Sorbents for carbon dioxide capture.

Provided herein are sorbents for carbon dioxide (CO2) capture, such as from natural gas and coal-fired power plant flue gases, and uses thereof

Mechanistic and computational studies of oxidatively-induced aryl-CF3 bond formation at palladium

This article describes the rational design of 1st generation systems for oxidatively-induced Aryl– CF3 bond-forming reductive elimination from PdII. Treatment of (dtbpy)PdII(Aryl)(CF3) (dtbpy = di-tert-butylbipyridine) with NFTPT (N-fluoro-1,3,5-trimethylpyridium triflate) afforded the isolable PdIV intermediate (dtbpy)PdIV(Aryl)(CF3)(F)(OTf). Thermolysis of this complex at 80 °C resulted in Aryl–CF3 bond-formation. Detailed experimental and computational mechanistic studies have been conducted to gain insights into the key reductive elimination step. Reductive elimination from this PdIV species proceeds via pre-equilibrium dissociation of TfO− followed by Aryl–CF3 coupling. DFT calculations reveal that the transition state for Aryl–CF3 bond formation involves the CF3 acting as an electrophile with the Aryl ligand acting as a nucleophilic coupling partner. These mechanistic considerations along with DFT calculations have facilitated the design of a 2nd generation system utilizing the tmeda (N,N,N’,N’-tetramethylethylenediamine) ligand in place of dtbpy. The tmeda complexes undergo oxidative trifluoromethylation at room temperature

Carbon(sp3)-fluorine bond-forming reductive elimination from palladium(IV) complexes.

The development of transition-metal-catalyzed reactions for the formation of CF bonds has been an area of intense research over the past decade.[1–3] Traditionally, the CF coupling step of these sequences has proven challenging because of the high kinetic barrier for CF bond-forming reductive elimination from most transition-metal centers.[1] Our approach to address this challenge has involved the use of PdII catalysts in conjunction with F+-based oxidants. Since 2006, a variety of PdII-catalyzed reactions of F+ reagents have been developed to introduce fluorine at both C(sp2 ) and C(sp3 ) centers.[4–6] These transformations have been proposed to proceed through CF bond-forming reductive elimination from transient, highly reactive PdIV alkyl/aryl fluoride intermediate

High-valent copper in biomimetic and biological oxidations

A long-standing debate in the Cu-O2 field has revolved around the relevance of the Cu(III) oxidation state in biological redox processes. The proposal of Cu(III) in biology is generally challenged as no spectroscopic or structural evidence exists currently for its presence. The reaction of synthetic Cu(I) complexes with O2 at low temperature in aprotic solvents provides the opportunity to investigate and define the chemical landscape of Cu-O2 species at a small molecule level of detail; eight different types are characterized structurally, three of which contain at least one Cu(III) center. Simple imidazole or histamine ligands are competent in these oxygenation reactions to form Cu(III) complexes. The combination of synthetic structural and reactivity data suggests (i) that Cu(I) should be considered as either a one or two electron reductant reacting with O2, (ii) that Cu(III) reduction potentials of these formed complexes are modest and well within the limits of a protein matrix and (iii) that primary amine and imidazole ligands are surprisingly good at stabilizing Cu(III) centers. These Cu(III) complexes are efficient oxidants for hydroxylating phenolate substrates with reaction hallmarks similar to that performed in biological systems. The remarkable ligation similarity of the synthetic and biological systems makes it difficult to continue to exclude Cu(III) from biological discussion

Platinum and palladium complexes containing cationic ligands as catalysts for arene HID exchange and oxidation.

The direct functionalization of CH bonds has frequently been deemed a “Holy Grail” of organometallic chemistry.[1] A seminal example of this transformation was the demonstration by Shilov and co-workers that platinum(II) salts catalyze the direct oxidation of alkanes into their corresponding alcohols and alkyl halides.[2] Subsequent work in this area has focused on surveying diverse ligands for these reactions in an effort to enhance reactivity and selectivity, slow catalyst decomposition, and replace platinum(IV)-based oxidants with more cost-effective alternatives.[3–5] In a key development, chemists at Catalytica identified [bpymPtCl2] (bpym = bipyrimidine) as a pre-catalyst for the oxidation of CH4 into CH3OSO3H in fuming H2SO

Rhetorical Analysis of Monsanto

Rhetoric, and therefore persuasion, can be utilized to impact society in profound ways. These communication devices can also be used for more sinister and nefarious purposes that can leave black marks on any society’s history. For the purpose of this rhetorical analysis, I thoroughly investigated three artifacts used by the Monsanto Corporation. This project attempts to show how Monsanto utilizes rhetoric and persuasion to convince consumers their products are safe to purchase, although there is no scientific consensus regarding that safety to humans and the environment. Through an examination of these artifacts, I was able to examine how Monsanto used apologia as image restoration during or after crise

A new phase of the complex trinitratotris(triphenylphosphineoxide)neodymium(lll)

There has been considerable interest in the complexes formed by the lanthanides with various monodentate neutral ligands with O as the donor atom. Phosphine oxides, in particular, have proven useful in complexing to lanthanide metal ions and have found practical application in the solvent extraction and separation of lanthanides.1 Several lanthanide(III) nitrate complexes with triphenylphosphine oxide (OPPh3) have been prepared resulting in complexes having as few as two and as many as four OPPh3 groups per lanthanide center.2−4 An earlier study by Cousins and Hart5 identified the complex [Nd(OPPh3)3(NO3)3]. Two crystal phases of this same complex were briefly reported later by Mascarenhas et al., 6 but no structural data was given. A complete structural analysis of a third phase of the complex [Nd(OPPh3)3(NO3)3] is reported below

Use of inedible wheat residues from the KSC-CELSS breadboard facility for production of fungal cellulase

Cellulose and xylan (a hemicellulose) comprise 50 percent of inedible wheat residue (which is 60 percent of total wheat biomass) produced in the Kennedy Space Center Closed Ecological Life Support System (CELSS) Breadboard Biomass Production Chamber (BPC). These polysaccharides can be converted by enzymatic hydrolysis into useful monosaccharides, thus maximizing the use of BPC volume and energy, and minimizing waste material to be treated. The evaluation of CELSS-derived wheat residues for production for cellulase enzyme complex by Trichoderma reesei and supplemental beta-glucosidase by Aspergillus phoenicis is in progress. Results to date are given