Abstract
This paper presents an NMR crystallography study of three polymorphs of furosemide. Experimental magic‐angle spinning (MAS) solid‐state NMR spectra are reported for form I of furosemide, and these are assigned using density‐functional theory (DFT)‐based gauge‐including projector augmented wave (GIPAW) calculations. Focusing on the three known polymorphs, we examine the changes to the NMR parameters due to crystal packing effects. We use a recently developed formalism to visualise which regions are responsible for the chemical shielding of particular sites and hence understand the variation in NMR parameters between the three polymorphs.
Highlights
A definition for polymorphism was given by McCrone in 1965: a polymorph is a solid crystalline phase of a given compound resulting from the possibility of at least two different arrangements of the molecules of that compound in the solid state.[1]
We have presented 13C CP magic-angle spinning (MAS), 1H–13C refocused INEPT and 1H double quantum (DQ) MAS nuclear magnetic resonance (NMR) spectra for form I of furosemide
The spectra have been assigned by comparison with chemical shifts computed using density-functional theory (DFT) and the gauge-including projector augmented wave (GIPAW) approach
Summary
A definition for polymorphism was given by McCrone in 1965: a polymorph is a solid crystalline phase of a given compound resulting from the possibility of at least two different arrangements of the molecules of that compound in the solid state.[1]. Scheme 1 the full crystal structure.[18,20,29,30] This difference reflects two contributions: long-range effects of current elements, for example, ring currents, and local changes in electronic structure that result from crystal packing, for example, hydrogen bonding. The correct form[36] of form I is known to have Z′ = 2 and Z = 4, and a recent study using GIPAW calculations that considered FURSEM01, FURSEM17, and a new form and solid-state NMR experiments has determined that FURSEM17 is likely an inaccurate solution of form I.[9] furosemide has poor bioavailability[37,38,39] and furosemide cocrystals[40,41,42] have been synthesised in an attempt to improve the solubility in water. The analysis notes subtleties between solved structures of the same form, and different geometry optimization approaches
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
