Study On The Interaction Of Cucurbit[n]uril With Some Drugs And Its Analytical Application

Supramolecular chemistry based on the intermolecularnon-covalent interactions and the formation of molecularaggregates. The supramolecular chemistry mainly studies memberof the weak interaction of the non-covalent, supramolecularchemistry has expanded to new infinite space for development tocreate new substances and new materials. In recent years, with therise of the supramolecular chemistry, cucurbit[n]uril chemistry hasformed an important branch of supramolecular science,demonstrated the broad application prospects in the field ofmolecular recognition, molecular catalysis, molecular assembly,ion channels, super molecular biology, nanoscience, andsupramolecular pharmacology. However, little attention has beendevoted to their potential analytical applications. This paper is thestarting point of the competitive reaction of fluorescent probes anddrugs in the cavity of cucurbit[n]uril, basing on the pharmaceutical analysis and supramolecular chemistry. The interaction has beenstudied by fluorescent titration,1H NMR spectrum, and theoreticalcalculations. Through the interaction of cucurbit[n]uril with somedrugs and fluorescent probes study, in order to achieve a variety ofnon-fluorescent or weakly fluorescent drug fluorescencespectrometry by the cucurbit[n]uril fluorescent probe.We aim tofind a simple, rapid, accurate, and sensitive method using theproposed procedures to determine the drug in their pharmaceuticaldosage forms and and biological fluids. The interaction models ofthe supramolecular complexes were established throughtheoretical calculations. The interaction mechanism was confirmedvia the1H NMR spectrum. The content of this paper are as follows:1. cucurbit[n]uril, the new generation of supramolecularcompound, is reviewed at the application of research, whichincluded structural characteristics, physical and chemicalproperties, molecular recognition, molecular assembly, andmolecular devices. It observe the research progress ofcucurbit[7]urils (CB[7]) hosts in application of fluorescenceanalysis, the fluorescence probe method and pharmaceuticalanalysis.2. The competitive reaction between ethambutol and twofluorescent probes (i.e., berberine and palmatine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorometry.Aqueous solutions of berberine and palmatine have no nativefluorescence. The CB[7] reacts with these probes to form stablecomplexes, and the fluorescence intensity of the complexes isgreatly enhanced. However, the addition of ethambutol dramaticallyquenches the fluorescence intensity of the two complexes.Accordingly, a couple of new fluorescence quenching methods forthe determination of ethambutol were established. The methodscan be applied for quantifying ethambutol. A linear relationshipbetween the fluorescence quenching values (ΔF) and ethambutolconcentration exists in the range of 5.0 to 1000.0 ng mL 1. Thedetection limit is 1.7 ng mL 1. This paper also discusses themechanism of fluorescence indicator probes.3. The competitive reaction between phenylephrinehydrochloride (or epinephrine) and palmatine for occupancy of thecucurbit[5] uril (CB[5]) cavity was studied by spectrofluorometry.The CB[5] reacts with this probe to form stable complexes, and thefluorescence intensity of the complexes is greatly enhanced.However, the addition of phenylephrine hydrochloride (orepinephrine) dramatically quenches the fluorescence intensity ofthe complex. Accordingly, new fluorescence quenching method forthe determination of phenylephrine hydrochloride (or epinephrine) were established. A linear relationship between the fluorescencequenching values (ΔF) and phenylephrine hydrochloride (orepinephrine) concentration. The method can be applied forquantifying phenylephrine hydrochloride (or epinephrine).4. The supramolecular interaction of cucurbit[7]urils (CB[7])hosts and Nitidine chloride (NC) was studied by spectrofluorimetrytitrations. The inclusion interaction between fluorescent probe ofCB[7] and NC mainly contributed to the formation of 1:1 typeCB[7]-NC. The fluorescence intensity of the complexes wasenhanced with increasing CB[7] concentration, while the excitationand emission peaks of the drug moved to longer wavelengths. Thefluorescence spectrometry were performed at differenttemperatures to determine stability constants, as well as toevaluate the thermodynamic parameters of the obtained complex.the room temperature was reached at a maximum of 9406.32 L mol 1.Moreover, to obtain information about the binding mechanism of theinteraction, 1H NMR studies and molecular modeling were carriedout. Based on the experiment data, the association process ofcomplexes was established.