Weakly bound molecular complexes in the laboratory and in the interstellar medium: A lost interest?

Weakly bound molecular complexes have been studied in the laboratory for more than 40 years. Interest in them was heightened when they were predicted to be important species in the chemistry of the atmosphere and the interstellar medium (ISM) and also because of their unusual rotational dynamics, described in some cases by nearly free rotation of monomers within the complex. About 15 years ago the interest was heated by the observation of microscopic superfluidity in small helium clusters. On the other hand, a number of unsuccessful tries to detect weakly bound complexes in the ISM considerably lowered the interest in their further investigations for astrophysicists. With this short review I would like to show a perspective for future studies of astrophysically relevant weakly bound molecular complexes in the laboratory and for their potential search in the ISM.