Experimental and Theoretical Study on the Inclusion Capability of a Fluorescent Indolizine β-Cyclodextrin Sensor Towards Volatile and Semi-volatile Organic Guest

Inclusion equilibria of a new fluorescent indolizine modified β-cyclodextrin were studied in aqueous solution to evaluate its use as a fluorescent chemo-sensor for volatile organic compounds (VOCs). The host compound shows a decrease of the fluorescence intensity by adding adamantanol, benzene, toluene, phenol and p-cresol as guest. The sensing parameter (ΔI/I ₀) was used to show the sensing ability of the host. The formation constant values measured using a spectral displacement method and a specific algorithm treatment are reported. Although the guest binding ability of the sensor is not enhanced by the existence of the hydrophobic cap, this new cyclodextrin sensor shows a very strong sensing ability. The experimental values of the constants were in good agreement with the computed complexation energies, ΔE, from molecular mechanics modelling of the inclusion process.