In addition, it represents my own opinion and not necessarily that of Cape Peninsula University of Technology. In this project the structures of the hydrates of diquininium L-malate, (2QUIN+)(L-MA2-)•2H2O and the diquininium D-malate, (2QUIN+)(D-MA2-)•2H2O have been investigated . The relationship between C-O bonds of the carboxylate and carboxylic acid moieties and ∆pKa was investigated in salt and co-crystal formation.
Absorption kinetics were performed for the reaction of (+)-deoxycholic acid (DCA) with n-propylamine and DCA with racemic sec-butylamine. Desolvation kinetics was performed on samples of powder mixtures of DCA and sec-butylamine and DCA with di-n-butylamine. We acknowledge financial support from the Graduate Office of the Cape Peninsula University of Technology for this research.
The opinions expressed in this thesis and the conclusions reached are those of the author and are not necessarily attributed to the postgraduate office of the Cape Peninsula University of Technology. 91 Table 5.2.1: Table of crystal data of DCA with sec-butylamine 92 Table 5.2.2: Hydrogen bond parameters in the structures of DCA with sec-butylamine 95 Table 6.1.1: DSC and TG results for inclusion compounds of DCA with MeBUAM210.
INTRODUCTION
Supramolecular Chemistry
1939 Linus Pauling: hydrogen bonds are included in the seminal book "The nature of the chemical bond". 1968 Park and Simmonds: katapinand anion hosts 1969 Jean-Marie Lehn: synthesis of the first cryptands 1969 Jerry Atwood: liquid clathrate from alkyl aluminum salts. 1973 Donald Cram: Spheres of hosts produced to test the importance of pre-organization. 1978 Jean-Marie Lehn: Introduction of the term supramolecular chemistry.
1996 Atwood, Davies, MacNicol and Vögtle: Comprehensive Supramolecular Chemistry publication, containing contributions from almost all key groups and summarizing the development of the discipline. Much work in supramolecular chemistry is directed at the synthesis of inclusion compounds with certain properties. It is a broad field that includes other areas of chemistry, such as inorganic chemistry and organic chemistry, which are needed to synthesize new supramolecular compounds, and physical chemistry, which is needed to understand the properties of supramolecular compounds.
The multidisciplinary character of supramolecular chemistry has brought together physicists, synthetic organic chemists, biochemists, computational modellers, inorganic and solid state chemists.1&3 1.1.1 Molecular recognition. Chirality is also one of the unique characteristics of things in both the macroscopic and microscopic worlds.
Chiral chemistry
This chemical phenomenon is responsible for all processes that take place in biology, and asymmetric synthesis is based on the potential of molecules or substrates to be selective.3&5. For the host and guest to form a supramolecule, they must share spatially and electronically complementary binding sites. The binding sites on the host and guest must also be chemically compatible to form a strong and selective bond.1.
Chirality, like molecular recognition, has existed on earth since the dawn of life, but the phenomenon is not well understood.
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Chirality in drug design and development
- Actions of isomers
- Global overview of Chiral Drugs
Zupiclone and some methylphenidate are also some of the drugs in psychiatric practice that are still administered as racemates. 16. For the reason that most of the chiral drugs are still in racemic mixtures, preparative separations of enantiomers are still essential. Because many of the biological macromolecules in humans are chiral, this has led to stereoselectivity of drugs or biological actives, (bioactives).
The difference in the pharmacological activity of the enantiomers led to the creation of two terms. A number of things can happen to or because of an inactive drug, from the drug not working, causing it to be eliminated, to the enantiomer causing side effects. Later, a rabbit model in New Zealand showed that both enantiomers were actually responsible for fetal malformations.
The use of the drug as a sedative was stopped in the 1960s due to the alarming rate of deformities it caused in children.19,20&21. If one enantiomer is responsible for most of the drug's therapeutic effects and the other causes side effects, separating them will not only eliminate the side effects, but also result in the administration of a smaller dose of the therapeutic enantiomer.
Resolution of racemates
Although enantiopure drugs offer greater health benefits, their development and manufacture are expensive, and this can be seen as a barrier for pharmaceutical developers. These interactions can be different in strength, direction and explain the differences in physical properties of racemates and the pure enantiomers. Diastereomer discrimination occurs when the interactions between a particular enantiomer of a compound and the two enantiomers of another species produce a diastereomeric pair.
The resulting diastereomeric products can be separated and converted to the pure enantiomers by reversing the initial chemical transformation as illustrated in Scheme 1.7.
Conversion of racemic acids to diastereomers
This has been observed with norborneol derivatives; the two enantiomers crystallized separately when the racemic solid was subjected to sublimation. Their interaction with one enantiomer is in diastereomeric ratio to the enzyme's interaction with the other enantiomer, making one enantiomer more reactive. The method is limited by the need to find the appropriate organism and the other enantiomer may be destroyed in the process.29.
The difference in the rate of reaction of the two enantiomers with a chiral reagent can be used as a method of separation. The procedure is based on the difference in transition state energies of diastereomeric transition states R1···R2 and R1···S2. The degree of difference between the rate of reaction and the extent of reaction.
The enantiomeric purity of the reacted and unreacted enantiomer will be elevated if the difference in rate of the equation is large. The degree of conversion can be controlled, which in turn will control the level of enantiomeric purity; partial separation can be achieved by stopping the reaction before completion.
Separation of racemates by kinetic resolution
- Host-guest chemistry
- History of inclusion compounds
- Inclusion Compounds
- Interactions of supramolecular chemistry
- Forms of inclusion compounds
- Host compounds for enantiomer resolution
- Research Aim
- Host compounds
- Guest compounds
- Methods
- Crystal growth
- Thermogravimetric analysis (TGA)
- Differential scanning calorimetry (DSC)
- Single Crystal X-ray Diffraction
- Computing Components
- Powder X-ray Diffraction
- Non-isothermal kinetics
- Kinetics of absorption
- Infrared (IR) spectroscopy
- Thermal analysis
- Structural analysis
- Di-quininium DL-malate
- Quininium D-(+)-malate in water
- SALT vs. CO-CRYSTAL
- IR Spectroscopy & Powder X-Ray Diffraction
- Thermal analysis
- Kinetics of desolvation
- Thermal analysis of crystals
- Structural analysis
- Thermal analysis
- Structural analysis
- Guest exchange experiment
- Structural analysis
The disorder of the guest and water molecules is responsible for the high R-factor. The initial mass loss (TG) for (DCA-)(DIBUAM+) is due to the loss of the amine. The three-center bond is formed at O24A of the carboxylate in the (DCA-)(DIBUAM+) structure, as shown in Figure 4.6.2 (C).
CONCLUSION
![Figure 3.2.3: Packing diagrams of (2QUIN + )(L-MA 2- )•2H 2 O (A) and (2QUIN + )(D-MA 2- )•2H 2 O (B) viewed down [010]](https://thumb-ap.123doks.com/thumbv2/pubpdfnet/8965797.40754/69.892.82.593.79.775/figure-packing-diagrams-quin-ma-quin-ma-viewed.webp)
