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Hydrogen bond exist in DNA

We have know that, a Hydrogen bond is formed between electronegative atoms, in a hydrogen atom attaches to another electronegative atom. i.e The strength in hydrogen bond depends on electronegativity atoms. In hydrogen bonding, an intermolecular force is a special type of dipole-dipole that occurs. When a hydrogen atom bounds in strongly electronegative atom exists in another electronegativity atoms.

Nomenclature in Hydrogen Bond

Hydrogen bond in a strong [F…….H…….F]-, strong [O-H…… O=C], or weak [C-H…….O]. During depends on bond energy, which ranges from 40 to 4 kcal mol-1 respectively.

The directionality of the bond increase in strength. The crystal engineering in a strong hydrogen bond is perhaps the most useful. In systems, Hydrogen Bonds between carboxylic groups [O-H…..O=C] are often used to drive self-assembly.

Intramolecular Hydrogen Bond

Intramolecular Hydrogen Bond are occur one single molecule. This occurs when two functional groups of a molecule can from Hydrogen Bond with each other. In order , both a hydrogen donor a hydrogen acceptor within one molecule. For example , Intramolecular hydrogen bonding occurs in ethylene glycol(C2H4(OH)2) between two hydroxyl groups due to molecular geometry.

Intramolecular Hydrogen Bond is a forms in which two highly electronegative atoms present in same molecule. Intramolecular H-bonding increases the volatility.

Intermolecular Hydrogen Bond

Intermolecular Hydrogen Bond are separate molecule in substance. They can occurs with any number in like and unlike molecules in large in hydrogen donors and acceptors are presents in position.

A Bond is in intermolecular forces in special type of dipole – dipole attraction in atom bounds strongest electronegativity. Basically atom exists in electronegative atom is lone pairs electrons. Intermolecular forces include in ordinary dipole -dipole interactions and dispersion forces.

In intermolecular forces occurs between other dispersion forces and weaker true covalent and ionic bond.


Many types properties follow in hydrogen bonding

Properties of Hydrogen Bonding

  • Solubility:
  •  Smallest alcohol is soluble in water because of the hydrogen bonds which can give both water and alcohol molecules.
  • Volatility:
  • As the compounds involve hydrogen bonds both different molecules have the highest boiling point, so they are less volatile.
  • Viscosity and surface tension: 
  • The substances that contain hydrogen bonding exists as associate molecules. So their flow becomes comparatively hard. They have higher viscosity and high surface tension.
  • The lower density of ice
  • In solid-state ice, the hydrogen bonding gives rise to a like structure of water molecules. A matter in which each water molecule is linked tetrahedral to four water molecules. The molecules are not close impact. Because they are in a liquid state. When ice melts, In this case like structure collaborates. Contrarily, the molecules are near each other. Thus for the same mass in water, the volume decreases and density increases. Then ice has a lower density in comparison to water at 273 K. That is why ice floats.


The principal molecular mechanism that can recognize and discriminate separately pairs in DNA is complementary hydrogen bonding through the double helix. These recognition patterns of H-bond donors and acceptors on DNA. It is described as Seeman. Accordingly the first in contributing to protein DNA recognition mechanism. After some time, it became apparent that such direct interactions constitute only one part of the whole issue. Conditions for Hydrogen Bonding?

In a molecule, When a hydrogen atom is linked to a highly electronegative atom. It attracts the shared pair of electrons is so this end of the molecules is slightly negative while the other end becomes slightly positive.  On the negative end, one molecule attaches to the positive end and the other and as a result. During a weak bond is form between them. This bond is known as the hydrogen bond.

Before a result is bonding, a hydrogen atom links the one electronegative atoms in a covalent bond and the others in a hydrogen bond. The conditions for hydrogen bonding are:

  1. The molecule containing a highly electronegative atom link to the hydrogen atom. Then higher electronegativity more is the polarization of the molecule.
  2. The size of the electronegative atom should be small. The smaller size, the greater is the electrostatic attraction.

Chemical bonding

Covalent bond

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