Polymorphism of pigments and dyes

2020 ◽  
pp. 376-397
Author(s):  
Joel Bernstein
Keyword(s):  
Molecular Crystals ◽  
Color Stability ◽  
Polymorphic Form ◽  
Consumer Products ◽  
Tabular Form ◽  
Light Fastness ◽  
Organic Pigments ◽  
Patent Literature ◽  
Structural Database ◽  
Low Solubility

The occurrence of the polymorphism of pigments is surveyed, with a special emphasis on three of the most important classes of pigments: quinacridones, perylenes, and phthalocyanines. Organic pigments are molecular crystals of very low solubility that provide the colors for industrial and consumer products. The properties of those compounds, including color, stability, light fastness, etc., all depend intimately on the structure, hence on the existence of polymorphism and the specific polymorphic form. The chapter summarizes much of the known information of the known and reported polymorphism of pigments in tabular form, including the scientific and patent literature, patent references, and entries in the Cambridge Structural Database. The chapter closes with a discussion of the isomorphism of pigments.

A method for the determination of heat and light fastness of insoluble organic pigments

1982 ◽  
Vol 11 (12) ◽  
pp. 14-18
Author(s):  
M.A. Rabah ◽  
A.A. Aboukhashaba ◽  
M.S. Aly
Keyword(s):  
Light Fastness ◽  
Organic Pigments

Introduction and historical background

2020 ◽  
pp. 1-40
Author(s):  
Joel Bernstein
Keyword(s):  
Historical Development ◽  
Historical Perspective ◽  
Inorganic Compounds ◽  
Biological Molecules ◽  
Historical Background ◽  
Crystal Polymorphism ◽  
Patent Literature ◽  
Structural Database ◽  
The Subject

Chapter 1 provides an introduction to the subject of polymorphism in molecular crystals, including definitions, terminology, nomenclature, and historical development of the subject since the first recognition of the phenomenon in 1823. Topics covered include the difficulty in establishing a database for statistical study of polymorphism, the frequency of occurrence of polymorphism, the literature sources of polymorphic compounds, and literature sources of examples of polymorphism, that is, Cambridge Structural Database, Powder Diffraction File, the patent literature, and the scientific literature. Statistics on crystal polymorphism among the elements in inorganic compounds and macromolecular (i.e., biological) molecules precede the historical perspective. The chapter closes with a brief survey of the commercial importance of polymorphism.

Calculation of the crystal densities of molecular salts and hydrates using additive volumes for charged groups

2003 ◽  
Vol 59 (4) ◽  
pp. 498-504 ◽  
Author(s):  
Sylvain Beaucamp ◽  
Nicolas Marchet ◽  
Didier Mathieu ◽  
Viatcheslav Agafonov
Keyword(s):  
Least Squares ◽  
Functional Groups ◽  
Organic Compounds ◽  
Molecular Crystals ◽  
Average Error ◽  
Standard Group ◽  
Least Squares Fit ◽  
Molecular Salts ◽  
Structural Database ◽  
Cell Volumes

Standard group volumes which can be used to estimate the crystal densities of molecular salts and hydrates are reported, as a complement to values derived recently for the functional groups of neutral organic compounds. These new parameters were derived from a least-squares fit of cell volumes for a set of 1132 ionic molecular crystals from the Cambridge Structural Database. Their values point to the unusual overlap between monovalent O atoms and neighbouring H atoms. Using the new group volumes presently obtained, the crystal densities of the salts are predicted with an average error of <2.5%, while previous atom-based schemes yield average errors of >3%. To illustrate the possible application of the present database, the problem of designing environmentally friendly propellants is addressed.

Wechselwirkungen in Molekülkristallen, 179 [1, 2]. σ-Donator/Akzeptor-Komplexe {I2C=CI2···X⊖ } (X⊖ = Cl⊖ , Br⊖ , I⊖ , SCN⊖ ) von Tetraiodethen in Tetra(n-butyl)ammoniumhalogenid-Salzen / Interaction in Molecular Crystals, 179 [1, 2]. σ-Donor/Acceptor Complexes {I2C=CI2···X⊖} (X⊖= Cl⊖, Br⊖, I⊖, SCN⊖) of Tetraiodoethene in Tetra(n-butyl)ammonium Halide Salts

2002 ◽  
Vol 57 (7) ◽  
pp. 713-725 ◽  
Author(s):  
Hans Bock ◽  
Sven Holl
Keyword(s):  
Low Temperature ◽  
Self Assembly ◽  
Molecular Crystals ◽  
Database Search ◽  
Acceptor Molecule ◽  
Halide Anion ◽  
Structure Comparison ◽  
Donor Acceptor ◽  
Structural Database ◽  
Halide Salts

Four donor/acceptor complexes between halide anion donors and the tetraiodoethene acceptor molecule with tetra(n-butyl)ammoniumcountercations, {(H9C4)4N⊕X⊖···I2C=CI2)} (X⊖ = Cl⊖, Br⊖, I⊖, SCN⊖) could be crystallized from acetone solutions of the components R4N⊕X⊖ and I2C=CI2 by using low gradient techniques, and their structures determined at low temperature. Their molecule packing motif are layers of halide anion/tetraiodoethene patterns, which are penetrated by one of the four R4N⊕ n-butyl chains. The structure comparison, including analogous ones from an extensive Cambridge Structural Database search, discusses the geminal or vicinal addition to dimer subunits {X⊖···I2C=CI2}2 as well as their ribbon formation via additional contacts X⊖···I, and the effects of the voluminous R4N⊕ countercations. Altogether some light is shedded on essential facets of the fascinating self-assembly comprising an electron-rich halide anion and a polyiodo acceptor molecule.

The nature of the C–Br⋯Br–C intermolecular interactions found in molecular crystals: a general theoretical-database study

CrystEngComm ◽  
2015 ◽  
Vol 17 (17) ◽  
pp. 3354-3365 ◽  
Author(s):  
Marçal Capdevila-Cortada ◽  
Juan J. Novoa
Keyword(s):  
Intermolecular Interactions ◽  
Theoretical Calculations ◽  
Molecular Crystals ◽  
Cambridge Structural Database ◽  
Database Study ◽  
Structural Database

The properties of C–Br⋯Br–C interactions have been determined by doing MP2 theoretical calculations on model dimers and on dimers taken from the Cambridge Structural Database (presenting Br⋯Br distances within the 3.0 to 4.5 Å range).

scholarly journals Crystal structure prediction of organic pigments: quinacridone as an example

2007 ◽  
Vol 40 (1) ◽  
pp. 105-114 ◽  
Author(s):  
N. Panina ◽  
F. J. J. Leusen ◽  
F. F. B. J. Janssen ◽  
P. Verwer ◽  
H. Meekes ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Energy Minimization ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Organic Pigments ◽  
Structural Database ◽  
Diffraction Patterns ◽  
Experimental Structure

The structures of the α, β and γ polymorphs of quinacridone (Pigment Violet 19) were predicted usingPolymorph Predictorsoftware in combination with X-ray powder diffraction patterns of limited quality. After generation and energy minimization of the possible structures, their powder patterns were compared with the experimental ones. On this basis, candidate structures for the polymorphs were chosen from the list of all structures. Rietveld refinement was used to validate the choice of structures. The predicted structure of the γ polymorph is in accordance with the experimental structure published previously. Three possible structures for the β polymorph are proposed on the basis of X-ray powder patterns comparison. It is shown that the α structure in the Cambridge Structural Database is likely to be in error, and a new α structure is proposed. The present work demonstrates a method to obtain crystal structures of industrially important pigments when only a low-quality X-ray powder diffraction pattern is available.

The shortest chalcogen...halogen contacts in molecular crystals

2019 ◽  
Vol 75 (5) ◽  
pp. 865-869 ◽  
Author(s):  
Michał Kaźmierczak ◽  
Andrzej Katrusiak
Keyword(s):  
Interatomic Distance ◽  
Main Type ◽  
Van Der Waals ◽  
Molecular Crystals ◽  
Structural Models ◽  
Covalent Bond ◽  
Cambridge Structural Database ◽  
Molecular Arrangement ◽  
Structural Database ◽  
Van Der Waals Radii

The survey of the shortest contacts in structures deposited in the Cambridge Structural Database shows that chalcogen...halogen, halogen...halogen and chalcogen...chalcogen interactions can compete as cohesion forces in molecular crystals. The smallest parameter δ (defined as the interatomic distance minus the sum of relevant van der Waals radii) for Ch...X contacts between chalcogens (Ch: S, Se) and halogens (X: F, Cl, Br, I) is present only in 0.86% out of 30 766 deposited structures containing these atoms. Thus, in less than 1% of these structures can the Ch...X forces be considered as the main type of cohesion forces responsible for the molecular arrangement. Among the 263 structures with the shortest Ch...X contact, there are four crystals where no contacts shorter than the sums of van der Waals radii are present (so-called loose crystals). The smallest δ criterion has been used for distinguishing between the bonding (covalent bond) and non-bonding contacts and for validating the structural models of crystals.

Distribution of Molecular Centres in Crystallographic Unit Cells

1997 ◽  
Vol 53 (4) ◽  
pp. 726-736 ◽  
Author(s):  
W. D. S. Motherwell
Keyword(s):  
Visual Inspection ◽  
Global Minimum ◽  
Molecular Crystals ◽  
Close Packing ◽  
Interaction Energies ◽  
Space Groups ◽  
Packing Parameter ◽  
Unit Cells ◽  
Structural Database ◽  
The Ideal

A survey has been made of the position of molecular centres in unit cells for the seven most populated space groups in the Cambridge Structural Database. Visual inspection of histograms and scattergrams reveals very clear peaks and clusters, showing preferred locations for molecules. These preferred positions are midway between centres of symmetry or screw axes. Some simple calculations of interaction energies of molecules with neighbours in a molecular coordination sphere suggest reasons for these preferred positions. These diagrams show that simplification of molecules to spheres is helpful in visualizing the prevalence of layers of molecules and tendencies to the ideal close packing of spheres. global minimum, but not always. This observation has been noted both by workers who have exhaustively explored packing parameter space (Williams, 1969; van Eijck, Mooij & Kroon, 1995) or have used Monte Carlo methods plus simulated annealing to take statistical samples of the total space and proceed to a local minimum (Karfunkel & Gdanitz, 1992). What is certain is the importance of the principle of close packing. The present study takes the approach of looking at the total available data on packing of molecular crystals to identify certain tendencies in packing and certain commonly occurring patterns. If such patterns exist then these will have implications as regards the methods of prediction, if only on the basis of probability of occurrence.

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