Supramolecular

Supramolecular refers to systems formed from discrete molecular units held together by non-covalent interactions rather than covalent bonds. It concerns the design, synthesis, and study of assemblies whose properties emerge from the collective behavior of their components.

Non-covalent forces—hydrogen bonding, electrostatics, hydrophobic effects, metal coordination, van der Waals, and pi-pi interactions—drive association and disassembly. These interactions are often reversible, enabling error correction, self-assembly, and responsive materials.

History: The term and field were developed in the late 20th century. Jean-Marie Lehn, Donald Cram, and Charles Pedersen were awarded the 1987 Nobel Prize for work on molecular recognition and self-assembly in chemistry and biology.

Key concepts include molecular recognition, host-guest chemistry, self-assembly, dynamic covalent chemistry, and dynamic combinatorial chemistry. Structures range from host-guest complexes to cages, capsules, rotaxanes, catenanes, gels, and self-assembled monolayers.

Examples and motifs include cyclodextrins, cucurbiturils, calixarenes, crown ethers, and coordination-driven assemblies that form metal-organic cages and frameworks.

Analytical methods commonly used are NMR spectroscopy, X-ray crystallography, mass spectrometry, isothermal titration calorimetry, and various microscopic techniques for surfaces and assemblies.

Applications span drug delivery, sensing, catalysis, functional materials, nanotechnology, and the construction of molecular machines.

In biology, supramolecular interactions underlie protein folding, DNA recognition, membranes, and bioinspired assemblies, illustrating the relevance of supramolecular principles to natural systems.