Porous organic polymers (POPs), a class of highly crosslinked amorphous polymers possessing nano-pores, have recently emerged as a versatile platform for the deployment of catalysts. The bottom-up approach for porous organic polymer synthesis provides the opportunity for the design of polymer frameworks with various functionalities, for their use as catalysts or ligands. This tutorial review focuses on the framework structures and functionalities of catalytic POPs. Their structural design, functional framework synthesis and catalytic reactions are discussed along with some of the challenges.

Activate and reduce: Carbon dioxide was reduced with silane using a stable N-heterocyclic carbene organocatalyst to provide methanol under very mild conditions. Dry air can serve as the feedstock, and the organocatalyst is much more efficient than transition-metal catalysts for this reaction. This approach offers a very promising protocol for chemical CO(2) activation and fixation.

5-Hydroxymethylfurfural (HMF) has been known as a product from hexose dehydration for over 100 years and is considered to be one of the most promising platform molecules that can be converted into a variety of interesting chemicals. HMF, together with furfural and 2,5-furandicarboxylic acid (FDCA) are derivatives of furan compounds, which were listed as the top 10 value-added bio-based chemicals by the US Department of Energy. The great and increasing interest in the production of furan derivatives from biomass resources is due to the great potential of furan derivatives as feedstock for bulk chemicals and fuels. HMF can be synthesized by dehydration of all types of C6 carbohydrates, including monomeric and polymeric carbohydrates, such as fructose, glucose, sucrose, starch, inulin, cellulose, and raw biomass.Numerous improvements and milestones have been made in the dehydration process during the past 130 years. The big challenge for the process of HMF production is its suitability for industrial scale yet being cost efficient. This perspective article will review the HMF development timeline, focusing on the important events, landmark contributions, engineering and practical challenges of HMF production.

Alpha/beta interferon (IFN-␣/␤) produces antiviral effects through upregulation of many interferon-stimulated genes (ISGs) whose protein products are effectors of the antiviral state. Previous data from our laboratory have shown that IFN-␣/␤ can limit Sindbis virus (SB) replication through protein kinase R (PKR)-dependent and PKR-independent mechanisms and that one PKR-independent mechanism inhibits translation of the infecting virus genome (K. D. Ryman et al., J. Virol. 79:1487-1499, 2005). Further, using Affymetrix microarray technology, we identified 44 genes as candidates for PKR/RNase L-independent IFN-induced antiviral activities. In the current studies, we have begun analyzing these gene products for antialphavirus activity using three techniques: (i) overexpression of the protein from SB vectors and assessment of virulence attenuation in mice; (ii) overexpression of the proteins in a stable tetracycline-inducible murine fibroblast culture system and assessment of effects upon SB replication; and (iii) small interfering RNA-mediated knockdown of gene mRNA in fibroblast cultures followed by SB replication assessment as above. Tested proteins included those we hypothesized had potential to affect virus genome translation and included murine ISG20, ISG15, the zinc finger antiviral protein (ZAP), viperin, p56, p54, and p49. Interestingly, the pattern of antiviral activity for some gene products was different between in vitro and in vivo assays. Viperin and ZAP attenuated virulence most profoundly in mice. However, ISG20 and ZAP potently inhibited SB replication in vitro, whereas and viperin, p56, and ISG15 exhibited modest replication inhibition in vitro. In contrast, p54 and p49 had little to no effect in any assay.

SUMMARY Virus infection is sensed in the cytoplasm by retinoic acid-inducible gene I (RIG-I, also known as DDX58), which requires RNA and polyubiquitin binding to induce type I interferon (IFN), and activate cellular innate immunity. We show that the human IFN-inducible oligoadenylate synthetases-like (OASL) protein had antiviral activity and mediated RIG-I activation by mimicking polyubiquitin. Loss of OASL expression reduced RIG-I signaling and enhanced virus replication in human cells. Conversely, OASL expression suppressed replication of a number of viruses in a RIG-I-dependent manner and enhanced RIG-I-mediated IFN induction. OASL interacted and colocalized with RIG-I, and through its C-terminal ubiquitin-like domain specifically enhanced RIG-I signaling. Bone marrow derived macrophages from mice deficient for Oasl2 showed that among the two mouse orthologs of human OASL; Oasl2 is functionally similar to human OASL. Our findings show a mechanism by which human OASL contributes to host antiviral responses by enhancing RIG-I activation.

The diminishing fossil fuel reserves and global warming effects have become major concerns, and the search for sustainable, alternative energy is of critical importance. [1,2] Biofuels are highly attractive as they are the only sustainable source of liquid fuels currently available [3] however, the replacement of a petroleum feedstock by biomass is limited by the lack of highly efficient methods to selectively convert carbohydrates into chemical compounds for biofuel production.[4] A practical catalytic process that can transform the abundant biomass into versatile chemicals would also provide the chemical industry with renewable feedstocks.[5] Recently, efforts have been devoted to the conversion of biomass into 5-hydroxymethylfurfural (HMF), a versatile and key intermediate in biofuel chemistry and the petroleum industry. [6] HMF and its 2,5-disubstituted furan derivatives can replace key petroleum-based building blocks. [7] There are currently a number of catalysts that are active in the dehydration of sugars to form HMF. However, most of them also promote side reactions that form undesired byproducts, and rehydrate HMF to form levulinic acid and formic acid. Thus, these catalysts are often limited to simple sugar feedstocks, such as fructose. [4, 6,8] Recent reports illustrate the use of 1-H-3-methyl imidazolium chloride (HMIM + Cl À ) as a solvent and an acid catalyst to efficiently convert fructose into HMF with approximately a 90 % yield.[9] However, such a system has not been shown to convert glucose, which is a more stable and abundant sugar source, into HMF. Dumesic and co-workers have developed a two-phase (aqueous/organic) system for the separation and stabilization of the HMF product.[6a,b] Zhang and co-workers have reported a metal chloride/ionic liquid system that gives moderate to good HMF yields for both fructose (83 % with Pt or Rh chloride, 65 % with CrCl 2 ) and glucose (a record high of 68 % with CrCl 2 ).[10] Herein, we report a new catalyst system that efficiently converts both fructose and glucose into HMF in good to excellent yields (81-96 %).Zhang and co-workers showed that transition metals were good catalysts for the transformation of sugars into HMF. [10] We selected NHC/metal (NHC = N-heterocyclic carbene) complexes as catalysts for the sugar dehydration reaction. [11] These ligands offer a great deal of flexibility as the catalytic activity can be modified by varying the stereo and electronic properties of the NHCs. The conversions of fructose and glucose into HMF were tested using 1-butyl-3-methyl imidazolium chloride (BMIM + Cl À ) with different catalysts (Scheme 1). The NHC-metal complexes were pre-generated by heating a mixture of imidazolium salts, potassium tertbutoxide (KOtBu), and metal chlorides in N,N-dimethylformamide (DMF) for several hours before adding to the reaction system. In a typical reaction protocol, 100 mg of sugar was mixed with 1 g of BMIM + Cl À and 2-9 mol % of preprepared NHC/Cr catalyst. The reaction mixture was kept at 100 8C for 6 hours. HMF was ext...

The use of carbon dioxide as a renewable and environmentally friendly source of carbon is highly attractive. This article focuses on recent developments in important new reactions and new catalysts for homogeneous CO(2) transformations under mild reaction conditions. Other than traditional organometallic catalysts, organocatalysts have also been applied in the chemical conversion of CO(2) and have demonstrated very promising ability in this field. As the coupling of epoxides with CO(2) to form cyclic carbonates or polycarbonates has been well documented, it will be excluded from this article.

The structures of the P cluster and cofactor cluster of nitrogenase are well-defined crystallographically. They have been obtained only by biosynthesis; their chemical synthesis remains a challenge. Synthetic routes are sought to the P cluster in the P(N) state in which two cuboidal Fe(3)S(3) units are connected by a mu(6)-S atom and two Fe-(mu(2)-S(Cys))-Fe bridges. A reaction scheme affording a Mo(2)Fe(6)S(9) cluster in molecular form having the topology of the P(N) cluster has been devised. Reaction of the single cubane [(Tp)MoFe(3)S(4)Cl(3)](1)(-) with PEt(3) gives [(Tp)MoFe(3)S(4)(PEt(3))(3)](1+) (2), which upon reduction with BH(4)(-) affords the edge-bridged all-ferrous double cubane [(Tp)(2)Mo(2)Fe(6)S(8)(PEt(3))(4)] (4) (Tp = tris(pyrazolylhydroborate(1-)). Treatment of 4 with 3 equiv of HS(-) produces [(Tp)(2)Mo(2)Fe(6)S(9)(SH)(2)](3)(-) (7) as the Et(4)N(+) salt in 86% yield. The structure of 7 is built of two (Tp)MoFe(3)(mu(3)-S)(3) cuboidal fragments bridged by two mu(2)-S atoms and one mu(6)-S atom in an arrangement of idealized C(2) symmetry. The cluster undergoes three one-electron oxidation reactions and is oxidatively cleaved by p-tolylthiol to [(Tp)MoFe(3)S(4)(S-p-tol)(3)](2)(-) and by weak acids to [(Tp)MoFe(3)S(4)(SH)(3)](2-). The cluster core of 7 has the bridging pattern [Mo(2)Fe(6)(mu(2)-S)(2)(mu(3)-S)(6)(mu(6)-S)](1+) with the probable charge distribution [Mo(3+)(2)Fe(2+)(5)Fe(3+)S(9)](1+). Cluster 7 is a topological analogue of the P(N) cluster but differs in having two heteroatoms and two Fe-(mu(2)-S)-Fe instead of two Fe-(mu(2)-S(Cys))-Fe bridges. A best-fit superposition of the two cluster cores affords a weighted rms deviation in atom positions of 0.38 A. Cluster 7 is the first molecular topological analogue of the P(N) cluster. This structure had been prepared previously only as a fragment of complex high-nuclearity Mo-Fe-S clusters.