Thermodynamic characteristics of adsorption of organic molecules on pyrimidinophane

Adsorption of organic molecules on 7,19-diaza-7,19-diethyl-12,16,132,134-tetraoxo-14,136-dimethyl-1(1,3),13(1,3)-dipyrimidinacyclotetracosaphane (pyrimidinophane) supported on Chromaton NAW was studied by inverse gas chromatography at infinite dilution. The values of specific retention volumes, molar changes in the internal energy, Helmholtz energy, entropy of adsorption, contributions of different intermolecular interactions to the Helmholtz energy, and tentative polarity of the adsorbent surface were calculated. On the obtained sorbent, the values of molar changes in the internal energy and entropy of adsorption of alcohols correlate with the size of the macrocycle cavity. When adsorbed in the cavity, alcohol molecules interact by the hydroxyl radicals with the N(7) and N(9) nitrogen atoms of pyrimidinophane. The adsorption of organic molecules is predominantly delocalized. The polarity of the surface of the studied adsorbent is close to that of silica gels.