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

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

JOURNAL OF LUMINESCENCE

ELSEVIER SCIENCE BV

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

0022-2313

he influence of the macrocyclic compound cucurbit[6]uril (CB6) on the photophysical properties of thefluorophore pyrene (PYR) has been studied. Guest?host interaction was observed by UV?visiblespectroscopy and spectrofluorimetry. The fluorescence of PYR was significantly increased in the presenceof CB6. The binding equilibrium constants for the complex with 1:1 stoichiometry were determined inHCOOH 55% w/v. The values of the association constants, KA, and the fluorescence quantum yield ratiosbetween complexed and free substrate, PYR?CB6/PYR, at different temperatures were (3.1+0.9) x102 M-1 and (5.1+0.2), (3.6+0.5) x 102 M-1 and (5.9+0.1), (4.8+0.7) x 102 M-1 and (5.5+0.1) at15.0 C, 25.0 C and 40.0 C, respectively.The enthalpic and entropic contributions to the complexation process were determined, yieldingΔS=(9273) J mol-1 K-1 and ΔH=(1371) kJ mol-1From these results it can be concluded that thecomplex formation is mainly driven by the entropic term. The forces involved in