Abstract:
Supramolecular chemistry is coined as ’chemistry beyond a molecule’ as it is
based on interactions between molecules, contrary to traditional chemistry focusing
on the formation of covalent bonding within a molecule. [1] The term ’supramolecule’
was introduced by Karl Lothar Wolf et al. in 1937. [2] The interactions between
the molecules are non-covalent and weak. They include dipole-dipole, [3–8] van der
Waals, electrostatic, [9–11] - , [12] hydrogen bonding, [13] hydrophobic, [14–16]
metal-ligand coordination, [17–19] charge-transfer, [20, 21] integrated non-covalent
interactions such as host-guest interactions [22, 23] and so forth. Although these
interactions are weak, their combined effect can produce structurally and chemically
stable structures of various architectures such as spheres, rods, cylinders, sheets etc. [24–
26]
Non-covalent interactions, such as hydrogen bonds are highly directional and
reversible in nature. Thus, materials formed through these interactions retain their
polymeric properties in solution. [27, 28] Owing to the directionality and reversibility
of these secondary interactions, these polymers have good material properties with
low viscosity, which makes them easily processible. Besides, they possess some
fascinating functionalities such as recyclability, ability to self-heal, and can be stimuliresponsive.
[29] The characterisation of the supramolecular polymers is a daunting
task due to their dynamic nature and cannot be done using standard techniques used
for conventional polymers. A combination of several techniques including size exclusion
chromatography, light scattering techniques, viscometry, fluorescence, circular
dichroism (CD), ultraviolet-visible (UV/Vis), mass spectrometry, NMR spectroscopy,
scanning probe microscopy, vapour pressure osmometry and electron microscopy can
characterise supramolecular polymerisation.
