We systematically studied effects of pH, ionic strength, and presence of Cu2+ (50 mg/L) or a dissolved humic acid (HA, Fluka) (50 mg/L) on adsorption of three nonionic aromatic compounds, naphthalene, 1,3-dinitrobenzene, and 1,3,5-trinitrobenzene to single-walled carbon nanotubes. Presence of Cu2+ or variance in the ionic strength between 0.02 and 0.1 M (NaNO3) only slightly affected adsorption affinities. Presence of HA reduced adsorption of the three compounds by 29-57% for CNTs, as measured by change in distribution coefficient(Kd), and by 80-95% for graphite. In contrast to nonporous graphite, whose surface area was completely accessible in adsorption, CNTs formed aggregates with microporous interstices in aqueous solution, which blocked large HA molecules from competing with the surface area. Changing the pH from 2 to 11 did not affect adsorption of naphthalene, while it increased adsorption of 1,3-dinitrobenzene and 1,3,5-trinitrobenzene by 2-3 times. Increasing pH apparently facilitated deprotonation of the acidic functional groups (-COOH, -OH) of CNTs, which promoted the pi-electron-donor ability of the graphene surface, therefore enhancing pi-pi electron-donor-acceptor (EDA) interactions of the two nitroaromatics (pi-electron acceptors).

Black carbon (BC) is believed to be an important adsorbent of organic pollutants. A complex suite of heavy metals and organic pollutants is commonly present in many situations. An issue that has received little direct attention is the effect of heavy metals on sorption of organic compounds to BC. We found that coadsorption of Cu2+ at an environmentally relevant, comparable concentration (50 mg L-1) decreases sorption of both the polar compound, 2,4-dichlorophenol (DCP), and nonpolar compounds, 1,2-dichlorobenzene (DCB) and naphthalene (NAP), by 30-60%, as measured bythe change in the distribution coefficient (Kd). This was attributed to surface complexation of CU2+ to form hydration shells of dense water that directly compete with organics for adsorption surface area. In contrast, coadsorption of Ag+ increases sorption of the organic solutes, which was accounted for by the decline in hydrophilicity of the local region around Ag+-complexed functionalities due to softness of the cation, leading to mitigated competitive sorption of water. Coadsorption of heavy metal ions to nonporous graphite, a model of the BC graphene (polycyclic aromatic) structure that has no 0-containing groups, however, only slightly inhibits organic adsorption due to the low affinities of metal ions to graphite surface. The results of the present study showed that the presence of coexisting heavy metals greatly affects sorption of organic pollutants on BC and thereby their fate and transport.

Reaction of [RhCl(NBD)] 2 with 2.0 equiv of triphos (triphos ) bis(2-diphenylphosphinoethyl)phenylphosphine; NBD ) bicyclo[2.2.1]hepta-2,5-diene) in THF solution at room temperature affords [Rh(NBD)(triphos)][Cl] (4a), which was isolated as [Rh(NBD)(triphos)]-[SbF 6 ] (4b) in 67% yield. Treatment of 4b with aqueous formaldehyde in THF solution at 80 °C forms [Rh(CO)(triphos)][SbF 6 ] (2a), which reversibly binds a second equivalent of CO (g) to give [Rh(CO) 2 (triphos)][SbF 6 ] (2b). The complex [Rh(CO)(triphos)][SbF 6 ] has been found to be an effective aldehyde decarbonylation catalyst for primary and aryl aldehydes at temperatures as low as that of refluxing dioxane, with little or no undesirable side products resulting from β elimination or radical rearrangement.Supporting Information Available: Tables of X-ray crystallographic data for complex 4c. This material is available free of charge via the Internet at http://pubs.acs.org. OM9905106

The discovery of modern medicine relies on the sustainable development of synthetic methodologies to meet the needs associated with drug molecular design. Heterocycles containing difluoromethyl groups are an emerging but scarcely investigated class of organofluoro molecules with potential applications in pharmaceutical, agricultural and material science. Herein, we developed an organophotocatalytic direct difluoromethylation of heterocycles using O 2 as a green oxidant. The C-H oxidative difluoromethylation obviates the need for pre-functionalization of the substrates, metals and additives. The operationally straightforward method enriches the efficient synthesis of many difluoromethylated heterocycles in moderate to excellent yields. The direct difluoromethylation of pharmaceutical moleculars demonstrates the practicability of this methodology to late-stage drug development. Moreover, 2′-deoxy-5-difluoromethyluridine (F 2 TDR) exhibits promising activity against some cancer cell lines, indicating that the difluoromethylation methodology might provide assistance for drug discovery.

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Polysaccharide-based hydrogels are attractive materials for biomedical applications for reasons that include their polyfunctionality, generally benign nature, and biodegradability. However, the use of polysaccharide-based hydrogels may be limited by toxicity arising from small-molecule crosslinkers, or may involve undesired chemical modification [Hennink, W. E.; et al. Adv. Drug Delivery Rev. 2012, 64, 223−236]. Here, we report a green, simple, efficient strategy for the preparation of polysaccharide-based, in situ forming hydrogels. The Edgar group reports in the accompanying manuscript that chemoselective oxidation of oligo(hydroxypropyl)-substituted polysaccharides introduces ketone groups at the termini of the side chains [Nichols, B. L. B.; et al]. Amine-containing moieties can condense with ketones to form imines. The imine linkage is dynamic in the presence of water, providing the potential for self-healing [Wei, Z.; et al.

A novel glutathione peroxidase (GPx) mimic has been prepared by incorporation of a selenium-based catalytic unit into the focal point of a fully-branched hyperbranched polymer. First, an AB(2) monomer consisting of isatin and an electron rich aromatic moiety was polycondensed in the presence of 5-nitroisatin as a core reagent, resulting in a polymer with 100% degree of branching. The latter was coupled to the catalytically active moiety, Br(CH(2))(5) SeSe(CH(2))(5) Br, by nucleophilic substitution of the bromides by the residual amide groups of the incorporated nitroisatin core. The obtained polymer has demonstrated prominent GPx activity as desired, which could be attributed to the hydrophobic, densely branched and core-shell structure of the polymer surrounding the catalytic center.