Binding energy and structure of the ground, first electronic and ion states of p-methoxyphenethylamine(H2O)1 isomers: a combined experimental and theoretical study Original Research Article

An extensive laser spectroscopic, structural and computational investigation on the neurotransmitter analogue p-methoxyphenethylamine (MPEA) chromophore weakly bound to one molecule of water, (MPEA(H2O)1) is reported. The complex was prepared by supersonic expansion of a gas mixture of seeded MPEA and water molecules in rare gas He. Two well-characterised experimental isomers have been observed, with geometries resulting from large contributions of the ordinary hydrogen bond and other intermolecular forces. Four key properties of the complex and related species are addressed in this paper: the characterisation of the isolated isomers observed spectra, the measurements of the binding energies of the ground, first electronic and ground ion states of the complex, the identification of each isomer spectrum with the computed geometries and the relationship of the complex stable isomers with the precursor conformers. A number of mass resolved laser spectroscopies have been used in order to get a complete set of experimental results, that complemented with ab initio density functional computations at four basis set, finally permitted us to settle and assign the mentioned properties of the two observed MPEA(H2O)1 isomers.