betadex and 3-hydroxy-2-naphthoic-acid

A spectrofluorimetric method has been developed for the determination of 3-hydroxy-2-naphthoic acid (3H2NA) by formation of a ternary complex with zirconium (IV) and beta-cyclodextrin (beta-CD). It has been observed that the fluorescence intensity of 3H2NA is greatly enhanced when the ternary complex is formed and is accompanied with shifts in the excitation and emission wavelengths. The conditions for the formation of the ternary complex have been optimized and the stoichiometry has been calculated, resulting a 1:2:1 complex (3H2NA:Zr: beta-CD). The linear range was 20-2000 ng mL(-1) and the detection and quantification limits calculated were 17 and 58 ng mL(-1), respectively. The proposed method was applied to the determination of 3H2NA in river water. To eliminate interferences an off-line solid phase extraction (SPE) procedure using C18 cartridges was used. The extraction procedure was optimized and good recoveries were obtained (around 100%) with relative standard deviations (RSDs) of less than 5%.

Topics: beta-Cyclodextrins; Fresh Water; Hydrogen-Ion Concentration; Naphthols; Spectrometry, Fluorescence; Zirconium

An effective and novel approach to obtaining electrorheological particles with high performance through the formation of host-guest complexes has been achieved. The significant preponderance of the host-guest complex formation is that the host structure can be controlled easily by adding different guests. Based on this point, six supramolecular complexes of beta-cyclodextrin cross-linking polymer with salicylic acid (beta-CDP-1), 5-chlorosalicylic acid (beta-CDP-2), 3,5-dichlorosalicylic acid (beta-CDP-3), 5-nitrosalicylic acid (beta-CDP-4), 3,5-dinitrosalicylic acid (beta-CDP-5), or 3-hydroxy-2-naphthoic acid (beta-CDP-6) particles were synthesized. The electrorheological yield stresses of the suspensions of these particles in silicone oil have been investigated under DC electric fields. It was found that the yield stress of the typical beta-CDP-1 ER fluid was 5.6 kPa in 4 kV/mm, which is much higher than that of pure beta-cyclodextrin polymer (beta-CDP), that of pure salicylic acid as well as that of the mixture of the host with the guest. It is clearly indicated that the formation of supramolecular complexes between beta-CDP and salicylic acid can enhance the ER properties of the host. The similar results for other supramolecular complexes with different guests have also been obtained under the same DC electric fields. The yield stress of supramolecular complexes is strongly affected by the structure of guests. Among the six investigated guests, 3-hydroxy-2-naphthoic acid gave the highest ER property having a yield stress of 9.8 kPa under 4 kV/mm DC while cross-linked with beta-CDP to form beta-CDP-6. The yield stress of beta-CDP-6 was significantly increased by 72% in comparison with that of the pure beta-CDP. However, the yield stress of beta-CDP-1-5 slightly increased by 34-41% as compared with that of the pure beta-CDP. The achieved results indicate that the ER effect of host-guest complexes can be greatly affected by the changes of the tremendous guest structure, whereas the slight guest structural transposition, such as altering different groups of a guest, can only obtain the adjacent electrorheological behavior. The dielectric properties of these host-guest complexes also proved that the ER effect can be affected by the properties of guest.

Topics: beta-Cyclodextrins; Chlorobenzoates; Electrophoresis; Molecular Structure; Naphthols; Particle Size; Polymers; Rheology; Salicylates; Salicylic Acid; Silicone Oils; Static Electricity