Chiral aggregates of indan-1-ol with secondary alcohols and water: laser spectroscopy in supersonic beams

One color, mass selected resonant two-photon ionization (1cR2PI) spectra of supersonically expanded bare (R)-(-)indan-1-ol (I-R) and its complexes with chiral and achiral molecules (solv) have been investigated. The excitation spectrum of bare I-R has been analyzed and discussed on the basis of theoretical predictions at the B3LYP/6-1G** level of theory. The excitation spectra of its diastereomeric complexes with (R)-(-)- and (S)- (+)hexan-2-ol (X-R or X-S, respectively) and water (W) are characterized by significant shifts of their S-0<--S-1 band origin relative to that of bare I-R. The extent and the direction of these shifts are found to depend upon the structure and the configuration of solv and are attributed to different short-range interactions in the ground and excited [I-R.solv] complexes. In particular the [I-R.W](n) complexes display band origins blue-shifted relative to that of bare I-R, attributed to the presence of an O-H...pi electrostatic interaction between I-R and W in [I-R.W](n). The [I-R.X-R] and [I-R.X-S] equilibrium structures have been calculated by a molecular dynamical (MM3) sampling and PM3 semiempirical local optimization.