Does Impurity-Induced Step-Bunching Invalidate Key Assumptions of the Cabrera−Vermilyea Model?

Ristić, R. I.; DeYoreo, James J.; Chew, Chun M.

doi:10.1021/cg7010474

Cited by 25 publications

(38 citation statements)

References 14 publications

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“…A school of thought exists that this face exhibits a dead zone at low supersaturation with recovery at higher supersaturation due to selective absorption of impurities on this face. 51 However, our analysis is that the {110} face is neither uniquely hydrophobic nor uniquely hydrophilic to behave very differently from other faces. Our explanation is that the relative growth rate of the {110} face is significantly low compared to the other faces at low supersaturation primarily due to its bonding structure (one of the periodic bond chains on this face, the [110] chain, has eight different types of kink sites).…”

Section: Critical Length Of Spiral Edgesmentioning

confidence: 81%

Spiral Growth Model for Faceted Crystals of Non-Centrosymmetric Organic Molecules Grown from Solution

Kuvadia

Doherty

2011

Crystal Growth & Design

185

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The classical Burton−Cabrera−Frank (BCF) spiral growth model fails to work satisfactorily for many non-centrosymmetric organic molecules such as active pharmaceutical ingredients (APIs), nonlinear optical compounds, etc., due to the inherent assumption of Kossel crystal structure in the solid-state. We develop a more general mechanistic spiral growth model that enables morphology prediction for all kinds of organic molecules. We develop generalized expressions for kink density, kink incorporation rate, and step velocities for such molecules. Stable and unstable edges arising due to the complex bonding pattern are discussed and treated. We demonstrate the applicability of the model by correctly predicting the experimental morphologies of paracetamol and lovastatin grown from solution.

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Section: Critical Length Of Spiral Edgesmentioning

confidence: 81%

Spiral Growth Model for Faceted Crystals of Non-Centrosymmetric Organic Molecules Grown from Solution

Kuvadia

Doherty

2011

Crystal Growth & Design

185

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“…Macrosteps, then, might be responsible for the deviation from classical behavior. 45,49 But for L-cystine, the only step configuration observed far from dislocation outcrops is a single bunch consisting of six elementary steps.…”

Section: Spacing Ofmentioning

confidence: 99%

Dislocation-Actuated Growth and Inhibition of Hexagonal l-Cystine Crystallization at the Molecular Level

Shtukenberg

Poloni

Zhu

et al. 2014

Crystal Growth & Design

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Crystallization of L-cystine is a critical process in the pathogenesis of kidney stone formation in cystinuria, a disorder affecting more than 20 000 individuals in the United States alone. In an effort to elucidate the crystallization of L-cystine and the mode of action of tailored growth inhibitors that may constitute effective therapies, real-time in situ atomic force microscopy has been used to investigate the surface micromorphology and growth kinetics of the {0001} faces of L-cystine at various supersaturations and concentrations of the growth inhibitor Lcystine dimethylester (CDME). Crystal growth is actuated by screw dislocations on the {0001} L-cystine surface, producing hexagonal spiral hillocks that are a consequence of six interlacing spirals of anisotropic molecular layers. The high level of elastic stress in the immediate vicinity around the dislocation line results in a decrease in the step velocities and a corresponding increase in the spacing of steps. The kinetic curves acquired in the presence of CDME conform to the classical Cabrera−Vermilyea model. Anomalous birefringence in the {101̅ 0} growth sectors, combined with computational modeling, supports a high fidelity of stereospecific binding of CDME, in a unique orientation, exclusively at one of the six crystallographically unique projections on the {101̅ 0} plane. ■ INTRODUCTIONCystinuria, a genetic disorder that afflicts more than 20 000 individuals in the United States alone, is associated with abnormal levels of L-cystine in the kidney and is often accompanied by recurring formation of L-cystine stones. Current treatments for L-cystine stone prevention include dilution through high fluid intake, 1 increasing urine pH through ingestion of alkalinizing potassium or sodium salts, 1,2 or the administration of L-cystine binding thiol drugs (CBTDs). 3 These treatments suppress, but typically do not completely prevent, stone formation. Moreover, CBTDs do not reduce Lcystine concentrations sufficiently at dosages regarded as below the threshold for hypersensitivity and toxicity. Our laboratory recently demonstrated that low concentrations of certain additivesmethyl esters of L-cystine that mimic the structure of L-cystineinhibited the formation of L-cystine crystals, suggesting a new approach to a therapy for this disease. 4 Realtime in situ atomic force microscopy (AFM) of L-cystine crystals in supersaturated L-cystine solutions revealed growth hillocks emanating from screw dislocations on the (0001) face. The micromorphology of these hillocks was attributed to interlaced spirals of anisotropic molecular layers of L-cystine bunching in a manner that deceptively appeared as stacks of hexagonal islands. The addition of the L-cystine methyl esters to the growth solution resulted in roughening of the hillock steps as well as a decrease in step velocity. These observations suggested that step pinning by "molecular imposters," sometimes referred to as tailor-made additives that are known to affect crystal morphology, 5−7 was responsible for growth i...

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“…This so-called Gibbs-Thomson relationship has not been confirmed by recent atomic force microscopy evidence that shows an abrupt increase in v when the step exceeds a critical dimension r c . [3][4][5] Despite the known limitations of the pinning mechanism, [6][7][8][9] recent experimental data [10][11][12] have confirmed many features of the effects of supersaturation and impurity concentration on the crystal growth rates predicted by the C-V theory.…”

Section: Introductionmentioning

confidence: 96%

Unsteady-state inhibition of crystal growth caused by solution impurities

et al. 2011

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Does Impurity-Induced Step-Bunching Invalidate Key Assumptions of the Cabrera−Vermilyea Model?

Cited by 25 publications

References 14 publications

Spiral Growth Model for Faceted Crystals of Non-Centrosymmetric Organic Molecules Grown from Solution

Spiral Growth Model for Faceted Crystals of Non-Centrosymmetric Organic Molecules Grown from Solution

Dislocation-Actuated Growth and Inhibition of Hexagonal l-Cystine Crystallization at the Molecular Level

Unsteady-state inhibition of crystal growth caused by solution impurities

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