Studies on the Structure of alpha‐Quinacridone

Abstract

Alpha-quinacridone crystallizes in the triclinic space group P i with Z = 2, a = 14.934 f 0.064 A, b = 3.622 f 0.004 A, c = 12.935 f 0.040 A; a = 91.39 f 0.28", p = 107.13 f 0.02", y = 92.84 f 0.24".The molecules are connected by hydrogen bonds more far from linearity (-145") than gamma-quin- 162").Together with x-x bonds. building molecular stacks along the short axis b acridone = 3.622 s , both types of bonds run through the whole lattice. Molecules within the hydrophobic planes exhibit orientational disorder. Transitions between gamma-and alpha-quinacridone has been discussed: all inversion centers are retained, only the vectors of bravais lattice and the angles of molecules in the stacks are changed. The calculated pattern of alpha-quinacridone is compared with the experimental one by means of overlay-and difference plots. -The transition character of the alpha-quinacridone is stressed by generation of a combined pattern of 50% alpha-and 50% gammaquinacridone, calculating an experimental alpha-quinacridone. Zusammen mit x-n-Bindungen, die entlang der kurzen Achse b = 3.622 8, Molekulstapel aufbauen, ziehen sich beide Bindungstypen durch d+ Gitter hindurch. Molekule innerhalb der hydrophoben Flache haben Orientierungsunordnung. Ubergange zwischen gamma-und alpha-Chinacridon werden diskutiert : alle Inversionszentren der Molekule fallen rnit solchen des Bravaisgitters zusammen. Nur die Vektoren des Bravaisgitters und die Winkel der Molekule in den Stapeln werden geandert . -Das berechnete Diagramm von alpha-Chinacridon wird rnit dem experimentellen Diagramm durch Overlay-und Differenzplot verglichen. Der Ubergangscharakter des alpha-Chinacridons wird durch Erzeugen eines kombinierten Diagramms von 50% alpha-und 50% gamma-Chinacridon betont, das ein experimentelles alpha-Chinacridon berechnet.Im Handel vorkommende, aber auch im Technikum oder Labor hergestellte Pigmentproben enthalten wahrscheinlich immer anteilig die andere Phase: gamma-QA enthalt Anteile von alpha-QA, alpha-QA enthalt Anteile von gamma-QA.

Crystal structure prediction of organic pigments: quinacridone as an example

“…The structure of -QA is deposited in the CSD under the reference code QNACRD03. It has been derived from the -QA structure by systematic variation of atomic coordinates (considering chemical bonding constraints) in order to fit the experimental powder pattern of -QA (Lincke & Finzel, 1996). The only difference with the structure is the angle between the molecules in the criss-cross arrangement.…”

“…The crystal structure of the polymorph (Mizuguchi et al, 2002) is available from the Cambridge Structural Database (CSD), while for the polymorph only the cell parameters, space group and a powder pattern have been published (Paulus et al, 1989;Struve, 1955). The structure of the polymorph, derived through calculations and reported in the CSD (Lincke & Finzel, 1996), is likely to be incorrect, as discussed later. Thus, this structural information was not used further in our work.…”

Theoretical study on charge transport of quinacridone polymorphs

“…An amorphous material can be considered as a collection of molecules with relative positions similar to that in crystalline state without long range order. Here, we use the single‐crystal structures of QA19–22 to generate all the possible nearest‐neighbor intermolecular hopping pathways (dimers). The hopping pathways of QA in all polymorphs are shown in Figure 2.…”

“…Therefore, an investigation taking the crystalline polymorphs into account is essential to interpret and to better understand the transport mechanism of QA. In recent years, four polymorphs (α I , α II , β, and γ) of QA have been identified at least19–22. In this article, we are most interested in relationship between the QA polymorphs and its hole and electron transport properties.…”

Fabrication and Characterization of Quinacridones Nanocrystals by High-Temperature and High-Pressure Crystallization Method

“…The form of nanocrystals prepared at 260 • C was pure γ form. [8][9][10] With increasing the temperature of HTPL solvent, the characteristic diffraction peak was appeared at about 12 • (2θ), and was ascribed to β form. As a whole, the form of nanocrystals prepared at 340 • C was a mixture of β form and γ form.…”