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The utility of [Co(P1)], the cobalt(II) complex of the [D.sub.2]-symmetric chiral porphyrin 3,5-[Di.sup.t]Bu-ChenPhyrin, as an effective catalyst for catalyzing asymmetric olefin cyclopropanation with the acceptor/acceptor-type diazo reagent [alpha]-cyanodiazoacetates is described. The Co(II)-based catalytic system could be operated in a one-time protocol under mild conditions to yield the desired cyclopropane products in high yields with both high diastereo- and enantioselectivity.

The examples of metal-organic frameworks (MOFs) are illustrated that are based on the assembly of cubohemioctahedra as supermolecular building blocks (SBBs) as opposed to discrete molecules or ions. These SBBs are linked by ligands to form nanoscale 12-connected fcu-like frameworks.

The article discusses the classification of carbon nanoallotropes, and its structural description, and characterization. It outlines several methods for preparing carbon nanostructures, and mentions the fundamental physicochemical properties of carbon nanoallotropes. It notes the interconversions of carbon nanoallotropes, and the combination of nanoarchitectures to produce advanced allotropic hybrids.

[Co(P1)], the cobalt(ll) complex of the D2-symmetric chiral porphyrin 3,5-DitBu-ChenPhyrin, is an effective catalyst for catalyzing asymmetric olefin cyclopropanation with the acceptor! acceptor-type diazo reagent a-cyanodiazoacetates. The [Co(P1 )]-catalyzed reaction is versatile and suitable for both aromatic and aliphatic olef ins with varied electronic properties, including electronrich and -poor olefins. The Co(ll)-based catalytic system can be operated in a one-time protocol under mild conditions, affording the desired cyclopropane products in high yields with both high diastereoand enantioselectivity. The resulting enantiomerically enriched 1,1 -cyclopropanenitrile esters provide convenient access to a number of densely functionalized chiral cyclopropane derivatives, including α-cyclopropyl-β-amino acids. [ABSTRACT FROM AUTHOR]

This work describes a facile approach to modify metal-organic frameworks (MOFs) with ionic liquids (ILs), rendering them as useful heterogeneous catalysts for CO 2 chemical fixation. An amino-functionalized imidazolium-based ionic liquid is firmly grafted into the porous MOF, MIL-101-SO 3 H by the acid-base attraction between positively charged ammonium groups on the IL and negatively charged sulfonate groups from the MOF. Analyses by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, 1 H NMR, and N 2 sorption experiments reveal the MOF-supported ionic liquid (denoted as IL@MOF) material remains intact while functioning as a recyclable heterogeneous catalyst that can efficiently convert CO 2 and epichlorohydrin into chloropropene carbonate without the addition of a cocatalyst.

In the drive toward green and sustainable methodologies for chemicals manufacturing, biocatalysts are predicted to have much to offer in the years to come. That being said, their practical applications are often hampered by a lack of long-term operational stability, limited operating range, and a low recyclability for the enzymes utilized. Herein, we show how covalent organic frameworks (COFs) possess all the necessary requirements needed to serve as ideal host materials for enzymes. The resultant biocomposites of this study have shown the ability boost the stability and robustness of the enzyme in question, namely lipase PS, while also displaying activities far outperforming the free enzyme and biocomposites made from other types of porous materials, such as mesoporous silica and metal-organic frameworks, exemplified in the kinetic resolution of the alcohol assays performed. The ability to easily tune the pore environment of a COF using monomers bearing specific functional groups can improve its compatibility with a given enzyme. As a result, the orientation of the enzyme active site can be modulated through designed interactions between both components, thus improving the enzymatic activity of the biocomposites. Moreover, in comparison with their amorphous analogues, the well-defined COF pore channels not only make the accommodated enzymes more accessible to the reagents but also serve as stronger shields to safeguard the enzymes from deactivation, as evidenced by superior activities and tolerance to harsh environments. The amenability of COFs, along with our increasing understanding of the design rules for stabilizing enzymes in an accessible fashion, gives great promise for providing "off the shelf" biocatalysts for synthetic transformations.

Mesoporous materials, Tb-mesoMOF and MCM-41, were used to study the transport phenomena of biomolecules entering the interior pores from solution. Vitamins B 12 and B 2 were successfully encapsulated into these mesoporous materials, whereas Tb-mesoMOF (0.33 g of B 12 /g, 0.01 g of B 2 /g) adsorbed a higher amount of vitamin per mass than MCM-41 (0.21 g of B 12 /g, 0.002 g of B 2 /g). The diffusion mechanism of the biomolecules entering Tb-mesoMOF was evaluated using a mathematical model. The Raman spectroscopy studies showed vitamin B 12 has been encapsulated within Tb-mesoMOF's pores, and evaluation of the peak shifts indicated strong interactions linking vitamin B 12 's pyrroline moiety with Tb-mesoMOF's triazine and benzoate rings. Because of these stronger interactions between the vitamins and Tb-mesoMOF, longer egress times were observed than with MCM-41.

A key challenge in environmental remediation is the design of adsorbents bearing an abundance of accessible chelating sites with high affinity, to achieve both rapid uptake and high capacity for the contaminants. Herein, we demonstrate how two-dimensional covalent organic frameworks (COFs) with well-defined mesopore structures display the right combination of properties to serve as a scaffold for decorating coordination sites to create ideal adsorbents. The proof-of-concept design is illustrated by modifying sulfur derivatives on a newly designed vinyl-functionalized mesoporous COF (COF-V) via thiol-ene "click" reaction. Representatively, the material (COF-S-SH) synthesized by treating COF-V with 1,2-ethanedithiol exhibits high efficiency in removing mercury from aqueous solutions and the air, affording Hg 2+ and Hg 0 capacities of 1350 and 863 mg g -1 , respectively, surpassing all those of thiol and thioether functionalized materials reported thus far. More significantly, COF-S-SH demonstrates an ultrahigh distribution coefficient value (K d ) of 2.3 × 10 9 mL g -1 , which allows it to rapidly reduce the Hg 2+ concentration from 5 ppm to less than 0.1 ppb, well below the acceptable limit in drinking water (2 ppb). We attribute the impressive performance to the synergistic effects arising from densely populated chelating groups with a strong binding ability within ordered mesopores that allow rapid diffusion of mercury species throughout the material. X-ray absorption fine structure (XAFS) spectroscopic studies revealed that each Hg is bound exclusively by two S via intramolecular cooperativity in COF-S-SH, further interpreting its excellent affinity. The results presented here thus reveal the exceptional potential of COFs for high-performance environmental remediation.

The combination of two or more reactive centers working in concert on a substrate to facilitate the reaction is now considered state of the art in catalysis, yet there still remains a tremendous challenge. Few heterogeneous systems of this sort have been exploited, as the active sites spatially separated within the rigid framework are usually difficult to cooperate. It is now shown that this roadblock can be surpassed. The underlying principle of the strategy presented here is the integration of catalytic components with excellent flexibility and porous heterogeneous catalysts, as demonstrated by the placement of linear ionic polymers in close proximity to surface Lewis acid active sites anchored on the walls of a covalent organic framework (COF). Using the cycloaddition of the epoxides and CO 2 as a model reaction, dramatic activity improvements have been achieved for the composite catalysts in relation to the individual catalytic component. Furthermore, they also clearly outperform the benchmark catalytic systems formed by the combination of the molecular organocatalysts and heterogeneous Lewis acid catalysts, while affording additional recyclability. The extraordinary flexibility and enriched concentration of the catalytically active moieties on linear polymers facilitate the concerted catalysis, thus leading to superior catalytic performance. This work therefore uncovers an entirely new strategy for designing bifunctional catalysts with double-activation behavior and opens a new avenue in the design of multicapable systems that mimic biocatalysis.

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π-π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxide.

A previously known class of porous coordination polymer (PCP) of formula [Cu(bpy-n)(2)(SiF(6))] (bpy-1 = 4,4'-bipyridine; bpy-2 = 1,2-bis(4-pyridyl)ethene) has been studied to assess its selectivity toward CO(2), CH(4), N(2), and H(2)O. Gas sorption measurements reveal that [Cu(bpy-1)(2)(SiF(6))] exhibits the highest uptake for CO(2) yet seen at 298 K and 1 atm by a PCP that does not contain open metal sites. Significantly, [Cu(bpy-1)(2)(SiF(6))] does not exhibit particularly high uptake under the same conditions for CH(4), N(2), and, H(2)O, presumably because of its lack of open metal sites. Consequently, at 298 K and 1 atm [Cu(bpy-1)(2)(SiF(6))] exhibits a relative uptake of CO(2) over CH(4) of ca. 10.5:1, the highest value experimentally observed in a compound without open metal sites. [Cu(bpy-2)(2)(SiF(6))] exhibits larger pores and surface area than [Cu(bpy-1)(2)(SiF(6))] but retains a high CO(2)/CH(4) relative uptake of ca. 8:1., (© 2012 American Chemical Society)

[Co(P1)], the cobalt(II) complex of the D(2)-symmetric chiral porphyrin 3,5-Di(t)Bu-ChenPhyrin, is an effective catalyst for catalyzing asymmetric olefin cyclopropanation with the acceptor/acceptor-type diazo reagent α-cyanodiazoacetates. The [Co(P1)]-catalyzed reaction is versatile and suitable for both aromatic and aliphatic olefins with varied electronic properties, including electron-rich and -poor olefins. The Co(II)-based catalytic system can be operated in a one-time protocol under mild conditions, affording the desired cyclopropane products in high yields with both high diastereo- and enantioselectivity. The resulting enantiomerically enriched 1,1-cyclopropanenitrile esters provide convenient access to a number of densely functionalized chiral cyclopropane derivatives, including α-cyclopropyl-β-amino acids.

[Co(P1)] is an effective catalyst for asymmetric cyclopropanation with succinimidyl diazoacetate. The Co(II)-catalyzed reaction is suitable for various olefins, providing the desired cyclopropane succinimidyl esters in high yields and excellent diastereo- and enantioselectivity. The resulting enantioenriched cyclopropane succinimidyl esters can serve as convenient synthons for the general synthesis of optically active cyclopropyl carboxamides.

The highly enantioselective organocatalytic addition of N-benzyl indoles to N-acyl imines is reported. A total of 15 examples with product yield ranging from 89% to 99% and enantioselectivities from 90% to 97% are presented. A chiral phosphoric acid catalyst derived from a hindered binol derivative was employed most effectively in the reaction. Attractive features of the reaction include desirable catalyst loadings, good reactivity, generality of substrates, and easily removable groups from both nitrogen atoms.