Binding energy determination in a π-stacked aromatic cluster: the anisole dimer.

The binding energies of the neutral and positively charged anisole dimer have been determined in molecular beam-laser spectroscopy experiments. This is the first report on the direct experimental determination of the binding energy for an aromatic cluster in π stacked configuration. The anisole dimer is formed by two anisole molecules superimposed in a planar arrangement and it has been proposed as a model system in which the π-stacking interaction, among other intermolecular forces, plays a relevant role. Its binding energy has been determined thanks to both velocity mapping ion/electron imaging experiments and previous spectroscopic information. The binding energy amounts to 3926(250) cm(-1) in the ground state and 4144(250) cm(-1) in the S2 (first spectroscopically accessible) electronic excited state; its value for the positively charged dimer ion increases to 6147(250) cm(-1). These values are quite higher with respect to the results of previous DFT calculations.

The gas phase anisole dimer: a combined high-resolution spectroscopy and computational study of a stacked molecular system.

The gas phase structures of anisole dimer in the ground and first singlet electronic excited states have been characterized by a combined experimental and computational study. The dimer, formed in a molecular beam, has been studied by resonance-enhanced multiphoton ionization and high-resolution laser-induced fluorescence techniques. The assignment of the rotational fine structure of the S(1) <-- S(0) electronic transition origin has provided important structural information on the parallel orientation of aromatic rings of anisole moieties. By comparison with the DFT/TD-DFT computational results, it has been possible to infer the detailed equilibrium structure of the complex. The analysis of the equilibrium structure and interaction energy confirms that the anisole dimer is stabilized by dispersive interaction in the gas phase. This is, to the best of our knowledge, the first detailed work (reporting both theoretical and high-resolution experimental data) on an isolated cluster in the pi-stacking configuration.

A study on the anisole-water complex by molecular beam-electronic spectroscopy and molecular mechanics calculations.

An experimental and theoretical study is made on the anisole-water complex. It is the first van der Waals complex studied by high resolution electronic spectroscopy in which the water is seen acting as an acid. Vibronically and rotationally resolved electronic spectroscopy experiments and molecular mechanics calculations are used to elucidate the structure of the complex in the ground and first electronic excited state. Some internal dynamics in the system is revealed by high resolution spectroscopy.