Selective recognition of bisphenol S isomers in water by β-cyclodextrin

ABSTRACT

The two isomers 4,4´-dihydroxydiphenyl sulphone and 2,4´-dihydroxydiphenyl sulphone (bisphenol S, BPS) form inclusion complexes with β-CD in solution, in the gas phase, and in the solid state. The complexes 4,4´-BPS@β-CD and 2,4´-BPS@β-CD were studied in solution by 1D and 2D NMR experiments. Calorimetric investigation by ITC evidenced that the β-CD host shows a greater affinity for 4,4´-BPS, with a 4,4´-BPS/2,4´-BPS selectivity ratio of 6.3. In the gas phase, CID MS experiments indicate that 4,4´-BPS has a higher kinetic barrier to escape from the β-CD cavity than the isomeric 2,4´-BPS. In the solid state, the 4,4´-BPS@β-CD and 2,4´-BPS@β-CD complexes form head-to-head dimers constituted by two β-CD macrocycles, with each β-CD hosting one BPS guest. The dimers of β-CD are sealed by H-bonding interactions involving exclusively the secondary OH groups. Finally, the formation of inclusion complexes between 4,4´-BPS or 2,4´-BPS and β-CD was also followed by FT-IR, DSC, and TGA analysis.

Graphical abstract

KEYWORDS:

• β-cyclodextrin
• Bisphenol S
• molecular recognition
• isomers
• neutral guest
• water

Acknowledgments

The authors thank the Regione Campania for the PhD Grant “Dottorati di Ricerca con Caratterizzazione Industriale” DGR n. 156 del 21/03/2017 P.O.R. CAMPANIA FSE 2014/2020 – ASSE III – Obiettivo Specifico 14 Azione 10.4.5: POR D44J18000310006. The authors thank the Regione Campania (POR CAMPANIA FESR 2007/2013 O.O.2.1, B46D14002660009, “Il potenziamento e la riqualificazione del sistema delle infrastrutture nel settore dell’istruzione, della formazione e della ricerca”), for the FT-ICR mass spectrometer facilities, the Centro di Tecnologie Integrate per la Salute (CITIS, Project PONa3_00138), Università di Salerno, for the 600 MHz NMR facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supporting information

X-ray details, and tables of crystal data, Job’s plot, DOSY experiments, TGA and FT IR spectra. This material is available free of charge via the Internet at http://www.tandfonline.com.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Regione Campania[B46D14002660009, POR D44J18000310006].