Growth, Spectroscopic Characterization and DFT-Based Vibrational Analysis of Morpholine Oxalic Acid Single Crystal

Abstract

Single crystals of morpholine oxalic acid (MO) were grown successfully by the slow evaporation solution growth technique using ethanol as a solvent. The structural and vibrational properties of the grown crystal were investigated using experimental FT-IR and FT-Raman spectroscopy along with density functional theory (DFT) calculations employing the B3LYP/6-311G(d,p) basis set. Optimized molecular geometry confirms the presence of strong intermolecular O–H···O and N–H···O hydrogen bonding interactions. Normal coordinate analysis based on scaled quantum mechanical force field (SQMFF) shows good agreement between experimental and theoretical vibrational frequencies. The observed lowering of carbonyl stretching modes further supports the existence of hydrogen bonding and charge transfer interactions, indicating the potential biological relevance of the MO crystal.