The interactions of small biological molecules with mineral surfaces are of fundamental importance. Moieties of the molecules will either be attracted to or repelled by areas of the surfaces - and occasionally by ions - causing adsorption or desorption processes. The IR adsorption frequencies of cationic lysine to the clay mineral montmorillonite were recently reported.  In this work the protonation state of lysine is extended to the zwitterion state  (prevalent at lower pH) and Density Functional Theory calculations with the Gaussian 09 software package are used to determine both the infra red vibrational frequencies of the isolated amino acid and of the amino acid adsorbed to montmorillonite surfaces. The values are compared to those from the literature to provide an independent assignment of the vibrational modes, and therefore, of the structure of the potential surface complexes.

Influence of protonation state of lysine adsorbed to montmorillonite surfaces on IR vibrational frequencies

243rd National Meeting (2012)

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