Competitive processes associated to the interaction of a cavitand derivative with caffeic acid

Abstract

The interaction of caffeic acid and a newly synthesised cavitand derivative was investigated by UV–vis and fluorescence spectroscopy in tetrahydrofuran–water matrix. The temperature dependence of the equilibrium constants was determined first, then the thermodynamic parameters were calculated using the van’t Hoff equation. Absorption measurements highlighted entropy-controlled formation of cavitand–caffeic acid complexes with 1:2 stoichiometry. It was proved by fluorescence measurements that caffeic acid dimerisation is followed by the formation of cavitand–caffeic acid complexes with 1:2 stoichiometry. It was also shown that both the caffeic acid dimerisation and the formation of 1:2 complexes are controlled by the entropy gain. PL signal is preferred to use for analytical application in this particular case.

Keywords:

• Cavitand
• caffeic acid
• host–guest chemistry
• thermodynamics

Funding

This work was supported by the SROP-4.2.2.D-15/1/Konv-2015-0015 project. The present scientific contribution is dedicated to the 650th anniversary of the foundation of the University of Pécs, Hungary.