Construction Of Rotaxane-Systems Based On Cucurbit[n]Uril And Naphthalene/Anthracene Derivatives And Their Fluorescent Properties

Rotaxane is a kind of classic mechanically interlocked molecules(MIMs).Because of its unique interlocking structure and the ability to respond to environmental stimuli,it is often used as an ideal building blocks for artificially designed nanomachines.The dissociation and reassembly of pseudorotaxane make us better understand the functions of keys and locks and molecular switches at the molecular level.In previous reports,scientists often used [n]rotaxanes to represent different rotaxane structures.However,it is difficult to accurately represent a complicated assembled structure.So we proposed(pseudo)[n,m]rotaxanes to accurately represent the structure of multiaxial rotaxanes,avoiding the inaccuracy of traditional definition.Cucurbit[n]uril(CB[n])is a kind of cyclic molecule with hydrophobic cavity and two polar carbonyl portals.Hydrophobic interaction and electrostatic interaction are the main driving forces for the binding of CB[n] with guest molecules.Because of CB[n]s’ unique structure,it is often used as building blocks for constructing various rotaxane.Luminescent molecules or systems are often used in cell imaging,probes,sensors,optical devices and other fields.Inspired by these applications,supramolecular chemists achieved the regulation of luminescent color based on host-guest chemistry.In this paper,three guest molecules,naphthalene and anthracene derivatives,were synthesized.Two kinds of pseudorotaxanes with different stoichiometric ratios and two kinds of polyrotaxanes with different stacking arrangements were obtained by host-guest interaction with cucurbit[7/8]uril.Moreover,with the addition of the host,the fluorescence properties have been significantly changed.The rotaxanes exhibit stimuli-responsive behavior triggered by competitive guest,and self-sorting behavior.In addition,scanning electron microscopy(SEM)were utilized to investigate the change of morphology of rotaxane.These CB-based rotaxanes has potential applications in fluorescent materials and biological systems.