Hydrogen bonds double

The unusual l-sila-l,2-diol (CH2=CH)CH(OH)SiPh2OH, prepared by hydrolysis of the acylsilane (CH2=CH)C(0)SiHPh2, has a structure comprising hydrogen-bonded double chains as shown in Fig. 9. Only COH - HOSi hydrogen bonds are present, with the bonds between the chains being shorter than those that build up the chain, 2.666 and 2.739 A, respectively (131, 210). 

Fig. 9. The hydrogen-bonded double chain structure of (CH2=CH)CH(0H)SiPh20H with hydrogen atoms omitted for clarity. Drawn using coordinates taken from the Cambridge Crystallographic Database.

We have chosen to investigate, primarily by circular dichroism measurements, a series of oligomers of adenylic acid (including the high polymer) as well as the closely related poly-A -hydroxyethyladenylic acid. The latter is of interest because the blocking of the nitrogen should prevent the formation of hydrogen-bonded double-strand helices under all conditions. 

Strong and weak hydrogen bonds Double-donor and other hydrogen bonds... 

Glycine crystallizes out of ethanol in the so-called P-ioira. The structure of single crystals of 8-glycine has been determined by litaka [15]. The crystal structure consists of hydrogen-bonded double molecular layers, or sheets, with a unit cell dimension of 6.268 A in the -direction, that is, in the direction perpendicular to the hydrogen-bonded double molecular layers. The layers are extended in the two perpendicular directions. Successive double-layers are bonded only by weak van der Waals forces [15]. 

Given two complementary strands of DNA containing 100 base pairs each, calculate the ratio of two separate strands to hydrogen-bonded double helix in solution at 300 K. Hint The formula for calculating this ratio is where A is the... 

Equimolar mixtures of poly G and poly C in aqueous salt solution at neutral pH slowly give rise to a complementary hydrogen-bonded double-... 

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