/)[l,2,3]oxadiazolium diiodide 125 arising from reaction of 124 with diphenylformamidine in refluxing acetic anhydride, is the precursor to 84b which follows from subsequent reaction with 2-methylisoquinolinium iodide (Scheme 16) <1994MI905-1>. 

In the 1,3-diethyl derivative of the benzimidazolephosphamethin-cyanine series 8d, one finds the four ethyl groups to be equivalent (pyridine as solvent). 

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... 

C.) at concentrations below 5 X 10"5M. The p-toluenesulfonate (pts) salt of this cyanine was also used it gave identical surface spectra and adsorption data in silver and silver halide dispersions (23). Astra-phloxin (55) (l,l -diethyl-3,3,3, 3 -tetramethylindocarbocyanine pts,... 

Another interesting class of molecules are stilbene derivatives with charge donating groups. These compounds offer the opportunity to explore the role of polar solvation dynamics (dielectric friction) in cis/trans isomerization. Interesting papers on this subject have been published by Waldeck et al. [145] and Rulliere et al. [146]. Other well-studied polar excited state isomerization examples include pinacyanol, l,l -diethyl-4,4 -cyanine, and crystal violet, which have been studied by Sundstrom, Gilbro and their coworkers [148] and Ben-Amotz and Harris [148] and others who are referenced in these papers [148,149],... 

Muenter and Cooper (30) measured the room-temperature fluorescence of two J-aggregated dyes, l,l -diethyl-2,2 -quino-cyanine and 1,1, 3,3 -tetraethyl-5,5, 6,6 -tetrachlorobenzimid-azolocarbocyanine, adsorbed on cubic AgBr grains. The quantum efficiency of spectral sensitization was inversely related to the relative fluorescence. The fluorescence by the dyes in the molecular state was low compared to that for the aggregated dyes. Addition of a styryl or thiohydantoin dye as a supersensitizer for the quinocyanine quenched its fluorescence and increased the relative efficiency from 0.06 to nearly 1.0. 

As noted, the uniformity of the detector used to make absorption measurement and whether it is energy-based or Figure 5.3.5-2 CR Absorption spectmm of aqueous quantum-flux based should be determined. A major solutions of diethyl-2,2 -cyanine chloride at 25C (1) 1.3 x problem has occurred in psychophysically determiningthe 5M 1-3 x 10 3M (3)7.1 x 10 3M (4) 1.4 x 10... 

Several polymethine dyes should be studied, preferably a series of dyes of a given type with varying chain length. In addition to the l,l -diethy 1-4,4 -carbocyanine iodides mentioned previously, 1,1 -diethyl-2,2 -carbocyanine iodides and 3,3 -diethyl thiacarbo-cyanine iodides are suitable. Other possible compounds can be found in the literature. ... 

Reagent-grade methyl alcohol (150 mL) several polymethine dyes, preferably a series such as 1,1 -diethyl-4,4 -cyanine iodide, -carbocyanine iodide, and -dicarbocyanine... 

Solid-phase extraction of various analyte complexes on e.g. microcrystalline naphthalene (Ni [23] and Cu [24] with nitroso-R salt and tetradecyldimethylbenzylammonium chloride), ammonium tetraphenylborate-naphthalene (U with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol) [25], chitin column (Cr(VI) with 1,5-diphenylcarbazide) [26], strong anion-exchange cartridge (Cr(VI) at pH 8) [27], Cig cartridge (CL-azo dye) [28] and minicolumn (As with ammonium diethyl dithiophosphate) [29], silica modified chemically with A-allyl- or A-phenyl-TV -propylthiourea (OSO4) [30] and Sephadex DEAE A-25 (chloride form) (V with Eriochrome Cyanine R) [31] prior to the spectrophotometric determination has recently been reported. The application of solid-phase spectrophotometry to determine nitrite and nitrate in water samples has recently been described [32]. 

A stable radical cation of the dimethylene bridged 2,2 -bithiazolium salt (18) could be observed by ESR spectroscopy after hydrolysis of the PF " salt of (18) at —0.29 eV in acetonitrile <90TL1539>. The ESR spectra of an organic ion-radical salt have been measured <93MI 306-05>. The salt consists of 3,3 -diethyl-4,4 -dimethyl-2,2 -thiazolo cyanine (19) and two TCNQ molecules. The structure of the salt has been confirmed by x-ray analysis <94Mi 306-01 >. 

---