Phosphorus-based p-tert-butylcalix[5]arene ligands

New calix[5]arene trivalent phosphorus derivatives have been synthesized which should be excellent ligands with which to study and control the interaction of a ligand atom with a metal. The larger cavity of the calix[5]arene (compared to calix[4]arene) provides a good balance between constraint and flexibility. Treatment of p-tert-butylcalix[5]arene with 2 equiv of either tris(dimethylamino)phosphine or dichlorophenylphosphine inserts two RP moieties into the calix[5]arene framework to give calix[5](PR)2(OH) (1, R = Me2N; 2, R = Ph). Further treatment of 1 with 4 equiv of HCl gives calix[5](PCl)2(OH) (3). Heating a solution of the monophosphorus compound calix[5](PNMe2)(OH)3 (4) releases dimethylamine to yield both monomeric calix[5](P)(OH)2 (6) and dimeric [calix[5](P)(OH)2](2) (7), the latter having a tubelike geometry. X-ray crystallographic studies confirm the structures and show that 1 and 2 have approximate cone conformations while 3 has an approximate 1,2-alternate conformation. The orientations of the phosphorus lone pairs and oxygen atoms in all derivatives provide a framework for both soft and hard ligand interactions within the calix[5]arene.     

Study on δ‐form complex in syndiotactic polystyrene–organic molecules systems. IV. Formation of complexes with a mixture of solvents and structural changes during the sorption of solvents by syndiotactic polystyrene mesophase membranes

The syndiotactic polystyrene (sPS) δ form was crystallized from mixtures with different compositions of p‐chlorotoluene–chlorobenzene (p‐CT–CB) and p‐chlorotoluene–1,1,2‐trichloroethane (p‐CT–TCE). The presence of the δ form and TTGG helical conformation was confirmed by Fourier transform infrared and wide‐angle X‐ray diffraction (WAXD) analyses. In sPS/p‐CT–CB and sPS/p‐CT–TCE δ‐form membranes, the relative absorbance (RA) of the p‐chlorotoluene (p‐CT) solvent peak was very high even at very low concentrations of p‐CT in comparison with the RA of higher concentrations of chlorobenzene (CB) or 1,1,2‐trichloroethane (TCE) in the mixtures. However, the RAs of both CB and TCE solvent peaks decreased with decreasing concentrations of CB and TCE in the mixtures. A negligible decrease in the RA of the TTGG helical content was observed with a decreasing concentration of CB or TCE. The WAXD results showed that the 2θ peak positions of the [010] and [ 10] planes of the sPS/p‐CT–CB and sPS/p‐CT–TCE δ‐form membranes appeared in the same position and were almost equal to those of the sPS–p‐CT δ‐form membrane. The mesophases of the sPS–p‐CT [p‐CT (A‐M)] and sPS–TCE [TCE (A‐M)] membranes were used for the sorption studies with different concentrations of various solvents. The sorption amount of aromatic solvents by both p‐CT (A‐M) and TCE (A‐M) mesophase membranes was higher than that of aliphatic solvents, regardless of the size, shape, and nature of the molecular cavity. The 2θ peak of the [010] plane of the sPS membranes slowly approached the original δ‐form value when the sPS mesophase membranes were immersed in various solvents of different concentrations for 48 h. The shifting of the 2θ peak of the [010] plane to the original δ form depended on the nature and concentration of the immersion solvents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2380–2387, 2005     

Production of ethanol from cellulosic biomass by Clostridium thermocellum SS19 in submerged fermentation

Carotenogenesis of the lactose-negative yeast Rhodotorula rubra GED5 was studied by cocultivation with Kluyveromyces lactis MP11 in whey ultrafiltrate (WU) (35, 50, and 70 g of lactose/L). Maximum yields of cell mass (24.3 g/L) and carotenoids (10.2 mg/L of culture fluid or 0.421 μ g/g of dry cells) were obtained by growing the microbial association in WU (50 g of lactose/L) in a fermentor with an airflow rate of 0.8 L/(L·min), agitation of 220 rpm, and temperature of 30°C. The identified carotenoid pigments—β-carotene, torulene, and torularhodin—reached maximum concentrations (133, 26.9, and 222.3 μg/g of dry cells, respectively) on d 5 for torulene and d 6 for β-carotene and torularhodin.     

Ligand location and biochemical productivity of silica-based immunoaffinity adsorbents.

Ligand location within particles, detected by immunogold labelling, was shown to influence the biochemical productivity of a silica-based solid phase, Sorbsil C-500, using a model ligand-biomolecule system (immobilised human immunoglobulin G-anti-human immunoglobulin G monoclonal antibody). The distribution of the ligand was in turn affected by the initial ligand challenge used to prepare the immunoadsorbents. Maximal productivity was achieved with adsorbents prepared with an initial challenge of about 3 mg human immunoglobulin G per ml: the ligand in these cases was shown to be more uniformally distributed within the adsorbent particles than adsorbents, exhibiting low productivity, prepared with either low (1 mg/ml) or high (9 mg/ml) concentrations of human immunoglobulin G. The ligand in the latter was restricted to the periphery of the particles.     

Stereochemical applications of mass spectrometry: 1—The utility of electron impact and chemical ionization mass spectrometry in the differentiation of stereoisomeric benzoin oximes and phenylhydrazones

A study of the electron impact and chemical ionization (H₂, CH₄, and iso-C₄H₁₀) mass spectra of stereoisomeric benzoin oximes and phenylhydrazones indicates that while the former can be distinguished only by their chemical ionization mass spectra the latter are readily distinguishable by both their electron impact and chemical ionization mass spectra. The electron impact mass spectra of the isomeric oximes are practically identical; however, the chemical ionization spectra show that the E isomer forms more stable [MH]⁺ and [MH? H₂O]⁺ ions than the Z isomer for which both the [MH]⁺ and [MH? H₂O]⁺ ions are relatively unstable. In electron impact the Z-phenylhydrazone shows a lower [M]⁺˙ ion abundance and more facile loss of H₂O than does the E isomer. This more facile H₂O loss also is observed for the [MH]⁺ ion of the Z isomer under chemical ionization conditions.     

Pharmacokinetic studies of a novel trioxane antimalarial (99/411) in rats and monkeys using LC–MS/MS

The pharmacokinetic profile of 99/411, a novel anti‐malarial drug, was established in rats (12 mg/kg of body weight) and monkeys (20 mg/kg of body weight). Following oral administration, the presence of 99/411 was rapidly determined in rat plasma, tissues, urine, feces and monkey plasma using a validated LC–MS/MS method. The tissue distribution studies in rats indicated that the drug was partially distributed in all major tissues and plasma, and peak concentration levels were achieved within 0.5–4 h. Area under the curve in different rat tissues and plasma was found in order of blood > lung > intestine > heart > muscle > brain > kidney > spleen > liver. The total recoveries (within 86 h) of 99/411 were <0.0017% and <0.08% in urine and feces, respectively. The peak plasma concentration was 3499 ng/mL in rats after ~2 h of oral administration and 697–767 ng/mL in monkeys after ~6 h of oral administration. No plasma accumulation was observed in both male and female monkeys, even after multiple dosing. The preclinical pharmacokinetic profile and tissue distribution data are expected to assist in future clinical explorations of 99/411 as a promising anti‐malarial agent.     

H-β-zeolite catalyzed synthesis of β-bromostyrenes from styrene bromohydrins

Synthesis of β-bromostyrenes from styrene bromohydrins using H-β-zeolite as catalyst under moderate conditions is reported. The catalyst could be regenerated and reused up to three consecutive cycles.     

Confinement and controlled release of quinine on chitosan–montmorillonite bionanocomposites

To accomplish the controlled‐release systems based on layered clay minerals, one of the best ways is to intercalate organic molecules into the interlayer gallery of clay minerals. Into a series of chitosan (CS) intercalated montmorillonite (MMT) nanocomposites, prepared via ion‐exchange route, antimalarial drug [quinine (QUI)] was loaded to act as effective drug delivery systems. Among the CS–MMT nanocomposites, higher drug adsorption with decreasing CS concentration was observed. CS–MMT and CS–MMT/QUI intercalated compounds were characterized by powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis. The synthesized nanocomposites, filled in the gelatin capsules followed by coating of Eudragit® L 100, were tested for in vitro drug release performance in the sequential buffer environments at 37 ± 0.5 °C. As no drug release (0%) was observed in the gastric fluid, the coating of Eudragit® L 100 to the capsules is highly adequate. However, the drug release rate was comparatively faster from the CS intercalated clay with compare with pure clay. The drug release kinetic data revealed that the release of QUI from the nanocomposites can be explained by modified Freundlich model. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and applications of a novel supramolecular polymer network with multiple H‐bonded melamine pendants and uracil crosslinkers

A conjugated main‐chain copolymer ( PBT ) consisting of bithiazole, dithieno[3,2‐b:2′,3′‐d]pyrroles (DTP), and pendent melamine units was synthesized by Stille polymerization, which can be hydrogen‐bonded (H‐bonded) with proper molar amounts of bi‐functional π‐conjugated crosslinker F (i.e., two uracil motifs covalently attached to a fluorene core through triple bonds symmetrically) to develop a novel supramolecular polymer network ( PBT/F ). The effects of multiple H‐bonds on light harvesting capabilities, HOMO levels, and photovoltaic properties of polymer PBT and H‐bonded polymer network PBT/F are investigated. The formation of supramolecular polymer network ( PBT/F ) between PBT and F was confirmed by FTIR and XRD measurements. Because of the stronger light absorption, lower HOMO level, and higher crystallinity of H‐bonded polymer network PBT/F , the solar cell device containing PBT/F showed better photovoltaic properties than that containing polymer PBT . The preliminary results show that the solar cell device containing 1:1 weight ratio of PBT/F and [6,6]‐phenyl C₇₁ butyric acid methyl ester (PC₇₁BM) offers the best power conversion efficiency (PCE) value of 0.86% with a short‐circuit current density (J_sc) of 4.97 mA/cm², an open circuit voltage (V_oc) of 0.55 V, and a fill factor (FF) of 31.5%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012