Amplification of Chirality from Molecules into Morphology of Crystals through Molecular Recognition

Oaki, Yuya; Imai, Hiroaki

doi:10.1021/ja048661+

Cited by 114 publications

(116 citation statements)

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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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“…Second, spontaneous symmetry breaking may occur through the self-assembly of achiral building blocks into a helical/helicoidal structure, as e.g. in case of crystals with chiral morphology [2,9].Theoretically, the symmetry-breaking route is more interesting. Universal aspects may emerge and the robust features of this self-organization process may be important for applications as well.…”

mentioning

confidence: 99%

Probability of the Emergence of Helical Precipitation Patterns in the Wake of Reaction-Diffusion Fronts

et al. 2013

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Helical and helicoidal precipitation patterns emerging in the wake of reaction-diffusion fronts are studied. In our experiments, these chiral structures arise with well defined probabilities PH controlled by conditions such as e.g., the initial concentration of the reagents. We develop a model which describes the observed experimental trends. The results suggest that PH is determined by a delicate interplay among the time-and length-scales related to the front and to the unstable precipitation modes and, furthermore, the noise amplitude also plays a quantifiable role.PACS numbers: 68.35.Ct Helices and helicoids are present from nano-to macroscale (ZnO nanohelices [1], macromolecules and inorganic crystals with a helical structure [2, 3], precipitation helices [4][5][6], fiber geometry of heart walls [7]). Formation of these fascinating structures generally follows two routes. First, templates with chiral symmetry (e.g., oragogel fibers) may exist in the system, and the symmetry is just transcribed to a structure (e.g., inorganic materials [8]) at a larger scale. Second, spontaneous symmetry breaking may occur through the self-assembly of achiral building blocks into a helical/helicoidal structure, as e.g. in case of crystals with chiral morphology [2,9].Theoretically, the symmetry-breaking route is more interesting. Universal aspects may emerge and the robust features of this self-organization process may be important for applications as well. Indeed, control over creating helical structures would make engineering (in particular, the bottom-up design of micro-patterns [10]) more flexible since chiral morphology of materials are known to affect their physical (electronic) properties [6,11].In order to develop insight into the genesis of helices/helicoids, we investigate an emblematic example of pattern formation, namely the formation of precipitation patterns in the wake of reaction-diffusion fronts [12,13]. The motivation for this choice comes from the observation that helicoidal structures have an axis, and the correlations are simple in the plane perpendicular to the axis. This suggests that building the perpendicular correlations in the wake of an advancing planar front may be a simple and natural mechanism of creating helices/helicoids. Additional motivation comes from the existence of a large body of knowledge in the related Liesegang phenomena [12,13]. It allows the use of well-established experimental and theoretical approaches, thus making it easier to develop a novel view on the formation of helical structures.Our main results concern the probabilistic aspects of the symmetry-breaking route. We determine the probability P H of the emergence of single helices/helicoids in Liesegang-type experiments as the conditions such as the initial concentration of inner or outer electrolytes, or the temperature are changed. P H is found to be well reproducible and large (P H > 0.5 for some parameter range). The results are understood by expanding and simulating a model of formation of precipitation patterns [14]...

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“…Previous studies show that calcite crystals grown in the presence of either L or D aspartic acid present asymmetry associated with the distribution of crystal steps and terraces [88,89], and even the CaCO3 polymorph could be controlled by the chirality of an interacting amino acid [90]. The amplification of these interactions at macroscopic length scales is demonstrated by the distinct chirality of vaterite toroids and the helicity of potassium dichromate crystals tuned by the enantiospecificity of amino acids [91,92]. In view of mineral nucleation, we show that the sugar enantiomers present distinct interactions with mineral precursors and as a consequence affect the nucleation process in a pH-dependent manner.…”

Section: Discussionmentioning

confidence: 99%

Modulating Nucleation by Kosmotropes and Chaotropes: Testing the Waters

2017

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Abstract:Water is a fundamental solvent sustaining life, key to the conformations and equilibria associated with solute species. Emerging studies on nucleation and crystallization phenomena reveal that the dynamics of hydration associated with mineral precursors are critical in determining material formation and growth. With certain small molecules affecting the hydration and conformational stability of co-solutes, this study systematically explores the effects of these chaotropes and kosmotropes as well as certain sugar enantiomers on the early stages of calcium carbonate formation. These small molecules appear to modulate mineral nucleation in a class-dependent manner. The observed effects are finite in comparison to the established, strong interactions between charged polymers and intermediate mineral forms. Thus, perturbations to hydration dynamics of ion clusters by co-solute species can affect nucleation phenomena in a discernable manner.

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Amplification of Chirality from Molecules into Morphology of Crystals through Molecular Recognition

Cited by 114 publications

References 84 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

Probability of the Emergence of Helical Precipitation Patterns in the Wake of Reaction-Diffusion Fronts

Modulating Nucleation by Kosmotropes and Chaotropes: Testing the Waters

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