Crystal structure of fluroxypyr

Area of Science:

• Crystallography and Chemical Structure Analysis
• Agrochemical Science and Herbicide Development

Background:

• Pyridine herbicides are vital in modern agriculture for weed management.
• Understanding the solid-state structure of herbicides is key to optimizing their formulation and efficacy.

Purpose of the Study:

• To elucidate the crystal structure of the pyridine herbicide 2-[(4-amino-3,5-di-chloro-6-fluoro-pyridin-2-yl)-oxy]acetic acid.
• To investigate the intermolecular interactions governing its solid-state packing.

Main Methods:

• Single crystal X-ray diffraction was employed to determine the molecular and crystal structure.
• Analysis of hydrogen bonding (O-H...O, N-H...F, N-H...O) and pi-pi interactions was performed.

Main Results:

• The crystal structure reveals a significant dihedral angle (77.5°) between the carboxylic acid group and the pyridyl ring.
• Inversion dimers formed by O-H...O hydrogen bonds and R22(8) ring motifs were observed.
• Extended chains along [011] via N-H...F bonds and a 3D network through N-H...O bonds and weak pi-pi interactions (3.4602 Å) were identified.

Conclusions:

• The detailed crystal structure provides fundamental insights into the solid-state behavior of this pyridine herbicide.
• The identified intermolecular interactions are critical for understanding its physical properties, stability, and potential formulation strategies.