Clustering of a hydrogen-bonding complex between indole and isoquinoline Correlation with nucleation of intermolecular compounds

Abstract

Upon crystallization from mixtures containing indole and isoquinoline, intermolecular compounds of 1:1 molecular ratio have been isolated as crystals. This crystallisation process, i.e., molecules→clusters→nucleus was studied in a specially designed mass spectrometer. From the mass spectrometric analysis of clusters isolated from liquid droplets containing indole, isoquinoline and acetonitrile, clusters composed of equimolecular indole and isoquinoline, i.e. (indole) _n (isoquinoline) _n : n=1, 2, 3,..., were observed as prominent species. This suggested that the hydrogen-bonded complex of indole and isoquinoline works as a unit species for the nucleation of the intermolecular compounds.