Phthalocyanine phase angles

Three dimensional X-ray diffraction analysis has been employed to elucidate the molecular and crystal structure of Copper Phthalocyanine Blue ((3-modifica-tion). In all modifications, the planar and almost square phthalocyanine molecules are arranged like rolls of coins, i.e., in one dimensional stacks. The modifications vary only in terms of how these stacks are arranged relative to each other. One important aspect is the angle between staple axis and molecular plane. The a-phase features an angle of 24.7°, while the stacks in the -modification deviate by as much as 45.8° [13]. 

A cholesteric phase represents a special case of a nematic phase. The planes of adjacent molecules are also parallel, but the longitudinal axis of adjacent planes are turned about a definite angle. The result is a screw structure of the system. Cholesteric thermotropic liquid crystalline phthalocyanines are also known. ( + )-2,3,9,10,16,17,23,24-octakis[4-(dodecyloxy)-2-oxapentyl]phthalo-cyanine (preparation see Schemes 13 and 14) shows a texture typical for cholesteric phases [155], At 160°C, this compound gives a fluid isotropic phase. Upon cooling an anisotropic phase appears at 153 °C. The texture similar to platelets (blue phase) changes at 66 °C to typical cholesteric fan-shape structure and remains fan-shaped down to room temperature. Except for the discotic... 

For solid phases of CEPcHj and CEPcCu orthorombic structures were found by X-ray determinations at small angles. In these forms two-dimensional rectangular arrays of the substituted phthalocyanines lead to corrugated planes whereby the Pc macrocycles form an angle with the crown ether moieties. The substituents are arranged in an eclipsed conformation and the crown ether macrocycles form channels. Metastable mesophases of the crown ether phthalocyanines are constituted of two-dimensional square lattices superposed in a staggered conformation. The behavior of these mesophases bas been compared to that of liquid crystalline phthalocyanines [179]. 

Copper(n) phthalocyanine is a very stable volatile complex, which has a number of remarkable properties. Axially symmetric phthalocyanine molecules in the solid phase are packed in stacks from which the crystalline lattice is created. The angle between the straight line bridging copper atoms in a stack and the direction of the z axis of an individual ion frame differs for a and p crystalline modifications (cf Fig. 2). It is known from literature [4] that phthalocyanine complex stacks on the substrate surface may be ordered in different ways depending on the substrate nature. They may lie along the surface in one case and stay orthogonal to it on another surface. 

The ordered phase contains 95% of the total amount of copper phthalocyanine in the sample. The obtained angle of 26 and very small dispersions allow us to conclude that this sample consists of a practically pure ordered a-phase. Its crystalline axis b is oriented along the normal line to the plane of the slice. The degree of ordering depends on the film thickness - thin films... 

Powder XRD has been applied, for example, to the quantitative determination of alpha and beta phase contents of copper phthalocyanines, as well as the beta and gamma forms of Quinacridone Violet and Quinacridone Red, PV 19. For quantitative analysis, pure standards of each phase are mixed at various ratios from 0 to 90 %. For copper phthalocyanine blue alpha and beta phase determination, the 26 angles used are at 16.1° for the alpha form and 18.1° and 18.5° for the beta form. For quinacridone beta/gamma analysis, the 26 angles are at 13.8° for the gamma and 15.8° for the beta form. 

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