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A systematic study of the synthesis and characterization of 3,3′‐disulfonated‐4,4′‐dichlorodiphenyl sulfone (SDCDPS) monomer was conducted by varying reactant stoichiometries (molar ratios of 4,4′‐dichlorodiphenyl sulfone (DCDPS) to SO3 1 : 2.2, 1 : 2.9, and 1 : 3.3), reaction temperature (90–120°C), and reaction time (4–6 h). The optimum synthesis batch process variables were 1 : 3.3 reactant molar ratio (DCDPS : SO3) at 110°C for 6 h. In earlier studies, recrystallization of the “crude” disulfonated monomer from alcohol–water mixture was necessary to remove the monosulfonated and DCDPS impurities that lowered yield. However, in the current research, SDCDPS was successfully synthesized at nearly 100% conversion, which effectively eliminated the need for recrystallization. Recrystallization of SDCDPS from several alcohol–water mixtures (methanol–, ethanol–, and isoproponal–water mixtures) was investigated to compare product purities. Several characterization methods including proton NMR, HPLC, UV–visible, and fast atom bombardment mass spectroscopy confirmed that the crude SDCDPS was completely disulfonated and identical to recrystallized SDCDPS, without having any monosulfonated or starting material DCDPS impurities. Hence, it was demonstrated that the crude SDCDPS monomer by the current one‐step process and the recrystallized SDCDPS monomer were identical. This optimized monomer synthesis has been used to scale up the SDCDPS and poly(arylene ether sulfone) random and statistical copolymers at controlled disulfonation (35 and 45 mol %) levels, which were then used to fabricate proton exchange membranes for fuel cell applications. The intrinsic viscosity data confirmed that high molecular weight film forming copolymers were synthesized. The calculated degree of disulfonations by proton NMR was in close agreement with target disulfonations. It may be concluded that this optimized SDCDPS synthesis eliminates the need for recrystallization, which would be expected to improve process economics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4595–4602, 2006

A boronic acid-containing coumarin aldehyde was designed and synthesized. The sensor binds to catecholamines such as dopamine and norepinephrine by forming an iminium ion with the amine as well as a boronate ester with the catechol. An internal hydrogen bond produces a colorimetric response to these analytes with good selectivity for catecholamines over simple amines. The fluorescence of the sensor is quenched by the catechol.

We report the isolation and characterization of an endohedral metallofullerene encapsulating three lanthanide atoms inside a nanoscale C80 cage, Lu3N@C80. In addition, we also report encapsulated mixed-metal species of gadolinium/lutetium and holmium/lutetium, Lu3-xAxN@C80 (x = 0−2), which may prove useful as multifunctional contrast agents for X-ray, MRI, and radiopharmaceuticals.

A number of new aryl phosphorus-containing polymers were found to be miscible with the commercially significant bisphenol A-based poly(hydroxy ether)s (PHE) over the entire composition range by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) measurements of the blends. Both the FTIR and CP-MAS ³¹P NMR results suggested extensive hydrogen-bonding interactions between hydroxyl groups and the phosphonyl groups. Specifically, the poly(arylene thioether diphenylphenylphosphine oxide) and phosphorus-containing polyimides were also miscible with PHE, again emphasizing the importance of phosphonyl groups for generating miscible polymer blends. In contrast, a structurally similar commercial polyimide, Ultem, was not miscible with PHE. These results suggested that the miscibility was induced mainly by hydrogen bonding between phosphonyl and hydroxyl groups, rather than other sites such as carbonyl or ether oxygen atoms and the hydroxyl groups. Furthermore, the measurements of proton spin−lattice relaxation times in the rotating frame (T1ρ) showed that the phosphorus-containing polyimide/PHE blends were homogeneous even at about a 4 nm scale.

This work describes the synthesis of two novel macrocyclic taxoid constructs by ring-closing olefin metathesis (RCM) and their biological evaluation. Computational studies examine conformational profiles of 1 and 2 for their fit to the β-tubulin binding site determined by electron crystallography. The results support the hypothesis that paclitaxel binds to microtubules in a “T” conformation.

A methanol extract of Combretum erythrophyllum showed inhibitory bioactivities in a yeast-based microtiter assay for DNA-damaging agents. Bioassay-guided fractionation of this extract yielded two known bioactive compounds, combretastatin A-1 and (−)-combretastatin, and two new bioactive glucosides, combretastatin A-1 2‘-β-d-glucoside (1) and combretastatin B-1 2‘-β-d-glucoside (2). The structures of the new compounds were assigned by ¹H and ¹³C NMR, DEPT, HMQC, and HMBC spectra.

The preservation of tropical rainforests is an important goal both for the intrinsic value of their cultural and biological diversity as well as for the well-being of the peoples who make these forests their home. In addition, tropical forests are potential sources of new pharmaceutical products that can only be found by chemical prospecting in Nature's genetically encoded combinatorial library. As part of an effort to integrate biodiversity conservation and drug discovery with economic development, we have initiated a collaborative program to discover potential pharmaceuticals in the rainforest of Suriname. The plant Renealmia alpinia (Zingiberaceae) was selected for investigation based on its ethnomedical use as a febrifuge, but testing in the yeast Sc-7 assay gave a positive response, indicative of cytotoxic activity. Using this bioassay, the two new labdane diterpenes, 11-hydroxy-8(17),12(E)-labdadien-15,16-dial 11,15-hemiacetal (1) and 16-oxo-8(17),12(E)-labdadien-15-oic acid (2), and the known diterpene, 8(17),12(E)-labdadien-15,16-dial (3), have been isolated. Their structures were elucidated by 1D and 2D NMR techniques (DEPT, COSY, HETCOR, HMBC, and NOESY) and IR, UV, and MS spectra, and the absolute stereochemistry of 1 was established by CD spectroscopy and by the formation and NMR analysis of α-methoxyphenylacetyl esters. The hemiacetal 1 was cytotoxic to M109 cells, with an IC50 value of 2.6 μg/mL.

Poly(urethane/crown ether rotaxane)s 7c−g were prepared from bis(p-tert-butylphenyl)bis[p-(2-(2‘-hydroxyethoxy)ethoxy)phenyl]methane (diol BG 4), tetrakis(ethylene glycol) (5) and 4,4‘-methylenebis(phenyl isocyanate) (MDI) (6) using 30-crown-10 (30C10) as solvent. It was found that threading efficiencies (m/n value, average number of cyclics per repeat unit) of 7c−g increased with the feed proportion of diol BG 4. Compared to poly(ester rotaxane)s in which the crown ethers can freely move along the backbone, the dethreading rate during polymerization is slow due to the H-bonds between in-chain NH groups and threaded crown ethers. In poly(urethane rotaxane)s, crown ethers are localized at the NH sites by H-bonding in chloroform, locked translationally and perhaps rotationally, to afford a well-defined microstructure. However, the cyclics tend to be in the vicinity of BG units in DMSO, which disrupts the H-bonding. Induction of shuttling between the two sites is caused by the use of mixtures of DMSO and CHCl3. Therefore, 7c−g are considered to be the first polymeric molecular switches reported so far. Threaded 30C10 has much shorter relaxation time than its free counterpart; this is a novel and easy method to characterize the formation of polyrotaxanes. The glass transition temperatures of 7c−g increase with the amount of BG units in the polymers, an easy approach to adjust Tg's of polyurethanes.

A novel strategy to completely eliminate dethreading of captured cyclics during the preparation of polyrotaxanes has been developed. A new difunctional blocking group (BG), namely bis(p-tert-butylphenyl)bis[p-((5-(chlorocarbonyl)pentyl)oxy)phenyl]methane (diacid chloride BG 14), was prepared in an overall yield of 63% by a three-step method. BG 14 polymerized with bis[p-((2-hydroxyethoxy)ethoxy)phenyl]bis(p-tert-butylphenyl)methane (diol BG 15) using 30-crown-10 (30C10) as solvent to afford poly(ester rotaxane)s 17 with unique architectures having two BGs per repeat unit. The formation of the polyrotaxanes was proved by a chemical shift of threaded 30C10 different from that of unthreaded species, hydrolytic recovery of 30C10, and a 2D NOESY study and supported by the GPC analysis. It was found that the resulting polyrotaxanes 17 had threading efficiencies (m/n values, average number of cyclic molecules per repeat unit) 2 times as high as those of poly(ester rotaxane)s 16 made under the same conditions from diol BG 15 and sebacoyl chloride. By optimizing the conditions, the threading efficiency was increased to 0.172 in polyrotaxane 17c, almost 14 times as high as that (0.012) of the polyrotaxane of type 1 made from decanediol and sebacoyl chloride.

In the pursuit of naphthalene-based calixarenes, a Friedel−Crafts alkylation with unusual regiochemistry was observed. Treatment of carbinol 14 with catalytic triflic acid was expected to produce calixarenes of the class represented by 16. Instead, the major product was cyclic trimer 15, in which alkylation of each naphthalene ring occurred at the electronically deactivated position. The structure of compound 15 was assigned by 2-D NMR studies.