Contains: general introduction, brief history, classification, examples and applications of supramolecular chemistry....

1. DEPARTMENT OF CHEMISTRY
(INORGANIC CHEMISTRY)
SUPRAMOLECULAR CHEMISTRY
by: RIJWAN AHMAD
MSc PART-2 (SEM-4)
email: rijwanbrightway@gmail.com

2. INTRODUCTION:
Supramolecular chemistry, a term introduced by Jean Marie Lehn, is
“chemistry beyond the molecule”, i.e. the chemistry of molecular
assemblies using noncovalent bonds.
Supramolecular chemistry is one of the new areas of chemistry which
deals with secondary interactions rather than covalent bonds in
molecules and focuses on the chemical systems made up of a discrete
number of assembled molecular subunits or components. The forces
responsible for the spatial organization may vary from weak
intermolecular forces to strong covalent bonding, The weak
intermolecular forces are hydrogen bonding, metal coordination,
hydrophobic forces, van der Waals forces, pi-pi interactions and
electrostatic effects.
The use of these principles led to the better understanding of protein
structure as well as other biological processes. For instance, elucidation
of the double helical structure of DNA (by Watson and Crick) occurred
when it was realized that there are two separate strands of nucleotides
connected through hydrogen bonds. The use of non-covalent bonds is
essential to replication because they allow the strands to be separated
and used to template new double stranded DNA.
The importance of supramolecular chemistry was established by the
research work of Nobel laureates Donald J. Cram, Jean-Marie Lehn, and
Charles J. Pedersen in 1987 for Chemistry. The development of selective
"host-guest" complexes particularly, in which a host molecule recognizes
and selectively binds a certain guest, was cited as an important
contribution. Supramolecular chemistry enriched by the research works
of James Fraser Stoddart with the development of concepts of highly
complex self assembled structures and molecular machinery. Again,
Itamar Wilmer developed concepts of bio-sensors and methods of

3. electronic and biological interfacing. Simultaneous development of
nanotechnology also had a strong influence on this subject, with building
blocks such as fullerenes, nanoparticles, and dendrimers becoming
involved in synthetic systems.
The subject gradually develops by the research works on molecular self-
assembly, folding molecular recognition, mechanically-interlocked,
molecular architectures and dynamic covalent chemistry the study of
non-covalent interactions is crucial to understanding many biological
processes from cell structure to vision that rely on these forces for
structure and function. Biological systems are often the best inspiration
for researches in supramolecular chemistry.

4. HISTORY:
In 1967, Pedersen observed that crown ether showed
molecular recognition – the first artificial molecule
found to do so.
Cram established, host–guest chemistry, where the host
molecule can accommodate another guest molecule.
In 1978, Lehn proposed the term “supramolecular
chemistry”. Together, Pedersen, Cram and Lehn
received the Nobel Prize for Chemistry in 1987.
The existence of intermolecular forces was first postulated by Johannes
Did Erik van der Waals in 1873. Later in 1894, Nobel laureate Hermann
Emil Fischer introduced the philosophical roots of supramolecular
chemistry by suggesting "lock and key" mechanism for enzyme-substrate
interactions, which is the fundamental principle of molecular recognition
and host-guest‘ chemistry. In the early twentieth century non-covalent
bonds were understood in gradually more detail, with the hydrogen
bond being described by Latimer and Rodebush in 1920.

5. NATURE OF THE INTERMOLECULAR FORCES:
Covalent bond Ion-ion interaction
Ion-dipole interaction
Dipole-dipole interaction
Hydrogen bond
Cation –n(π) interaction
π-π interaction
Van-der-Waals interaction
Hydrophobic effects
200-300 kJ/mol
50-200 kJ/mol
5-50 kJ/mol
4-120 kJ/mol
5-80 kJ/mol
0-50 kJ/mol
(<5 kJ/mol)
Entropy

7. THE HIERARCHY OF STRUCTURAL ORGANIZATION OF MATTER:
Supramolecular chemistry involves investigating molecular systems in
which the most important feature is that components are held together
by intermolecular forces, not by covalent bonds.
Atoms Molecules
Molecules Superamolecules

8. SUPRAMOLECULAR CHEMISTRY- IN NATURE:
Multiple hydrogen bonds hold the DNA double helix together.

9. CLASSIFICATION OF SUPRAMOLECULES:
Molecular recognition chemistry (host–guest chemistry) + chemistry of
molecular assemblies + chemistry of molecular associations 
“supramolecular chemistry”
chemistry of
molecules built to
specific shapes
(Rotaxane, catenane,
Dendrimers,
Fullerene, CNTs..)
molecular recognition
chemistry: chemistry
associated with a
molecule recognizing a
partner molecule
(Crown ether, Polyamines,
Cyclodextrin, calixarne..)
chemistry of
molecular assembly
from numerous
molecules
(Amphiphilic
molecules –
micelles, lipids..)

10. MACHENISM:
Supramolecular chemistry involves basically two types of
mechanism or the combination of substrate and reactant, i.e.
“lock & key” and Host-guest chemistry, which are as fallows,
Lock and Key:
Host-guest:

11. APPLICATIONS:

12. PHASE TRANSFER AGENTS:
Separation of mixtures:

13. MOLECULAR SENSORS:
CATALYSTS:

14. FLUORESCENT SENSOR:
(Crown- anthracene system)
Receptor (Host): crown ether,
Substrate (Guest): K+
Signaling unit: anthracene,
Spacer: –CH2-
There are many more other applications of supramolecular chemistry,
• molecular electronic devices
• molecular photonic devices
• molecular computer
• molecular machines
• Microscopes
• Optical Microscope
I. Scanning Electron Microscope (SEM)
II. Transmission Electron Microscope (TEM)
III. Scanning Tunneling Microscope (STM) etc.

15. REFERENCES:
• SUPRAMOLECULAR CHEMISTRY
Jonathan W. Steed & Jerry L. Atwood
• SUPRAMOLECULAR CHEMISTRY, FUNDAMENTALS & APPLICATION
Katsuhiko Ariga, Toyoki Kunitake
• SUPRAMOLECULAR CHEMISTRY-CONCEPTS AND APPLICATIONS
International Journal of Science and Research (IJSR); Paper ID:
29031502; Ajay Kumar Manna; Ramananda College, Department of
Chemistry, Bishnupur, Bankura, West Bengal, 722122, INDIA.
• SUPRAMOLECULAR CHEMISTRY - SCOPE AND PERSPECTIVES
MOLECULES - SUPERMOLECULES MOLECULAR DEVICES
Nobel lecture, December 8, 1987; by JEAN-MARIE LEHN; Institut Le
Bel, Université Louis Pasteur, 4, rue Blaise Pascal, 67000 Strasbourg
and Collège de France, 11 Place Marcelin Berthelot, 75005 Paris.