F.6 Chemistry Project
Dipole-dipole interaction and its
application
Fung Chun Yu (8)
Kwok Chun Nga (9)
Chan Wai Sum (5)
Introduction
• What is dipole-dipole interaction?
– The difference in electronegativities between elements
in a covalent bond produces a certain degree of
polarization
– The electron cloud is distorted, and a dipole is produced
Introduction
• What is dipole-dipole interaction?
– example can be seen in hydrogen chloride (HCl)
– Cl, being more electronegative, pulls the electron cloud
towards it  Distortion of electron cloud
– The positive end attracts the negative end
 the molecules are packed regularly in a head-to- tail
fashion
Introduction
An illustration of the head-to-tail arrangement
of molecules due to dipole-dipole interaction
Introduction
An extraordinarily simple animation showing the interaction
between HCl molecules
Application of dipole-dipole
interaction
–LCD
–Biological field
Liquid Crystal Display
• consists of two sheets of
polarizing material with
a liquid crystal solution
in between
• can be orientated into a
a desired direction under
current.
• light will be polarized by
this pattern
Why can the liquid crystal be arranged by electricity?
Liquid Crystal Display
• liquid crystal molecule used is introduced below
• Methoxybenzilidene Butylanaline (MBBA)
• p-decyloxybenzylidene
p'- amino 2-methylbutylcinnamate
(DOBAMBC)
Liquid Crystal Display
• The molecules are dipoles
• they twist the plane of
polarization originally
• They are aligned regularly
in a head-to-tail fashion as
mentioned above when
electric field is applied
formed a polaroid
• light is then blocked
Biological Field
• Molecular arrangement of
protein
There are four levels of protein
structure
Primary level
arrangement of
amino acid
Secondary structure
 helical coiling of the
peptide
Biological Field
Tertiary structure
 spatial relationship of
different secondary
structures
Quaternary structure
How can we stabilize the protein
structure???
Biological Field
• Polypeptide is a long chain
molecule
• Dipole is present in polypeptide
• Interactions including Dipole –
dipole interaction stabilize the
structure
Biological Field
• Example: Haemoglobin
Consists of four protein
subunits + haem molecule
Formation of
haemoglobin involved
dipole-dipole interaction
Dipole-dipole interaction
allow the haemoglobin to
take its final shape
Acknowledgement
• Wikipedia (http://en.wikipedia.org/
• http://www.gullwinguk.com
• http://bucarotechelp.com/computers/anatom
y/91060003.asp
The End