Concerning the crystal morphologies of the α and β polymorphs of p-aminobenzoic acid

Sullivan, Richard A.; Davey, Roger J.

doi:10.1039/c4ce01857e

Cited by 52 publications

(80 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a structure based on the carboxylic acid dimer (AMBNAC07, 28 ). 29 The growth rate data measured on single seed crystals at 20 C in a temperature controlled growth cell (Toroz et al, DOI: 10.1039/ c4fd00275j) are shown for both growth directions (a and b). The authors made one major assumption that for data measured by the same researcher, in the same laboratory and using the same equipment C 0 , the number of (heterogeneous) nucleation sites, is essentially xed so that relative values of f*C 0 /M reect the solvent effect on f*, the attachment frequency of a molecule to a cluster.…”

Section: Kinetic Data and Rate Determining Stepsmentioning

confidence: 99%

Crystal nucleation from solutions – transition states, rate determining steps and complexity

2015

Self Cite

View full text Add to dashboard Cite

This introductory paper offers a contemporary view of crystal nucleation. We begin with a molecular interpretation of the transition state and then revisit the use of classical nucleation theory as a means of obtaining molecular scale information from kinetic data. Traditional physical organic chemistry has always utilised the combination of kinetics and thermodynamics in order to gain insight over reaction pathways. Here we demonstrate for the cases of sucrose and p-aminobenzoic acid how solution chemistry, crystallography and kinetics come together to provide self-consistent pictures of the molecular scale processes occurring during nucleation. In this and a number of other systems desolvation of specific functional groups is highlighted as the rate determining step. Finally we move on to discuss the question of complexity, both from a phase and molecular perspective.

show abstract

Section: Kinetic Data and Rate Determining Stepsmentioning

confidence: 99%

Crystal nucleation from solutions – transition states, rate determining steps and complexity

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…The flow of data is largely represented using lamotrigine (Sridhar & Ravikumar, 2009), the 500 000th entry in the CSD, CSD refcode: EFEMUX01; CCDC number: CCDC 749719; DOI: 10.5517/cct54hl. Image (a) is a crystal of p-aminobenzoic acid (Sullivan & Davey, 2015) publication year. This enables citation of the dataset independently of the associated article and thus helps ensure recognition of the specific contribution made by the crystallographer, who may not always be included in the article's author list.…”

Section: Identifying and Linking Digital Objectsmentioning

confidence: 99%

The Cambridge Structural Database

Groom

Bruno

Lightfoot

et al. 2016

Acta Crystallogr B Struct Sci Cryst Eng Mater

8,345

214

5,026

View full text Add to dashboard Cite

The Cambridge Structural Database (CSD) contains a complete record of all published organic and metal-organic small-molecule crystal structures. The database has been in operation for over 50 years and continues to be the primary means of sharing structural chemistry data and knowledge across disciplines. As well as structures that are made public to support scientific articles, it includes many structures published directly as CSD Communications. All structures are processed both computationally and by expert structural chemistry editors prior to entering the database. A key component of this processing is the reliable association of the chemical identity of the structure studied with the experimental data. This important step helps ensure that data is widely discoverable and readily reusable. Content is further enriched through selective inclusion of additional experimental data. Entries are available to anyone through free CSD community web services. Linking services developed and maintained by the CCDC, combined with the use of standard identifiers, facilitate discovery from other resources. Data can also be accessed through CCDC and third party software applications and through an application programming interface.

show abstract

“…In the case of aqueous solutions however, because the solubility is low and the solubilities of the forms close together the available data are less equivocal in defining the transition temperature. 15 To circumvent this we have force-fitted the aqueous solubility data of Gracin and Rasmusson 15 through 13.8°C using the CrystEngComm This journal is…”

mentioning

confidence: 99%

“…2 for both aqueous and ethanolic experiments. Crystallisation temperatures both above (15,25, 26°C) at (13.8°C) and below (5, 10°C) the transition temperature were chosen.…”

mentioning

confidence: 99%

Ostwald's rule and enantiotropy: polymorph appearance in the crystallisation of p-aminobenzoic acid

et al. 2015

Self Cite

View full text Add to dashboard Cite

The development of rational crystallisation strategies in polymorphic systems requires the experimental manipulation of both kinetics and thermodynamics. We show for the first time the results of the interplay between these competing driving forces in an enantiotropic system, p-aminobenzoic acid. The outcomes are unexpected with temperature having no impact.The enormous scientific and commercial significance of crystalline polymorphism underlines the importance of rational crystallisation strategies for preparing structurally pure polymorphic materials from solution. In 2000 Threlfall noted 1 that 'Most of the accounts which purport to address this issue prove on close examination to be plausible deductions from a limited set of specific experimental observations, but unrelatable to the general problem of the interaction between thermodynamic and kinetic factors…'. In fact our best guide in this context remains Ostwald's rule of stages first put forward in 1897. 2 For the many systems in which polymorphic forms are monotropically related much recent work (e.g. glycine, 3 L-glutamic acid, 4 2,6 dihydroxybenzoic acid, 5 o and m-aminobenzoic acids, 6,7 mannitol, 8 benzamide 9 ) offers continued support of the rule with initial crystallisation of metastable phases over a wide range of conditions. Limited data on the water/inosine system 10 showed this to be the case for the crystallisation of the two monotropically related polymorphs but below 10°C, where the enantiotropically related dihydrate exists, direct crystallisation of this stable phase was possible. Apart from this and the much earlier report of Sato and Boistelle 11 on polymorphic mixtures of stearic acid, we are unaware of any systematic studies concerning the relationship between polymorph appearance, solvent, supersaturation and temperature in an enantiotropic system. It is our belief, surprisingly that this current work is the first to explore this topic for a molecular material crystallising from solution.As a model system we have chosen p-aminobenzoic acid (PABA) crystallising from aqueous and ethanolic solutions. The two enantiotropically related polymorphs, α and β have a transition temperature 13.8°C 12 with known crystal structures. 13,14 α is the stable form above 13.8°C and β below. The two forms are based on differing hydrogen bonded motifs and have distinct needle and rhombic morphologies. 15 Gracin and Rasmuson 16 reported that in aqueous solutions both forms, α and β, can be crystallised, while only α PABA appears from organic solvents, over a wide temperature range. Svard et al. 17 confirmed this in 330 cooling crystallisation experiments in the temperature range 15-30°C from methanol, acetonitrile and ethyl acetate. Most recently Sullivan et al. 18 used the induction time probability technique to determine the nucleation rates of α PABA from 2-propanol, acetonitrile and ethyl acetate and demonstrated the importance of desolvation and self-assembly in the nucleation pathway. Again, in these experiments performed at 20°C, over the supersatu...

show abstract

Concerning the crystal morphologies of the α and β polymorphs of p-aminobenzoic acid

Cited by 52 publications

References 29 publications

Crystal nucleation from solutions – transition states, rate determining steps and complexity

Crystal nucleation from solutions – transition states, rate determining steps and complexity

The Cambridge Structural Database

Ostwald's rule and enantiotropy: polymorph appearance in the crystallisation of p-aminobenzoic acid

Contact Info

Product

Resources

About