BEST-CSP Benchmark Study of Polymorphs I and II of Sulfamerazine and the Perils of Polytype Polymorphs.

ABSTRACT: We report the outcome of an interdisciplinary investigation, by the BEST-CSP network, of the kinetically favored form I and the low-temperature stable form II polymorphs of the drug sulfamerazine (SMZ). Form II can be reproducibly obtained by slurrying in acetonitrile-(MeCN)/water at room temperature, though seeding with form II significantly speeds up the conversion. New structure determinations have been obtained for both forms over a wide temperature range, with both single crystal and powder X-ray diffraction methods. Room temperature FT-IR and solid-state ¹³C NMR spectra are provided. The enantiotropic but practically irreversible crystal-to-crystal transition from form II to form I is observed at temperatures ranging from 150 to 170 °C in various differential scanning calo

SUBMITTER: Wood WP 

PROVIDER: S-EPMC12784330 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature