Structural study of hydrogen-bonded complexes between 2-aminoethanol derivatives and a chiral aromatic alcohol

Jet-cooled complexes of 2-naphthyl-1-ethanol (NapOH) with 2-aminoethanol and its N-methylated derivatives have been investigated using different spectroscopic techniques (fluorescence excitation, UV–UV and IR–UV depletion spectroscopy). The structures of the observed complexes have been assigned on the basis of the comparison between experimental IR spectra in the region of the OH stretch mode and ab initio DFT calculations. Two different isomers have been identified for the 1:1 complex of NapOH with 2-aminoethanol. In the first structure, the OH group of the chromophore acts as a hydrogen bond donor toward the O atom of the solvent, which keeps its most stable g0Gg0 conformation (‘O addition complex’). In the second one, the chromophore OH binds to the N atom of the gGt form of the solvent, whose hydroxy group interacts with the aromatic ring through a weak OH· · ·p type bond (‘N addition complex’). The main isomers observed in the case of NapOH complexes with 2-(N-methylamino)ethanol and 2-(N,N-dimethylamino)ethanol have been assigned to the ‘N and O addition’ forms respectively. q 2004 Elsevier B.V. All rights reserved.