FT-Raman, FTIR and surface-enhanced Raman spectroscopy of the antiviral and antiparkinsonian drug amantadine

FT-Raman, FTIR and surface-enhanced Raman spectroscopy (SERS) are applied t o the vibrational characterization of the antiviral and antiparkinsonian dr ug amantadine. SERS spectroscopy is employed for the first time for charact erizing the interfacial behavior of this molecule and to study its interact ion with colloidal silver. The comparison of SERS spectrum with the Raman s pectra of amantadine in solid state and in aqueous solution reveals remarka ble changes attributed to the interaction of the drug with the metal throug h the unprotonated amino group and the formation of a self-assembled amanta dine layer on the metal surface. A tentative assignment of the obtained vib rational spectra is carried out on the basis of the vibrational spectra of the structurally related molecules adamantane and tert-buthylamine and the ab initio calculations accomplished for amantadine. (C) 1999 Elsevier Scien ce B.V. All rights reserved.