Flow injection spectrofluorimetric study of the supramolecular interaction between beta-cyclodextrin and dequalinium chloride and its analytical application

Fluorimetric investigation of supramolecular system by modified β-cyclodextrin and its analytical application

The supramolecular interaction of MAH-β-cyclodextrin (MAH-β-CD, a modified β-cyclodextrin carrying seven vinyl carboxylic acid groups) and meferamic acid (MF) has been studied by spectrofluorimetry. The results showed that MAH-β-CD reacted with MF to form a host-guest complex (MAH-β-CD-MF) with stoichiometry (1:1) and the inclusion constant (K=7.15×10(2) L/mol) was ascertained by the typical double reciprocal plots. From the phase-solubility diagram, an increase in the water solubility of the drug was observed and the apparent stability constant (K(1:1)) was calculated to be 8.62×10(2) L/mol. Furthermore, the thermodynamic parameters (ΔG°, ΔH° and ΔS°) of MAH-β-CD-MF were obtained and the inclusion mechanism was also preliminarily discussed. In order to further confirm the experimental results, investigation on the molecular modeling was performed. On the basis of the significant enhancement of the fluorescence intensity of MF, a spectrofluorimetric method for MF determination in bulk aqueous solution in the presence of MAH-β-CD was developed. The linear range was 2.00×10(-8)-9.00×10(-5) mol/L and the detection limit was 3.36×10(-9) mol/L. The proposed method was successfully applied to determine MF in tablets, serum and urine with the satisfactory result.

Study on beta-cyclodextrin inclusion of Zn(II) aromatic complex and its analytical application

A new beta-cyclodextrin (beta-CD) inclusion compound Zn(2H1NA)(2)x 2beta-CD (2H1NA=2-hydroxy-1-naphthoic acid) was prepared. The structure was characterized by (1)H NMR, IR, the fluorescence spectra, thermogravimetric analysis (TG-DTA) and elementary analysis. Meanwhile, the mechanism of the formation of the supramolecular system (2H1NA:Zn(II):beta-CD) was studied and discussed by spectrofluorimetry. The results showed that the naphthalene rings of the Zn(II) aromatic complex Zn(2H1NA)(2) were encapsulated within the beta-CD's cavity to form a 2:1 stoichiometry host-guest compound. The inclusion constant calculated was 1.27 x 10(4)(L/mol)(2). A spectrofluorimetric method for the determination of 2H1NA in bulk aqueous solution in the presence of beta-CD was developed based on the great enhancement of the fluorescence intensity of 2H1NA. The linear relationship was obtained in the range of 9.00 x 10(-7) to 2.50 x 10(-5)mol/L and the detection limit was 8.00 x 10(-7)mol/L. The proposed method was successfully applied to determine 2H1NA in waste water with recoveries of 97-104%.

Study on the supramolecular system of 5-(p-hydroxyphenyl)-10,15,20-tris-(4-chlorophenyl)porphyrin with cyclodextrins and its analytical characteristics

The supramolecular systems of 5-(p-hydroxyphenyl)-10,15,20-tris-(4-chlorophenyl)porphyrin (p-HTClPP) with beta-cyclodextrin (beta-CD), heptakis(2,3,6-tri-O-methyl)-beta-CD (TM-beta-CD), carboxymethyl-beta-cyclodextrin (CM-beta-CD) and sulfurbutylether-beta-CD (SBE-beta-CD) have been investigated by means of absorption, fluorescence and (1)H NMR spectroscopy. The formation of inclusion complexes has been confirmed on the base of changes of spectroscopy properties. "The double reciprocal method" has been used to determine the stoichiometry and the inclusion constants of p-HTClPP with the four cyclodextrins (CDs). The results show that p-HTClPP can form 1:1 inclusion complexes with the four CDs. Compared with parent native beta-CD, the inclusion abilities of modified beta-CDs with p-HTClPP are stronger. It indicates that the hydrophobic effect plays an important role in the inclusion procedure. The mechanism of inclusion interaction was examined by (1)H NMR technique. During the study of p-HTClPP-TM-beta-CD supramolecular complex, an efficient enhancement of fluorescence intensity was observed. Based on this phenomenon, fluorometric method for the determination of p-HTClPP was developed. The relationship between fluorescence intensity and the concentration of p-HTClPP is linear from 1.0 x 10(-9) to 7.0 x 10(-6)mol L(-1). The limit of detection is 8.3 x 10(-10)mol L(-1) and the relative standard deviation (R.S.D.) is 1.3% (n=8). This research will provide useful information for further application of p-HTClPP.

Synthesis of ethylenediamine linked β-cyclodextrin dimer and its analytical application for tranilast determination by spectrofluorimetry

A synthesis of beta-cyclodextrin (beta-CD) dimer, containing two beta-CD moieties that are linked through their sides by ethylenediamine, was presented. The dimer was characterized by means of IR, (1)H NMR, (13)C NMR, and elemental analysis. The inclusion complexation behavior of beta-cyclodextrin dimer with tranilast was studied in an aqueous KH(2)PO(4)-citric acid buffer solution of pH 2.00 at room temperature by spectrofluorimetry. Based on the significant enhancement of fluorescence intensity of tranilast, a spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of tranilast in bulk aqueous solution in the presence of ethylenediamine beta-CD dimer. The apparent association constant of the complex was 8.39 x 10(3) L mol(-1), and the linear range was 10.8-1.40 x 10(4) ng mL(-1) with the detection limit 3.2 ng mL(-1). There was no interference from the excipients normally used in tablets and serum constituents. The proposed method was successfully applied to the determination of tranilast in serum.