Application Spotlight
Solifenacin is an antimuscarinic drug used to treat overactive bladder. Its therapeutic activity depends on stereochemistry — only the (1S,3R) stereoisomer is the active form. Accurately identifying the correct stereoisomer is critical for drug development and quality control.
Raman Optical Activity (ROA) enables unambiguous absolute configuration determination — directly in solution, without the need for crystallization or reference standards.
Why it matters
- Multiple stereoisomers – solifenacin has four possible stereoisomers from two stereogenic centers.
- One active form – only (1S,3R)-solifenacin is therapeutically active.
- Reliable, fast, and direct – ROA provides a non-destructive, solution-phase method for confident stereochemical identification.
Our approach
- Sample dissolved in DMSO for optimal solubility and ROA compatibility.
- ROA spectra acquired across the fingerprint region.
- Quantum chemical simulations generated for all four stereoisomers.
- Experimental spectra compared with simulations for unambiguous stereochemical assignment.
Quantitative matching
A Pearson correlation analysis was performed in the diagnostically relevant region between 740 and 1020 cm⁻¹. Compared with the experimental (1S,3R) spectrum, the simulated (1S,3R) spectrum gave the strongest positive match (r = 0.63), while its enantiomer (1R,3S) gave a near mirror-image result (r = −0.62). The (1R,3R) and (1S,3S) simulations scored −0.10 and 0.30 respectively (the (1S,3S) sample showed stability issues). A Pearson value of 1 means the compared spectra are identical, while −1 means they are mirror images.
Key takeaways
- Distinct ROA features enable reliable discrimination of stereoisomers and enantiomers.
- Fingerprint regions at 1540–1740 cm⁻¹ (enantiomer marker) and 740–1020 cm⁻¹ (diastereomer marker) provide strong and reproducible signals.
- ROA spectroscopy is a fast, non-destructive, and reference-free method — ideal for supporting confident decision-making in pharmaceutical development and quality control.
Need stereochemical answers for your molecules? Contact us at contact@enantios.com to discuss your application or schedule a measurement study.
