A functional triazine framework based on N-heterocyclic building blocks

Covalent organic frameworks constitute a subclass of polymeric materials offering enhanced porosity, functionality and stability. In this work a covalent triazine framework based on bipyridine building blocks is presented, along with a comprehensive elucidation of its local structure, porosity, and capacity for metal uptake. A typical synthesis was carried out under ionothermal conditions at 400-700 degrees C using ZnCl2 as a Lewis acidic trimerization catalyst. A high degree of local order and the presence of triazine and bipyridine moieties are ascertained at a synthesis temperature of 400 degrees C, along with micropores and specific surface areas of up to 1100 m(2) g(-1). Mesopores are increasingly formed at synthesis temperatures above 450 degrees C, yielding highly porous frameworks with hierarchical porosity and exceptionally large surface areas in excess of 3200 m(2) g(-1) at 700 degrees C. We demonstrate the capability of the bipyridine unit to provide specific and strong binding sites for a large variety of transition metal ions, including Co, Ni, Pt and Pd. The degree of metal loading (up to 38 wt%) can be tuned by the metal concentration in solution and is dependent on both the type of metal as well as the temperature at which the CTF was synthesized. Evidence for site-specific metal coordination bodes well for the use of metal-loaded CTFs as heterogeneous catalysts carrying homogeneous-type active sites

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

A T-shape diphosphinoborane palladium(0) complex

The reaction of CpPd(η3-C3H5) with the new diphosphinoborane ligand derivative (o-PCy2-C6H4)2BPh CyDPBPh affords the T-shape complex (CyDPBPh)Pd(0) 9, which was characterized by X-ray analysis

Synthesis and Reactivity of Palladium Complexes Featuring a Diphosphinoborane Ligand

Synthetic access to the zerovalent palladium complexes {[(<i>o</i>-Ph₂PC₆H₄)₂BPh]­Pd­(L)} (L = pyridine (<b>8a</b>), 2,6-lutidine (<b>8b</b>)) is reported. Structural characterization and DFT analysis of <b>8a</b> revealed a strong Pd→B interaction, which appears to inhibit oxidative addition reactions. Activation of allyl acetate is possible by reversible transfer of the acetate leaving group to the ligand’s borane functionality. Catalytic activity in the allylic substitution of allyl acetate with HNEt₂ is sensitive to the presence of free acetate, which reduces borane inhibition by reversible borate formation

Mechanism of the Rhodium(III)-Catalyzed Arylation of Imines via C–H Bond Functionalization: Inhibition by Substrate

Rh­(III)-catalyzed arylation of imines provides a new method for C–C bond formation while simultaneously introducing an α-branched amine as a functional group. This detailed mechanistic study provides insights for the rational future development of this new reaction. Relevant intermediate Rh­(III) complexes have been isolated and characterized, and their reactivities in stoichiometric reactions with relevant substrates have been monitored. The reaction was found to be first order in the catalyst resting state and inverse first order in the C–H activation substrate

Mechanism of the Rhodium(III)-Catalyzed Arylation of Imines via C–H Bond Functionalization: Inhibition by Substrate

Rh­(III)-catalyzed arylation of imines provides a new method for C–C bond formation while simultaneously introducing an α-branched amine as a functional group. This detailed mechanistic study provides insights for the rational future development of this new reaction. Relevant intermediate Rh­(III) complexes have been isolated and characterized, and their reactivities in stoichiometric reactions with relevant substrates have been monitored. The reaction was found to be first order in the catalyst resting state and inverse first order in the C–H activation substrate