Abstract:We use a method for the calculation of the molecular dipole ( µ ) and quadrupole ( θ ) moments and dipole-dipole ( α ), dipole-quadrupole ( A ) and quadrupole-quadrupole ( C ) polarizabilities which we have successfully applied to the benzothiazole (A)-benzobisthiazole (B) linear oligomer A-B 13 -A. Two model rotational isomers have been characterized: (1) the fully-planar (000) conformation; and (2) a rotational isomer with each unit rotated in the range 1 − 10° in the same direction (+++). For isomer 000, µ is smaller than for +++. The calculation of α , A and C has been carried out by the interacting induced dipoles polarization model that calculates tensor effective anisotropic point polarizabilities (method of Applequist et al.). The values of A are specially sensitive to µ which varies under rotation. This fact explains the great values of A x xx , for the +++ polar isomer. It is found that small torsional changes can enhance solubility by a clear increasing of the hydrophilic accessible surface area. However, the torsion of the oligomer varies the value of µ and so modifies α , C , and, specially, A . For conformer +++, polarization effects occur even when each unit is rotated only φ = 1°. The observed effect is an increase in µ and, hence, in α , C , and, specially, A .