Lanthanide-based luminescent hybrid materials.

Sterically encumbered Lewis acid and Lewis base combinations do not undergo the ubiquitous neutralization reaction to form "classical" Lewis acid/Lewis base adducts. Rather, both the unquenched Lewis acidity and basicity of such sterically "frustrated Lewis pairs (FLPs)" is available to carry out unusual reactions. Typical examples of frustrated Lewis pairs are inter- or intramolecular combinations of bulky phosphines or amines with strongly electrophilic RB(C(6)F(5))(2) components. Many examples of such frustrated Lewis pairs are able to cleave dihydrogen heterolytically. The resulting H(+)/H(-) pairs (stabilized for example, in the form of the respective phosphonium cation/hydridoborate anion salts) serve as active metal-free catalysts for the hydrogenation of, for example, bulky imines, enamines, or enol ethers. Frustrated Lewis pairs also react with alkenes, aldehydes, and a variety of other small molecules, including carbon dioxide, in cooperative three-component reactions, offering new strategies for synthetic chemistry.

Frustrated Lewis pairs: metal-free hydrogen activation and more.

Data Reduction And Error Analysis For The Physical Sciences

Heavy metal remediation of aqueous streams is of special concern due to recalcitrant and persistency of heavy metals in environment. Conventional treatment technologies for the removal of these toxic heavy metals are not economical and further generate huge quantity of toxic chemical sludge. Biosorption is emerging as a potential alternative to the existing conventional technologies for the removal and/or recovery of metal ions from aqueous solutions. The major advantages of biosorption over conventional treatment methods include: low cost, high efficiency, minimization of chemical or biological sludge, regeneration of biosorbents and possibility of metal recovery. Cellulosic agricultural waste materials are an abundant source for significant metal biosorption. The functional groups present in agricultural waste biomass viz. acetamido, alcoholic, carbonyl, phenolic, amido, amino, sulphydryl groups etc. have affinity for heavy metal ions to form metal complexes or chelates. The mechanism of biosorption process includes chemisorption, complexation, adsorption on surface, diffusion through pores and ion exchange etc. The purpose of this review article is to provide the scattered available information on various aspects of utilization of the agricultural waste materials for heavy metal removal. Agricultural waste material being highly efficient, low cost and renewable source of biomass can be exploited for heavy metal remediation. Further these biosorbents can be modified for better efficiency and multiple reuses to enhance their applicability at industrial scale.

Agricultural waste material as potential adsorbent for sequestering heavy metal ions from aqueous solutions

White light‐emitting electroluminescent devices were fabricated using poly(N‐vinylcarbazole) (PVK) as a hole‐transporting emitter layer and a double layer of 1,2,4‐triazole derivative (TAZ) and tris(8‐quinolinolato)aluminum(III) complex (Alq) as an electron transport layer. The PVK layer was doped with fluorescent dyes such as blue‐emitting 1,1,4,4‐tetraphenyl‐1,3‐butadiene, green‐emitting coumarin 6, and orange‐emitting DCM 1. A cell structure of glass substrate/indium‐tin‐oxide/doped PVK/TAZ/Alq/Mg:Ag was employed. White emission covering a wide range of the visible region and a high luminance of 3400 cd/m2 were obtained at a drive voltage of 14 V.

White light‐emitting organic electroluminescent devices using the poly(N‐vinylcarbazole) emitter layer doped with three fluorescent dyes

Copolymers of methyl methacrylate (MMA) and pentafluorophenyl methacrylate (PFPMA) of various compositions were prepared with a free-radical initiator. When PFPMA was included in the copolymers, the glass-transition temperatures increased and showed a positive deviation from the Gordon–Taylor equation. A copolymer containing 20 wt % PFPMA exhibited almost zero orientational birefringence, and the photoelastic birefringence became zero when the copolymer contained 13 wt % PFPMA. When 20 wt % PFPMA was incorporated into the MMA copolymer, its water absorption decreased to 0.4 wt % versus 1.8 wt % for poly(methyl methacrylate) (PMMA) under the same condition. The flammability of the PFPMA/MMA copolymer was reduced in comparison with that of the MMA homopolymer. The refractive indices of the PFPMA/MMA copolymers were very close to that of PMMA, and the transmittances of the copolymers were slightly better than that of PMMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Improvement of the physical properties of poly(methyl methacrylate) by copolymerization with pentafluorophenyl methacrylate

Copolymers of methyl methacrylate (MMA) with 2,3,5,6-tetrafluorophenyl methacrylate (TFPMA), pentafluorophenyl methacrylate (PFPMA), and 4-trifluoromethyl-2,3,5,6-tetrafluorophenyl methacrylate (TFMPMA) were investigated. All the three systems showed a random copolymerization character. The composition, glass transition temperature (Tg), and refractive index of the copolymers obtained were studied. Tgs of TFPMA/MMA and PFPMA/MMA copolymers were found to deviate positively from the Gordon–Taylor equation. However, Tgs of TFMPMA/MMA copolymers were well fit with the Gordon–Taylor equation. These results indicated the existence of interaction between MMA and either TFPMA or PFPMA units in copolymers. This interaction resulted in the enhancement of the Tg of MMA polymers through the copolymerization with TFPMA and PFPMA. The refractive index and the light transmittance of copolymers were close to those of PMMA. Copyright © 2007 John Wiley & Sons, Ltd.

Property modification of poly(methyl methacrylate) through copolymerization with fluorinated aryl methacrylate monomers

Synthesis and properties of N-ethynylcarbazole and poly-N-ethynylcarbozole

A disulfide bond is known to cleave under certain electrochemical conditions. The authors have developed a model in vitro drug delivery system based on this type of cleavage with possible applications in the transdermal drug delivery field. The system consists of a drug moiety chemically bound by a disulfide bridge to a polymeric backbone, which, once exposed to a predetermined voltage, would cleave the disulfide bond, thereby releasing drug into a soluble medium. The fluorescence of the drug was then monitored to ascertain its concentration. The model drug used was 2-mercaptobenzothiazole, a drug reported to exhibit hypoglycemic activity and combat the effects of experimental diabetes. The polymeric backbone used was poly(mercaptopropylmethyl siloxane). A copolymeric prodrug was synthesized using diethylazodicarboxylate (DAD) as a coupling agent in order to give the resulting mercapto/disulfide copolymer of composition 6:4. The disulfide bridge was electrochemically cleaved using an intermittent ...

An Electrochemically Controlled Drug Delivery System Based on a Disulfide-Containing Polymer

Detecting and/or measuring a chemical substance, such as explosives or poison gases, using a change in a property of light passing through a microsphere of a sensor. Since the microsphere has a large quality factor, the sensor is extremely sensitive. The sensor includes the microsphere coupled with at least one optical fiber. The surface of the microsphere includes receptors complementary to the chemical substance.

Yoshiyuki Okamoto

Papers

Improvement of the physical properties of poly(methyl methacrylate) by copolymerization with pentafluorophenyl methacrylate

Property modification of poly(methyl methacrylate) through copolymerization with fluorinated aryl methacrylate monomers

Synthesis and properties of N-ethynylcarbazole and poly-N-ethynylcarbozole

An Electrochemically Controlled Drug Delivery System Based on a Disulfide-Containing Polymer

Using a change in one or more properties of light in one or more microspheres for sensing chemicals such as explosives and poison gases