Nepali Chemists in 248th ACS National Conference in San Francisco

Many nepalese chemists attended and/or presented their research in the 248^th American Chemical Society (ACS) National Meeting and Exposition August 10-14, 2014 in San Francisco, CA, USA. The theme of the conference was “Chemistry and Global Stewardship”. American Chemical Society is the US-based world’s largest scientific society, which has currently more than 161,000 members world-wide, was founded in 1876 as a non-profit organization. ACS holds national conference twice a year covering the complete fields of Chemistry. A large number (over 15k) of Chemists and Chemical Engineers from around the globe attended this conference.

The name of Nepalese Researchers and their presentation titles with abstracts are as follows:

Badrinath Dhakal, Ph. D. Candidate, Health & amp; Environmental Chemistry, Oakland University, Rochester, MI, USA

     1. Electrocatalytic reduction of CO₂ to CO by [M(dpphen)(CO)₃X](M=Re & Mn): Catalysis without an external proton source [Selected for the Sci-Mix].

Abstract: [M(dpphen)(CO)₃X] (dpphen= 4,7-Diphenyl-1,10-phenanthroline, M=Mn & X=Br (1 ), and M=Re & X=Cl(2 )) were synthesized and their catalytic activities for CO₂ reduction to CO were studied by using electrochemical methods. Complex 1 is the first known organomanganese catalyst to catalyze the CO₂ reduction significantly (i_c/i_p = 12.2 at the potential of -2.5 V vs. Fc^+/0) without the help of any external proton source. Factors other than the electrocatalyst reduction potentials such as steric effects and degree of conjugation are responsible for the catalytic activities. The manganese analogue (1) displays larger catalytic currents than that of rhenium (2 ) which indicates the possibility of using earth abundant manganese as a substitute for expensive rhenium metal in making CO₂ reduction electrocatalysts.

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      2. Organometallic manganese electrocatalysts for the reduction of CO₂ to CO.

Abstract: The synthesis, characterization and electrochemical properties of a series of novel organometallic electrocatalysts will be presented. Particular focus will be made upon the use of benzene-1,2-diamine-based ligands. Mn(2,3-diaminobenzoic acid)(CO)₃Br displays rapid catalysis, in the presence of a proton source, with an i_p:i_cat(catalytic peak to catalyst peak ratio) value of 33. This compares favorably to an i_p:i_catof 13 for the published competent catalyst Mn(4,4´-di-tert-butyl-2,2´-bipyridine)(CO)₃Br under our conditions (14% methanol as proton source). Catalysis is not observed for Mn(benzene-1,2-diamine)(CO)₃Br and Re(2,3-diaminobenzoic acid)(CO)₃Cl.

3. Using electronic tuning of [Mn(diimine)(CO)₃L]⁺ to affect the electrocatalytic conversion of CO₂ to CO.

Abstract: A series of compounds of the type [Mn(diimine)(CO)₃L]⁺ are presented, where diimine = 4,4'-di-tert-butyl-2,2'-bipyridine and bathophenanthroline, and L = phosphine/phosphite/nitrile. Synthesis of complexes is discussed, as well as characterization of all novel complexes (NMR, IR, high resolution mass spectrometry, elemental analysis, X-ray crystallography, and cyclic voltammetry). The electrochemical properties of the complexes are studied as a function of the electron donating abilities of the L ligands, and the effect on the electrocatalytic conversion of carbon dioxide to carbon monoxide is presented.

Bishnu H. Dhakal, Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, United States.

1. Approach toward the synthesis of apomorphine derivatives.

Abstract: A rapid double annulation transforms simple alkynyl benzaldehyde derivative (A) in to the annulated phenanthrene (B), which possesses the carbon skeleton of deoxy-apomorphine (C), a known dopamine receptor agonist. This talk will focus on optimization of the double annulated process and efforts to transform (B) into apomorphine analog (C).

Dr. Bishnu Prasad Bastakoti, Yusuke Yamauchi. National Institute for Materials Science, Tsukuba, Ibaraki, Japan.

1. Polymeric micelles assembly for the preparation of large sized mesosporous TiO₂.

Abstract: The micelles of triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-PVP-b-PEO) are used for the synthesis of large sized mesoporous TiO₂. The three different blocks in the obtained stable micelles each contribute towards the formation of the targeted mesoporous materials. The hydrophobic PS block stabilizes the micelles and controls the pore size of mesostructure. The strong interaction of titanium tetraisopropoxide with the PVP shell enables fabrication of highly robust walls and the hydrophilic PEO helps orderly packing of the micelles during solvent evaporation. The wall thickness and pore size can be easily tuned by changing either molecular weight of polymer or solution properties. This approach is based on assembly of the stable micelles using a simple, highly reproducible method and is widely applicable towards numerous compositions that are difficult for the formation of mesoporous structures.

Bishnu P Neupane, NRES, UNR Reno, NV, Reno, Nevada, USA.

1. Arid lands biofuel.

Abstract: Gumweed seeds collected from wild stands were planted in research plots at the University of Nevada farm. Germination was found to be inconsistent and transplantation was required for uniform stands. Average dried biomass (49% of wet weight) based on three years' (2011, 2012 and 2013) production was 6783 kg/ha. The biocrude production, via acetone extraction was estimated at an average of 839 kg/ha which is 12.5% of the biomass. The biocrude extract consists primarily of grindelic acid, a C20 carboxylic acid, which is converted into grindelic acid methyl ester (GAME) treating with diazomethane or acid catalyzed methylation. A reference standard of 98% pure GAME was prepared by column chromatography and that was used to quantify grindelic acid content in different parts of gumweed. The GAME was found to be about 52% in the biocrude which is 6.5% of the dried plant biomass. Floral parts are found to have higher amount of grindelic acid than leaves and stem. Although the derivatized extract which consists of about 80% grindelic acid, is viscous, it can be mixed well with diesel up to 20% by volume for potential use as a diesel fuel.

Bhusan Thapaliya, Department of Chemistry, University of Wyoming, Laramie, Wyoming, USA

1. Synthesis and reactions of monodentate acceptor platinum phosphine complexes.

Abstract: A series of monodentate perfluoroalkylphosphine complexes of platinum are presented and surveyed as precursors to ethylene dimerization catalysts. The novel arene complexes (h⁶-C₆H₃Me₃)Pt(dfebp)H⁺ (dfebp = ^tBu(C₂F₅)₂P) and (h⁶-C₆H₃Me₃)Pt(dfmp)Me⁺ (dfmp = Me(C₂F₅)₂P) have been prepared by reacting (dfebp)₂Pt and (dfmp)₂PtMe₂, respectively, with mesitylenium acid, C₆H₄Me₃⁺B(C₆F₅)₄^-. Treatment of (dfebp)₂Pt with mesitylenium acid in orthodifluorobenzene in the presence of excess ethylene at 20 °C resulted in ethylene conversion into trans and cis 2-butenes in a ratio 2:1 (TON 4.7 hˉ¹). In comparison, (dfmp)₂PtMe₂) formed butenes at a slower rate (TON 2.5 hˉ¹). The underlying phosphine/ethylene displacement equilibria and intermediates in these reactions will be discussed.

Namrata Khanal, Department of Chemistry, University of Texas at El Paso, El Paso, Texas, USA.

1. Pt(II) alkynyl complexes of pyridine and diphenylphosphine derivatives.

Abstract: Dialkynyl Pt(II) complexes (1 -3 ) composed of pyridine and diphenylphosphine derivatives of triphenylamine (TPA) were synthesized, characterized, and their electronic properties were investigated. Although TPA is well known for electron-transfer processes in polymers and small molecules with potential as photovoltaic materials, pyridine and triphenylphosphine derivatives of TPA have not been studied in this area. These complexes were prepared to study the effect that structural changes of the electron-donor may have on its ability to transfer an electron to benzothiadiazole, a well-known electron acceptor. Here, we report the electronic properties of these new complexes.

                       

By Badrinath Dhakal