GC

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Hydrogen bonding
G-C
Guanine
Cytosine
A-T
Adenine
Thymine
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How much is a hydrogen bond worth? experimental
value is extremely variable values in the
literature from 0.1 to 40 kcal/mol
Strength of an H-bond is related to the D-H---A
distance and the DHA angle. The shorter the
distance between D A the stronger the
interaction. Ideally, DHA angle should be 180.
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Hydrogen bonding
If we calculate the energy of H-bond in
chloroform (? 4.8) to be 10 kcal/mol, and then
change solvent to water (? 78.8) all else being
the same we would expect the new energy of
interaction to be 10 . 4.8 / 78.8 0.6 kcal/mol
based on our equation for dipole-dipole
interactions. However, we find experimentally
that the H-bond is only worth 0.1 kcal/mol. Why
might this be?
R
2
O
H
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Hydrogen bonding in water
ST2 Model of water molecule
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Crystal Structure of Ice
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Hydrogen Bonding
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Hydrogen bonding in supramolecular synthesis
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Hydrogen bonding in supramolecular synthesis
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Hydrogen bonding in supramolecular synthesis