A DFT-Based Investigation of Tosyl-D-Proline: Structure and Vibrational Spectroscopy

Tosyl-D-Proline, a chiral derivative of proline functionalized with a tosyl group, plays a significant role in asymmetric synthesis and organocatalysis. In this study, the molecular geometry of Tosyl-D-Proline was optimized using Density Functional Theory (DFT) at the B3LYP/6-311++G(d) level of theory. The optimized structure revealed stable conformations with no imaginary frequencies, confirming a true energy minimum on the potential energy surface. Vibrational frequency analysis was performed to obtain the theoretical infrared (IR) spectrum, and the characteristic vibrational modes were assigned. Key functional groups such as the sulfonyl, carboxyl, and amine groups were identified through their distinct IR absorption peaks. This computational investigation provides fundamental insights into the structural and vibrational properties of Tosyl-D-Proline, serving as a reference for future experimental and theoretical studies involving related chiral sulfonyl amino acids. The optimized structure and IR spectrum analysis of Tosyl-D-Proline molecule was performed using the Gaussian 09W software package.