engleski

Thermodynamics of complexation reactions of antracene-based fluorescent calix[4]arene derivatives with alkali metal cations

Calixarenes bearing fluorescent moieties can be considered as potential very sensitive fluorimetric ion sensors due to the high sensitivity of fluorimetry.1–4 In the scope of this work novel fluorescent antracene- and diphenylantracene-based calix[4]arene derivatives 1 and 2 were designed and synthesized. Antracene and diphenylantracene moieties were introduced at a lower calixarene rim and served as fluorescent groups positioned close to the cation-binding site. Due to the low solubilities of the prepared calix[4]arene derivatives in solvents of moderate permittivities, their complexation with alkali metal cations was studied in methanol–dichloromethane and acetonitrile–dichloromethane solvent mixtures (φ = 0.5). Stability constants of the corresponding complexes were determined by means of fluorimetry, UV spectrophotometry, and isothermal titration calorimetry. The latter technique also provided information on reaction enthalpies and entropies. The obtained thermodynamic quantities were discussed regarding the structural characteristics of the ligands and solvation properties of the solvents used.

calix[4]arene ; antracene ; diphenylantracene ; alkali metal cations

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