Preparation of layered double hydroxides and their applications as additives in polymers, as precursors to magnetic materials and in biology and medicine

In recent years layered double hydroxides (LDHs), also known as hydrotalcite-like materials, have attracted considerable interest from both industry and academia. In this article, we discuss methods of preparing LDHs with an emphasis on the way in which particle size and morphology can be controlled with regard to specific target applications; scale-up of one such preparation procedure is also described. In addition, we review selected applications of LDHs developed by our own and other laboratories.     

Polyporolide, a new acetogenin from the mycelial culture of a Polyporus fungus

A new acetogenin, polyporolide (1), was isolated from the mycelial solid cultures of a Polyporus basidiomycete. Its structure was elucidated as 4-hydroxy-5-(1-hydroxyhexyl)-dihydrofuran-2-one by spectroscopic methods. Its toxicity to brine shrimps was assessed.     

A convenient synthesis and biological activities of novel 6‐aryl‐3‐(1,2,3,4‐tetrahydroxybutan‐1‐yl)‐7H‐1,2,4‐triazolo‐[3,4‐b][1,3,4]thiadiazines

A series of novel 6‐aryl‐3‐(1,2,3,4‐tetrahydroxybutanol‐1‐yl)‐7H‐1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazines were easily synthesized in high yields by means of the reactions of 4‐amino‐5‐(1,2,3,4‐tetrahydroxybutyl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione ( 1 ) with substituted ω‐bromoacetophenones or ω‐chloroacetophenone. Nearly all of the title compounds possess plant growth‐promoting activities.     

Fluorenylvinylenes bridged triphenylamine-based dyes with enhanced performance in dye-sensitized solar cells

We have synthesized a series of new dipolar organic dyes Bn (n=0, 1, 2) employing triarylamine as the electron-donor, 2-cyanoacrylic acid as the electron-acceptor, and fluorenevinylene as the conjugated bridge, which were used as sensitizers in dye-sensitized solar cells. It is found that the solar-energy-to-electricity conversion efficiencies of the prepared DSSCs are in the range of 2.79-5.56%, which reach 35-70% of a standard device based on N719 fabricated and measured under the same conditions. The DSSC sensitized with B1 with balanced length of conjugated bridge shows the highest photo-to-electrical energy conversion efficiency and the open-circuit photovoltage (V_oc) of 0.86 V.     

Simultaneous determination of seven flavonoids in Potentilla multifida by HPLC

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of seven flavonoids in Potentilla multifida: hyperin, quercetin-3-O-beta-D-glucopyranoside, luteolin-7-O-beta-D-glucuronide, apigenin-7-O-beta-D-glucuronide, quercetin, tribuloside, and apigenin. The method involves the use of a Hypersil octadecylsilyl silica (ODS) analytical column (125A, 5 microm, 4.6 x 250 mm) at 25 degrees C with the mixture of acetonitrile and aqueous H(3)PO(4) as the mobile phase and detection at 254 nm. The recovery of the method is 95.4-104.8%, and linearity (r > 0.9998) is obtained for all the flavonoids. The results indicate that the flavonoid content of P. multifida varied significantly from locality to locality.     

First Example of Highly Stereoselective Synthesis of 1,2,3‐Trisubstituted Cyclopropanes via Chiral Selenonium Ylides

A new strategy for the highly stereoselective synthesis of three stereoisomers of chiral 1,2,3‐trisubstituted cyclopropanes in good yields with excellent diastereoselectivities and very high enantioselectivities (up to >99 % ee) was developed via selenonium ylides (see scheme). Possible pathways for the asymmetric cyclopropanations were also proposed.

     

Novel carbazole-based organogels modulated by tert-butyl moieties

tert-Butyl groups can modulate the self-assembling properties of carbazole derivatives; organogel fibers with a bright blue emission are generated, directed by the cooperation of hydrogen bonding as well as pi-pi interactions.     

Purification and preparation of compounds from an extract of Scutellaria barbata D. Don using preparative parallel high performance liquid chromatography

Preparative parallel high performance liquid chromatography combined with solvent partition and other pretreatments were adopted to separate and purify compounds from an extract of Scutellaria barbata D. Don. Mass-triggered fraction collection allowed the rapid and precise isolation of target compounds. Twelve compounds were isolated from the extract of S. barbata D. Don, their purity in area percent was determined by HPLC analysis, and the structures of seven compounds were further identified with HPLC/ESI-MS, (1)H NMR, and( 13)C NMR, among which 4-(3,4-dihydroxy-phenyl)-but-3-en-2-one, acacetin-7-diglucuronide, and luteolin-7-diglucuronide were the first to be identified from this plant. The results demonstrated that multi-channel parallel preparative HPLC/UV/MS is an efficient method for isolation and purification of compounds from natural products.