scholarly journals Platinum and platinum based nanoalloys synthesized by wet chemistry

2015 ◽  
Vol 181 ◽  
pp. 19-36 ◽  
Author(s):  
Caroline Salzemann ◽  
Farid Kameche ◽  
Anh-Tu Ngo ◽  
Pascal Andreazza ◽  
Monica Calatayud ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Phase Transfer ◽  
Wide Field ◽  
Chemical Route ◽  
Fundamental Interest ◽  
Wet Chemistry ◽  
Platinum Nanocrystals ◽  
Transfer Method ◽  
Pure Palladium

Platinum nanocrystals and their derivatives with palladium and cobalt are of fundamental interest due to their wide field of application in chemistry and physics. Their properties are strongly dependent on their shape and composition. However the chemical route is far from allowing control of both shape and composition. In this paper, we show both experimentally and theoretically the important role of the interaction of small adsorbed molecules on the shape but also on the composition. This has been studied by comparing the case of pure palladium and platinum nanocrystals and the case of PtPd and PtCo nanoalloys synthesized by the liquid–liquid phase transfer method.

Role of a third liquid phase in phase-transfer catalysis

1991 ◽  
Vol 56 (26) ◽  
pp. 7229-7232 ◽  
Author(s):  
Doron Mason ◽  
Shlomo Magdassi ◽  
Yoel Sasson
Keyword(s):  
Liquid Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer

ChemInform Abstract: Role of a Third Liquid Phase in Phase-Transfer Catalysis.

ChemInform ◽  
2010 ◽  
Vol 23 (21) ◽  
pp. no-no
Author(s):  
D. MASON ◽  
S. MAGDASSI ◽  
Y. SASSON
Keyword(s):  
Liquid Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer

Three Phase Catalytic Reactions: Role of Omega Aqueous Phase in Solid-Liquid Phase Transfer Catalyzed Etherification of 2'- Hydroxy Acetophenone

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Ganapati D. Yadav ◽  
Neesha M. Desai
Keyword(s):  
Liquid Phase ◽  
Phase Transfer ◽  
Tetrabutylammonium Bromide ◽  
Catalytic Reactions ◽  
Omega Phase ◽  
Solid Reactant ◽  
Three Phase ◽  
Catalyzed Reactions ◽  
Solid Liquid

Phase Transfer Catalyst (PTC) is used in more than 600 commercial processes, with wide ranging applications in the pharmaceuticals, agrochemicals, polymer industries. Despite thousands of publications on the PTC, several intricacies of PTC in reactions are not understood or properly modeled. Liquid-liquid (L-L) PTC is inferior to solid-liquid (S-L) phase transfer catalyzed reactions, which in turn can be converted into Solid (reactant)-Liquid-(aqueous omega)- Liquid (organic) using trace quantities of water to realize 100% selectivity to the product. There is great enhancement in rates of reactions in comparison with corresponding S-L or L-L PTC. Thus, the O-alkylation of sodium salt of 2'-hydroxy acetophenone was achieved using 1-bromopentane using tetrabutylammonium bromide as the catalyst at 90 0C.2’-Pentyloxy acetophenone is used as a starting material for synthesis of fungicides. The current study deals with the efficacy of so-called omega phase with special emphasis on kinetic and modeling aspects.

Elucidation of block boundaries as the dissolution channels in hydrated cement

1978 ◽  
Vol 36 (1) ◽  
pp. 484-485
Author(s):  
N.V. Belov ◽  
U.I. Papiashwili ◽  
B.E. Yudovich
Keyword(s):  
Liquid Phase ◽  
Grain Boundaries ◽  
Benzoyl Peroxide ◽  
Phase Contrast ◽  
Active Role ◽  
Point Of View ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Hardened Cement Paste

It has been almost universally adopted that dissolution of solids proceeds with development of uniform, continuous frontiers of reaction.However this point of view is doubtful / 1 /. E.g. we have proved the active role of the block (grain) boundaries in the main phases of cement, these boundaries being the areas of hydrate phases' nucleation / 2 /. It has brought to the supposition that the dissolution frontier of cement particles in water is discrete. It seems also probable that the dissolution proceeds through the channels, which serve both for the liquid phase movement and for the drainage of the incongruant solution products. These channels can be appeared along the block boundaries.In order to demonsrate it, we have offered the method of phase-contrast impregnation of the hardened cement paste with the solution of methyl metacrylahe and benzoyl peroxide. The viscosity of this solution is equal to that of water.

The Role of Phase Transfer Catalysis in the Microwave-Assisted N-Benzylation of Amides, Imides and N-Heterocycles

2009 ◽  
Vol 6 (7) ◽  
pp. 529-534 ◽  
Author(s):  
Istvan Greiner ◽  
Fanni Sypaseuth ◽  
Alajos Grun ◽  
Eva Karsai ◽  
Gyorgy Keglevich
Keyword(s):  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Microwave Assisted

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

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