Visible copper phthalocyanines

There is also the question of 7r-bonding and of bonding interaction between neighboring molecules. The large Hall mobility of copper phthalocyanine relative to that in the metal-free ligand (Section VI,D,3) is interpreted in terms of an interaction between copper orbitals and the t orbitals on a neighboring phthalocyanine molecule (3.38 A distant) (146, 158). There is also evidence for this type of interaction from solid state visible spectra studies (69, 70). 

Photoconductivity in copper phthalocyanine (III) now has been observed to occur with near-infrared light. Weak absorption of light in the near infrared by copper phthalocyanine has previously been observed. Although the ratio of extinction coefficients for visible and infrared light is 100 1, the ratio of the photoresponse peak heights (Fig. 7) is 3 1. This suggests that the... 

Copper phthalocyanine blue pigments are soluble in concentrated sulfuric add. The solutions are quite stable at room temperature for several hours. The sample preparation for this analysis is quite simple. The pigment sample (3-5 mg) is weighed on a microbalance and then dissolved in concentrated sulfuric acid by stirring and/ or sonication. After complete dissolution the sample is diluted to a known volume and the Visible to Near IR spectrum is scanned from 400 to 900 run. Based on the absorbance and weight concentration of the sample and that of the reference pure standard at the wavelength of maximum absorption (Imax). the amount of pigment in the sample is determined. 

Because of the fairly high extinction coefficient (3.36538 x 10 ), very small amounts of copper phthalocyanine blue pigments can be detected and measured. Figure 21-1 shows the visible spectrum of Copper Phthalocyanine Blue at a concentration of 62 p.g/L in 1-methyl-naphthalene (Imax 677nm). 

Visible spectrophotometry has also been applied similarly to the analysis of copper phthalocyanine green (PG7). This pigment is even less soluble than the non-chlorinated phthalocyanine blue. For quantitative analysis, extreme care is needed in order to ensure that the sample is in solution. Sulfuric acid is the preferred solvent except in the case of polymeric matrices. Figure 21-3 shows the Visible spectrum of PG 7 at a concentration of 140 pg/L in DMSO (A ax is at 727.5nm). 

Chloro-naphthalene and 1-methyl-naphthalene can also be used for dissolution of copper phthalocyanine blue pigments. This is particularly useful for plastic matrices where sulfuric acid is not recommended. The solubility in these solvents is limited to about 10 mg/L (10 ppm). The use of a microbalance is necessary for weighing low mg amounts. Figure 21.4 shows the visible spectrum of copper phthalocyanine blue at a concentration of 7 mg/L in 1-methyl-naphtahlene (absorbance at 677 nm is 2.1). 

Figure 21.4 Visible spectrum of copper phthalocyanine blue as solution in methyl naphthalene.

An interesting and illustrative example is provided by a study rm a dilute aqueous suspension of copper phthalocyanine crystallites. These needle-like particles are composed of layers of regularly stacked planar molecules. According to X-ray data (id) the molecular plates adopt a continuous zig-z configuration. The crystallite su ensions exhibit characteristic ctra in the red region of the visible spectmm. 

Chen F, Deng Z, Li X, Zhang J, Zhao J. Visible hght detoxification by 2,9,16,23-tetracar-boxyl phthalocyanine copper modified amorphous titania. Chem Phys Lett 2005 415 85-8. 

Anionic copper(II)phthalocyanine monosulphonate (CuPcMs) and copper(II) phthalocyanine tetrasulphonate (CuPcTs) complexes have been successfully intercalated into the intergallery of Mg-Al layered double hydroxides through direct synthesis method. XRD results indicated an inclined orientation of the anion in the interlamellar space. A better thermal stability was noticed for the macrocycle ligand upon intercalation. The visible spectra showed a hyspochromic shift upon intercalation indicating disturbance of the macrocycle ligand pltmarity. An enhanced activity for the selective oxidation of cyclohexanol to cyclohexanone was observed for the intercalated complex in comparison with neat complex. 

Polymetallophthalocyanines are structurally similar to polymetalloporphyrins however, the presence of an additional four arenes and four nitrogen atoms in their structures has a strong influence on their UV-visible spectra In 1958, Marvel and Rassweiler reported the synthesis of copper-coordinated phthalocyanine polymers, where polymerization occurred through the aromatic rings Polymer 33 is an... 

Zhang M, Shao C, Guo Z, Zhang Z, Mu J, Cao T, Liu Y (2011) Hierarchical nanostmctuie of copper (II) phthalocyanine on electrospun TiOj nanofibers controllable solvothermal-fabrication and enhanced visible photocatalytic properties. ACS Appl Mater Interfaces... 

---