Predicting properties of species derived from N-(1H-indol-3-ylmethyl)-N,N-dimethylamine, Gramine, a indol alkaloid.

Abstract

Hybrid B3LYP/6-31G* calculations were employed to study the structural, electronic,topological and vibrational properties of free base, cationic and hydrochloride species ofindol alkaloid, N-(1H-indol-3-ylmethyl)-N,N-dimethylamine known as gramine. Theexperimental available IR, Raman, 1H- and 13C-NMR spectra were compared with thecorresponding predicted showing reasonable concordanceproperties were studies with the polarized continuum (PCM) and the universal solvationmodel. The cationic species of gramine presents a corrected solvation energy ofkJ/mol slightly higher than the corresponding to cocaine (studies have evidenced higher stabilities for free base and hydrochloride species while thecomparisons of N-CH3 distances obtained for three species of gramine with similarcompounds have evidenced that the hydrochloride species of gramine in solution presentspractically the same value than the corresponding species of heroin. The frontier orbitalsstudies suggest higher reactivities for the hydrochloride species in both media due to itslow gap values while on the contrary are observed for the cationic species in both media.Furthermore, the cationic species of gramine shows global nucleophilicity andelectrophilicity indexes closer to cocaine. Probably, these results could justify why thecorrected solvation energy value observed for the cationic species is approximately closerto the value corresponding to cocaine. The harmonic force fields, force constants and thecomplete vibrational assignments for the 75, 78 and 81 normal vibration modes of freebase, cationic and hydrochloride species are reported for first time.