Pentamethine dyes

Pentagonal bipyramidal geometry, for metal coordination numbers, 7 574 Pentaheteroglycans, classification by structure, 4 723t Pentalene ligand, 24 772-773 Pentamethine dyes, 9 505 Pentamethylantimony, 3 77 Pentamethylcyclopentadiene, 25 116 Pentamethylcyclopentasiloxane,... 

The cleavage with cyanogen bromide (117) or chloride (KCN plus chloramine T) (118), or with thionyl chloride, has a similar course. In all instances glutaconic dialdehyde is the cleavage product and it is detected by condensation either with an aromatic amine (see p. 215), for example, aniline, 2-naphthylamine (119) or benzidine, with the formation of dianils, or with compounds with an active methylene group, as, for example, barbituric acid or dimedone with the formation of pentamethine dyes (120, 121). 

In WORM disks, pentamethine and heptamethine are the materials of choice (see Cyanine dyes Polymethine dyes). 

Optical properties of cyanines can be usefiil for both chiral substituents/environments and also third-order nonlinear optical properties in polymer films. Methine-chain substituted die arbo cyanines have been prepared from a chiral dialdehyde (S)-(+)-2-j -butylmalonaldehyde [127473-57-8] (79), where the chiral properties are introduced via the chiral j -butyl group on the central methine carbon of the pentamethine (die arbo cyanine) chromophore. For a nonchiral oxadicarbocyanine, the dimeric aggregate form of the dye shows circular dichroism when trapped in y-cyclodextrin (80). Attempts to prepare polymers with carbocyanine repeat units (linked by flexible chains) gave oligomers with only two or three repeat units (81). However, these materials... 

Fig. 9. Examples of dyes used in optical disks. (14), pentamethine cyanine [36536-22-8] (1 )> nickel dithiene complex [38465-55-3] and (16) lR-810.

Scheme 1. Principle of cyanine dye synthesis leading to trimethine (n = l), pentamethine (n = 2) and heptamethine (n = 3) chromophores. Structures comprising indolic subunits are usually named indocarbocyanine, indodicarbocyanine and indotricarbocyanine, respectively. Formic acid, malonic aldehyde, glutaconic aldehyde are used in their protected dianUide or orthoester form. They can be applied as substituted derivatives to introduce residues into the polymethine unit. The indolic substructure might bear further residues or annelated aromatic rings...

The UV spectra of selenazole, thiazoles, and thiophene derivatives as solvatochromic dyes were compared. Identically substituted compounds of the selenazole and thiazole series absorb at nearly the same wavelength (Figure 4). In contrast, the comparable compounds in the thiophene series absorb at about 40 nm longer wavelength. The spectral shift observed on going from a monomethine dye to an identically substituted trimethine dye has been studied. The shift is ca. 100 nm, nearly the same as going from a trimethine dye to a pentamethine <2001DP67>. 

Recently, Chairs analyzed the oxazolium pentamethine cyanine dye 35 (DODC, Fig. 14.8) in DNA binding studies utilizing his competitive dialysis method [75]. The nucleic acid structures included single-stranded, duplex, triplex, and tetraplex forms. The comparative assay demonstrated that DODC binds to triplex DNA more selectively than any of the tetraplex forms included in the assay. In addition, the... 

The CH-acidity-based side-chain reactivity of the corresponding 2,N-dialkylbenzo-thiazolium ions is even more pronounced. An instractive example is the condensation of two molecules of the 2,3-dimethylbenzothiazolium ion 4 (available as methosulfate by alkylation of 2-methylbenzothiazole with (CH30)2S02) with triethyl orthoformiate in pyridine, which leads to the pentamethine cyanine dye 5 [359] ... 

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