Abstract
The temperature influence on creation of a supramolecular complex in which β-cyclodextrin (β-CD) is the host molecule and phenolphtalein (PP) is the guest has been studied in aqueous solution by UV-visible absorption spectroscopy. The decrease of temperature of β-cyclodextrin-phenolphtalein system resulted in a decrease in absorbance of the UV-vis spectrum. Under favourable conditions (0.1 mM β-CD, 30 μM PP) the termochromic effect is very significant (≅0.1 U of absorbance/10°C). The formation constant of inclusion complex was determined at various temperatures (from 10 to 70°C) using Scott’s equation. The association constants (K11) for the binding in 0.02 M sodium carbonate (pH 10.5) at 10 and 70°C are 7.44 and 0.26×104 M−1, respectively. The stoichiometric ratio of investigated complex was found to be 1:1 on wide range of β-cyclodextrin:phenolphtalein concentration ratio (from 0.8:1 to 427:1). Additionally, strong interaction between cyclodextrin and tetrahydrofuran (THF) was observed and the inhibitory effect of tetrahydrofurane on the association of β-CD–PP complex was studied. From linear Van’t Hoff plots thermodynamic parameters such as: the change of enthalpy (ΔH°) and change of entropy (ΔS°) were estimated and interpreted.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
