Dye phthalocyanines

Phthalocyanine-based dyes are especially useful for CD-R, as the chromophore absorption band falls in the desirable spectral range, and they are noted for excellent photostability. Unlike cyanine dyes, phthalocyanines tend to have very poor solubility, particularly in solvents such as alcohols and aliphatic hydrocarbons (which do not attack polycarbonate and are therefore used for spin coating). Therefore, the main barrier to the wider use of these dyes is the relatively high cost of synthesizing soluble derivatives. Suitable modifications to the Pc core which have been developed, notably by Mitsui Toatsu, are shown in Scheme 7. The bulky R groups reduce undesirable molecular association (which in turn lower the extinction coefficient and hence reflectivity), whereas partial bromination allows fine-tuning of the film absorbance and reflectivity. The metal atom influences the position of the absorption band, the photostability, and the efficiency of the radiationless transition from the excited state.199 This material is marketed by Ciba as Supergreen.204... 

Ink -dewatering of [DEWATERING] (Vol 8) -fluorescent pigments in [LUMINESCENTMATERIALS - FLUORESCENT PIGMENTS (DAYLIGHT)] (Vol 15) -as paper contaminant [RECYCLING - PAPER] (Vol 21) -phthalocyanine dyes [PHTHALOCYANINE COMPOUNDS] (Vol 18)... 

The best lightfastness and brilliant blue and green (turquoise) shades are obtained with copper phthalocyanine dyes. Phthalocyanines are synthesized by heating phthalodinitrile with copper chloride and then sulfonated, e.g.,C.I. Direct Blue 86, 74180 [1330-38-7] (17). 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

According to their chemical structures and the Cl system, dyes can be classified into 17 groups nitro dyes, triphenylmethane derivatives, xanthenes, acridine derivatives, quinoline derivatives, azines, ant-hraquinones, indigoid dyes, phthalocyanines dyes, oxydation bases, insoluble azo dye precursors, and azo dyes (classes XII-XVII). In practice, dyes are classified into different application classes disperse, acid, basic, direct, vat, fiber-reactive, sulfur, preme-tallic, solvent dyes, and naphthols. 

Adsorption of dyes (phthalocyanines, porphyrins, rhodamine 6G) onto superconductor YBa2Cu307 j-coated MgO surfaces Specific colors of light [49]... 

Recently, a series of chemical substances called functional dyes have attracted considerable attention. Because such dyes have long conjugated pi-electron systems and in many cases possess intramolecular charge transfer structures, functional dyes are expected to show interesting optical and electronic properties. Among functional dyes, phthalocyanine compounds have been extensively investigated because of their excellent physical, chemical and coloristic properties, as mentioned above. For example, about 1000 related US patents, published from 1990 onwards, are retrievable from the World Patent Index data base of Derwent, and more than 30 % of these are classified in such non-colorant applications as electrophotography, catalysis, and infrared radiation absorption. 

Mitsui Chemicals and Ricoh employ such phthalocyanine compounds for their CD-R products. Compared with cyanine dyes (usually pentacyanine dyes), phthalocyanine compounds are excellent with respect to light fastness and performance for high rate recording, but are much more expensive. Evaluation results of commercially available CD-R are available to consumers from the Internet web sites. In order to increase the demand for phthalocyanine compounds in CD-R recording materials, cost reduction may be the most significant hurdle to overcome. 

---