Study On The Interaction Of Cucurbit[n]Uril With Some Dyes And Its Analytical Application

Supramolecular chemistry based on the intermolecularnon-covalent interactions and the formation of molecularaggregates. The research of the supramolecular chemistry ismainly non-covalent weak interactions. It has broad applicationprospects in materials science, information science, life scienceand drug analysis. This paper studies the mechanism between thenew generation of supramolecular body cucurbituril and someorganic molecular, basing on the chemical thermodynamics,analytical chemistry and supramolecular chemistry, usingfluorescence spectroscopy, UV spevtroscopy, fluorescence probemethod,1H NMR spectrum and theoretical calculations. The aim isto format some new fluorescence probe systems. Through usingnew fluorescence probe detects a variety of non-fluorescent orweakly fluorescent drug, we establish a rapid, sensitive andaccurate fluorescence spectra method to determine the drug intheir pharmaceutical dosage forms. The contents of this paper are divided into four parts:1. Supramolecular chemists have observed that the structuraland chemical properties of CB[n] can exert a profound effect on thephysical and chemical properties of a guest duringcomplexation.These effects open up a variety of uses for CB[7],including chemical sensing, molecular switches, molecularmachines, drug delivery, controlled drug release, competitionintetaction, and molecular catalysis within and between guests.The uses of CB[n] in these field are summarized.2. The supramolecular interaction of a homologous series ofcucurbit[7]urils and acridine Azure A（AA） was studied respectivelyby fluorescence spectrophotometry, UV spectroscopy and manyother techniques. According to the fluorescence spectra, it wasfound that CB[7] and AA could form a stable complex. Thefluorescence intensity of the complex enhanced gradually with theincrease in CB[7] concentration. Consistent with the fluorescencespectrometry, UV spectroscopy also detected a blue shift about13nm. Stability constants were determined at different temperaturesand pH levels by spectrofluorometry titrations, and thethermodynamic parameters of the obtained complex wereidentified. In addition,1H NMR study and molecular modelingcalculations were performed to identify the binding mechanism of the interaction and establish the association process of thecomplex.3. The supramolecular interaction of a homologous series ofcucurbit[n]urils （CB[n]s, n=5,6,7） and acridine orange （AO） wasstudied respectively by fluorescence spectrophotometry, UVspectroscopy and many other techniques. According to thefluorescence spectra, it was found that CB[7] and acridine orangecould form a stable complex. The fluorescence intensity of thecomplex enhanced gradually with the increase in CB[7]concentration. The excitation and emission wavelengths movedfrom494and520nm to487and508nm, respectively, with a blueshift. Consistent with the fluorescence spectrometry, UVspectroscopy also detected a blue shift about9nm. Stabilityconstants were determined at different temperatures and pH levelsby spectrofluorometry titrations, and the thermodynamicparameters of the obtained complex were identified. In addition,1HNMR study and molecular modeling calculations were performed toidentify the binding mechanism of the interaction and establish theassociation process of the complex.4. Valaciclovir Hydrochloride has a weak fluorescence inaqueous solutions, so using a direct fluorescent method is difficult.The competitive reaction between Valaciclovir Hydrochloride and acridine orange for occupancy of cucurbit[7]uril （CB[7]） cavity wasstudied by spectrofluorometry. CB[7] reacts with AO to formcomplexes with strong fluorescence. However, the presence ofValaciclovir Hydrochloride quenches the fluorescence intensity ofthe complexes. The quenching of the CB[7]/AO system is fast, andthe degree of quenching is proportional to the concentration ofsotalol. Therefore, a new and useful spectrofluorometric methodwith high sensitivity and selectivity was developed for thedetermination of Valaciclovir Hydrochloride in aqueous solutions.The proposed method is fairly accurate, simple, rapid, reproducible,and sensitive. It is also specific for the identification of sotalol. Itsdetection limit is0.0023μg mL^-1.