Low-Temperature and High-Pressure Phase Transitions in Two 2‑Amino-4'-halobenzophenones: Incommensurate Modulation and a Case of Temperature-Induced Twinning.

ABSTRACT: The structures of 2-amino-4'-chlorobenzophenone and 2-amino-4'-bromobenzophenone, previously determined at room temperature in the space group Pna2₁, have been redetermined at low-temperature revealing two different reversible phase transitions. Additionally, high-pressure X-ray diffraction studies were conducted to allow for a comparison of the behavior of these structures in response to different external stimuli. Variable temperature analyses reveal that 2-amino-4'-bromobenzophenone transitions to the monoclinic space group Pa accompanied by a nonmerohedral twinning. The monoclinic phase exhibits approximate symmetry mimicking that of the supergroup Pna2₁ but with a metric symmetry that precludes true Pna2₁ symmetry. The struc

SUBMITTER: Attiwell L 

PROVIDER: S-EPMC12921689 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature