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Synthesis of aluminosilicates under high pressure and using sulfur as directing agent

100%

Loera S., Lima E., Pfeiffer H., Lara V.

Open Chemistry

2012

vol. 10

issue 1

105-112

Two aluminosilicates were prepared under hydrothermal conditions. Silica, sodium aluminate, sodium sulfide and sulfur were used as raw materials. Starting with similar reacting mixtures, analcime (zeolite, Na(Si2Al)O6·H2O) and beidellite (clay, Na0.3Al2(Si, Al)4O10(OH)2·2H2O) were synthesized by varying pressures, 2 kbar and 1 kbar, respectively. Sulfur was present in both aluminosilicate surfaces, which confer to them particular adsorption properties. Additionally, water adsorption isotherms, under dynamical conditions, were obtained. Fractal dimension values and SEM micrographs reveal very different textural and morphological properties of the two prepared aluminosilicates

Watson-crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA

100%

Guerra C., Baerends E., Bickelhaupt F.

Open Chemistry

2008

vol. 6

issue 1

15-21

We have theoretically analyzed mimics of Watson-Crick AT and GC base pairs in which N-H···O hydrogen bonds are replaced by N-H···S, using the generalized gradient approximation (GGA) of density functional theory at BP86/TZ2P level. The general effect of the above substitutions is an elongation and a slight weakening of the hydrogen bonds that hold together the base pairs. However, the precise effects depend on how many, and in particular, on which hydrogen bonds AT and GC are substituted.. Another purpose of this work is to clarify the relative importance of electrostatic attraction versus orbital interaction in the hydrogen bonds involved in the mimics, using a quantitative bond energy decomposition scheme. At variance with widespread believe, the orbital interaction component in these hydrogen bonds is found to contribute more than 40% of the attractive interactions and is thus of the same order of magnitude as the electrostatic component, which provides the remaining attraction. [...]

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2 Open Chemistry

1 2012

1 2008

1 Baerends E.

1 Bickelhaupt F.

1 Guerra C.

1 Lara V.

1 Lima E.

1 Loera S.

1 Pfeiffer H.

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Synthesis of aluminosilicates under high pressure and using sulfur as directing agent

Watson-crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA