Abstract <p>Using quantum chemistry methods (B3LYP/cc-pVTZ), the structure of 1 : 1 and 2 : 1 complexes of 4-[(4-butoxyphenyl)diazenyl]benzenesulfonic acid with 4,4′-azopyridine (Py–N=N–Py) and 1,2-bis(4-pyridyl)ethane (Py–CH₂–CH₂–Py), respectively, in the gas phase and in solvents of different polarities (polarizable continuum model) reproducing the environment of the complexes in condensed phases has been determined. It is shown that the environment significantly affects the geometric structure of the complexes, their shape, and the characteristics of intermolecular hydrogen bonds in them. In the gas phase, only complexes without proton transfer are actualized for the studied systems, and taking nonspecific solvation by solvents with different polarities into account ensure conditions for proton transfer from the sulfo group to the pyridine fragment, which corresponds to the form of such complexes in the crystalline phase. By calculating the potential functions of proton transfer and analyzing the energy and geometric characteristics of the complexes under various conditions, the values of dielectric constant leading to the greatest stabilization of the complexes in the form with proton transfer have been established.</p>