Perspective anti-thyroid drug 2-thioxo-5-(3,4,5-trimethoxybenzylidene) thiazolidin-4-one: X-ray and thermogravimetric characterization of two novel molecular adducts, obtained by interaction with I2

Abstract

The attention of many researchers has focused on the search of novel, specific thyreostatics and study the mechanism of their interaction with molecular iodine. However, the study of rhodanine derivatives as the potential thyreostatics was not carried out. The reaction product of 2-thioxo-5-(3,4,5-trimethoxybenzylidene) thiazolidin-4-one is presented by two types of adducts – stoichiomorphs: C13H13NO4S2·I2 and (C13H13NO4S2)2·I2 in chloroform and methylene chloride, respectively. According to the single crystal X-ray diffraction method the I1I2 bond length (2.762 Å) is rather elongated with respect to the average distance in gas phase II 2.662 Å and the S1⋯I1 distance is shortened 2.905 Å (0.875 Å less than VdW radii sum) in adduct 1. The iodine molecule in adduct 2 coordinated by two heterocycle molecules forms two contacts: the S (exocyclic) … I - 3.203 Å (0.577 less than VdW radii sum) and S (endocyclic) … I – 3.532 Å (0.248 less than VdW radii sum), respectively. The results of thermogravimetric analysis have revealed that the product 2 is more stable than product 1 due to each atom of iodine molecule is coordinated by endo and exocyclic sulfur atoms of two heterocycle molecules. The presence of thyreostatic properties is a main starting point in further investigations of rhodanine series as the potential pharmaceuticals.