Crystal Structure of a Novel Sandwich Inclusion Complex of β-Cyclodextrin with α-Naphthylacetic Acid

A supramolecular inclusion complex between β-cyclodextrin（β-CD） and α-naphthylacetic acid was prepared, and its crystal structure was investigated by single-crystal X-ray crystallography. The complex contains two β-CD molecules, one α-naphthylacetic acid, two ethanols and twenty-eight water molecules in the asymmetric unit, which could be formulated as [（C42H70O35）2·（C12H10O2）·（C2H5OH）2·28H2O]. Two β-CD molecules constitute a dimer by face-to-face contact of their secondary hydroxyl sides. At the interface of the dimer, one α-naphthylacetic acid molecule is sandwiched between two β-CD molecules. Each β-CD unit of the dimer includes one ethanol molecule in its cavity. The β-CD dimers are linked together via hydrogen bonding to form layers that are stacked in a brickwork-like pattern. The comparative study of some sandwich complexes elucidates that the interface of the β-CD dimer has a stronger inclusion capacity than the cavity of β-CD for some suitable planar guest molecules. The novel inclusion structure results from the competitive inclusion of α-naphthylacetic acid and ethanol.

The Transient Time-Resolved Absorption Spectra of 1-Naphthylacetic Acid

The transient absorption spectra of 1-naphthylacetic acid in tetrahydrofuran have been obtained by laser flash photolysis technique. The transient species bands are at 509.535 and 553 urn. These peak intensities increase in the maximum values at 10.4u s.

Synthesis, Structure and Thermochromic Properties of a Copper(Ⅱ) Complex Based on Naphthyl Carboxylate and Benzimidazolyl Ligands

One novel copper（Ⅱ） complex, [Cu（NAA）2（bim）2]·H2O （1, HNAA = a-naphthylacetic acid, bim = benzimidazole） has been synthesized and characterized by X-ray single-crystal diffraction analysis, elemental analysis, and IR spectrum. It crystallizes in monoclinic, space group C2/c with a = 1.15969（12）, b = 1.9757（2）, c = 1.45763（16） nm, β = 104.712（2）°, V = 3.2298（6） nm3, Z = 4, C38H32N4O5Cu, Mr = 688.22, Dc = 1.418 g/cm-3, μ = 0.729 mm-1, S = 1.039, F（000） = 1428, the final R = 0.0380 and wR = 0.0912 for 2849 unique reflections. In 1, two carboxylate and two benzimidazole ligands coordinate to the central Cu（Ⅱ） atom by a bidentate chelate mode. Interesting, reversible thermochromic properties of 1 can be observed and investigated by thermal analysis method.

Multi-walled carbon nanotube as a solid phase extraction adsorbent for analysis of indole-3-butyric acid and 1-naphthylacetic acid in plant samples

In this work, a new sample pretreatment method prior to HPLC separations was developed for the determination of auxins in plant samples, Owing to its large surface area and high adsorption capacity, multi-walled carbon nanotube （MWCNT） was chosen as the adsorbent for the extraction of auxins from plant samples. In this study, two important auxins were selected as model analytes, namely indole-3- butyric acid （IBA） and 1-naphthylacetic acid （NAA）. They could be extracted and concentrated due to their π-π stacking interactions with MWCNT. Then HPLC-UV was introduced to detect IBA and NAA after sample pretreatment. Factors that may affect the enrichment efficiency were investigated and optimized. Comparative studies showed that MWCNT was superior to CI 8 for the extraction of the two analytes. Validation experiments showed that the optimized method had good linearity （0.9998 and 0.9960）, high recovery （81.4%-85.4%）, and low detection limits （0.0030 mg/L and 0.0012 mg/L）. The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it was feasible for the determination of auxins in plant samples.

Characterization of Esterases of Tamarindus indica Seeds

Germinating seeds of Tamarindus indica synthesizes various enzymes which are required for the degradation of seed reserves such as xyloglucans, fatty acid esters and proteins. Among these, esterases, belonging to a group of hydrolytic enzymes catalyze the hydrolysis of various types of esters. They play an important role in cell expansion as well as detoxification of xenobiotics and many agrochemicals and insecticides. The esterases are extracted from the germinating tamarind seeds using 50 mM phosphate buffer, pH 7. The Km with α-naphthyl acetate as the substrate is 19.23 μM and the enzymes are optimally active at pH 7.0 to 7.5 and are stable between pH 5.0 to 9.0. The optimum temperature of esterase activity of tamarind seed is between 37?C - 50?C and is stable up to 40?C. The activity declined by 30% at 60?C and about 90% at 70?C. Highest esterase activity and specific activity are observed on the 21st day of germination. The polyacrylamide gel electrophoresis (PAGE) indicated the presence of nine isozymes of esterases. Band numbers 1, 5 and 6 are the major esterolytic bands present throughout the germination period while band numbers 2 & 3 are minor bands present only during the latter period of the germination. Based on substrate and inhibitor specificity in conjunction with electrophoresis, the esterases 1 to 8 have been classified as carboxylesterases sensitive to organophosphate inhibitor (OP) and PCMB (p-chloromercuribenzoate) while esterase 9 is classified as carboxylesterase sensitive to OP. These esterases are unaffected by carbamate inhibitor, eserine sulphate.