Supramolecular chemistry focuses on the binding of chemical species to form structures like molecular devices that can perform specific functions, such as movement and switching. Research in this area highlights the benefits of using molecules as building blocks for nanoscale devices due to their stability and inherent properties. Molecular devices operate through chemical reactions and require energy and signals for functionality, similar to macroscopic devices.

1. Department of Chemistry
• Supramolecular chemistry is the chemistry of intermolecular bonds covering the structures and functions of the
entities formed by binding of two or more chemical species i.e. receptor (host) and substrate (guest) .
• Molecular devices are molecules or molecular assemblies that can perform functions such as linear or rotational
movement, switching, and entrapment.
• Molecular devices are structurally organized and functionally integrated chemical systems based on supramolecular
chemistry .
• Recognition and transformation features of molecular devices are analyzed on the basis of their operations via
photons, electrons or ions . These devices thus called molecular photonics, electronics and ionics respectively.
• The upside-down design, construction and operation of molecular devices on the molecular scale is a topic of great
interest and attractive challenge for nanoscience and nanotechnology.
INTRODUCTION

2. • In recent years, the evolution of molecular devices on structural and functional level is a great area of research
and has wide scope in the field of nanotechnology.
• First Feynman introduced the atoms for construction of nanoscale machines.
• After that K. Eric Drexler claimed that it would be possible to build a general purpose ‘nanorobot’, (an
assembler). Such a device could build almost anything atom-by-atom, including copies of itself.
• On the basis of atom-by-atom approach, the idea, that molecules could be much more convenient building
blocks than atoms to construct nanoscale devices and machines, were postulated.
Department of Chemistry
Contd….

3. Department of Chemistry
Bottom-up molecule-by-molecule
In the late 1970s, in the frame of research on supramolecular chemistry, the idea arose that molecules could be much more
convenient building blocks than atoms to construct nanoscale devices and machines because-
1. Molecules are stable species, whereas atoms are difficult to handle
2. Nature uses molecules not atoms to construct the great number and variety of nanodevices and nanomachines that sustain
life) Most laboratory chemical processes deal with molecules, not atoms
3. Molecules are objects that already exhibit distinct shapes and carry device-related properties (e.g. properties that can be
manipulated by photochemical and electrochemical inputs)
4. Molecules can self-assemble or can be connected to make larger structures.

4. • Devices and machines are assemblies of components designed to achieve a specific function. Each component of
the assembly performs a simple act, while the entire assembly performs a more complex, useful function,
characteristic of that particular device or machine.
• To explain we can take an example of the function performed by a hairdryer is the result of operations performed
by a switch, a heater, and a fan, suitably connected by wires and assembled in an appropriate framework.
• This phenomena can be extended to the molecular level. Each molecular component performs a single act, while
the entire supramolecular assembly performs a more complex function, which results from the cooperation of the
various components.
• Molecular-level devices and machines operate via electronic and/or nuclear rearrangements and, like macroscopic
devices and machines, need energy to operate and signals to communicate with the operator.
Department of Chemistry
Devices and machines

5. Department of Chemistry
Energy supply, signal exchange, and other features
 Molecular devices and machines are chemical systems and therefore operate by means of chemical reactions.
Nuclear
Rearrangement
Electronic
Rearrangement
 Molecular-level devices and machines need energy to operate and signals to communicate with the operator.
Chemical fuels Sunlight
Very less used due to costly and non eco-friendly Mostly used due to worthiest and eco-friendly
 any chemical reaction involved in the operation has to be reversible. Although no chemical reaction is fully reversible
Energy Transfer Electron
Transfer(Redox)
proton-transfer
(acid base)
Photoisomerization Metal ligand
coordination
 Molecular-level devices and machines need energy to operate and signals to communicate with the operator.