Spontaneous crystal growth of co-crystals: the contribution of particle size reduction and convection mixing of the co-formers

Ibrahim, Asim Y.; Forbes, Robert T.; Blagden, Nicholas

doi:10.1039/c004371k

Cited by 42 publications

(46 citation statements)

References 23 publications

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“…Chemical shift tensor parameters have been reported for a series of diacids, including the two studied here (Tegenfeldt et al, 1980;Jagannathan 1989). The CA-MA system has been the subject of several recent investigations (Ibrahim et al, 2011;Mandala et al, 2014;Nartowski et al, 2016). Our goal in this study was to investigate four comparable cocrystals, with two API mimics and two coformers, and examine the effects of structural variations on chemical shift parameters.…”

Section: Resultsmentioning

confidence: 99%

A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline

Vigilante

Mehta

2017

Acta Crystallogr C

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We report an analysis of the C solid-state NMR chemical shift data in a series of four cocrystals involving two active pharmaceutical ingredient (API) mimics (caffeine and theophylline) and two diacid coformers (malonic acid and glutaric acid). Within this controlled set, we make comparisons of the isotropic chemical shifts and the principal values of the chemical shift tensor. The dispersion at 14.1 T (600 MHzH) shows crystallographic splittings in some of the resonances in the magic angle spinning spectra. By comparing the isotropic chemical shifts of individual C atoms across the four cocrystals, we are able to identify pronounced effects on the local electronic structure at some sites. We perform a similar analysis of the principal values of the chemical shift tensors for the anisotropic C atoms (most of the ring C atoms for the API mimics and the carbonyl C atoms of the diacid coformers) and link them to differences in the known crystal structures. We discuss the future prospects for extending this type of study to incorporate the full chemical shift tensor, including its orientation in the crystal frame of reference.

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Section: Resultsmentioning

confidence: 99%

A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline

Vigilante

Mehta

2017

Acta Crystallogr C

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“…[78][79][80][81][82][83][84][85][86] This has been attributed to the empirical rule "the best donor bonds to the best acceptor." 67,87 It should be noted that in contrast to other sulfonamides, X-ray structures of cocrystals of SMZ are surprisingly rare. 88…”

Section: Formation and Structure Of The Smz/oxalic Acid Cocrystalmentioning

confidence: 99%

Effects of Ball-Milling and Cryomilling on Sulfamerazine Polymorphs: A Quantitative Study

MacFhionnghaile

Gniado

et al. 2014

Journal of Pharmaceutical Sciences

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The effects of ball-milling and cryomilling on sulfamerazine forms I and II (SMZ FI, FII) were investigated using X-ray powder diffraction, IR and NIR spectroscopy. Cryomilling resulted in the complete amorphization of both polymorphs. Milling at room temperature gave mixtures of amorphous SMZ (FA) and FII. Calibration models were developed for the quantitative analysis of binary (FI/FII, FI/FA and FII/FA) and ternary (FI/FII/FA) mixtures using NIR spectroscopy combined with partial least-squares (PLS) regression. The PLS models for binary (0 -100 %), ternary (0 -100 %) and low level (0 -10 %) binary mixtures had root-mean-square errors of prediction of 1.8, 5.1 and 0.80 %, respectively. The calibration models were used to obtain a detailed quantitative picture of solid-state transformations during milling and any subsequent recrystallizations. FA prepared by cryomilling FI for less than 60 min. recrystallized to mixtures of FI and FII, while samples milled for more than 60 min. crystallized to pure FII. The effect of co-milling SMZ with stoichiometric amounts of additives was investigated. SMZ formed amorphous materials with oxalic, DL-tartaric and citric acids that were more stable towards recrystallization than FA.Amorphous SMZ/oxalic acid was found to recrystallize to a 2:1 co-crystal during storage.

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“…1) however has been reported to form spontaneously, which sets it apart from other Caf co-crystals. This was first seen on the reduction of its particle size, 13,14 and has subsequently been studied by solid-state NMR. 15 Neither study however yielded a firm conclusion as to the specific molecular-level growth mechanism for this form.…”

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confidence: 99%

“…Previous reports on the spontaneous formation of the cocrystal have focused on the particle size, which has been shown to have a significant impact on the rate of conversion from the individual components to the co-crystal. 14 Here the dry starting materials were ball-milled to a consistent particle size before all further investigations to remove the influence of this effect ( Fig. S1 and S2, ESI †).…”

mentioning

confidence: 99%

Tuning the spontaneous formation kinetics of caffeine : malonic acid co-crystals

2016

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Spontaneous crystal growth of co-crystals: the contribution of particle size reduction and convection mixing of the co-formers

Cited by 42 publications

References 23 publications

A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline

A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline

Effects of Ball-Milling and Cryomilling on Sulfamerazine Polymorphs: A Quantitative Study

Tuning the spontaneous formation kinetics of caffeine : malonic acid co-crystals

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Spontaneous crystal growth of co-crystals: the contribution of particle size reduction and convection mixing of the co-formers

Cited by 42 publications

References 23 publications

A13C solid-state NMR investigation of four cocrystals of caffeine and theophylline

A13C solid-state NMR investigation of four cocrystals of caffeine and theophylline

Effects of Ball-Milling and Cryomilling on Sulfamerazine Polymorphs: A Quantitative Study

Tuning the spontaneous formation kinetics of caffeine : malonic acid co-crystals

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A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline

A¹³C solid-state NMR investigation of four cocrystals of caffeine and theophylline