Hydrostatic‐Pressure‐Controlled Molecular Recognition: A Steroid Sensing Case Using Modified Cyclodextrin

Abstract

Dansyl‐modified cyclodextrin (CD) demonstrates molecular recognition behavior under high pressure as revealed by means of hydrostatic‐pressure UV/Vis, circular dichroism, and fluorescence spectroscopies, as well as fluorescence lifetime measurements. The dansyl branch, originally included into the CD cavity, was gradually excluded with increasing pressure, and then reached to lie on the primary rim. The CD sector rule can be used to explain the pressure‐dependent pre‐equilibration of ‘naphthyl‐in’ and ‘naphthyl‐out’ complexes. These in‐out conformers play pivotal roles in guest binding under high pressure. The supramolecular complexation of cholic acid, i. e., ursodeoxycholic or chenodeoxycholic acid, with the modified CD was also suppressed upon hydrostatic pressurization due to both positive reaction volumes (ΔV>0). The present work provides a useful strategy for designing a pressure‐responsive chemical sensor based on modified CD.