Study On The Construction And Performance Of The Articulated 14-membered Cucurbit Ring/heterocyclic Dye Supramolecular Assembly System

Twisted cucurbit[14]uril?tQ[14]?is the cucurbit[n]uril with 14 normal glycoluril units linked by 28 methylene bridges.As a consequence,it does not have a normal cavity like the most cucubit[n]urils,and has the appearance of a folded,figure of eight conformation.It has two different cavities?two side cavity and one central cavity?.In this article,we mainly build a supramolecular system based on the t Q[14]and heterocyclic dyes as a guest,such as thiazole cyanine dyes?DTTHC,DTCI?,styrene quinoline dyes?DASQMI,DSQ?and quinoline cyanine dyes?PIC,PIN?.The binding interactions between tQ[14]and heterocyclic dyes was investigated using ultraviolet spectroscopy,fluorescencespectroscopyandnuclearmagneticresonance spectroscopy.Supramolecular systems of tQ[14]@DTTHC and tQ[14]/DASQMI were constructed and sensed metal ions.The PIC and PIN aggregates are also decomposed by the host-guest property between tQ[14]with PIC and PIN.It provides an approach for the study of stucture and property of tQ[14],and a new detection method for the identification of metal ions.It also provides an new ideas for controlling the aggregation and depolymerization of cyanine dyes.The main research contents and results are as follows:Firstly,the binding interactions between tQ[14]with DTTHC and DTCI by means of ultraviolet-visible absorption spectrum?UV-Vis?,fluorescence spectroscopy?IF?,isothermal titration calorimetry?ITC?and two-dimensional diffusion ordering?2D DOSY?NMR spectroscopy.The ¹H NMR spectra suggests that the guest was located in portal of tQ[14]molecule.The tQ[14]@DTTHC supramolecular system was constructed to identify metal ions.When the ratio of host to guest is lower,the addition of Ba²⁺and Hg²⁺to the tQ[14]@DTTHC system resulted in a complete decrease of the emission intensity.When the ratio of host to guest is higher,the addition of Hg²⁺o the system makes the solution turbid.The precipitate was studied by fluorescent inverted microscope,scanning electron microscope and transmission electron microscope,it is an amorphous solid with green fluorescence.Determining the concentration before and after the reaction between Hg²⁺and supramolecular system by atomic absorption spectroscopy?AAS?.The removal rate reached 89.17%,which indicated that system B could better remove Hg²⁺.Secondly,the binding interactions between tQ[14]with DASQMI and DSQ by common analytical methods such as ultraviolet-visible absorption spectroscopy?UV-Vis?,fluorescence spectroscopy?IF?,and isothermal titration calorimetry?ITC?.The tQ[14]@DASQMI supramolecular system identified metal ions as a sensor.According to the fluorescence spectra,the addition of Ba²⁺,Hg²⁺and Fe³⁺to the system resulted in a complete decrease of the emission intensity.It is envisaged that stimuli-responsive supramolecular assemblies might be applicable in turn-off fluorescent sensors to sense Ba²⁺,Hg²⁺and Fe³⁺.The tQ[14]@DASQMI supramolecular system has high sensitivity and selectivity with the detection limit were 7.89×10^-77 mol/L,5.75×10^-77 mol/L,and 1.39×10^-77 mol/L.Finally,the binding interactions between two quinoline cyanine dyes,pseudoisocyanine?PIC?and pinacyanol?PIN?,and the twisted cucurbit[14]uril hosts,were investigated by ultraviolet-visible absorption spectroscopy?UV-Vis?,isothermal titration calorimetry?ITC?and ¹H NMR spectroscopy.The binding interaction between PAA and PIC,PIN was also studied.The results showed that the addition of PAA could promote the formation of J-agg by PIC,promote the formation of H-agg by PIN.tQ[14]completely disrupted the J-aggregates formed by PIC and the H-aggregates formed by PIN.tQ[14]complexation was found to effectively disrupt the intermolecular forces responsible for the aggregation of both dyes.