The complex characteristics of p-sulfonated calix[n]arene (SCnA) and two tryptophans N-[(tert-butoxy) carbonyl]-tryptophan (trp-A) and N-carbobenzoxy-tryptophane (trp-B) were examined through various techniques. Spectrofluorimetry was performed at different temperatures to determine the stability constants and evaluate the thermodynamic parameters of the two complexes. The effect of pH on complex formation was estimated. According to the fluorescence data, the assumption about the steric hindrance of the tert-butyl group of trp-A and the phenyl group of trp-B was put forward. (1)H NMR was also performed to determine the binding interaction mechanism. Results showed that the indole benzene rings of the two tryptophans partly penetrated into the cavity of p-sulfonated calix[n]arene. The shift in Ha, Hb and Hc, Hd positions became more significant as the number of phenolic units of the calixarene ring increased. Molecular modeling of the complexes elucidated the assumption about the steric hindrance of the tert-butyl group of trp-A and the phenyl group of trp-B. These observations of molecular modeling computation are consistent with previous fluorescence data and (1)H NMR results.
In this paper, the interaction behavior of p-sulfonated calix[n]arene (SCnA) with tramadol hydrochloride was investigated by fluorescence spectra, 1 H NMR spectra, and theoretical calculations in aqueous solution. At the optimized conditions, the fluorescence intensity of tramadol hydrochloride showed positive correlation to the concentration of SCnA, which led to a validated, simple, and sensitive fluorescence quenching method for the determination of tramadol hydrochloride was established for the first time. Moreover, the interaction based on SCnA superstructure provided has promising potential for therapeutic monitoring and pharmacokinetics and clinical application
In the present work, we describe a novel application of functionalized single-walled carbon nanotubes (SWCNTs) as a stationary phase for the liquid chromatographic separation of polycyclic aromatic hydrocarbons and structurally similar analogues. The SWCNTs were first oxidized to give carboxylic derivatives (SWCNT-COOH), afterwards these were covalently derivatized with hydroxypropyl-β-cyclodextrin (HP-β-CD). Then, the HP-β-CD-SWCNTs were bonded to silica gel with 3-(triethoxysilyl) propyl isocyanate, which were used as a stationary phase to separate the investigated solutes by HPLC. On this stationary phase, eight polycyclic aromatic hydrocarbons were separated using water/methanol (5:5, v/v) as the mobile phase and six structurally similar dipine drugs were also separated using (3:7, v/v) methanol/triethylammonium acetate buffer (0.1%, v/v, pH 4.1) as the mobile phase. The results showed that the HP-β-CD-SWCNTs stationary phase had stronger separation ability for the aromatic hydrocarbons and analogues compared with the HP-β-CD stationary phase. This method can be used to improve the separation efficiency of the β-CD stationary phases, and the HP-β-CD-SWCNTs column can be used for the determination of the aromatic hydrocarbons in wastewater.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.