PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Organic chemistry → Supramolecular Chemistry ↓


Host-Guest Chemistry


Host-guest chemistry is a fascinating and important area of supramolecular chemistry. It focuses on the study of complex structures formed between two or more molecules. In this type of chemistry, a molecule, called the "host", forms a complex with a "guest" molecule through non-covalent interactions such as hydrogen bonds, ionic bonds, van der Waals forces, and π-π interactions. Let's delve into the details to better understand how host-guest chemistry works in the context of supramolecular chemistry.

Fundamentals of supramolecular chemistry

Supramolecular chemistry is the field of chemistry that focuses on non-covalent interactions between molecules. Unlike conventional chemical reactions that involve covalent bonds, supramolecular chemistry relies on reversible interactions that allow the formation of complex structures without chemical reactions. Interaction forces in supramolecular chemistry include:

  • Hydrogen bond: A type of dipole-dipole interaction, it is responsible for the properties of water and many biological macromolecules.
  • Ionic bond: Formed between like charged bodies.
  • Van der Waals forces: Weak, short-range forces that include dipole-dipole forces, London dispersion forces, and dipole-induced dipole forces.
  • π-π interactions: These occur between aromatic rings.

Supramolecular chemistry studies the structure and function of complex units formed from multiple molecules linked through these interactions. It is essential for understanding biological systems and developing new materials.

Host–guest chemistry observation

Host-guest chemistry is a branch of supramolecular chemistry that specifically investigates the relationships and interactions between host molecules and guest molecules. The host is typically a larger, more complex molecule that has a cavity or a specific structural arrangement designed to enclose or otherwise interact with the guest. The guest molecule is typically small and fits into the space of the host.

Host molecules

Host molecules contain cavities or open structures that allow them to accommodate guest molecules. Some common examples of host molecules include:

  • Cyclodextrins: Cyclic oligomers of glucose that form a cup-like structure that can accommodate a variety of guests.
  • Crown Ether: Cyclic compounds containing multiple ether groups capable of coordinating with metal cations.
  • Calixarenes: Cyclic oligomers of phenolic units that can trap guest molecules.
  • Cucurbiturils: Barrel-shaped molecules that can host a variety of guest molecules.

Guest molecules

In host-guest chemistry, guest molecules are typically small molecules or ions that can fit into the structure of the host. Guests can be a variety of molecules, ranging from simple ions to complex organic or organometallic compounds. The guest interacts with the host through noncovalent interactions.

Conversation between host and guest

Host-guest interactions mainly involve forces such as hydrogen bonding, hydrophobic interactions, electrostatic forces, and van der Waals forces. Here are some examples showing the various interactions:

Hydrogen bonding

Host: Cyclodextrin
Guest: Urea

Cyclodextrins can form hydrogen bonds with guest molecules such as urea due to the numerous hydroxyl groups present on their structure.

Electrostatic interactions

Host: Crown Ether
Guest: Potassium ion (K + )

Crown ethers are suitable for holding cations due to the electronegative oxygen atoms in their structure, and form stable complexes with positively charged ions.

Hydrophobic interactions

Host: Calixarenes
Guest: Benzene

Calixarenes can hold nonpolar molecules, such as benzene, within their hydrophobic cavities, thereby immobilizing the guest within them.

π–π interaction

Host: Cucurbituriles
Guest: aromatic compounds

Cucurbiturils can form host–guest complexes with aromatic compounds via π–π interactions, where the π-electron clouds overlap.

Host–guest chemistry applications

Host–guest chemistry has many practical applications in various fields:

  • Drug delivery: Host–guest complexes can encapsulate medicinal compounds, potentially improving solubility, stability, and bioavailability.
  • Sensors: Host–guest systems can be used to create chemical sensors that detect specific molecules.
  • Environmental remediation: Host molecules can capture and remove pollutants from the environment.
  • Catalysis: Host–guest chemistry can increase the efficiency and selectivity of chemical reactions.

Visual example

Below are some schematic representations to show the host-guest interaction:

host Guest

This is a simplified illustration of how a small guest can fit into a larger host structure.

host Guest

This diagram shows more complex host structures interacting with guest molecules, and possible non-covalent bonds acting between them.

Importance in chemistry

Host-guest chemistry holds an important place in chemistry because it shows how non-covalent interactions can form complex structures with defined properties and functions. These complexes are important for mimicking biological systems, understanding molecular recognition processes, and developing new materials and drugs.

Research into host-guest systems ranges from the discovery of new molecular hosts to experimentation with diverse guest compounds. This versatility makes host-guest chemistry a constantly evolving and expanding field, opening up avenues for innovative research and applications on a global scale.

Conclusion

In summary, host-guest chemistry is a sophisticated but highly influential domain within supramolecular chemistry. It explores how molecules can interact via non-covalent means to form unique complexes with diverse applications ranging from drug delivery to environmental science. Understanding these interactions provides deep insights into the microscopic processes that govern molecular and macro-level systems.


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Host-Guest Chemistry

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