Spectroscopic and thermal characterization of two solid forms of a new arylpiperazine oxicam derivative

Abstract Polymorphism and its extended form, pseudopolymorphism, significantly affect the physicochemical properties, thermal stability, and potential pharmaceutical performance of biologically active compounds. Oxicams are a class of nonsteroidal anti-inflammatory drugs (NSAIDs) widely used in clinical practice; however, they are associated with a range of adverse effects. Consequently, there is ongoing interest in developing new derivatives with improved safety profiles. Moreover, owing to their structural flexibility and ability to form intramolecular hydrogen bonds and tautomeric structures, oxicam derivatives represent an interesting class of compounds exhibiting diverse solid-state behavior. In this work, a new arylpiperazine oxicam derivative was obtained as two distinct crystalline forms and characterized using spectroscopic methods ( 1 H NMR, 13 C NMR, ESI–MS, and FTIR) together with X-ray powder diffraction (XRPD). The results confirmed that the two forms differ in crystal packing and intermolecular interactions despite retaining the same molecular structure. Their thermal behavior was investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results demonstrated that form I is the thermodynamically stable form, whereas form II is a pseudopolymorphic form incorporating ethanol molecules during crystallization. These findings provide insights into the relationship between solvation and crystal packing in novel oxicam derivatives and contribute to a better understanding of solid-state transformations in pharmaceutically relevant molecules.