Complexation (cucurbit[6]uril-pyrene): Thermodynamic and spectroscopic properties

VALERIA N. SUELDO OCCELLO; RITA H. DE ROSSI; ALICIA V. VEGLIA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 158 p. 435 - 435

bstract: The influence of the macrocyclic compound cucurbit[6]uril (CB6) on the photophysical properties of the fluorophore pyrene (PYR) has been studied. Guest-host interaction was observed by UV-visible spectroscopy and spectrofluorimetry. The fluorescence of PYR was significantly increased in the presence of CB6. The binding equilibrium constants for the complex with 1:1 stoichiometry were determined in HCOOH 55% w/v. The values of the association constants, KA, and the fluorescence quantum yield ratios between complexed and free substrate at different temperatures were (3.1±0.9)×100/M and (5.1±0.2), (3.6±0.5)×100/M and (5.9±0.1), (4.8±0.7)×100/M and (5.5±0.1) at 15.0 °C, 25.0 °C and 40.0 °C, respectively.The enthalpic and entropic contributions to the complexation process were determined, yielding (13±1) kJ/mol and (92±3) J/ mol K, respectively. From these results it can be concluded that the complex formation is mainly driven by the entropic term. The forces involved in the compl