Crystal structures of quinacridones

Paulus, E. F.; Leusen, Frank J. J.; Schmidt, Martin

doi:10.1039/b613059c

Cited by 156 publications

(219 citation statements)

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“…The linear QAC molecules built up stable 3D crystal structures by connecting with their neighbours by four hydrogen bonds of the type NH···O=C, forming four possible polymorphs: α I , α II , β, and γ. 36 A detailed analysis of the related crystal structures of these polymorphs using X-ray powder diffraction was provided by Paulus et al 36 and by Lincke. 37 The crystal morphology of a 3D QAC crystal, formed by the gamma quinacridone polymorph (γQAC), is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Growing low-dimensional supramolecular crystals directly from 3D particles

et al. 2017

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We show that one-dimensional (1D) nanostructures and two-dimensional (2D) supramolecular crystals of organic semiconductors can be grown on substrates under ambient conditions directly from three-dimensional (3D) organic crystals. The approach does not require dissolving, melting or evaporating of the source crystals and is based on the Organic SolidSolid Wetting Deposition (OSWD). We exemplify our approach by the pigment quinacridone (QAC). Scanning Tunnelling Microscopy (STM) investigations show that the structures of the resulting 2D crystals are similar to the chain arrangement of the alpha and beta QAC polymorphs and are independent of the 3D source crystal polymorph (gamma). Furthermore, distinct 1D chains can be produced systematically.

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Section: Introductionmentioning

confidence: 99%

Growing low-dimensional supramolecular crystals directly from 3D particles

et al. 2017

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“…In the next section, the process of experimentally searching for new solid forms is discussed. Solid forms can also be distinguished using thermogravimetric analysis [22,45,49], differential scanning calorimetry [14,45,48,49,53], as well as by examining the physical appearance such as color or crystalline shape [14,25,29,49,72]. Differential scanning calorimetry has the benefit of also providing key thermodynamic quantities such as heat capacities and enthalpies of transition between different forms.…”

Section: Improving Materials Performance Through Crystal Polymorphismmentioning

confidence: 99%

“…Properties than can change between polymorphs include density [11,20,31], compressibility [32], hardness [33,34], gel strength [35], flexibility [36], conductivity [26][27][28][29][30][37][38][39], explosivity [20,[22][23][24], catalytic activity [40,41], transparency [42,43], weather resistance [25,44], heat capacity [20], melting point [32,45,46], vapor pressure [46], stability [25,29], solubility [14,[47][48][49], bioavailability [14,33,48,[50][51][52][53][54], and dissolution rate [47,55,56].…”

Section: What Is Polymorphism?mentioning

confidence: 99%

“…Many commercial products such as drugs [14][15][16][17][18][19], explosives [20][21][22][23][24], dyes [25], and electrochemical materials [26][27][28][29][30] involve crystallized organic molecules with multiple solid forms.…”

Section: What Is Polymorphism?mentioning

confidence: 99%

“…The influence of polymorphism in commercial materials is not limited to pharmaceutical applications and has been observed to affect the hydraulic properties of cement [44], the reactivity of energetic materials [20,[22][23][24], the weather resistance of dyes [25], the transparency of optical photonics materials [42,43] and the charge carrier mobility in semi-conductor materials [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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Capturing the Role of Temperature and Entropy in Crystal Polymorphs Through Molecular Simulations

Dybeck

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AcknowledgementsI would like to acknowledge the guidance and support provided by my advisor MichaelShirts. I would also like to thank Levi Naden, Natalie Schieber, Nate Abraham and the entire Shirts group for their help and technical support during my research. I also would like to acknowledge the UVA high performance computing team for the computational resources necessary to complete this work. Finally, I would like to acknowledge the endless love and support that my friends and family provided me during this challenging Ph.D. journey.iii AbstractThe presence of multiple stable crystal structures in solid organic materials can limit their commercial viability when two or more observable polymorphs exhibit markedly different physical properties. Unintended restructuring events have hindered pharmaceutical solid form development in numerous therapeutic candidates and have led to costly market recalls.Conversely, intentional synthesis of a metastable form has led to significantly more favorable performance in numerous materials.Current computational methods for predicting polymorphic behavior evaluate candidate crystal structures based on the minimized lattice energy. However, these static lattice energybased approaches generate far more lattice energy minima than there are experimentally observed structures. Thermal motion of the crystals under working conditions has the potential to explain why many of these lattice minima are not observed experimentally. Lattice minima that are identified from a static crystal structure prediction can ultimately be unstable at experimental conditions through either temperature-mediated stability reranking, kinetic interconversion of multiple minima, or inaccuracies of the energy function in producing the real crystal ensemble.In this work, we explore the role of thermal motion in eliminating candidate crystal structures using fully atomistic molecular dynamics simulations. Enthalpically favorable structures with low entropy will become unfavorable at high temperatures through temperaturemediated stability reranking. Our simulations correctly identify the high temperature solid form as having a larger entropy than the low temperature form in twelve small molecule organic systems with known temperature-mediated transformations. The estimated entropy differences in the classical point-charge potential are significantly closer to experimental measurements than estimated enthalpy differences. This result suggests that entropy difference estimates are less sensitive to the complexity of the simulation potential than the corresponding enthalpy estimates. We additionally find that a cheaper harmonic approximation provides a sufficient estimate of entropic contributions in small rigid molecules. However, entropies with iv the harmonic approximation diverge from molecular dynamics-derived entropies in systems with multiple rotatable degrees of freedom or dynamically disordered crystalline structures.We additionally probe the sensitivity of the stability estimates to the energy function ...

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Imidazolone‐Annellated Triphenedioxazine Pigments

Schmidt

2009

High Performance Pigments

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Crystal structures of quinacridones

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Cited by 156 publications

References 42 publications

Growing low-dimensional supramolecular crystals directly from 3D particles

Growing low-dimensional supramolecular crystals directly from 3D particles

Capturing the Role of Temperature and Entropy in Crystal Polymorphs Through Molecular Simulations

Imidazolone‐Annellated Triphenedioxazine Pigments

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