Efficient CO₂ capture by a task-specific porous organic polymer bifunctionalized with carbazole and triazine groups.

A porous triazine and carbazole bifunctionalized task-specific polymer has been synthesized via a facile Friedel-Crafts reaction. The resultant porous framework exhibits excellent CO2 uptake (18.0 wt%, 273 K and 1 bar) and good adsorption selectivity for CO2 over N2.

Dynamic and structural properties of room-temperature ionic liquids near silica and carbon surfaces.

The dynamic and structural properties of a room-temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium(trifluoromethanesulfonimide) ([C4mim][Tf2N]) confined in silica and carbon mesopores were investigated by molecular dynamics (MD) simulations and nuclear magnetic resonance (NMR) experiments. The complex interfacial microstructures of confined [C4mim][Tf2N] are attributed to the distinctive surface features of the silica mesopore. The temperature-dependent diffusion coefficients of [C4mim][Tf2N] confined in the silica or carbon mesopore exhibit divergent behavior.

New tricks for old molecules: development and application of porous N-doped, carbonaceous membranes for CO2 separation.

A new strategy is successfully applied to "old" acetyl compounds. A free-standing, porous, N-doped carbonaceous membrane is facilely prepared from the thermal treatment of a pyrrole-ring-containing polymeric membrane based on the superacid-catalyzed copolymerization of acetyl monomers. An exceptional ideal CO2 /N2 permselectivity of 43.

Synthesis of porous, nitrogen-doped adsorption/diffusion carbonaceous membranes for efficient CO2 separation.

A porous, nitrogen-doped carbonaceous free-standing membrane (TFMT-550) is prepared by a facile template-free method using letrozole as an intermediate to a triazole-functionalized-triazine framework, followed by carbonization. Such adsorption/diffusion membranes exhibit good separation performance of CO2 over N2 and surpassing the most recent Robeson upper bound. An exceptional ideal CO2 /N2 permselectivity of 47.

Efficient CO(2) capture by porous, nitrogen-doped carbonaceous adsorbents derived from task-specific ionic liquids.

The search for a better carbon dioxide (CO(2) ) capture material is attracting significant attention because of an increase in anthropogenic emissions. Porous materials are considered to be among the most promising candidates. A series of porous, nitrogen-doped carbons for CO(2) capture have been developed by using high-yield carbonization reactions from task-specific ionic liquid (TSIL) precursors.

Rotational and translational dynamics of rhodamine 6G in a pyrrolidinium ionic liquid: a combined time-resolved fluorescence anisotropy decay and NMR study.

NMR spectroscopy and time-resolved fluorescence anisotropy decay (TRFAD) are two of the most commonly used methods to study solute-solvent interactions. However, only a few studies have been reported to date using a combined NMR and TRFAD approach to systematically investigate the overall picture of diffusional and rotational dynamics of both the solute and solvent. In this paper, we combined NMR and TRFAD to probe fluorescent rhodamine dye in a pyrrolidinium-based room temperature ionic liquid (RTIL), an emergent environmentally friendly solvent type used in several energy-related applications.

Solid-state 17O NMR study of benzoic acid adsorption on metal oxide surfaces.

Solid-state (17)O NMR spectra of (17)O-labeled benzoic and anisic acids are reported and benzoic acid is used to probe the surface of metal oxides. Complexes formed when benzoic acid is dry mixed with mesoporous silica, and nonporous titania and alumina are characterized. Chemical reactions with silica are not observed.

Physicochemical properties of imidazolium-derived ionic liquids with different C-2 substitutions.

Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anions were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability, were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by the Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity.

A low-temperature crossover in water dynamics in an aqueous LiCl solution: diffusion probed by neutron spin-echo and nuclear magnetic resonance.

Aqueous solutions of lithium chloride are an excellent model system for studying the dynamics of water molecules down to low temperatures without freezing. The apparent dynamic crossover observed in an aqueous solution of LiCl at about 220 to 225 K [Mamontov, JPCB 2009, 113, 14073] is located practically at the same temperature as the crossover found for pure water confined in small hydrophilic pores. This finding suggests a strong similarity of water behavior in these two types of systems.

Surface alumina species on modified titanium dioxide: A solid-state (27)Al MAS and 3QMAS NMR investigation of catalyst supports.

(27)Al MAS and 3QMAS NMR have been used to study Al(2)O(3)/TiO(2) catalyst supports synthesized via excess-solution impregnation and surface sol-gel methods. Temperature and alumina loading level strongly affect chemical states of aluminum oxide species observed. Surface cations, Al(H2O)6(3+), a surface alumina monolayer, and disordered transitional aluminas (multilayers) and alpha-alumina, coexist on the TiO(2) surface.

Layer-by-layer grafting of titanium phosphate onto mesoporous silica SBA-15 surfaces: synthesis, characterization, and applications.

Metal phosphates have many applications in catalysis, separation, and proton conduction, but their small surface areas and/or constrained pore structures limit their utilization. Here, we report two new methods for the liquid-phase grafting of titanium phosphate onto mesoporous silica (SBA-15) surfaces: (1) alternate grafting of Ti(OPr(i))(4) and then POCl(3) and (2) one-pot grafting of titanium phosphate formed in situ by employing Ti(OPr(i))(4) (a base) and POCl(3) (an acid) as an appropriate "acid-base pair". Both the size of mesopores and the content of titanium phosphate can be changed by increasing the number of modification cycles in a stepwise (or layer-by-layer) fashion.

The generation of intense radiofrequency fields in microcoils.

Large amplitude radiofrequency (rf) fields hold great promise in wide line NMR where it becomes possible to excite the full breadth of the line in a quantitative fashion. Applications in quadrupole NMR and in NMR of paramagnetic systems benefit greatly from intense fields. Spin manipulations in multiple quantum NMR experiments, specifically, the generation of multiple quantum coherence in MQ NMR, are more efficiently produced using intense rf fields.

119Sn NMR chemical shift tensors in anhydrous and hydrated Si8O20(SnMe3)8 crystals.

(119)Sn chemical shift tensors of crystalline trialkyltin functionalized octameric spherosilicates, Si(8)O(20)(SnMe(3))(8), have been determined by fitting sideband intensities in solid-state magic angle spinning (MAS) NMR spectra. Tin chemical shift parameters are exquisitely sensitive to the presence of water of crystallization. Both hydrogen bonding and incipient oxygen-tin bonding from molecular water impact the local tin environment.

Synthesis and characterization of periodic mesoporous organosilicas as anion exchange resins for perrhenate adsorption.

A new methodology to immobilize ionic liquids through the use of a bridged silsesquioxane N-(3-triethoxysilylpropyl), N(3)-(3-trimethoxysilylpropyl-4,5-dihydroimidazolium iodide that incorporates an ionic functionality for the assembly of novel periodic mesoporous organosilica (PMO) materials has been developed. The resulting PMO materials were investigated for use as novel anion exchange resins for the separation of perrhenate anions in aqueous solution. As compared with cetyltrimethylammonium chloride, 1-hexadecane-3-methylimidazolium bromide has been demonstrated to be a more efficient surfactant template for the generation of mesopores and surface areas for such PMO materials.

Facile one-pot synthesis of gold nanoparticles stabilized with bifunctional amino/siloxy ligands.

A method for the direct one-pot synthesis of amine-stabilized gold nanoparticles using 3-(trimethoxysilylpropyl)diethylenetriamine (TMSP dien) is described. The amine groups of this bifunctional molecule act as a stabilizer for gold nanoparticles as they form by reduction of HAuCl4. Highly stable gold nanoparticles with sizes tunable between 8 and 20 nm can be readily obtained.

Pyrolysis of mesoporous silica-immobilized 1,3-diphenylpropane. Impact of pore confinement and size.

Mesoporous silicas such as SBA-15 and MCM-41 are being actively investigated for potential applications in catalysis, separations, and synthesis of nanostructured materials. A new method for functionalizing these mesoporous silicas with aromatic phenols is described. The resulting novel hybrid materials possess silyl aryl ether linkages to the silica surface that are thermally stable to ca.

13C NMR characterization of the organic constituents in ligand-modified hexagonal mesoporous silicas: media for the synthesis of small, uniform-size gold nanoparticles.

This paper reports the (13)C NMR characterization of functionalized MCM-41's and describes the chemistry that occurs in the pores of these materials in the process of forming gold nanoparticles. Nanoparticles formed on hexagonal mesoporous silica (MCM-41) by hydrogen reduction of chloroauric acid have little affinity for pure silica surfaces. The gold can be removed from the support with very mild treatment, for example, solvent extraction.

Search for retrogressive reactions accompanying demineralization in native and air-oxidized coals.

This solid state 13C NMR study confirms, for coals, and extends, for air-oxidized coals, the claim that the Bishop and Ward strong aqueous-acid coal demineralization procedure [M. Bishop, D.L.

Synthesis and solid state (13)c and (19)f NMR characterization of aliphatic and aromatic carboxylic Acid fluoride polymers.

A new chemical/spectroscopic couple that differentiates aromatic from aliphatic carboxylic acid polymers was developed. The method is complementary to more traditional methods of identification (IR) and is applicable to the analysis of complex mixtures where IR determinations are complicated by extensive vibrational band overlap. The method entails (1) conversion of carboxylic acids into acid fluorides and (2) specific detection of the resonances of the acid fluoride carbon and of the carbon directly attached to the carbonyl carbon by solid state (19)F-(13)C cross polarization (CP)/MAS (13)C NMR.