Multi-component crystalline systems based on supramolecular networks

A series of selected essential hydrophobic amino acids, L-Valine, L-Leucine and L-Isoleucine were studied to prepare novel co-crystalline forms for comparison with their pure forms. The crystals of these amino acid complexes were characterised by various techniques including spectroscopy, thermal and X-ray diffraction. The analysis has confirmed the formation of three new co-crystals of L-Leucine-L-Isoleucine (compound 1), L-Valine-L-Leucine (compound 2) and L-Valine-L-Isoleucine (compound 3), the first co-crystals of naturally occurring hydrophobic amino acids with the same chirality. The second experimental chapter describes the use of a Continuous Stirred Tank Crystalliser (CSTC) for bulk preparation of a multi-component system via an anti-solvent crystallisation process. The results indicate that the process conditions used to fabricate co-crystals of amino acids with anti-solvent crystallisation are reproducible with regard to the final product properties, purity and yield. In the last theme, a host-guest complex is shown wherein the c(RGDfV), a cyclic pentapeptide [c(ArgGlyAspD-PheVal], forms an inclusion complex with β-cyclodextrin. In addition, the batch to batch variation between two batches of the pentapeptide procured from the same source is highlighted. The c(RGDfV) and the inclusion complex were characterised by differential scanning calorimetry, fourier transform infrared spectroscopy, circular dichroism, powder X-ray diffraction and nuclear magnetic resonance spectroscopy. Based on ¹H nuclear magnetic resonance (NMR) experiments, the possible mode of interaction of betacyclodextrin with the c(RGDfV) is proposed. Different methods to crystallise c(RGDfV) batch (B-1) and its self-assembly to form hydrogel is also presented.A series of selected essential hydrophobic amino acids, L-Valine, L-Leucine and L-Isoleucine were studied to prepare novel co-crystalline forms for comparison with their pure forms. The crystals of these amino acid complexes were characterised by various techniques including spectroscopy, thermal and X-ray diffraction. The analysis has confirmed the formation of three new co-crystals of L-Leucine-L-Isoleucine (compound 1), L-Valine-L-Leucine (compound 2) and L-Valine-L-Isoleucine (compound 3), the first co-crystals of naturally occurring hydrophobic amino acids with the same chirality. The second experimental chapter describes the use of a Continuous Stirred Tank Crystalliser (CSTC) for bulk preparation of a multi-component system via an anti-solvent crystallisation process. The results indicate that the process conditions used to fabricate co-crystals of amino acids with anti-solvent crystallisation are reproducible with regard to the final product properties, purity and yield. In the last theme, a host-guest complex is shown wherein the c(RGDfV), a cyclic pentapeptide [c(ArgGlyAspD-PheVal], forms an inclusion complex with β-cyclodextrin. In addition, the batch to batch variation between two batches of the pentapeptide procured from the same source is highlighted. The c(RGDfV) and the inclusion complex were characterised by differential scanning calorimetry, fourier transform infrared spectroscopy, circular dichroism, powder X-ray diffraction and nuclear magnetic resonance spectroscopy. Based on ¹H nuclear magnetic resonance (NMR) experiments, the possible mode of interaction of betacyclodextrin with the c(RGDfV) is proposed. Different methods to crystallise c(RGDfV) batch (B-1) and its self-assembly to form hydrogel is also presented