A stereospecific synthesis of conjugated fluorodienes by a ring-opening reaction of gem-difluorocyclopropane derivatives

Ring-opening reactions of trans- and cis-gem-difluorocyclopropane derivatives (1) with appropriate bases proceeded stereospecifically to give (E, E)- and (E, Z)-fluorodiene derivatives (2), respectively.     

Monoclonal-based enzyme-linked immunosorbent assay and immunochromatographic assay for enrofloxacin in biological matrices

Enrofloxacin has been increasingly used in veterinary medicine to treat microbial infections. A simple and reliable analytical method for this drug is required. The current determination by high performance liquid chromatography (HPLC) is sensitive but labor-intensive. This paper reports an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (MAb) and the development of a rapid test kit based on immunochromatography. The detection limits using the ELISA were 10 ppb for chicken liver and muscle, and 1 ppb for cattle milk, respectively. The mean recovery values were 77.3-96.0% for chicken liver, 72.4-92.0% for chicken muscle and 84.0-99.0% for cattle milk. The detection limits using the kit were ca. 100 ppb for chicken muscle and ca. 10 ppb for cattle milk, respectively. All ELISA results for assay of chicken liver, chicken muscle and cattle milk were confirmed using HPLC which is used as the routine assay. The HPLC (x) and ELISA (y) results showed close correlation for chicken liver (y = 8.7 + 0.85x, r2 = 0.99, n = 25), chicken muscle (y = -3.9 + 0.94x, r2 = 0.98, n = 25) and cattle milk (y = 18.4 + 0.92x, r2 = 0.99, n = 25).     

Oriented attachment-based assembly of dendritic silver nanostructures at room temperature

How particles aggregate into an interesting dendritic structure has been the object of research for many years because of its importance in understanding physical processes involved and in designing novel materials. In this work, we for the first time describe an oriented attachment-based assembly mechanism for formation of different types of dendritic silver nanostructures at room temperature. It is found that the concentration of both AgNO(3) and p-aminoazobenzene (PA) molecules has a significant effect on the formation and growth of these novel nanostructures. Characterization by transmission electron microscopy (TEM) clearly shows that the dendritic silver nanostructures can be obtained through the preferential oriented growth along a crystallographically special direction. Interestingly, we observe that the oriented attachment at room temperature can also take place between relatively large single-crystalline silver particles with a diameter range from 20 to 60 nm, which may provide a new possibility for the design of novel metal nanostructures by using large metal nanoparticles as building blocks at room temperature. Moreover, a surface-enhanced Raman scattering (SERS) technique is used to investigate the role of PA molecules during the growth of the dendritic silver nanostructures.     

Graft polymerization of polysilsesquioxane containing chloromethylphenyl groups by atom transfer radical polymerization

Polysilsesquioxane with phenyl and chloromethylphenyl groups (PCPSQ) was prepared readily from phenyltrimethoxysilane and [2‐(chloromethylphenyl)ethyl]trimethoxysilane under acidic conditions. Polymerization with chloromethylphenyl groups on PCPSQ with methyl methacrylate (MMA) was conducted in the presence of a catalytic amount of copper(I) bromide and (−)‐sparteine. Atom transfer radical polymerization yielded a graft polymer (PCPSQ‐g‐MMA) efficiently, and no gelation was observed. The process was also applied to the preparation of graft block copolymers on PCPSQ with several methacrylate monomers. An advantage of the graft hybrid polymers was shown in improved thermal behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4212–4221, 2004     

Remarkable effects of terminal groups and solvents on helical folding of o-phenylene oligomers

Although o-phenylene oligomers (OP(n)R) made of dimethoxyphenylene units are thought to be intrinsically dynamic due to π-electronic repulsion, we show that they fold into a regular helical geometry in CH(3)CN when they carry terminal groups such as CH(3), CH(2)OH, Br, CO(2)Bn, and NO(2). We evaluated their helical inversion kinetics via optical resolution of long-chain oligomers (e.g. 16- and 24-mers) by chiral HPLC. OP(24)Br at 298 K shows a half-life for the optical activity of 5.5 h in CH(3)OH/water (7/3 v/v) and requires 34 h for complete racemization. The perfectly folded helical conformers of OP(n)R, unlike their imperfectly folded ones, are devoid of extended π-conjugation and show a cyclic voltammogram featuring reversible multistep oxidation waves.     

syn-Selective Asymmetric Mannich Reaction of Sulfonyl Imines with Iminoesters Catalyzed by the N,N,N-Tridentate Bis(imidazolidine)pyridine (PyBidine)-Cu(OTf)(2) Complex

Chiral ligand: The [PyBidine-Cu(OTf)(2) ] (Tf=trifluoromethanesulfonate) complex catalyzed the asymmetric Mannich reaction of sulfonyl imines and iminoesters to give the products in a high syn-selective manner. For both 4-toluene (Ts)- and 4-nitrophenylsulfonyl (Ns)-imines, the syn-adducts were obtained in up to 99?% ee.     

Analysis of the release process of phenylpropanolamine hydrochloride from ethylcellulose matrix granules III. Effects of the dissolution condition on the release process

In the pharmaceutical preparation of a controlled release drug, it is very important and necessary to understand the entire release properties. As the first step, the dissolution test under various conditions is selected for the in vitro test, and usually the results are analyzed following Drug Approval and Licensing Procedures. In this test, 3 time points for each release ratio, such as 0.2-0.4, 0.4-0.6, and over 0.7, respectively, should be selected in advance. These are analyzed as to whether their values are inside or outside the prescribed aims at each time point. This method is very simple and useful but the details of the release properties can not be clarified or confirmed. The validity of the dissolution test in analysis using a combination of the square-root time law and cube-root law equations to understand all the drug release properties was confirmed by comparing the simulated value with that measured in the previous papers. Dissolution tests under various conditions affecting drug release properties in the human body were then examined, and the results were analyzed by both methods to identify their strengths and weaknesses. Hereafter, the control of pharmaceutical preparation, the manufacturing process, and understanding the drug release properties will be more efficient. It is considered that analysis using the combination of the square-root time law and cube-root law equations is very useful and efficient. The accuracy of predicting drug release properties in the human body was improved and clarified.     

Reductive elimination of C6F5-C6F5 in the reaction of bis(pentafluorophenyl)palladium(II) complexes with protic acids

Reductive elimination of C6F5-C6F5 from cis-[Pd(C6F5)2L] (L = cod, bpy, and dppb) was promoted by Br?nsted acids. HNO3 is a convenient acid for the formation of C6F5-C6F5 from [Pd(C6F5)2(cod)]. The products are controlled by the auxiliary ligand.