Solvation and surface effects on polymorph stabilities at the nanoscale

Belenguer, Ana M.; Lampronti, Giulio I.; Cruz-Cabeza, AJ; Hunter, Christopher A.; Sanders, Jeremy K. M.

doi:10.1039/c6sc03457h

Cited by 158 publications

(237 citation statements)

References 53 publications

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“…[21,25] The results that we present here suggest that this holds also at high pressure. [21,25] The results that we present here suggest that this holds also at high pressure.…”

supporting

confidence: 67%

“…[22] LAG, at echnique which consists of grinding solid materials in the presence of af ew drops of solvent, has dramatically broadened the applications of mechanochemistry; [23] LAG often accelerates reactionk inetics and indeed sometimes yields different outcomes to NG techniques. [21,25] The reactiony ield is 50 %i ns olution,w hereas it is over 97 %u nder mechanochemical conditions. The former was generated under ball-mill NG conditions, whereas polymorph Bw as formed under ball-mill LAG conditions where a few drops of MeCN (> 23 mLp er 200 mg) were added to the powder.…”

mentioning

confidence: 99%

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Dynamic Covalent Chemistry under High‐Pressure:A New Route to Disulfide Metathesis

Sobczak

Drożdż

Lampronti

et al. 2018

Chemistry A European J

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This work describes, for the first time, the application of combined pressure and temperature stimuli in disulfide metathesis reactions. In the system studied, above a pressure of 0.2 GPa, equimolar amounts of symmetric disulfides bis 4-chlorophenyl disulfide [(4-ClPhS) ] and bis 2-nitrophenyl disulfide [(2-NO PhS) ] react to give the heterodimeric product 4-Cl-PhSSPh-2-NO . In contrast to experiments conducted in solution at atmospheric pressure or in mechanochemical experiments under ball-mill grinding conditions, there is no necessity to use a base or thiolate anion as a catalyst for the exchange reaction under investigated conditions. Single-crystal and powder X-ray diffraction revealed also that, despite the high-pressure conditions of this reaction, the heterodimeric-disulfide product unexpectedly crystallizes into the low-density polymorph A. This counterintuitive result contrasts with the high-pressure stability of the higher-density polymorph B, confirmed by its compression up to 2.8 GPa with no signs of a phase transition.

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“…[21,25] The results that we present here suggest that this holds also at high pressure. [21,25] The results that we present here suggest that this holds also at high pressure.…”

supporting

confidence: 67%

mentioning

confidence: 99%

Dynamic Covalent Chemistry under High‐Pressure:A New Route to Disulfide Metathesis

Sobczak

Drożdż

Lampronti

et al. 2018

Chemistry A European J

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show abstract

“…31 These were rationalised by considering solvent-dependent surface energies relative to the bulk lattice energy. The effect that size can have on the relative stability of nuclei of different forms comes out clearly from consideration of the nano-cluster modelling of inorganic oxides (DOI: 10.1039/c8fd00060c).…”

Section: Csp_thd; Defining the Crystal Energy Landscapementioning

confidence: 99%

Is zeroth order crystal structure prediction (CSP_0) coming to maturity? What should we aim for in an ideal crystal structure prediction code?

Price

2018

Faraday Discuss.

117

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Crystal structure prediction based on searching for the global minimum in the lattice energy (CSP_0) is growing in use for guiding the discovery of new materials, for example, new functional materials, new phases of interest to planetary scientists and new polymorphs relevant to pharmaceutical development. This Faraday Discussion can assess the progress of CSP_0 over the range of types of materials to which CSP is currently and could be applied, which depends on our ability to model the variety of interatomic forces in crystals. The basic hypothesis, that the outcome of crystallisation is determined by thermodynamics, needs examining by considering methods of modelling relative thermodynamic stability not only as a function of pressure and temperature, but also of size, solvent and the presence of heterogeneous templates or impurities (CSP_thd). Given that many important materials persist, and indeed may be formed, when they are not the most thermodynamically stable structure, we need to define what would be required of an ideal CSP code (CSP_aim).

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“…Ex situ analysis has demonstrated that the type of mechanical treatment [14,24,25], the addition of liquid [14,26,27], a polymer [28,29] and starting polymorph [14] can all play a role in determining the outcome of a polymorphic transformation. This phenomenon is of particular importance to industry, where the solid form of a material is vital to the integrity of its function and the legalities that surround its applications.…”

Section: Introductionmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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ABSTARCTMechanochemical methodologies, particularly ball milling, have become commonplace in many laboratories. In the present work, we examine the effects of milling ball mass on the polymorphic conversion of anhydrous caffeine. By investigating a single-phase system, the rate-limiting step of particle-particle contact formation is eliminated. It is found that larger milling balls lead to considerably faster conversion rates. Modelling of the transformation rate suggests that a single, time-independent rate constant is insufficient to describe the transformation. Instead, a convolution of at least two rate-determining processes is required to correctly describe the transformation. This suggests that the early stages of the transformation are governed only by the number of particle-ball collisions. As the reaction proceeds, these collisions less frequently involve reactant, and the rate becomes limited by mass transport, or mixing, even in originally single-phase systems, which become multi-phase as the product is formed. Larger milling balls are less hindered by poorly mixed material. This likely results from a combination of higher impact energies and higher surface areas associated with the larger milling balls. Such insight is important for the selective and targeted design of mechanochemical processes.

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Solvation and surface effects on polymorph stabilities at the nanoscale

Abstract: We explore the effects of particle size and solvent environment on the thermodynamic stability of two pairs of polymorphs subjected to ball-mill neat grinding (NG) and liquid assisted grinding (LAG).

Cited by 158 publications

References 53 publications

Dynamic Covalent Chemistry under High‐Pressure:A New Route to Disulfide Metathesis

Dynamic Covalent Chemistry under High‐Pressure:A New Route to Disulfide Metathesis

Is zeroth order crystal structure prediction (CSP_0) coming to maturity? What should we aim for in an ideal crystal structure prediction code?

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

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