Thermal stability of the complex of pyrene–β-cyclodextrin dimer with aromatic amino acids
- Russian Academy of Sciences, Institute of Problems of Chemical Physics (Russian Federation)
Using the method of adsorption spectroscopy, the temperature dependence of the electronic absorption spectra of the fluorescent chemosensor (CS), based on the supramolecular pyrene–2β-cyclodextrin complex (Pyr@2βCD, PCD), was studied in the absence and in the presence of phenylalanine (Phe). The application of CS, where pyrene serves as a fluorescent probe, is based on the ability of CS to form the inclusion complexes with small organic molecules as well as with aromatic amino acids (AA) such as Phe, tryptophan (Trp), tyrosine (Tyr), and histidine (His) in aqueous solutions. Upon heating to 55 °C, the PCD complex in the presence of Phe shows a higher stability as compared to that in the absence of Phe. The molecular dynamics simulation was applied to study the thermal stability of PCD and its complexes with the above AAs in water. The PCD complex exists in two configurations. In configuration 1 the planar Pyr molecule lies in the equatorial plane of the βCD dimer, the plane of Pyr is nearly perpendicular to the vertical axis of the dimer 2βCD, and water fills up the empty part of the cavity. In configuration 2, the plane of Pyr is inclined with respect to the axis of the 2βCD dimer by ~30°. The PCD complex initially prepared in state 1 is spontaneously transformed into state 2 and remains stable up to the boiling temperature. The transition of PCD from the form 1 to 2 is provided by fluctuations in water content in its cavities. The inclusion complexes of amino acids 2AA@PCD exist in a single conformation 1. Complexes of PCD with Trp and Phe are stable up to the boiling temperature, i.e., these AAs are preserved within the PCD cavities even at the elevated temperature. The complex with Tyr decays at 60 °C, and the complex with His is unstable at room temperature and above.
- OSTI ID:
- 22943338
- Journal Information:
- Russian Chemical Bulletin, Vol. 67, Issue 12; Other Information: Copyright (c) 2018 Springer Science+Business Media, LLC, part of Springer Nature; Country of input: International Atomic Energy Agency (IAEA); ISSN 1066-5285
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTRA
ABSORPTION SPECTROSCOPY
ADSORPTION
AQUEOUS SOLUTIONS
BOILING POINTS
FLUORESCENCE
HISTIDINE
MOLECULAR DYNAMICS METHOD
OLIGOSACCHARIDES
PHENYLALANINE
PYRENE
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TRYPTOPHAN
TYROSINE