Phthalocyanine infrared spectra

These color characteristics are similar to those of the model phthalocyanine (VII) as well as unsubstituted phthalocyanine. Furthermore, the infrared spectrum of a sample of I cured as a thin film with added hydroquinone is very similar to that of the model phthalocyanine including the distinctly weak but sharp N-H band at 3290 cm. Notably absent are bands corresponding to carbonyl or triazine functional groups. 

A differential thermal analysis study has been made of these complexes and also of a 1-chloronaphthalene adduct (195). The complexes decompose above 560°C in vacuo with the formation of unmetallated phthalocyanine and stannous phthalocyanine. The infrared spectrum of (XLVI) is not greatly different from that of other phthalocyanines, suggesting very little distortion in the phthalocyanine rings (195). Stannic phthalocyanine (XLVI) may have a sandwich structure in which the tin atoms lie between the two phthalocyanine units in an eight-coordinate environment (109). An X-ray structural determination is in progress (307). 

This is a rather surprising result, and it seems more likely that the complex should be formulated as oxytitanium(IV) phthalocyanine monohydrate. An infrared study would confirm this since oxy titanium (IV) phthalocyanine shows, in addition to the spectrum characteristic of a phthalocyanine, a strong band at 978 cm"1 (341) (965 cm-1) (213), assigned to the Ti=0 stretching vibration. The complex may therefore be regarded as five-coordinate and presumably square pyramidal. The complex is slowly decolorized in chlorobenzene solution in air, phthalimide being the final product (213) (see also Section VI,C). 

Uranyl phthalocyanine 31) has a linear 0—U—O bond system whose asymmetric stretching frequency occurs at 920 cm-1. A band observed at 278 cm-1 in the far infrared is assigned to the 0—U—O bending vibration. The electronic spectrum of uranyl phthalocyanine in 1-chloronaphthalene is unique in having no absorption in the 500-800 mju region. All other phthalocyanines exhibit bands in this region (see Section V,B). The complex may be purified by sublimation, but is demetallated in sulfuric acid. 

Phthalocyanines typically exhibit absorption in the red region of the spectrum. It is therefore relatively easy to make phthalocyanine compounds absorb near infrared radiation by molecular modification. For example, the introduction of elec-... 

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