Exploring the Structural Versatility and Dynamic Behavior of Acyl/Aroyl Hydrazones: A Comprehensive Review

Acyl and aroyl hydrazones are hydrazine derivatives with unique structural variations and multiple applications in various disciplines, including medicinal chemistry, materials, and agrochemicals research. The presence of numerous reactive sites in acyl hydrazones established it as a privileged structure class in organic chemistry and, hence, serve as an important intermediate in the synthesis of pharmaceutically significant compounds. The intrinsic nature of the acylhydrazone group leads to various dynamic processes, including conformational, configurational, and tautomeric interconversions. Their dynamic behavior in organic frameworks is mainly attributed to hindered rotation around the imine C=N bond and -CONH- amide bond. It is crucial to comprehend the geometrical and conformational behavior of hydrazone derivatives in order to understand their structural attributes, reactivity, and interactions with other molecules. This review article provides an in-depth and up-to-date examination of the geometrical and conformational properties of acyl and aroyl hydrazones showcasing chronological progression of advancements in N-acyl/aroyl hydrazones (NAHs) over time spanning from 1955 to 2025. The insights gained from this analysis will be a helpful resource for researchers and chemists working on designing and developing new compounds with improved characteristics for various applications in chemistry and medicine.