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"CLASSIC NMR": an in-situ NMR strategy for mapping the time-evolution of crystallization processes by combined liquid-state and solid-state measurements.

Hughes CE, Williams PA, Harris KD - Angew. Chem. Int. Ed. Engl. (2014)

Bottom Line: This combined strategy allows complementary information to be obtained on the evolution of both the solid and liquid phases during the crystallization process.In particular, as crystallization proceeds (monitored by solid-state NMR), the solution state becomes more dilute, leading to changes in solution-state speciation and the modes of molecular aggregation in solution, which are monitored by liquid-state NMR.The CLASSIC NMR experiment is applied here to yield new insights into the crystallization of m-aminobenzoic acid.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, Cardiff University, Cardiff CF10 3AT, Wales (UK).

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Evolution of 13C chemical shifts in the liquid-state (13C direct-excitation) component of the CLASSIC NMR data. The vertical dashed line indicates the time at which crystallization commenced (see also Figure 3).
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fig05: Evolution of 13C chemical shifts in the liquid-state (13C direct-excitation) component of the CLASSIC NMR data. The vertical dashed line indicates the time at which crystallization commenced (see also Figure 3).

Mentions: We now develop a more detailed interpretation of the changes in the liquid-state 13C NMR spectrum during crystallization. Figure 5 shows the 13C chemical shift δi(t) for each site (i) in m-ABA as a function of time relative to the corresponding initial value δistart. Initially, the system is a supersaturated solution10 (concentration ca. 1.4 times the solubility of Form III at 33 °C). After crystallization begins, the supersaturation decreases with time. By the end of the crystallization process, the system is an equilibrium saturated solution [chemical shifts denoted δieq(DMSO)]. To rationalize the changes in the solution state as crystallization proceeds, we consider values of Δδiclassic=δistart−δieq(DMSO), representing the difference in each chemical shift between the initial maximally supersaturated solution and the final equilibrium saturated solution. Values of Δδiclassic determined from the data in Figure 5 are given in Table 1.


"CLASSIC NMR": an in-situ NMR strategy for mapping the time-evolution of crystallization processes by combined liquid-state and solid-state measurements.

Hughes CE, Williams PA, Harris KD - Angew. Chem. Int. Ed. Engl. (2014)

Evolution of 13C chemical shifts in the liquid-state (13C direct-excitation) component of the CLASSIC NMR data. The vertical dashed line indicates the time at which crystallization commenced (see also Figure 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4227553&req=5

fig05: Evolution of 13C chemical shifts in the liquid-state (13C direct-excitation) component of the CLASSIC NMR data. The vertical dashed line indicates the time at which crystallization commenced (see also Figure 3).
Mentions: We now develop a more detailed interpretation of the changes in the liquid-state 13C NMR spectrum during crystallization. Figure 5 shows the 13C chemical shift δi(t) for each site (i) in m-ABA as a function of time relative to the corresponding initial value δistart. Initially, the system is a supersaturated solution10 (concentration ca. 1.4 times the solubility of Form III at 33 °C). After crystallization begins, the supersaturation decreases with time. By the end of the crystallization process, the system is an equilibrium saturated solution [chemical shifts denoted δieq(DMSO)]. To rationalize the changes in the solution state as crystallization proceeds, we consider values of Δδiclassic=δistart−δieq(DMSO), representing the difference in each chemical shift between the initial maximally supersaturated solution and the final equilibrium saturated solution. Values of Δδiclassic determined from the data in Figure 5 are given in Table 1.

Bottom Line: This combined strategy allows complementary information to be obtained on the evolution of both the solid and liquid phases during the crystallization process.In particular, as crystallization proceeds (monitored by solid-state NMR), the solution state becomes more dilute, leading to changes in solution-state speciation and the modes of molecular aggregation in solution, which are monitored by liquid-state NMR.The CLASSIC NMR experiment is applied here to yield new insights into the crystallization of m-aminobenzoic acid.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, Cardiff University, Cardiff CF10 3AT, Wales (UK).

Show MeSH