Shaping tetraazaparacyclophanes for selective solvent vapour detection: Structural variations in coating design

Paracyclophanes serve well as receptor sites mimicking enzyme analogue reco gnition. Their application as coatings for the mass-sensitive detection of toxic organic solvent vapours is demonstrated involving synthetic variation of the macrocycle in terms of cavity size, shape and stereoelectronics. In this way it is possible to tailor these hosts towards different analytes s uch as chloroform or toluene. The computational modelling of the inclusion allows the prediction of both the sensitivities and selectivities of promis ing coatings before doing time consuming syntheses. Force-field calculation s show that the outstanding inclusion behaviour of a xylylene bridged tetra azaparacyclophane towards large aromatic and halogenated analyte molecules is due to the elongated cavity of the host. Temperature-dependent determina tion of the equilibrium constant K of the guest inclusion shows that calcul ated and measured interaction enthalpies do correlate satisfactorily.