Mechanics of twisted hippuric acid crystals untwisting as they grow

Shtukenberg, Alexander G.; Gujral, Ankit; Rosseeva, Elena; Cui, Xiaoyan; Kahr, Bart

doi:10.1039/c5ce00195a

Cited by 37 publications

(66 citation statements)

References 19 publications

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“…Besides banded polymer spherulites, the banded spherulites of small molecules, such as K2Cr2O7 [43], hippuric acid [44], and aspirin [45], are composed of twisted crystals as well.…”

Section: Real Time Atomic Force Microscopy (Afm) Observation Reveals mentioning

confidence: 99%

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Zhang

et al. 2017

Crystals

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Abstract:In this mini-review, we summarize the evidences of lamellar twisting in the birefringent banded polymer spherulites demonstrated by various characterization techniques, such as polarized optical microscopy, real-time atomic force microscopy, micro-focus wide angle X-ray diffraction, etc. The real-time observation of lamellar growth under atomic force microscopy unveiled the fine details of lamellar twisting and branching in the banded spherulites of poly(R-3-hydroxybutyrate-co-17 mol % R-3-hydroxyhexanoate). Organization of the twisting lamellar crystals in the banded spherulites was revealed as well. The lamellar crystals change the orientation via twisting rather than the macro screw dislocations. In fact, macro screw dislocation provides the mechanism of synchronous twisting of neighboring lamellar crystals. The driving force of lamellar twisting is attributed to the anisotropic and unbalanced surface stresses. Besides molecular chirality, variation of the growth axis and the chemical groups on lamellar surface can change the distribution of the surface stresses, and thus may invert the handedness of lamellar twisting. Thus, based on both experimental results and physical reasoning, the relation between crystal chirality and chemical molecular structures has been suggested, via the bridge of the distribution of surface stresses. The factors affecting band spacing are briefly discussed. Some remaining questions and the perspective of the topic are highlighted.Keywords: banded polymer spherulite; ringed spherulite; lamellar twisting; organization of lamellar crystals; surface stresses; chirality When crystallized from quiescent melt or concentrated solution, polymer chains usually form spherulites consisted of multiple lamellar crystals radiating from the spherulite center. Observed under polarized optical microscope (POM), a spherulite shows the characteristic Maltese-cross extinction. Besides the Maltese cross, some spherulites demonstrate alternative bright and dark bands under POM. These spherulites are termed as banded spherulites or ringed spherulites. The band structure with different light intensities may result from different thicknesses or different birefringences but similar thickness. In the former case, the bands are due to the periodical modulation of sample thickness and there is no variation of refractive index in the spherulite. These nonbirefringent banded spherulites have been observed in some polymer single crystals formed from thin melt films [1] or solutions [2] and are reviewed by Li et al. [3] in this special issue. In the latter case, the birefringent bands can result from the wavy bending growth or twisting growth of crystals. The wavy bands have been reported in sheared liquid crystals [4,5], which do not form spherulites under the condition. In this mini-review, we focus on the birefringent banded spherulites, which consist of synchronously twisted lamellar crystals. The organization of the twisted lamellar crystals in the banded spherulites and the driving force for lamell...

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“…Besides banded polymer spherulites, the banded spherulites of small molecules, such as K2Cr2O7 [43], hippuric acid [44], and aspirin [45], are composed of twisted crystals as well.…”

Section: Real Time Atomic Force Microscopy (Afm) Observation Reveals mentioning

confidence: 99%

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Zhang

et al. 2017

Crystals

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“…This behavior is unexpected because for most other helicoidal crystals,t he pitch decreases as driving force for crystallization (i.e.supercooling or supersaturation) increases. [15,17,19,34] This difference sug-…”

Section: Resultsmentioning

confidence: 99%

“…Thet wist period or pitch, P,m easured as the length of acrystal needed for each 1808 8 rotation increases as the crystal cross section size increases.Inorder to account for the varying aspect ratio,crystal thickness, h,and width, w,were converted into one variable (radius, r)a ssuming the constancy of the torsion constant (rigidity of ac ross section against torque) according to J = pr 4 /2 = (0.332 wÀ0.203 h)h 3 ,a sw ea nalyzed for twisted hippuric acid crystals. [34] Thepitch scales with the crystal radius as log P = 1.42(3) + 0.87(5)log r (number of crystals N = 149) for individual crystals and log P = 1.08(5) + 0.83 (16)log r (N = 12) for ropes that is equivalent to P = 26.3 r 0.87 and P = 12 r 0.83 ,r espectively ( Figure 6). These P(r) dependences can be approximated by linear functions; however, we should emphasize that the real behavior is likely more complex.…”

Section: Forschungsartikelmentioning

confidence: 99%

“…Similar,almost linear P(r)relationships were seen for hippuric acid and af ew other crystals. [34] For benzamide,t hese relationships do not change significantly if pitch is plotted versus crystal thickness:l og P = 1.27(2) + 0.82(5)log h (N = 149) for individual crystals and log P = 0.90-(6) + 0.88 (17)log h (N = 12) for ropes equivalent to P = 18.6 h 0.82 and P = 7.9 h 0.88 ,r espectively.…”

Section: Forschungsartikelmentioning

confidence: 99%

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Crystals of Benzamide, the First Polymorphous Molecular Compound, Are Helicoidal

et al. 2020

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The growth of spontaneously twisted crystals is a common but poorly understood phenomenon. An analysis of the formation of twisted crystals of a metastable benzamide polymorph (form II) crystallizing from highly supersaturated aqueous and ethanol solutions is given here. Benzamide, the first polymorphic molecular crystal reported (1832), would have been the first helicoidal crystal observed had the original authors undertaken an analysis by light microscopy. Polymorphism and twisting frequently concur as they are both associated with high thermodynamic driving forces for crystallization. Optical and electron microscopies as well as electron and powder X‐ray diffraction reveal a complex lamellar structure of benzamide form II needle‐like crystals. The internal stress produced by the overgrowth of lamellae is shown to be able to create a twist moment that is responsible for the observed non‐classical morphologies.

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“…Interestingly, this is contrasted by a number of studies involving the non-iodinated hippuric acid parent compound, a target of interest for non-linear optics. [270][271][272][273] Thus the solid-state chemistry of IHA remains largely uncharted, and exploration of the crystallographic landscape may provide insight into the All diffraction experiments were run using MoK α radiation (λ = 0.71073 Å).…”

Section: Chapter Overviewmentioning

confidence: 99%

Explorations in crystal engineering

Duncan¹

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Explorations in crystal engineering : supramolecular templates, Explorations in crystal engineering : supramolecular templates, helical assemblies, pharmaceutical reactivity, and applications to helical assemblies, pharmaceutical reactivity, and applications to radio-imaging radio-imaging ____________________________________________ Michael Schultzii To Krista and Jasmine, Sasha, Tayla, Kenzie, and my loving parents iii I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me. Isaac Newtoniv ACKNOWLEDGEMENTSThere are a number of people I owe my success to, and I would like to take this space to offer them the most sincere love and gratitude for all the things they've done for me. Above all I must thank my research advisor, Professor Leonard R. MacGillivray. He has been a constant source of guidance in navigating the trials of earning a graduate degree. His mentoring has helped me hone my skills as a scientist and, looking back over the past six years, I can hardly believe how much my approach to research and problem solving has changed thanks to his influence. My gratitude to him is never-ending and I will continue to build on the foundation he has helped me establish as I continue in my career. Of course, I must thank the members of the MacGillivray research group, past and present: Beth, and Celymar. The insight, collaboration, and companionship they provided over the years will be some of the fondest memories from my time at Iowa. Also, I would like to thank the undergrads that worked with me, Roxie, Shawna, Kyle, Carlson, and Jeremy, who assisted me in my dissertation work. I am indebted to Dr. Dale Swenson for the enumerable times I bugged him in his office for help with crystallography. Dale never turned me away when I needed help working on a structure or needed advice on how to present and justify less-than-perfect quality data. I owe my knowledge and skill in X-ray crystallography to him and his generous teaching mentality. vi ABSTRACT Crystal engineering is a rapidly developing area of research with goals aimed at designing molecular solids with desired physical and chemical properties. By utilizing reliable intermolecular interactions, the principles of supramolecular chemistry are exploited in the solid state in order to achieve favorable arrangements of molecules in a crystal lattice. We have applied crystal engineering strategies to further develop the strategy of template-directed reactivity in the solid state. An evaluation of catechol, a regioisomer of the commonly used resorcinol template, was performed. Co-crystallization of the template candidate with a bis-pyridyl olefin produced a discrete self-assembled architecture wherein hydrogen-bonded dimers of catechol pre-organize the olefins for a[2+2] photodimerization in the solid state. The dimerization was determined to pro...

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Mechanics of twisted hippuric acid crystals untwisting as they grow

Cited by 37 publications

References 19 publications

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Crystals of Benzamide, the First Polymorphous Molecular Compound, Are Helicoidal

Explorations in crystal engineering

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